PRODUCTION OF GAMMA LINOLENIC ACID BY A DELTA 6-DESATURASE

Abstract: Linoleic acid is converted into gamma -linolenic acid by the enzyme DELTA 6-desaturase. The present invention is directed to isolated nucleic acids comprising the DELTA 6-desaturase gene. More particularly, the isolated nucleic acid comprises the promoter, coding region and termination regions of the DELTA 6-desaturase gene. The present invention provides recombinant constructions comprising the DELTA 6-desaturase coding region in functional combination with heterologous regulatory sequences. The nucleic acids and recombinant constructions of the instant invention are useful in the production of GLA in transgenic organisms.

Description: PRODUCTION OF GAMMA LINOLENIC ACID BY A Δ6-DESATURASE Linoleic acid (18:2) (LA) is transformed into gamma linolenic acid (18:3) (GLA) by the enzyme Δ6-desaturase. When this enzyme, or the nucleic acid encoding it, is transferred into LA-producing cells, GLA is produced. The present invention provides nucleic acids comprising the Δ6-desaturase gene. More specifically, the nucleic acids comprise the promoters, coding regions and termination regions of the Δ6-desaturase genes. The present invention is further directed to recombinant constructions comprising a Δ6-desaturase coding region in functional combination with heterologous regulatory sequences. The nucleic acids and recombinant constructions of the instant invention are useful in the production of GLA in transgenic organisms. Unsaturated fatty acids such as linoleic (C 1B Δ 9 : ) and α-linolenic (C 18 Δ 91215 ) acids are essential dietary constituents that cannot be synthesized by vertebrates since vertebrate cells can introduce double bonds at the Δ 9 position of fatty acids but cannot introduce additional double bonds between the A 3 double bond and the methyl-terminus of the fatty acid chain. Because they are precursors of other products, linoleic and α-linolenic acids are essential fatty acids, and are usually obtained from plant sources. Linoleic acid can be converted by mammals into γ-linolenic acid (GLA, C :s Δ 6,9 ' 12 ) which can in turn be converted to arachidonic acid (20:4), a critically - 2 - 1 important fatty acid since it is an essential precursor of most prostaglandins. The dietary provision of linoleic acid, by virtue of its resulting conversion to GLA and 5 arachidonic acid, satisfies the dietary need for GLA and arachidonic acid. However, a relationship has been demonstrated between consumption of saturated fats and health risks such as hypercholesterolemia, atherosclerosis and other clinical disorders which 10 correlate with susceptibility to coronary disease, while the consumption of unsaturated fats has been associated with decreased blood cholesterol concentration and reduced risk of atherosclerosis. The therapeutic benefits of dietary GLA may result 15 from GLA being a precursor to arachidonic acid and thus subsequently contributing to prostaglandin synthesis. Accordingly, consumption of the more unsaturated GLA, rather than linoleic acid, has potential health benefits. However, GLA is not 20 present in virtually any commercially grown crop plant. Linoleic acid is converted into GLA by the enzyme Δ6-desaturase. Δ6-desaturase, an enzyme of more than 350 amino acids, has a membrane-bound domain 25 and an active site for desaturation of fatty acids. When this enzyme is transferred into cells which endogenously produce linoleic acid but not GLA, GLA is produced. The present invention, by providing the gene encoding Δ6-desaturase, allows the production of ■3 Q transgenic organisms which contain functional Δ6- desaturase and which produce GLA. In addition to 35 allowing production of large amounts of GLA, the present invention provides new dietary sources of GLA. The present invention is directed to isolated Δ6-desaturase genes. Specifically, the isolated genes comprises the Δ6-desaturase promoters, coding regions, and termination regions. The present invention is further directed to expression vectors comprising the Δ6-desaturase promoter, coding region and termination region. Yet another aspect of this invention is directed to expression vectors comprising a Δ6- desaturase coding region in functional combination with heterologous regulatory regions, i.e. elements not derived from the Δ6-desaturase gene. Cells and organisms comprising the vectors of the present invention, and progeny of such organisms, are also provided by the present invention. A further aspect of the present invention provides isolated bacterial Δ6-desaturase. An isolated plant Δ6-desaturase is also provided. Yet another aspect of this invention provides a method for producing plants with increased gamma linolenic acid content. A method for producing chilling tolerant plants is also provided by the present invention. Fig. 1 depicts the hydropathy profiles of the deduced amino acid sequences of Svnechocvstis Δ6- desaturase (Panel A) and Δl2-desaturase (Panel B) . Putative membrane spanning regions are indicated by solid bars. Hydrophobic index was calculated for a -4 - window size of 19 amino acid residues [Kyte, et al . (1982) J. Molec. Biol. 157] . Fig. 2 provides gas liquid chromatography profiles of wild type (Panel A) and transgenic (Panel B) Anabaena. Fig. 3 is a diagram of maps of cosmid cSy75, cSyl3 and Csy7 with overlapping regions and subclones. The origins of subclones of Csy75, Csy75-3.5 and Csy7 are indicated by the dashed diagonal lines. Restriction sites that have been inactivated are in parentheses. Fig. 4 provides gas liquid chromatography profiles of wild type (Panel A) and transgenic (Panel B) tobacco. Fig. 5A depicts the DNA sequence of a Δ-6 desaturase cDNA isolated from borage. Fig. 5B depicts the protein sequence of the open reading frame in the isolated borage Δ-6 desaturase cDNA. Three amino acid motifs characteristic of desaturases are indicated and are, in order, lipid box, metal box 1, and metal box 2. Fig. 6 is a dendrogram showing similarity of the borage Δ6-desaturase to other membrane-bound desaturases. The amino acid sequence of the borage Δ6-desaturase was compared to other known desaturases using Gene Works (IntelliGenetics) . Numerical values correlate to relative phylogenetic distances between subgroups compared. Fig. 7 is a restriction map of 221.Δ6. OS and 121.Δ6.NOS. In 221.Δ6. OS, the remaining portion of the plasmid is pBI221 and in 121.Δ6.NOS, the remaining portion of the plasmid is pBI121. Fig. 8 provides gas liquid chromatography profiles of mock transfected (Panel A) and 221.Δ6. OS transfected (Panel B) carrot cells. The positions of 18:2, 18:3 or, and 18:3 γ(GLA) are indicated. Fig. 9 provides gas liquid chromatography profiles of an untransformed tobacco leaf (Panel A) and a tobacco leaf transformed with 121.Δ6.NOS. The positions of 18:2, 18:3 , 18:3γ(GLA), and 18:4 are indicated. Fig. 10 provides gas liquid chromotography profiles for untransformed tobacco seeds (Panel A) and seeds of tobacco transformed with 121.Δ6.NOS. The positions of 18:2, 18:3α and 18:3γ(GLA) are indicated. The present invention provides isolated nucleic acids encoding Δ6-desaturase. To identify a nucleic acid encoding Δ6-desaturase, DNA is isolated from an organism which produces GLA. Said organism can be, for example, an animal cell, certain fungi (e.g. Mortierella) , certain bacteria (e.g. Svnechocystis) or certain plants (borage, Oenothera, currants) . The isolation of genomic DNA can be accomplished by a variety of methods well-known to one of ordinary skill in the art, as exemplified by Sambrook et al. (1989) in Molecular Cloning: A Laboratory Manual, Cold Spring Harbor, NY. The isolated DNA is fragmented by physical methods or enzymatic digestion and cloned into an appropriate vector, e.g. a bacteriophage or cosmid vector, by any of a variety of well-known methods which can be found in references such as Sambrook et . al. (1989) . Expression vectors containing the DNA of the present invention are specifically contemplated herein. DNA encoding Δ6-desaturase can be identified by gain of function analysis. The vector containing fragmented DNA is transferred, for example by infection, transconjugation, transfection, into a host organism that produces linoleic acid but not GLA. As used herein, "transformation" refers generally to the incorporation of foreign DNA into a host cell. Methods for introducing recombinant DNA into a host organism are known to one of ordinary skill in the art and can be found, for example, in Sambrook et . al . (1989) . Production of GLA by these organisms (i.e., gain of function) is assayed, for example by gas chromatography or other methods known to the ordinarily skilled artisan. Organisms which are induced to produce GLA, i.e. have gained function by the introduction of the vector, are identified as expressing DNA encoding Δ6-desaturase, and said DNA is recovered from the organisms. The recovered DNA can again be fragmented, cloned with expression vectors, and functionally assessed by the above procedures to define with more particularity the DNA encoding Δ6- desaturase. As an example of the present invention, random DNA is isolated from the cyanobacteria Svnechocystis Pasteur Culture Collection (PCC) 6803, American Type Culture Collection (ATCC) 27184, cloned into a cosmid vector, and introduced by transconjugation into the GLA-deficient cyanobacterium Anabaena strain PCC 7120, ATCC 27893. Production of GLA from Anabaena linoleic acid is monitored by gas chromatography and the corresponding DNA fragment is isolated. The isolated DNA is se-quenced by methods well-known to one of ordinary skill in the art as found, for example, in Sambrook et. al.. (1989) . In accordance with the present invention, DNA molecules comprising Δ6-desaturase genes have been isolated. More particularly, a 3.588 kilobase (kb) DNA comprising a Δ6-desaturase gene has been isolated from the cyanobacteria Synechocystis. The nucleotide sequence of the 3.588 kb DNA was determined and is shown in SEQ ID NO:l. Open reading frames defining potential coding regions are present from nucleotide 317 to 1507 and from nucleotide 2002 to 3081. To define the nucleotides responsible for encoding Δ6- desaturase, the 3.588 kb fragment that confers Δ6- desaturase activity is cleaved into two subfragments, each of which contains only one open reading frame. Fragment 0RF1 contains nucleotides 1 through 1704, while fragment 0RF2 contains nucleotides 1705 through 3588. Each fragment is subcloned in both forward and reverse orientations into a conjugal expression vector (AM542, Wolk et al. [1984] Proc. Natl. Acad. Sci. USA 81, 1561) that contains a cyanobacterial carboxylase promoter. The resulting constructs (i.e. ORFl(F), ORF1 (R) , ORF2(F) and ORF2 (R) ] are conjugated to wild- type Anabaena PCC 7120 by standard methods (see, for example, Wolk et al . (1984) Proc. Natl. Acad. Sci. USA 8,1, 1561) . Conjugated cells of Anabaena are identified as Neo s green colonies on a brown background of dying non-conjugated cells after two weeks of growth on selective media (standard mineral media BGllN + containing 30μg/ml of neomycin according to Rippka et al. , (1979) J. Gen Microbiol. Ill, 1) . The green colonies are selected and grown in selective liquid media (BGllN + with 15μg/ml neomycin) . Lipids are extracted by standard methods (e.g. Dahmer et al., (1989) Journal of American Oil Chemical Society 66, 543) from the resulting transconjugants containing the forward and reverse oriented ORF1 and 0RF2 constructs. For comparison, lipids are also extracted from wild- type cultures of Anabaena and Synechocystis. The fatty acid methyl esters are analyzed by gas liquid chromatography (GLC) , for example with a Tracor-560 gas liquid chromatograph equipped with a hydrogen flame ionization detector and a capillary column. The results of GLC analysis are shown in Table 1. Table 1: Occurrence of C18 fatty acids in wild-type and transgenic cyanobacteria As assessed by GLC analysis, GLA deficient Anabaena gain the function of GLA production when the construct containing ORF2 in forward orientation is introduced by transconjugation. Transconjugants containing constructs with 0RF2 in reverse orientation to the carboxylase promoter, or ORFl in either orientation, show no GLA production. This analysis demonstrates that the single open reading frame (0RF2) within the 1884 bp fragment encodes Δ6-desaturase. The 1884 bp fragment is shown as SEQ ID NO:3. This is substantiated by the overall similarity of the hydropathy profiles between Δ6-desaturase and Δ12- desaturase [Wada et a_l. (1990) Nature 347] as shown in Fig. 1 as (A) and (B) , respectively. Also in accordance with the present invention, a cDNA comprising a Δ6-desaturase gene from borage (Borago officinalis) has been isolated. The nucleotide sequence of the 1.685 kilobase (kb) cDNA was determined and is shown in Fig. 5A (SEQ ID NO: 4) . The ATG start codon and stop codon are underlined. The amino acid sequence corresponding to the open reading frame in the borage delta 6-desaturase is shown in Fig. 5B (SEQ ID NO: 5). Isolated nucleic acids encoding Δ6- desaturase can be identified from other GLA-producing organisms by the gain of function analysis described above, or by nucleic acid hybridization techniques using the isolated nucleic acid which encodes Synechocystis or borage _β-desaturase as a hybridization probe. Both genomic and cDNA cloning methods are known to the skilled artisan and are contemplated by the present invention. The hybridization probe can comprise the entire DNA sequence disclosed as SEQ. ID NO:l or SEQ. ID NO:4, or a restriction fragment or other DNA fragment thereof, including an oligonucleotide probe. Methods for cloning homologous genes by cross-hybridization are known to the ordinarily skilled artisan and can be found, for example, in Sambrook (1989) and Beltz et al . (1983) Methods in Enzymology 100, 266. In another method of identifying a delta 6- desaturase gene from an organism producing GLA, a cDNA library is made from poly-A * RNA isolated from polysomal RNA. In order to eliminate hyper-abundant expressed genes from the cDNA population, cDNAs or fragments thereof corresponding to hyper-abundant cDNAs genes are used as hybridization probes to the cDNA library. Non hybridizing plaques are excised and the resulting bacterial colonies are used to inoculate liquid cultures and sequenced. For example, as a means of eliminating other seed storage protein cDNAs from a cDNA library made from borage polysomal RNA, cDNAs corresponding to abundantly expressed seed storage proteins are first hybridized to the cDNA library. The "subtracted" DNA library is then used to generate expressed sequence tags (ETSs) and such tags are used to scan a data base such as GenBank to identify potential desaturates. Transgenic organisms which gain the function of GLA production by introduction of DNA encoding Δ- desaturase also gain the function of octadecatetraeonic acid (18 :4" 6 ' 9 ' 12 15 ) production. Octadecatetraeonic acid is present normally in fish oils and in some plant species of the Boraginaceae family (Craig et al. [1964] J. Amer. Oil Chem. Soc. 41, 209-211; Gross et. al. [1976] Can. J. Plant Sci. 56, 659-664) . In the transgenic organisms of the present invention, octadecatetraenoic acid results from further desaturation of or-linolenic acid by Δ6- desaturase or desaturation of GLA by Δ15-desaturase. The 359 amino acids encoded by ORF2, i.e. the open reading frame encoding Synechocystis Δ6- desaturase, are shown as SEQ. ID NO:2. The open reading frame encoding the borage Δ6-desaturase is shown in SEQ ID NO: 5. The present invention further contemplates other nucleotide sequences which encode the amino acids of SEQ ID NO:2 and SEQ ID NO: 5. It is within the ken of the ordinarily skilled artisan to identify such sequences which result, for example, from the degeneracy of the genetic code. Furthermore, 1 one of ordinary skill in the art can determine, by the gain of function analysis described hereinabove, smaller subfragments of the fragments containing the open reading frames which encode Δ6-desaturases. - The present invention contemplates any such polypeptide fragment of Δ6-desaturase and the nucleic acids therefor which retain activity for converting LA to GLA. In another aspect of the present invention, 0 a vector containing a nucleic acid of the present invention or a smaller fragment containing the promoter, coding sequence and termination region of a Δ6-desaturase gene is transferred into an organism, for example, cyanobacteria, in which the Δ6-desaturase promoter and termination regions are functional. Accordingly, organisms producing recombinant Δ6- desaturase are provided by this invention. Yet another aspect of this invention provides isolated Δ6- desaturase, which can be purified from the recombinant o organisms by standard methods of protein purification. (For example, see Ausubel e_t a^. [1987] Current Protocols in Molecular Biology, Green Publishing Associates, New York) . Vectors containing DNA encoding Δ6- 5 desaturase are also provided by the present invention. It will be apparent to one of ordinary skill in the art that appropriate vectors can be constructed to direct the expression of the Δ6-desaturase coding sequence in a variety of organisms. Replicable 0 expression vectors are particularly preferred. Replicable expression vectors as described herein are 5 1 DNA or RNA molecules engineered for controlled expression of a desired gene, i.e. the Δ6-desaturase gene. Preferably the vectors are plasmids, bacteriophages, cosmids or viruses. Shuttle vectors, 5 e.g. as described by Wolk et. al. (1984) Proc. Natl. Acad. Sci. USA. 1561-1565 and Bustos et al. (1991) J ^ Bacteriol. 174, 7525-7533, are also contemplated in accordance with the present invention. Sambrook et al. (1989), Goeddel, ed. (1990) Methods in Enzymology 0 185 Academic Press, and Perbal (1988) A Practical Guide to Molecular Cloning. John Wiley and Sons, Inc., provide detailed reviews of vectors into which a nucleic acid encoding the present Δ6-desaturase can be inserted and expressed. Such vectors also contain nucleic acid sequences which can effect expression of nucleic acids encoding Δ6-desaturase. Sequence elements capable of effecting expression of a gene product include promoters, enhancer elements, upstream activating sequences, transcription termination o signals and polyadenylation sites. Both constitutive and tissue specific promoters are contemplated. For transformation of plant cells, the cauliflower mosaic virus (CaMV) 35S promoter and promoters which are regulated during plant seed maturation are of particular interest. All such promoter and transcriptional regulatory elements, singly or in combination, are contemplated for use in the present replicable expression vectors and are known to one of ordinary skill in the art. The CaMV 355 promoter is described, for example, by Restrepo et al. (1990) Plant Cell 2, 987. Genetically engineered and mutated regulatory sequences are also contemplated. The ordinarily skilled artisan can determine vectors and regulatory elements suitable for expression in a particular host cell. For example, a vector comprising the promoter from the gene encoding the carboxylase of Anabaena operably linked to the coding region of Δ6-desaturase and further operably linked to a termination signal from Synechocystis is appropriate for expression of Δ6-desaturase in cyanobacteria. "Operably linked" in this context means that the promoter and terminator sequences effectively function to regulate transcription. As a further example, a vector appropriate for expression of Δ6-desaturase in transgenic plants can comprise a seed-specific promoter sequence derived from helianthinin, napin, or glycinin operably linked to the Δ6-desaturase coding region and further operably linked to a seed termination signal or the nopaline synthase termination signal. As a still further example, a vector for use in expression of Δ 6- desaturase in plants can comprise a constitutive promoter or a tissue specific promoter operably linked to the Δ 6-desaturase coding region and further operably linked to a constitutive or tissue specific terminator or the nopaline synthase termination signal . In particular, the helianthinin regulatory elements disclosed in applicant's copending U.S. Application Serial No. 682,354, filed April 8, 1991 and incorporated herein by reference, are contemplated 1 as promoter elements to direct the expression of the Δ6-desaturase of the present invention. Modifications of the nucleotide sequences or regulatory elements disclosed herein which maintain 5 the functions contemplated herein are within the scope of this invention. Such modifications include insertions, substitutions and deletions, and specifically substitutions which reflect the degeneracy of the genetic code. 0 Standard techniques for the construction of such hybrid vectors are well-known to those of ordinary skill in the art and can be found in references such as Sambrook et al. (1989) , or any of the myriad of laboratory manuals on recombinant DNA technology that are widely available. A variety of strategies are available for ligating fragments of DNA, the choice of which depends on the nature of the termini of the DNA fragments. It is further contemplated in accordance with the present invention 0 to include in the hybrid vectors other nucleotide sequence elements which facilitate cloning, expression or processing, for example sequences encoding signal peptides, a sequence encoding KDEL, which is required for retention of proteins in the endoplasmic reticulum c or sequences encoding transit peptides which direct Δ6-desaturase to the chloroplast. Such sequences are known to one of ordinary skill in the art. An optimized transit peptide is described, for example, by Van den Broeck et al. (1985) Nature 313, 358. Prokaryotic and eukaryotic signal sequences are 1 disclosed, for example, by Michaelis et al . . (1982) Ann. Rev. Microbiol. 36, 425. A further aspect of the instant invention provides organisms other than cyanobacteria or plants 5 which contain the DNA encoding the Δ6-desaturase of the present invention. The transgenic organisms contemplated in accordance with the present invention include bacteria, cyanobacteria, fungi, and plants and animals. The isolated DNA of the present invention 10 can be introduced into the host by methods known in the art, for example infection, transfection, transformation or transconjugation. Techniques for transferring the DNA of the present invention into such organisms are widely known and provided in τ_5 references such as Sambrook et . al. (1989) . A variety of plant transformation methods are known. The Δ6-desaturase gene can be introduced into plants by a leaf disk transformation-regeneration procedure as described by Horsch et . al. (1985) Science 20 227 - 1229. Other methods of transformation, such as protoplast culture (Horsch et . al. (1984) Science 223 , 496; DeBlock et al. (1984) EMBO J. 2, 2143; Barton et al. (1983) Cell 32, 1033) can also be used and are within the scope of this invention. In a preferred c embodiment plants are transformed with Agrobacterium- derived vectors. However, other methods are available to insert the Δ6-desaturase genes of the present invention into plant cells. Such alternative methods include biolistic approaches (Klein et al. (1987) 30 Nature 327, 70) , electroporation, chemically-induced DNA uptake, and use of viruses or pollen as vectors. 5 When necessary for the transformation method, the Δ6-desaturase genes of the present invention can be inserted into a plant transformation vector, e.g. the binary vector described by Bevan (1984) Nucleic Acids Res. 12. 8111. Plant transformation vectors can be derived by modifying the natural gene transfer system of Agrobacterium tumefaciens. The natural system comprises large Ti (tumor-inducing) -plasmids containing a large segment, known as T-DNA, which is transferred to transformed plants. Another segment of the Ti plasmid, the vir region, is responsible for T-DNA transfer. The T-DNA region is bordered by terminal repeats. In the modified binary vectors the tumor-inducing genes have been deleted and the functions of the vir region are utilized to transfer foreign DNA bordered by the T-DNA border sequences. The T-region also contains a selectable marker for antibiotic resistance, and a multiple cloning site for inserting sequences for transfer. Such engineered strains are known as "disarmed" A. tumefaciens strains, and allow the efficient transformation of se-quences bordered by the T-region into the nuclear genomes of plants. Surface-sterilized leaf disks are inoculated with the "disarmed" foreign DNA-containing A. tumefaciens, cultured for two days, and then transferred to antibiotic-containing medium. Transformed shoots are selected after rooting in medium containing the appropriate antibiotic, transferred to soil and regenerated. Another aspect of the present invention provides transgenic plants or progeny of these plants containing the isolated DNA of the invention. Both monocotyledenous and dicotyledenous plants are contemplated. Plant cells are transformed with the isolated DNA encoding Δ6-desaturase by any of the plant transformation methods described above. The transformed plant cell, usually in a callus culture or leaf disk, is regenerated into a complete transgenic plant by methods well-known to one of ordinary skill in the art (e.g. Horsch et aJL. (1985) Science 227, 1129) . In a preferred embodiment, the transgenic plant is sunflower, oil seed rape, maize, tobacco, peanut or soybean. Since progeny of transformed plants inherit the DNA encoding Δ6-desaturase, seeds or cuttings from transformed plants are used to maintain the transgenic plant line. The present invention further provides a method for providing transgenic plants with an increased content of GLA. This method includes introducing DNA encoding Δ6-desaturase into plant cells which lack or have low levels of GLA but contain LA, and regenerating plants with increased GLA content from the transgenic cells. In particular, commercially grown crop plants are contemplated as the transgenic organism, including, but not limited to, sunflower, soybean, oil seed rape, maize, peanut and tobacco. The present invention further provides a method for providing transgenic organisms which contain GLA. This method comprises introducing DNA encoding Δ6-desaturase into an organism which lacks or has low levels of GLA, but contains LA. In another embodiment, the method comprises introducing one or more expression vectors which comprise DNA encoding Δ12-desaturase and Δ6-desaturase into organisms which are deficient in both GLA and LA. Accordingly, organisms deficient in both LA and GLA are induced to produce LA by the expression of Δ12-desaturase, and GLA is then generated due to the expression of Δ6- desaturase. Expression vectors comprising DNA encoding Δl2-desaturase, or Δl2-desaturase and Δ6- desaturase, can be constructed by methods of recombinant technology known to one of ordinary skill in the art (Sambrook et al. , 1989) and the published sequence of Δl2-desaturase (Wada et al [1990] Nature (London) 347, 200-203. In addition, it has been discovered in accordance with the present invention that nucleotides 2002-3081 of SEQ. ID NO:l encode cyanobacterial Δl2-desaturase. Accordingly, this sequence can be used to construct the subject expression vectors. In particular, commercially grown crop plants are contemplated as the transgenic organism, including, but not limited to, sunflower, soybean, oil seed rape, maize, peanut and tobacco. The present invention is further directed to a method of inducing chilling tolerance in plants. Chilling sensitivity may be due to phase transition of lipids in cell membranes. Phase transition temperature depends upon the degree of unsaturation of fatty acids in membrane lipids, and thus increasing the degree of unsaturation, for example by introducing Δ6-desaturase to convert LA to GLA, can induce or improve chilling resistance. Accordingly, the present method comprises introducing DNA encoding Δ6- desaturase into a plant cell, and regenerating a plant with improved chilling resistance from said transformed plant cell. In a preferred embodiment, the plant is a sunflower, soybean, oil seed rape, maize, peanut or tobacco plant. The following examples further illustrate the present invention. EXAMPLE 1 Strains and Culture Conditions Svnechocvstis (PCC 6803, ATCC 27184), Anabaena (PCC 7120, ATCC 27893) and Svnechococcus (PCC 7942, ATCC 33912) were grown photoautotrophically at 30°C in BG11N+ medium (Rippka et al. [1979] J. Gen. Microbiol. 111. 1-61) under illumination of incandescent lamps (60μE.m "2 .S _1 ) . Cosmids and plasmids were selected and propagated in Escherichia coli strain DH5α on LB medium supplemented with antibiotics at standard concentrations as described by Maniatis et a_l. (1982) Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring, New York. SUBST TU SHEET φ* »> EXAMPLE 2 Construction of Synechocystis Cosmid Genomic Library Total genomic DNA from Synechocystis (PCC 6803) was partially digested with Sau3A and fractionated on a sucrose gradient (Ausubel et . al . [1987] Current Protocols in Molecular Biology, Greene Publishing Associates and Wiley Interscience, New York) . Fractions containing 30 to 40 kb DNA fragments were selected and ligated into the dephosphorylated BamHI site of the cosmid vector, pDUCA7 (Buikema et . al. [1991] J. Bacteriol. 173, 1879-1885) . The ligated DNA was packaged in vitro as described by Ausubel et . al . (1987) , and packaged phage were propagated in EM . coli DH5cγ containing the Aval and Eco4711 methylase helper plasmid, pRL528 as described by Buikema et al . (1991) . A total of 1152 colonies were isolated randomly and maintained individually in twelve 96-well microtiter plates. EXAMPLE 3 Gain-of-Function Expression of GLA in Anabaena Anabaena (PCC 7120) , a filamentous cyanobacterium, is deficient in GLA but contains significant amounts of linoleic acid, the precursor for GLA (Figure 2; Table 2) . The Synechocystis cosmid library described in Example 2 was conjugated into Anabaena (PCC 7120) to identify transconjugants that produce GLA. Anabaena cells were grown to mid-log phase in BG11N+ liquid medium and resuspended in the same medium to a final concentration of approximately 2x10- cells per ml. A mid-log phase culture of E. coli RP4 (Burkardt et al. [1979] J. Gen. Microbiol. 114 , 341-348) grown in LB containing ampicillin was washed and resuspended in fresh LB medium. Anabaena and RP4 were then mixed and spread evenly on BG11N+ plates containing 5% LB. The cosmid genomic library was replica plated onto LB plates containing 50 μg/ml kanamycin and 17.5 μg/ml chloramphenicol and was subsequently patched onto BG11N+ plates containing Anabaena and RP4. After 24 hours of incubation at 30°C, 30 μg/ml of neomycin was underlaid; and incubation at 30°C was continued until transconjugants appeared. Individual transconjugants were isolated after conjugation and grown in 2 ml BG11N+ liquid medium with 15 μg/ml neomycin. Fatty acid methyl esters were prepared from wild type cultures and cultures containing pools of ten transconjugants as follows. Wild type and transgenic cyanobacteria! cultures were harvested by centrifugation and washed twice with distilled water. Fatty acid methyl esters were extracted from these cultures as described by Dahmer et al. (1989) J. Amer. Oil. Chem. Soc. 66. 543- 548 and were analyzed by Gas Liquid Chromatography (GLC) using a Tracor-560 equipped with a hydrogen flame ionization detector and capillary column (30 m x 0.25 mm bonded FSOT Superox II, Alltech Associates Inc., IL) . Retention times and co-chromatography of standards (obtained from Sigma Chemical Co.) were used for identification of fatty acids. The average fatty acid composition was determined as the ratio of peak area of each C18 fatty acid normalized to an internal standard. Representative GLC profiles are shown in Fig. 2. C18 fatty acid methyl esters are shown. Peaks were identified by comparing the elution times with known standards of fatty acid methyl esters and were confirmed by gas chromatography-mass spectrometry. Panel A depicts GLC analysis of fatty acids of wild type Anabaena. The arrow indicates the migration time of GLA. Panel B is a GLC profile of fatty acids of transconjugants of Anabaena with pAM542+1.8F. Two GLA producing pools (of 25 pools representing 250 transconjugants) were identified that produced GLA. Individual transconjugants of each GLA positive pool were analyzed for GLA production; two independent transconjugants, AS13 and AS75, one from each pool, were identified which expressed significant levels of GLA and which contained cosmids, cSyl3 and cSy75, respectively (Figure 3) . The cosmids overlap in a region approximately 7.5 kb in length. A 3.5 kb Nhel fragment of cSy75 was recloned in the vector pDUCA7 and transferred to Anabaena resulting in gain- of-function expression of GLA (Table 2) . Two Nhel/Hind III subfragments (1.8 and 1.7 kb) of the 3.5 kb Nhe I fragment of cSy75-3.5 were subcloned into "pBLUESCRIPT" (Stratagene) (Figure 3) for sequencing. Standard molecular biology techniques were performed as described by Maniatis e_t al . . (1982) and Ausubel et. al. (1987) . Dideoxy sequencing (Sanger et al. [1977] Proc. Natl. Acad. Sci. USA 74, 5463- 5467) of pBSl.8 was performed with "SEQUENASE" (United States Biochemical) on both strands by using specific oligonucleotide primers synthesized by the Advanced DNA Technologies Laboratory (Biology Department, Texas A & M University) . DNA sequence analysis was done with the GCG (Madison, WI) software as described by Devereux et al. (1984) Nucleic Acids Res. 12, 387-395. Both Nhel/HindiII subfragments were transferred into a conjugal expression vector, AM542, in both forward and reverse orientations with respect to a cyanobacterial carboxylase promoter and were introduced into Anabaena by conjugation. Transconjugants containing the 1.8 kb fragment in the forward orientation (AM542-1.8F) produced significant quantities of GLA and octadecatetraenoic acid (Figure 2; Table 2). Transconjugants containing other constructs, either reverse oriented 1.8 kb fragment or forward and reverse oriented 1.7 kb fragment, did not produce detectable levels of GLA (Table 2) . Figure 2 compares the C18 fatty acid profile of an extract from wild type Anabaena (Figure 2A) with that of transgenic Anabaena containing the 1.8 kb fragment of cSy75-3.5 in the forward orientation (Figure 2B) . GLC analysis of fatty acid methyl esters from AM542-1.8F revealed a peak with a retention time identical to that of authentic GLA standard. Analysis of this peak by gas chromatography-mass spectrometry (GC-MS) confirmed that it had the same mass fragmentation pattern as a GLA reference sample. Transgenic Anabaena with altered levels of polyunsaturated fatty acids were similar to wild type in growth rate and morphology. Table 2 Composition of C18 Fatty Acids in Wild Type and Transgenic Cyanobacteria Fatty Acid (%) Strain 18:0 18:1 18:2 18.3(a) 18.3(γ) 18.4 Wild Type Synechocystis 13.6 4.5 54.5 - 27.3 (sp.PCC6803) Anabaena 2.9 24.8 37.1 35.2 - (sp.PCC7120) SynechococcuB 20.6 79.4 - - - (sp.PCC7942) Anajbaena Transconjugants cSy75 3.8 24.4 22.3 9.1 27.9 12.5 cSy75-3.5 4.3 27.6 18.1 3.2 40.4 6.4 pAM542 - 1.8P 4.2 13.9 12.1 19.1 25.4 25.4 pAM542 - 1.8R 7.7 23.1 38.4 30.8 - pAM542 - 1.7F 2.8 27.8 36.1 33.3 - PAM542 - 1.7R 2.8 25.4 42.3 29.6 - Synechococcus Transformants pAM854 27.8 72.2 - pAM854 -Δ" 4.0 43.2 46.0 pAM854 -Δ* 18.2 81.8 - pAM854 -Δ'&Δ" 42.7 25.3 19.5 - 16.5 18:0, stearic acid; 18:1, oleic acid; 18:2, linoleic acid; i8:3(α), linolenic acid; 18:3(γ), γ-linolenic acid; 18:4, octadecatetraenoic acid EXAMPLE 4 Transformation of Synechococcus with Δ6 and Δ12 Desaturase Genes A third cosmid, cSy7, which contains a Δ12- desaturase gene, was isolated by screening the Synechocystis genomic library with a oligonucleotide synthesized from the published Synechocystis Δ12- desaturase gene sequence (Wada et al . [1990] Nature (London) 347, 200-203) . A 1.7 kb Aval fragment from this cosmid containing the Δ12-desaturase gene was identified and used as a probe to demonstrate that cSyl3 not only contains a Δ6-desaturase gene but also a Δ12-desaturase gene (Figure 3) . Genomic Southern blot analysis further showed that both the Δ6-and Δ12- desaturase genes are unique in the Synechocystis genome so that both functional genes involved in C18 fatty acid desaturation are linked closely in the Synechocystis genome. The unicellular cyanobacterium Synechococcus (PCC 7942) is deficient in both linoleic acid and GLA(3) . The Δ12 and Δ6-desaturase genes were cloned individually and together into pAM854 (Bustos et . al . [1991] J. Bacteriol. 174, 7525-7533) , a shuttle vector that contains sequences necessary for the integration of foreign DNA into the genome of Synechococcus (Golden et al. [1987] Methods in Enzymol . 153. 215- 231) . Synechococcus was transformed with these gene constructs and colonies were selected. Fatty acid methyl esters were extracted from transgenic Synechococcus and analyzed by GLC. Table 2 shows that the principal fatty acids of wild type Svnechococcus are stearic acid (18:0) and oleic acid (18:1). Svnechococcus transformed with pAM854-Δl2 expressed linoleic acid (18:2) in addition to the principal fatty acids. Transformants with pAM854-Δ6 and Δ12 produced both linoleate and GLA (Table l) . These results indicated that Synechococcus containing both Δ12- and Δ6-desaturase genes has gained the capability of introducing a second double bond at the Δ12 position and a third double bond at the Δ6 position of C18 fatty acids. However, no changes in fatty acid composition was observed in the transformant containing pAM854-Δ6, indicating that in the absence of substrate synthesized by the Δ12 desaturase, the Δ6-desaturase is inactive. This experiment further confirms that the 1.8 kb Nhel/Hindlll fragment (Figure 3) contains both coding and promoter regions of the Synechocystis Δ6- desaturase gene. Transgenic Svnechococcus with altered levels of polyunsaturated fatty acids were similar to wild type in growth rate and morphology. EXAMPLE 5 Nucleotide Sequence of Δ6-Desaturase The nucleotide sequence of the 1.8 kb fragment of cSy75-3.5 including the functional Δ6- desaturase gene was determined. An open reading frame encoding a polypeptide of 359 amino acids was identified (Figure 4) . A Kyte-Doolittle hydropathy analysis (Kyte et al. [1982] J. Mol. Biol. 157. 105- 132) identified two regions of hydrophobic amino acids that could represent transmembrane domains (Figure IA) ,- furthermore, the hydropathic profile of the Δ6- desaturase is similar to that of the Δ12-desaturase gene (Figure IB; Wada et al.) and Δ9-desaturases (Thiede et al. [1986] J. Biol. Chem. 261, 13230- 13235) . However, the sequence similarity between the Synechocystis Δ6- and Δ12-desaturases is less than 40% at the nucleotide level and approximately 18% at the amino acid level . EXAMPLE 6 Transfer of Cyanobacterial Δ 6 -Desaturase into Tobacco The cyanobacterial Δ 6 -desaturase gene was mobilized into a plant expression vector and transferred to tobacco using Agrobacterium mediated gene transfer techniques. To ensure that the transferred desaturase is appropriately expressed in leaves and developing seeds and that the desaturase gene product is targeted to the endoplasmic reticulum or the chloroplast, various expression cassettes with Synechocystis Δ-desaturase open reading frame (ORF) were constructed. Components of these cassettes include: (i) a 35S promoter or seed specific promoter derived from the sunflower helianthinin gene to drive Δ 6 -desaturase gene expression in all plant tissues or only in developing seeds respectively, (ii) a putative signal peptide either from carrot extensin gene or sunflower helianthinin gene to target newly synthesized Δ 6 -desaturase into the ER, (iii) an ER lumen retention signal sequence (KDEL) at the COOH- terminal of the Δ 6 -desaturase ORF, and (iv) an optimized transit peptide to target Δ 6 desaturase into the chloroplast. The 35S promoter is a derivative of pRTL2 described by Restrepo et al. (1990) . The optimized transit peptide sequence is described by Van de Broeck et al.. (1985) . The carrot extensin signal peptide is described by Chen et al (1985) EMBO J. 9 , 2145. Transgenic tobacco plants were produced containing a chimeric cyanobacterial desaturase gene, comprised of the Synechocystis Δ 6 desaturase gene fused to an endoplasmic reticulum retention sequence (KDEL) and extensin signal peptide driven by the CaMV 35S promoter. PCR amplifications of transgenic tobacco genomic DNA indicate that the Δ 6 desaturase gene was incorporated into the tobacco genome. Fatty acid methyl esters of leaves of these transgenic tobacco plants were extracted and analyzed by Gas Liquid Chromatography (GLC) . These transgenic tobacco accumulated significant amounts of GLA (Figure 4) . Figure 4 shows fatty acid methyl esters as determined by GLC. Peaks were identified by comparing the elution times with known standards of fatty acid methyl ester. Accordingly, cyanobacterial genes involved in fatty acid metabolism can be used to generate transgenic plants with altered fatty acid compositions. SUBSTITUTE SHEET ^RUL 26) EXAMPLE 7 Construction of Borage cDNA library Membrane bound polysomes were isolated from borage seeds 12 days post pollination (12 DPP) using the protocol established for peas by Larkins and Davies (1975 Plant Phvs. 55:749-756). RNA was extracted from the polysomes as described by Mechler (1987 Methods in Enzymology 152:241-248. Academic Press) . Poly-A+ RNA was isolated from the membrane bound polysomal RNA by use of Oligotex-dT beads (Qiagen) . Corresponding cDNA was made using Stratagene's ZAP cDNA synthesis kit. The cDNA library was constructed in the lambda ZAP II vector (Stratagene) using the lambda ZAP II vector kit. The primary library was packaged in Gigapack II Gold packaging extract (Stratagene) . The library was used to generate expressed sequence tags (ESTs) , and sequences corresponding to the tags were used to scan the GenBank database. EXAMPLE 8 Hybridization Protocol Hybridization probes for screening the borage cDNA library were generated by using random primed DNA synthesis as described by Ausubel et al (1994 Current Protocols in Molecular Biology, Wiley Interscience, N.Y.) and corresponded to previously identified abundantly expressed seed storage protein cDNAs . Unincorporated nucleotides were removed by use of a G-50 spin column (Boehringer Manheim) . Probe was denatured for hybridization by boiling in a water bath for 5 minutes, then quickly cooled on ice. Filters for hybridization were prehybridized at 60°C for 2-4 hours in prehybridization solution (6XSSC [Maniatis et al 1984 Molecular Cloning A Laboratory Manual, Cold Spring Harbor Laboratory] , IX Denharts Solution, 0.05% sodium pyrophosphate, 100 μg/ml denatured salmon sperm DNA) . Denatured probe was added to the hybridization solution (6X SSC, IX Denharts solution, 0.05% sodium pyrophosphate, 100 μg/ml denatured salmon sperm DNA) and incubated at 60°C with agitation overnight. Filters were washed in 4x, 2x, and lx SET washes for 15 minutes each at 60°C. A 20X SET stock solution is 3M NaCl, 0.4 M Tris base, 20 mM Na 2 EDTA-2H 2 0. The 4X SET wash was 4X SET, 12.5 mM PO.,, pH 6.8 and 0.2% SDS. The 2X SET wash was 2X SET, 12.5 mM PO.,, pH 6.8 and 0.2% SDS. The IX SET wash was IX SET, 12.5 mM P0 4 , pH 6.8 and 0.2% SDS. Filters were allowed to air dry and were then exposed to X-ray film for 24 hours with intensifying screens at -80°C. EXAMPLE 9 Random sequencing of cDNAs from a borage seed (12 DPP) membrane-bound polysomal library The borage cDNA library was plated at low density (500 pfu on 150 mm petri dishes) . Highly prevalent seed storage protein cDNAs were "subtracted" by screening with the previously identified corresponding cDNAs. Non-hybridizing plaques were excised using Stratagene's excision protocol and reagents. Resulting bacterial colonies were used to inoculate liquid cultures and were either sequenced manually or by an ABI automated sequencer. Each cDNA was sequenced once and a sequence tag generated from 200-300 base pairs. All sequencing was performed by cycle sequencing (Epicentre) . Over 300 ESTs were generated. Each sequence tag was compared to GenBank database by BLASTX computer program and a number of lipid metabolism genes, including the Δ6-desaturase were identified. Database searches with a cDNA clone designated mbp-65 using BLASTX with the GenBank database resulted in a significant match to the Synechocystis Δ6-desaturase. It was determined however, that this clone was not a full length cDNA. A full length cDNA was isolated using mbp-65 to screen the borage membrane-bound polysomal library. The sequence of the isolated cDNA was determined (Fig. 5A, SEQ ID NO:4) and the protein sequence of the open reading frame (Fig. 5B, SEQ ID NO:5) was compared to other known desaturases using Geneworks SUBSTITUTESHEET(RUIE26) (IntelligGenetics) protein alignment program (Fig. 2) . This alignment indicated that the cDNA was the borage Δ6-desaturase gene. Although similar to other known plant desaturases, the borage delta 6-desaturase is distinct as indicated in the dendrogram shown in Fig. 6. Furthermore, comparison of the amino acid sequences characteristic of desaturases, particularly those proposed to be involved in metal binding (metal box 1 and metal box 2) , illustrates the differences between the borage delta 6-desaturase and other plant desaturases (Table 3) . The borage delta 6-desaturase is distinguished from the cyanobacterial form not only in over all sequence (Fig. 6) but also in the lipid box, metal box 1 and metal box 2 amino acid motifs (Table 3) . As Table 3 indicates, all three motifs are novel in sequence. Only the borage delta 6-desaturase metal box 2 shown some relationship to the Synechocystis delta-6 desaturase metal box 2. In addition, the borage delta 6-desaturase is also distinct from another borage desaturase gene, the delta-12 desaturase. Pl-81 is a full length cDNA that was identified by EST analysis and shows high similarity to the Arabidopsis delta-12 desaturase (Fad 2) . A comparison of the lipid box, metal box 1 and metal box 2 amino acid motifs (Table 3) in borage delta 6 and delta-12 desaturases indicates that little homology exists in these regions. The placement of the two sequences in the dendrogram in Fig. 6 indicates how distantly related these two genes are. SUBSTITUTE SHEET (RULE 2 V ) Table 3. Comparison of common amino acid motifs in membrane-bound desaturases Amino Acid Motif D-asaturas* Lipid Box Metal Box 1 Metal Box 2 Borage Δ 6 W1GHDAGH (SEQ. ID. NO: 6) HNAHH ( (SSEEQQ.. I IDD.. N NOO: 12) FQIEHH (SEQ. ID. NO: 20) Synechocystis Δ' NVGHDA H (SEQ. ID. NO: 7) HNYLHH ( (SSEEQQ.. I IDD.. N NOO: 13) HQVTHH (SEQ. ID. NO: 21) Arab, chloroplast A 1 ' VLGHDCGH (SEQ. ID. NO: 8) HRTHH ( (SSEEQQ.. I IDD.. N NOO:: 14) HVIHH (SEQ. ID. NO: 22) Rice Δ 15 VLGHDCGH (SEQ. ID. NO: 8) HRTHH ( (SSEEQQ.. I IDD.. N NOO:: 14) HVIHH (SEQ. ID. NO: 22) Glycine chloroplast Δ 1 * VLGHDCGH (SEQ. ID. NO: 8) HRTHH ( (SSEEQQ.. I IDD.. N NOO:; 14) HVIHH (SEQ. ID. NO: 22) Arab. fad3 (Δ IS ) VLGHDCGH (SEQ. ID. NO: 8) HRTHH ( (SSEEQQ.. I IDD.. N NOO:: 14) HVIHH (SEQ. ID. NO: 22) Brassica fad3 (Δ") VLGHDCGH (SEQ. ID. NO: 8) HRTHH ( (SSEEQQ.. I IDD.. N NOO:: 14) HVIHH (SEQ. ID. NO: 22) Borage Λ 12 (Pl-81)* VIAHECGH (SEQ. ID. NO: 9) HRRHH ( (SSEEQQ.. I IDD.. N NOO: 15) HVAHH (SEQ. ID. NO: 23) CΛ Arab. fad2 (Δ 17 ) VIAHECGH (SEQ. ID. NO: 9) HRRHH ( (SSEEQQ.. I IDD.. N NOO: 15) HVAHH (SEQ. ID. NO: 23) Arab, chloroplast Λ 12 VIGHDCAH (SEQ. ID. NO: 10) HDRHH ( (SSEEQQ.. I IDD.. N NOO: 16) HIPHH (SEQ. ID. NO: 24) Glycine plastid Δ 12 VIGHDCAH (SEQ. ID. NO: 10) HDRHH ( (SSEEQQ.. I IDD.. N NOO: 16) HIPHH (SEQ. ID. NO: 24) Spinach plastidial n-6 VIGHDCAH (SEQ. ID. NO: 10) HDQHH ( (SSEEQQ ., . IIDD . . NNO( : 17) HIPHH (SEQ . ID . NO : 24) ro o_ Synechocystis Δ 12 WGHDCGH (SEQ. ID. NO: 11) HDHHH ( (SSEEQQ.. I IDD.. N NOO: 18) HIPHH (SEQ. ID. NO: 24) Anabaena Δ 12 VLGHDCGH (SEQ. ID. NO: 8) HNHHH ( (SSEEQQ.. I IDD.. NOO: 19) HVPHH (SEQ. ID. NO: 25) *P1-81 is a full length cDNA which was identified by EST analysis and shows .gh simj Llarif v to the Arbidopsis Δ12 desaturase (fad2) EXAMPLE 10 Construction of 222.1Δ 6 NOS for transient and expression The vector pBI221 (Jefferson et al . 1987 EMBO J. 6 :3901-3907) was prepared for ligation by digestion with BamHI and EcoICR I (Promega) which excises the GUS coding region leaving the 35S promoter and NOS terminator intact. The borage Δ 6-desaturase cDNA was excised from the Bluescript plasmid (Stratagene) by digestion with BamHI and Xhol. The Xhol end was made blunt by use of the Klenow fragment . This fragment was then cloned into the BamHI/EcoICR I sites of pBI221, yielding 22l.Δ 6 NOS (Fig. 7) . In 221.Δ 6 .NOS, the remaining portion (backbone) of the restriction map depicted in Fig. 7 is pBI221. 1 EXAMPLE 11 Construction of 121.Δ 6 .NOS for stable transformation The vector pBI121 (Jefferson et al. 1987 5 EMBO J. 6 :3901-3907) was prepared for ligation by digestion with BamHI and EcoICR I (Promega) which excises the GUS coding region leaving the 35S promoter and NOS terminator intact. The borage Δ 6-desaturase cDNA was excised from the Bluescript plasmid τ_0 (Stratagene) by digestion with BamHI and Xhol. The Xhol end was made blunt by use of the Klenow fragment. This fragment was then cloned into the BamHI/EcoICR I sites of pBI121, yielding 121.1Δ 6 NOS (Fig. 7). In 121.Δ 6 .NOS, the remaining portion (backbone) of the Tc restriction map depicted in Fig. 7 is pBI121. 0 5 0 2 EXAMPLE 12 Transient Expression All work involving protoplasts was performed - in a sterile hood. One ml of packed carrot suspension cells were digested in 30 is plasmolyzing solution (25 g/1 KCI, 3.5 g/1 CaCl : -H 2 0, lOmM ES, pH 5.6 and 0.2 M mannitol) with 1% cellulase, 0.1% pectolyase, and 0.1% dreisalase overnight, in the dark, at room 0 temperature. Released protoplasts were filtered thχ-ough a 150 μm mesh and pelleted by centrifugation (lOOx g, 5 min.) then washed twice in plasmolyzing solution. Protoplasts were counted using a double chambered hemocytometer. DNA was transfected into the _c protoplasts by PEG treatment as described by Nunberg and Thomas (1993 Methods in Plant Molecular Biology and Biotechnology, B.R. Glick and J.E. Thompson, eds. pp. 241-248) using 10 6 protoplasts and 50-70 ug of plasmid DNA (221.Δ6.NOS) . Protoplasts were cultured 0 i n 5 m l s °f MS media supplemented with 0.2M mannitol and 3 μm 2,4-D for 48 hours in the dark with shaking. 5 0 5 EXAMPLE 13 Stable transformation of tobacco 121.Δ 6 .NOS plasmid construction was used to transform tobacco (Nicotiana tabacum cv. xanthi) via Agrobacterium according to standard procedures (Horsh et al., 1985 Science 227: 1229-1231; Bogue et al. , 1990 Mol. Gen. Genet. 221:49-57) , except that initial transformants were selected on 100 ug/ml kanamycin. EXAMPLE 14 Preparation and analysis of fatty acid methyl esters (FAMEs) Tissue from transfected protoplasts and transformed tobacco plants was frozen in liquid nitrogen and lyophilized overnight. FAMEs were prepared as described by Dahmer et al (1989 J. Amer. Oil Chem. Soc. £6:543-548) . In some cases, the solvent was evaporated again, and the FAMEs were resuspended in ethyl acetate and extracted once with deionized water to remove any water soluble contaminants. The FAMEs were analyzed by gas chromatography (GC) on a J&W Scientific DB-wax column (30 m length, 0.25 mm ID, 0.25 um film) . An example of a transient assay is shown in Fig. 8 which represents three independent transfections pooled together. The addition of the borage Δ6-desaturase cDNA corresponds with the appearance of gamma linolenic acid (GLA) which is one of the possible products of Δ6-desaturase. Figures 9 and 10 depict GC profiles of the FAMES derived from leaf and seed tissue, respectively, of control and transformed tobacco plants. Figure 9A provides the profile of leaf tissue of wild-type tobacco (xanthi) ; Figure 9B provides the profile of leaf tissue from a tobacco plant transformed with the borage Δ-6 desaturase under the transcriptional control of the 35S CaMV promoter (pBI 121Δ 6 N0S) . Peaks correspond to 18:2, 18:3-y (GLA), 18:3α and 18:4 (octadecanonic acid) . Figure 10A shows the GC profile of seeds of a wild-type tobacco; Figure 10B shows the profile of seed tissue of a tobacco plant transformed with pBI 121Δ 6 N0S. Peaks correspond to 18:2, 18:3γ(GLA) and 18:3α. The relative distribution of the C 18 fatty acids in control and transgenic tobacco seeds is shown in Table 4. TABLE 4 Fatty Acid Xanthi pBI121Δ 6 NOS 18:0 4.0% 2.5% 18:1 13% 13% 18:2 82% 82% 18:3γ(GLA) - 2.7% 18:3α 0.82% 1.4% The foregoing results demonstrate that GLA is incorporated into the triacylglycerides of transgenic tobacco leaves and seeds containing the borage Δ6-desaturase. SEQDENCE LISTING (1) GENERAL INFORMATION: (i) APPLICANT: Rhone-Poulenc Agrochimie (ii) TITLE OF INVENTION: PRODUCTION OF GAMMA LINOLENIC ACID BY A DELTA 6-DESATURASE (iii) NUMBER OF SEQUENCES: 25 (iv) CORRESPONDENCE ADDRESS: (A) ADDRESSEE: Scully, Scott, Murphy & Presser (B) STREET: 400 Garden City Plaza (C) CITY: Garden City (D) STATE: New York (E) COUNTRY: United States (F) ZIP: 11530 (v) COMPUTER READABLE FORM: (A) MEDIUM TYPE: Floppy disk (B) COMPUTER: IBM PC compatible (C) OPERATING SYSTEM: PC-DOS/MS-DOS (D) SOFTWARE: Patentin Release #1.0, Version #1.25 (vi) CURRENT APPLICATION DATA: (A) APPLICATION NUMBER: (B) FILING DATE: 30-DEC-1994 (C) CLASSIFICATION: (viii) ATTORNEY/AGENT INFORMATION: (A) NAME: Presser, Leopold (B) REGISTRATION NUMBER: 19,827 (C) REFERENCE/DOCKET NUMBER: 8383ZYXW (ix) TELECOMMUNICATION INFORMATION: (A) TELEPHONE: (516) 742-4343 (B) TELEFAX: (516) 742-4366 (C) TELEX: 230 901 SANS UR (2) INFORMATION FOR SEQ ID NO:l: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 3588 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: both (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) ( ix) FEATURE : (A) NAME/KEY: CDS (B) LOCATION: 2002..3081 (xi) SEQUENCE DESCRIPTION: SEQ ID N0:1: GCTAGCCACC AGTGACGATG CCTTGAATTT GGCCATTCTG ACCCAGGCCC GTATTCTGAA 60 TCCCCGCATT CGCATTGTTA ATCGTTTGTT CAACCATGCC CTGGGTAAAC GTTTAGACAC 120 CACCTTGCCA GACCACGTTA GTTTGAGTGT TTCCGCCCTG GCGGCCCCGA TTTTTTCCTT 180 TGCGGCTTTG GGCAATCAGG CGATCGGGCA ATTGCGTTTG TTTGACCAGA CTTGGCCCAT 240 TCAGGAAATT GTCATTCACC AAGACCATCC CTGGCTCAAT TTACCCCTGG CGGATTTATG 300 GGATGATCCG AGCCGAATGT TGATCTATTA CCTACCGGCC CACAGTGAAA CGGATTTAGT 360 AGGCGCAGTG GTGAATAATT TAACGTTGCA ATCTGGGGAC CATTTAATAG TGGGACAAAA 420 ACCCCAACCC AAGACCAAAC GGCGATCGCC TTGGCGCAAA TTTTCCAAAC TGATTACCAA 480 CCTGCGGGAG TATCAGCGGT ATGTCCAACA GGTGATATGG GTGGTGTTGT TTTTATTGTT 540 GATGATTTTT CTGGCCACCT TCATCTACGT TTCCATTGAT CAACATATTG CCCCAGTGGA 600 CGCGTTGTAT TTTTCCGTGG GCATGATTAC CGGGGCCGGT GGCAAGGAAG AGGTGGCCGA 660 AAAGTCCCCC GATATCATCA AAGTATTCAC AGTGGTGATG ATGATCGCCG GGGCGGGGGT 720 GATTGGTATT TGTTATGCCC TACTGAATGA TTTCATCCTT GGCAGTCGCT TTAGTCAGTT 780 TTTGGATGCG GCCAAGTTAC CCGATCGCCA TCACATCATC ATTTGTGGGC TGGGGGGAGT 840 GAGCATGGCC ATTATTGAAG AGTTAATTCA CCAGGGCCAT GAAATTGTGG TAATCGAAAA 900 GGATACAGAT AATCGTTTCT TGCATACGGC CCGCTCCCTG GGGGTGCCCG TAATTGTGGA 960 GGATGCCCGC CTAGAAAGAA CGTTGGCCTG CGCCAATATC AACCGAGCCG AAGCCATTGT 1020 GGTGGCCACC AGCGACGACA CCGTTAACTT GGAAATTGGC CTAACTGCCA AGGCGATCGC 1080 CCCTAGCCTG CCAGTGGTGT TGCGTTGCCA GGATGCCCAG TTTAGCCTGT CCCTGCAGGA 11 0 AGTATTTGAA TTTGAAACGG TGCTTTGTCC GGCGGAATTG GCCACCTATT CCTTTGCGGC 1200 GGCGGCCCTG GGGGGCAAAA TTTTGGGCAA CGGCATGACC GATGATTTGC TGTGGGTAGC 1260 CCTAGCCACC TTAATCACTC CTAACCATCC CTTTGCCGAC CAATTGGTTA AAATTGCAGC 1320 CCAAAAGTCT GATTTCGTTC CCCTCTATCT AGAACGGGGT GGCAAAACCA TCCATAGCTG 1380 GGAATTATTG GGTACCCATC TCGACTCTGG AGACGTGTTG TATTTAACCA TGCCCGCCAC 1440 TGCCCTAGAG CAACTTTGGC GATCGCCCCG TGCCACTGCT GATCCTCTGG ACTCTTTTTT 1500 GGTTTAGCAT GGGGGGATGG AACTCTTGAC TCGGCCCAAT GGTGATCAAG AAAGAACGCT 1560 TTGTCTATGT TTAGTATTTT TAAGTTAACC AACAGCAGAG GATAACTTCC AAAAGAAATT 1620 AAGCTCAAAA AGTAGCAAAA TAAGTTTAAT TCATAACTGA GTTTTACTGC TAAACAGCGG 1680 TGCAAAAAAG TCAGATAAAA TAAAAGCTTC ACTTCGGTTT TATATTGTGA CCATGGTTCC 1740 CAGGCATCTG CTCTAGGGAG TTTTTCCGCT GCCTTTAGAG AGTATTTTCT CCAAGTCGGC 1800 TAACTCCCCC ATTTTTAGGC AAAATCATAT ACAGACTATC CCAATATTGC CAGAGCTTTG 1860 ATGACTCACT GTAGAAGGCA GACTAAAATT CTAGCAATGG ACTCCCAGTT GGAATAAATT 1920 TTTAGTCTCC CCCGGCGCTG GAGTTTTTTT GTAGTTAATG GCGGTATAAT GTGAAAGTTT 1980 TTTATCTATT TAAATTTATA A ATG CTA ACA GCG GAA AGA ATT AAA TTT ACC 2031 Met Leu Thr Ala Glu Arg lie Lys Phe Thr 1 5 10 CAG AAA CGG GGG TTT CGT CGG GTA CTA AAC CAA CGG GTG GAT GCC TAC 2079 Gin Lys Arg Gly Phe Arg Arg Val Leu Asn Gin Arg Val Asp Ala Tyr 15 20 25 TTT GCC GAG CAT GGC CTG ACC CAA AGG GAT AAT CCC TCC ATG TAT CTG 2127 Phe Ala Glu His Gly Leu Thr Gin Arg Asp Asn Pro Ser Met Tyr Leu 30 35 40 AAA ACC CTG ATT ATT GTG CTC TGG TTG TTT TCC GCT TGG GCC TTT GTG 2175 Lys Thr Leu lie lie Val Leu Trp Leu Phe Ser Ala Trp Ala Phe Val 45 50 55 CTT TTT GCT CCA GTT ATT TTT CCG GTG CGC CTA CTG GGT TGT ATG GTT 2223 Leu Phe Ala Pro Val lie Phe Pro Val Arg Leu Leu Gly Cys Met Val 60 65 70 TTG GCG ATC GCC TTG GCG GCC TTT TCC TTC AAT GTC GGC CAC GAT GCC 2271 Leu Ala lie Ala Leu Ala Ala Phe Ser Phe Asn Val Gly His Asp Ala 75 80 85 90 AAC CAC AAT GCC TAT TCC TCC AAT CCC CAC ATC AAC CGG GTT CTG GGC 2319 Asn His Asn Ala Tyr Ser Ser Asn Pro His lie Asn Arg Val Leu Gly 95 100 105 ATG ACC TAC GAT TTT GTC GGG TTA TCT AGT TTT CTT TGG CGC TAT CGC 2367 Met Thr Tyr Asp Phe Val Gly Leu Ser Ser Phe Leu Trp Arg Tyr Arg 110 115 120 CAC AAC TAT TTG CAC CAC ACC TAC ACC AAT ATT CTT GGC CAT GAC GTG 2415 His Asn Tyr Leu His His Thr Tyr Thr Asn lie Leu Gly His Asp Val 125 130 135 GAA ATC CAT GGA GAT GGC GCA GTA CGT ATG AGT CCT GAA CAA GAA CAT 2463 Glu lie His Gly Asp Gly Ala Val Arg Met Ser Pro Glu Gin Glu His 140 145 150 GTT GGT ATT TAT CGT TTC CAG CAA TTT TAT ATT TGG GGT TTA TAT CTT 2511 Val Gly lie Tyr Arg Phe Gin Gin Phe Tyr lie Trp Gly Leu Tyr Leu 155 160 165 170 TTC ATT CCC TTT TAT TGG TTT CTC TAC GAT GTC TAC CTA GTG CTT AAT 2559 Phe lie Pro Phe Tyr Trp Phe Leu Tyr Asp Val Tyr Leu Val Leu Asn 175 180 185 AAA GGC AAA TAT CAC GAC CAT AAA ATT CCT CCT TTC CAG CCC CTA GAA 2607 Lys Gly Lys Tyr His Asp His Lys lie Pro Pro Phe Gin Pro Leu Glu 190 195 200 TTA GCT AGT TTG CTA GGG ATT AAG CTA TTA TGG CTC GGC TAC GTT TTC 2655 Leu Ala Ser Leu Leu Gly lie Lys Leu Leu Trp Leu Gly Tyr Val Phe 205 210 215 GGC TTA CCT CTG GCT CTG GGC TTT TCC ATT CCT GAA GTA TTA ATT GGT 2703 Gly Leu Pro Leu Ala Leu Gly Phe Ser lie Pro Glu Val Leu lie Gly 220 225 230 GCT TCG GTA ACC TAT ATG ACC TAT GGC ATC GTG GTT TGC ACC ATC TTT 2751 Ala Ser Val Thr Tyr Met Thr Tyr Gly lie Val Val Cys Thr lie Phe 235 240 245 250 ATG CTG GCC CAT GTG TTG GAA TCA ACT GAA TTT CTC ACC CCC GAT GGT 2799 Met Leu Ala His Val Leu Glu Ser Thr Glu Phe Leu Thr Pro Asp Gly 255 260 265 GAA TCC GGT GCC ATT GAT GAC GAG TGG GCT ATT TGC CAA ATT CGT ACC 2847 Glu Ser Gly Ala lie Asp Asp Glu Trp Ala lie Cys Gin lie Arg Thr 270 275 280 ACG GCC AAT TTT GCC ACC AAT AAT CCC TTT TGG AAC TGG TTT TGT GGC 2895 Thr Ala Asn Phe Ala Thr Asn Asn Pro Phe Trp Asn Trp Phe Cys Gly 285 290 295 GGT TTA AAT CAC CAA GTT ACC CAC CAT CTT TTC CCC AAT ATT TGT CAT 2943 Gly Leu Asn His Gin Val Thr His His Leu Phe Pro Asn lie Cys His 300 305 310 ATT CAC TAT CCC CAA TTG GAA AAT ATT ATT AAG GAT GTT TGC CAA GAG 2991 lie His Tyr Pro Gin Leu Glu Asn lie lie Lys Asp Val Cys Gin Glu 315 320 325 330 TTT GGT GTG GAA TAT AAA GTT TAT CCC ACC TTC AAA GCG GCG ATC GCC 3039 Phe Gly Val Glu Tyr Lys Val Tyr Pro Thr Phe Lys Ala Ala lie Ala 335 340 345 TCT AAC TAT CGC TGG CTA GAG GCC ATG GGC AAA GCA TCG TGACATTGCC 3088 Ser Asn Tyr Arg Trp Leu Glu Ala Met Gly Lys Ala Ser 350 355 360 TTGGGATTGA AGCAAAATGG CAAAATCCCT CGTAAATCTA TGATCGAAGC CTTTCTGTTG 3148 CCCGCCGACC AAATCCCCGA TGCTGACCAA AGGTTGATGT TGGCATTGCT CCAAACCCAC 3208 TTTGAGGGGG TTCATTGGCC GCAGTTTCAA GCTGACCTAG GAGGCAAAGA TTGGGTGATT 3268 TTGCTCAAAT CCGCTGGGAT ATTGAAAGGC TTCACCACCT TTGGTTTCTA CCCTGCTCAA 3328 TGGGAAGGAC AAACCGTCAG AATTGTTTAT TCTGGTGACA CCATCACCGA CCCATCCATG 3388 TGGTCTAACC CAGCCCTGGC CAAGGCTTGG ACCAAGGCCA TGCAAATTCT CCACGAGGCT 34 8 AGGCCAGAAA AATTATATTG GCTCCTGATT TCTTCCGGCT ATCGCACCTA CCGATTTTTG 3508 AGCATTTTTG CCAAGGAATT CTATCCCCAC TATCTCCATC CCACTCCCCC GCCTGTACAA 3568 AATTTTATCC ATCAGCTAGC 3588 (2) INFORMATION FOR SEQ ID NO:2: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 359 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID N0:2: Met Leu Thr Ala Glu Arg lie Lys Phe Thr Gin Lys Arg Gly Phe Arg 1 5 10 15 Arg Val Leu Asn Gin Arg Val Asp Ala Tyr Phe Ala Glu His Gly Leu 20 25 30 Thr Gin Arg Asp Asn Pro Ser Met Tyr Leu Lys Thr Leu lie lie Val 35 40 45 Leu Trp Leu Phe Ser Ala Trp Ala Phe Val Leu Phe Ala Pro Val He 50 55 60 Phe Pro Val Arg Leu Leu Gly Cys Met Val Leu Ala He Ala Leu Ala 65 70 75 80 Ala Phe Ser Phe Asn Val Gly His Asp Ala Asn His Asn Ala Tyr Ser 85 90 95 Ser Asn Pro His He Asn Arg Val Leu Gly Met Thr Tyr Asp Phe Val 100 105 110 Gly Leu Ser Ser Phe Leu Trp Arg Tyr Arg His Asn Tyr Leu His His 115 120 125 Thr Tyr Thr Asn He Leu Gly His Asp Val Glu He His Gly Asp Gly 130 135 140 Ala Val Arg Met Ser Pro Glu Gin Glu His Val Gly He Tyr Arg Phe 145 150 155 160 Gln Gin Phe Tyr He Trp Gly Leu Tyr Leu Phe He Pro Phe Tyr Trp 165 170 175 Phe Leu Tyr Asp Val Tyr Leu Val Leu Asn Lys Gly Lys Tyr His Asp 180 185 190 His Lys He Pro Pro Phe Gin Pro Leu Glu Leu Ala Ser Leu Leu Gly 195 200 205 He Lys Leu Leu Trp Leu Gly Tyr Val Phe Gly Leu Pro Leu Ala Leu 210 215 220 Gly Phe Ser He Pro Glu Val Leu He Gly Ala Ser Val Thr Tyr Met 225 230 235 240 Thr Tyr Gly He Val Val Cys Thr He Phe Met Leu Ala His Val Leu 245 250 255 Glu Ser Thr Glu Phe Leu Thr Pro Asp Gly Glu Ser Gly Ala He Asp 260 265 270 Asp Glu Trp Ala He Cys Gin He Arg Thr Thr Ala Asn Phe Ala Thr 275 280 285 Asn Asn Pro Phe Trp Asn Trp Phe Cys Gly Gly Leu Asn His Gin Val 290 295 300 Thr His His Leu Phe Pro Asn He Cys His He His Tyr Pro Gin Leu 305 310 315 320 Glu Asn He He Lys Asp Val Cys Gin Glu Phe Gly Val Glu Tyr Lys 325 330 335 Val Tyr Pro Thr Phe Lys Ala Ala He Ala Ser Asn Tyr Arg Trp Leu 340 345 350 Glu Ala Met Gly Lys Ala Ser 355 (2) INFORMATION FOR SEQ ID NO:3: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1884 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: both (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3: AGCTTCACTT CGGTTTTATA TTGTGACCAT GGTTCCCAGG CATCTGCTCT AGGGAGTTTT 60 TCCGCTGCCT TTAGAGAGTA TTTTCTCCAA GTCGGCTAAC TCCCCCATTT TTAGGCAAAA 120 TCATATACAG ACTATCCCAA TATTGCCAGA GCTTTGATGA CTCACTGTAG AAGGCAGACT 180 AAAATTCTAG CAATGGACTC CCAGTTGGAA TAAATTTTTA GTCTCCCCCG GCGCTGGAGT 240 TTTTTTGTAG TTAATGGCGG TATAATGTGA AAGTTTTTTA TCTATTTAAA TTTATAAATG 300 CTAACAGCGG AAAGAATTAA ATTTACCCAG AAACGGGGGT TTCGTCGGGT ACTAAACCAA 360 CGGGTGGATG CCTACTTTGC CGAGCATGGC CTGACCCAAA GGGATAATCC CTCCATGTAT 420 CTGAAAACCC TGATTATTGT GCTCTGGTTG TTTTCCGCTT GGGCCTTTGT GCTTTTTGCT 480 CCAGTTATTT TTCCGGTGCG CCTACTGGGT TGTATGGTTT TGGCGATCGC CTTGGCGGCC 540 TTTTCCTTCA ATGTCGGCCA CGATGCCAAC CACAATGCCT ATTCCTCCAA TCCCCACATC 600 AACCGGGTTC TGGGCATGAC CTACGATTTT GTCGGGTTAT CTAGTTTTCT TTGGCGCTAT 660 CGCCACAACT ATTTGCACCA CACCTACACC AATATTCTTG GCCATGACGT GGAAATCCAT 720 GGAGATGGCG CAGTACGTAT GAGTCCTGAA CAAGAACATG TTGGTATTTA TCGTTTCCAG 780 CAATTTTATA TTTGGGGTTT ATATCTTTTC ATTCCCTTTT ATTGGTTTCT CTACGATGTC 840 TACCTAGTGC TTAATAAAGG CAAATATCAC GACCATAAAA TTCCTCCTTT CCAGCCCCTA 900 GAATTAGCTA GTTTGCTAGG GATTAAGCTA TTATGGCTCG GCTACGTTTT CGGCTTACCT 960 CTGGCTCTGG GCTTTTCCAT TCCTGAAGTA TTAATTGGTG CTTCGGTAAC CTATATGACC 1020 TATGGCATCG TGGTTTGCAC CATCTTTATG CTGGCCCATG TGTTGGAATC AACTGAATTT 1080 CTCACCCCCG ATGGTGAATC CGGTGCCATT GATGACGAGT GGGCTATTTG CCAAATTCGT 1140 ACCACGGCCA ATTTTGCCAC CAATAATCCC TTTTGGAACT GGTTTTGTGG CGGTTTAAAT 1200 CACCAAGTTA CCCACCATCT TTTCCCCAAT ATTTGTCATA TTCACTATCC CCAATTGGAA 1260 AATATTATTA AGGATGTTTG CCAAGAGTTT GGTGTGGAAT ATAAAGTTTA TCCCACCTTC 1320 AAAGCGGCGA TCGCCTCTAA CTATCGCTGG CTAGAGGCCA TGGGCAAAGC ATCGTGACAT 1380 TGCCTTGGGA TTGAAGCAAA ATGGCAAAAT CCCTCGTAAA TCTATGATCG AAGCCTTTCT 1440 GTTGCCCGCC GACCAAATCC CCGATGCTGA CCAAAGGTTG ATGTTGGCAT TGCTCCAAAC 1500 CCACTTTGAG GGGGTTCATT GGCCGCAGTT TCAAGCTGAC CTAGGAGGCA AAGATTGGGT 1560 GATTTTGCTC AAATCCGCTG GGATATTGAA AGGCTTCACC ACCTTTGGTT TCTACCCTGC 1620 TCAATGGGAA GGACAAACCG TCAGAATTGT TTATTCTGGT GACACCATCA CCGACCCATC 1680 CATGTGGTCT AACCCAGCCC TGGCCAAGGC TTGGACCAAG GCCATGCAAA TTCTCCACGA 1740 GGCTAGGCCA GAAAAATTAT ATTGGCTCCT GATTTCTTCC GGCTATCGCA CCTACCGATT 1800 TTTGAGCATT TTTGCCAAGG AATTCTATCC CCACTATCTC CATCCCACTC CCCCGCCTGT 1860 ACAAAATTTT ATCCATCAGC TAGC 1884 (2) INFORMATION FOR SEQ ID NO:4: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1685 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: both (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO: : AATATCTGCC TACCCTCCCA AAGAGAGTAG TCATTTTTCA TCAATGGCTG CTCAAATCAA 60 GAAATACATT ACCTCAGATG AACTCAAGAA CCACGATAAA CCCGGAGATC TATGGATCTC 120 GATTCAAGGG AAAGCCTATG ATGTTTCGGA TTGGGTGAAA GACCATCCAG GTGGCAGCTT 180 TCCCTTGAAG AGTCTTGCTG GTCAAGAGGT AACTGATGCA TTTGTTGCAT TCCATCCTGC 240 CTCTACATGG AAGAATCTTG ATAAGTTTTT CACTGGGTAT TATCTTAAAG ATTACTCTGT 300 TTCTGAGGTT TCTAAAGATT ATAGGAAGCT TGTGTTTGAG TTTTCTAAAA TGGGTTTGTA 360 TGACAAAAAA GGTCATATTA TGTTTGCAAC TTTGTGCTTT ATAGCAATGC TGTTTGCTAT 420 GAGTGTTTAT GGGGTTTTGT TTTGTGAGGG TGTTTTGGTA CATTTGTTTT CTGGGTGTTT 480 GATGGGGTTT CTTTGGATTC AGAGTGGTTG GATTGGACAT GATGCTGGGC ATTATATGGT 540 AGTGTCTGAT TCAAGGCTTA ATAAGTTTAT GGGTATTTTT GCTGCAAATT GTCTTTCAGG 600 AATAAGTATT GGTTGGTGGA AATGGAACCA TAATGCACAT CACATTGCCT GTAATAGCCT 660 TGAATATGAC CCTGATTTAC AATATATACC ATTCCTTGTT GTGTCTTCCA AGTTTTTTGG 720 TTCACTCACC TCTCATTTCT ATGAGAAAAG GTTGACTTTT GACTCTTTAT CAAGATTCTT 780 TGTAAGTTAT CAACATTGGA CATTTTACCC TATTATGTGT GCTGCTAGGC TCAATATGTA 840 TGTACAATCT CTCATAATGT TGTTGACCAA GAGAAATGTG TCCTATCGAG CTCAGGAACT 900 CTTGGGATGC CTAGTGTTCT CGATTTGGTA CCCGTTGCTT GTTTCTTGTT TGCCTAATTG 960 GGGTGAAAGA ATTATGTTTG TTATTGCAAG TTTATCAGTG ACTGGAATGC AACAAGTTCA 1020 GTTCTCCTTG AACCACTTCT CTTCAAGTGT TTATGTTGGA AAGCCTAAAG GGAATAATTG 1080 GTTTGAGAAA CAAACGGATG GGACACTTGA CATTTCTTGT CCTCCTTGGA TGGATTGGTT 1140 TCATGGTGGA TTGCAATTCC AAATTGAGCA TCATTTGTTT CCCAAGATGC CTAGATGCAA 1200 CCTTAGGAAA ATCTCGCCCT ACGTGATCGA GTTATGCAAG AAACATAATT TGCCTTACAA 1260 TTATGCATCT TTCTCCAAGG CCAATGAAAT GACACTCAGA ACATTGAGGA ACACAGCATT 1320 GCAGGCTAGG GATATAACCA AGCCGCTCCC GAAGAATTTG GTATGGGAAG CTCTTCACAC 1380 TCATGGTTAA AATTACCCTT AGTTCATGTA ATAATTTGAG ATTATGTATC TCCTATGTTT 1440 GTGTCTTGTC TTGGTTCTAC TTGTTGGAGT CATTGCAACT TGTCTTTTAT GGTTTATTAG 1500 ATGTTTTTTA ATATATTTTA GAGGTTTTGC TTTCATCTCC ATTATTGATG AATAAGGAGT 1560 TGCATATTGT CAATTGTTGT GCTCAATATC TGATATTTTG GAATGTACTT TGTACCACTG 1620 TGTTTTCAGT TGAAGCTCAT GTGTACTTCT ATAGACTTTG TTTAAATGGT TATGTCATGT 1680 TATTT 1685 (2) INFORMATION FOR SEQ ID NO:5: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 448 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5: Met Ala Ala Gin He Lys Lys Tyr He Thr Ser Asp Glu Leu Lys Asn 1 5 10 15 His Asp Lys Pro Gly Asp Leu Trp He Ser He Gin Gly Lys Ala Tyr 20 25 30 Asp Val Ser Asp Trp Val Lys Asp His Pro Gly Gly Ser Phe Pro Leu 35 40 45 Lys Ser Leu Ala Gly Gin Glu Val Thr Asp Ala Phe Val Ala Phe His 50 55 60 Pro Ala Ser Thr Trp Lys Asn Leu Asp Lys Phe Phe Thr Gly Tyr Tyr 65 70 75 80 Leu Lys Asp Tyr Ser Val Ser Glu Val Ser Lys Asp Tyr Arg Lys Leu 85 90 95 Val Phe Glu Phe Ser Lys Met Gly Leu Tyr Asp Lys Lys Gly His He 100 105 110 Met Phe Ala Thr Leu Cys Phe He Ala Met Leu Phe Ala Met Ser Val 115 120 125 Tyr Gly Val Leu Phe Cys Glu Gly Val Leu Val His Leu Phe Ser Gly 130 135 140 - 53 - Cys Leu Met Gly Phe Leu Trp He Gin Ser Gly Trp He Gly His Asp 145 150 155 160 Ala Gly His Tyr Met Val Val Ser Asp Ser Arg Leu Asn Lys Phe Met 165 170 175 Gly He Phe Ala Ala Asn Cys Leu Ser Gly He Ser He Gly Trp Trp 180 185 190 Lys Trp Asn His Asn Ala His His He Ala Cys Asn Ser Leu Glu Tyr 195 200 205 Asp Pro Asp Leu Gin Tyr He Pro Phe Leu Val Val Ser Ser Lys Phe 210 215 220 Phe Gly Ser Leu Thr Ser His Phe Tyr Glu Lys Arg Leu Thr Phe Aβp 225 230 235 240 Ser Leu Ser Arg Phe Phe Val Ser Tyr Gin His Trp Thr Phe Tyr Pro 245 250 255 He Met Cys Ala Ala Arg Leu Asn Met Tyr Val Gin Ser Leu He Met 260 265 270 Leu Leu Thr Lys Arg Asn Val Ser Tyr Arg Ala Gin Glu Leu Leu Gly 275 280 285 Cys Leu Val Phe Ser He Trp Tyr Pro Leu Leu Val Ser Cys Leu Pro 290 295 300 Asn Trp Gly Glu Arg He Met Phe Val He Ala Ser Leu Ser Val Thr 305 310 315 320 Gly Met Gin Gin Val Gin Phe Ser Leu Asn His Phe Ser Ser Ser Val 325 330 335 Tyr Val Gly Lys Pro Lys Gly Asn Asn Trp Phe Glu Lys Gin Thr Asp 340 345 350 Gly Thr Leu Asp He Ser Cys Pro Pro Trp Met Asp Trp Phe His Gly 355 360 365 Gly Ser Gin Phe Gin He Glu His His Leu Phe Pro Lys Met Pro Arg 370 375 380 Cys Asn Leu Arg Lys He Ser Pro Tyr Val He Glu Leu Cys Lys Lys 385 390 395 400 His Asn Leu Pro Tyr Asn Tyr Ala Ser Phe Ser Lys Ala Asn Glu Met 405 410 415 Thr Leu Arg Thr Leu Arg Asn Thr Ala Leu Gin Ala Arg Asp He Thr 420 425 430 Lys Pro Leu Pro Lys Asn Leu Val Trp Glu Ala Leu His Thr His Gly 435 440 445 (2) INFORMATION FOR SEQ ID NO:6: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 8 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6: Trp He Gly His Asp Ala Gly His 1 5 (2) INFORMATION FOR SEQ ID NO:7: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 8 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7: Asn Val Gly His Asp Ala Asn His 1 5 (2) INFORMATION FOR SEQ ID NO:8: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 8 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 8: Val Leu Gly His Asp Cys Gly His 1 5 (2) INFORMATION FOR SEQ ID NO: 9: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 8 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9: O96/21022 -55- Val He Ala His Glu Cys Gly His 1 5 (2) INFORMATION FOR SEQ ID NO:10: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 8 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10: Val He Gly His Asp Cys Ala His 1 5 (2) INFORMATION FOR SEQ ID NO:11: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 8 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11: Val Val Gly His Asp Cys Gly His 1 5 (2) INFORMATION FOR SEQ ID NO:12: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 5 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12: His Asn Ala His Hie 1 5 (2) INFORMATION FOR SEQ ID NO:13: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 6 amino acids (B) TYPE.- amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:13: His Asn Tyr Leu His His 1 5 (2) INFORMATION FOR SEQ ID NO:14: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 5 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 14: His Arg Thr His His 1 5 (2) INFORMATION FOR SEQ ID NO:15: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 5 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 15: His Arg Arg His His 1 5 (2) INFORMATION FOR SEQ ID NO:16: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 5 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:16: His Asp Arg His His 1 5 (2) INFORMATION FOR SEQ ID NO:17: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 5 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:17: His Asp Gin His His 1 5 (2) INFORMATION FOR SEQ ID NO:18: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 5 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:18: His Asp His His His 1 5 (2) INFORMATION FOR SEQ ID NO:19: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 5 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:19: His Asn His His His 1 5 (2) INFORMATION FOR SEQ ID NO:20: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 6 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:20: Phe Gin He Glu His His 1 5 (2) INFORMATION FOR SEQ ID NO:21: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 6 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:21: His Gin Val Thr His His 1 5 (2) INFORMATION FOR SEQ ID NO:22: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 5 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:22: His Val He His His 1 5 (2) INFORMATION FOR SEQ ID NO:23: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 5 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:23: His Val Ala His His 1 5 (2) INFORMATION FOR SEQ ID NO:24: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 5 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:24: His He Pro His His 1 5 (2) INFORMATION FOR SEQ ID NO:25: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 5 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (xi) SEQUENCE DESCRIPTION: SEQ ID NO:25: His Val Pro His His 1 5

Claims: _ WHAT IS CLAIMED: 1. An isolated nucleic acid encoding a borage Δ6-desaturase. 5 2. The isolated nucleic acid of Claim 1 comprising the nucleotide sequence of SEQ ID NO: 4. 3. An isolated nucleic acid that codes for the 0 amino acid sequence of SEQ ID NO: 5. 4. A vector comprising the nucleic acid of any one Claims 1-3. j c 5. An expression vector comprising the isolated nucleic acid of any one of Claims 1-3 operably linked to a promoter and optionally a termination signal capable of effecting expression of the gene product of said isolated nucleic acid. 20 6. The expression vector of Claim 5 wherein said promoter is a Δ-6 desaturase promoter, an Anabaena carboxylase promoter, a helianthinin promoter, a glycinin promoter, a napin promoter, the 35S promoter from CaMV, or a helianthinin tissue-specific promoter. 5 7. The expression vector of Claim 5 wherein said promoter is constitutive or tissue-specific. 8. The expression vector of Claim 5 wherein 0 said termination signal is a Synechocystis termination 5 1 signal, a nopaline synthase termination signal, or a seed termination signal. 9. A cell comprising the vector of any one of - Claims 4-8. 10. The cell of Claim 9 wherein said cell is an animal cell, a bacterial cell, a plant cell or a fungal cell. 10 11. A transgenic organism comprising the isolated nucleic acid of any one of Claims 1-3. 12. A transgenic organism comprising the vector ] c of any one of Claims 4-8. 13. The transgenic organism of Claim 11 or 12 wherein said organism is a bacterium, a fungus, a plant or an animal. 20 14. A plant or progeny of said plant which has been regenerated from the plant cell of Claim 10. 15. The plant of Claim 14 wherein said plant is 5 a sunflower, soybean, maize, tobacco, peanut, carrot or oil seed rape plant. 16. A method of producing a plant with increased gamma linolenic acid (GLA) content which o comprises: 5 2 (a) transforming a plant cell with the isolated nucleic acid of any one of Claims 1-3; and (b) regenerating a plant with increased GLA content from said plant cell. 5 17. A method of producing a plant with increased gamma linolenic acid (GLA) content which comprises: (a) transforming a plant cell with the vector of 0 an Y one °f Claims 4-8; and (b) regenerating a plant with increased GLA content from said plant cell. 18. The method of Claim 16 or 17 wherein said 25 plant is a sunflower, soybean, maize, tobacco, peanut, carrot or oil seed rape plant. 19. A method of inducing production of gamma linolenic acid (GLA) in an organism deficient or lacking 2o ιn GL which comprises transforming said organism with the isolated nucleic acid of any one of Claims 1-3. 20. A method of inducing production of gamma linolenic acid (GLA) in an organism deficient or lacking 2 c in GLA which comprises transforming said organism with the vector of any one of Claims 4-8. 21. A method of inducing production of gamma linolenic acid (GLA) in an organism deficient or lacking - n in GLA and linoleic acid (LA) which comprises transforming said organism with an isolated nucleic acid encoding 5 2 borage Δ6-desaturase and an isolated nucleic acid encoding Δl2-desaturase. 22. The method of Claim 21 wherein said - isolated nucleic acid encoding ώ6-desaturase comprises nucleotides 44 to 1390 of SEQ. ID NO: 4. 23. A method of inducing production of octadecatetraeonic acid in an organism deficient or lacking in gamma linolenic acid which comprises transforming said organism with the isolated nucleic acid of any one of Claims 1-3. 24. A method of inducing production of octadecatetraeonic acid in an organism deficient or lacking in gamma linolenic acid which comprises transforming said organism with the vector of any one of Claims 4-8. 25. The method of Claim 23 or 24 wherein said organism is a bacterium, a fungus, a plant or an animal. 26. A method of producing a plant with improved chilling resistance which comprises: (a) transforming a plant cell with the isolated nucleic acid of any one of Claims 1-3; and (b) regenerating said plant with improved chilling resistance from said transformed plant cell. 27. A method of producing a plant with improved chilling resistance which comprises: (a) transforming a plant cell with the vector of any one of Claims 4-8; and (b) regenerating said plant with improved chilling resistance from said transformed plant cell. 28. The method of Claim 26 or 27 wherein said plant is a sunflower, soybean, maize, tobacco, peanut, carrot or oil seed rape plant.

Inventors: FREYSSINET GEORGES L, NUCCIO MICHAEL, NUNBERG ANDREW N, REDDY AVUTU S, THOMAS TERRY L, FREYSSINET, GEORGES, L., NUCCIO, MICHAEL, NUNBERG, ANDREW, N., REDDY, AVUTU, S., THOMAS, TERRY, L.
Applicants: RHONE POULENC AGROCHIMIE, RHONE-POULENC AGROCHIMIE
Application year: 1995
Main classification: C12N15
IPC codes: A01H1, C12N1, C12N5, C12N9, C12N15, C12P7, C12R1