FUNGAL GENE ENCODING RESISTANCE TO THE PHYTOTOXIN CERCOSPORIN

Abstract: The present invention is directed to nucleic acid and amino acid sequences which are responsible for moving the fungal toxin cercosporin across the plasma membrane of living cells. The DNA can be introduced into a plant using conventional methods of transformation in order to confer cercosporin resistance to plants.

Description: FUNGAL GENE ENCODING RESISTANCE TO THE PHYTOTOXIN CERCOSPORIN BACKGROUND OF THE INVENTION Field of the Invention This invention relates to nucleic acid and amino acid sequences which regulate the polyketide toxin cercosporin, gene constructs, and methods related thereto. It further relates to the use of a nucleic acid to genetically engineer plants for resistance to the toxin. Description of the Prior Art Fungi of the genus Cercospora are widespread, economically important pathogens of a diverse array of crop plants, including for example, banana, sugar beet, coffee, tobacco, corn, sorghum, peanut, and soybean (Agrios, Plant Pathology, 3rd Ed., Academic Press, San Diego, Calif., 356-357, 1988) . Resistance to the phytotoxin, cercosporin, produced by many species of plant pathogenic Cercospora fungi, has not been found in any commercial crops. Cercosporin is the major disease factor in purple-seed stain of soybeans and other crop diseases caused by this fungus. United States corn growers have experienced increasingly serious outbreaks of gray leaf spot disease due to Cercospora zeae-maydis. The lack of highly resistant plant cultivars, particularly early maturing corn in the Midwest, is crucial. With a total United States value of over $16 billion, corn growers, state economies, and commercial hybrid seed producers face potentially dramatic economic loss due to gray leaf spot. The situation with soybeans, while significant, is less dramatic. Soybean yield losses due to purple-seed stain have averaged about 1-2% or less in recent years. But the United States soybean crop is now valued at over $11 billion. The presence of more than 5% purple-stained beans at market results in significantly lower grower prices due to lower bean quality and the additional processing required for purple-stained beans. Furthermore, substantial crop losses have been attributed to the leaf phase of the disease in the southern United States when weather conditions favor the disease. One new approach to crop disease management is the use of pathogen-derived genes for resistance. Scientists have traditionally used cross-breeding and hybridization techniques to provide plants having particular desired traits such as increased hardiness, nutritional value, taste, appearance, and disease resistance, etc., but these techniques are at best lengthy, time-consuming processes which do not necessarily result in achievement of a particular goal. With soybean, an oilseed of major importance to the world's economy, the search for enhanced or durable resistance to Cercospora is complicated by the fact that cultivar susceptibility to foliar and seed infections have no strong relationship. Indeed, some cultivars show resistance to seed stain and susceptibility to leaf blight. The advent of genetic engineering provides the opportunity to introduce genetic material directly into a plant, which upon expression in the plant, would result in a plant with resistant to cercosporin. Polyketides such as cercosporin, for example, are products of secondary metabolism in bacteria, fungi, and plants. This group of compounds includes important bacterial and fungal antibiotics, plant flavonoids and fungal mycotoxins and phytotoxins (Hopwood et al, Annual Review of Genetics, Volume 24, 37-66, 1990) . Many phytopathogenic fungi of the genus Cercospora produce the red polyketide toxin, cercosporin (Daub, Phytopathology, Volume 72, 370-374, 1982; Lynch et al, Trans. Br. Mycol. Soc, Volume 69, 496-498, 1977) which was first isolated from C. JciJcuchii (Kuyama et al., J. Am. Chem. Soc, Volume 79, 5725-5762, 1957) . The structure of cercosporin, a red perylene quinone derivative, [1, 12-bis (2-hydroxy-propyl) - 2, 11 dimethoxy-6, 7-methylenedioxy-4, 9-dihydroxyperylene-3, 10- quinone; Molecular Weight: 534] was determined independently by Lousberg et al (J. Chem. Soc. Chem. Commun., 1971:1463-1464, 1971) and Yamazaki et al (Agric. Biol. Chem., Volume 36, 1707- 1718, 1972) . Cercosporin is a non-host-specific toxin, which, in the presence of light, interacts with molecular oxygen to produce both superoxide radicals and singlet oxygen {Daub et al, Plant Physiol., Volume 73, 855-857, 1983) . These activated oxygen species cause peroxidation of cell membrane lipids resulting in electrolytic leakage, a decrease in membrane fluidity and cell death {Daub, ACS Sy p. Ser., Volume 339, 271- 280, 1987) . Several lines of evidence indicate that cercosporin plays an essential role in Cercospora pathogenicity: high light intensity is absolutely required for both disease development (Calpouzos, Ann. Rev. Phytopathology, Volume 4, 369-390, 1966; Calpouzos et al, Phytopathology, Volume 57, 799-800, 1967) and toxin action (Daub, 1982 supra) , toxin can be isolated from naturally infected tissues (Fajola, Physiol. Plant Pathol., Volume 13, 157-164, 1978; Upchurch et al, Appl. Environ. Microbiol., Volume 57(10), 2940-2945, 1991) ; application of the toxin alone can produce disease symptoms on host plants (Balis et al. Phytopathology, Volume 61, 1477-1484, 1971; Fajola, 1978, supra) , and non-toxin-producing mutants of Cercospora kikuchii fail to induce disease symptoms in soybean plants (Upchurch, 1991, supra) . Although little is known about the biosynthesis of cercosporin, results from nuclear magnetic resonance and mass spectrometry analysis have indicated a polyketide route of synthesis and one unstable polyketomethylene intermediate has been proposed but not isolated (Okubo et al, Agric. Biol. Chem., Volume 39, 1173- 1175, 1975) . No enzymes or chemical intermediates in the cercosporin biosynthetic pathway have been identified. The identification and isolation of a gene responsible for conferring a major level of resistance to cercosporin-producing microorganisms would allow the development of crops resistant to fungal diseases caused by this toxin. Although there are no reports of resistance to cercosporin in crop plants, Batchvarova et al (Phytopathol. , Volume 82, 1477-1484, 1992) disclose a cercosporin resistance in a common weed. The annual weed, Louisiana red rice is resistant to all known races of Cercospora oryzae and has a resistant to cercosporin. In sensitive rice plants, cercosporin was demonstrated to accumulate in plant tissue, a phenomenon which has been seen in soybean. It was hypothesized that the resistance seen in Louisiana red rice is due to a combined effect of active efflux of the toxin from resistant cells possibly associated with cercosporin degradation or the action of carotenoids in quenching active oxygen species. United States Patent No. 5,262,303 (Robeson et al) discloses cercosporin-resistant bacteria that have the ability to degrade cercosporin. The patent also states that the gene responsible for this cercosporin-degrading characteristic could be isolated and cloned in an appropriate vector and inserted into a plant . Cercosporin-resistant crop plants have not been discovered to date. Therefore, the development of transgenic cercosporin-resistant plant varieties would be a useful approach to the control of Cercospora-induced plant diseases. The present invention, described below, provides a direct means to genetically engineer plants with resistance to this universally toxic polyketide, cercosporin, which is different from the prior art. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide DNA capable of conferring cercosporin resistance to plants. A further object of the invention is to provide DNA for the expression of the Cercospora kikuchii cercosporin membrane pump protein. Another object of the present invention is to provide a protein capable of conferring cercosporin resistance to plants. A still further object of the invention is to provide a protein which is a cercosporin membrane pump protein. A further object of the present invention is to provide a cercosporin resistant hybrid plant that produces progeny with cercosporin resistance. Another object of the present invention is to provide a vector containing a DNA sequence capable of conferring cercosporin resistance to plants. A still further object of the present invention is to provide a vector containing a DNA sequence for the expression of a protein which is a cercosporin membrane pump protein. Another object of the present invention is to provide a transformed prokaryote containing a vector with a DNA sequence for the expression of a cercosporin membrane pump protein. A further object of the present invention is to provide a method for conferring cercosporin resistance to plants using a plant transformation vector containing a DNA sequence for the expression of a cercosporin membrane pump protein. Further objects and advantages of the present invention will become apparent from the following description. Deposit of Microorganisms The LE6 (cfp) cDNA of the present invention known as plasmid cLE6-cfp was deposited in accordance with the provisions of the Budapest Treaty with the American Type Culture Collection, 12301 Parklawn Drive, Rockville, Maryland 20852 on March 15, 1996. The Accession Number is ATCC 97482. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a Northern hybridization analysis of wild-type C. kikuchii PR. Two micrograms of poly-A + RNA from light (L) - and dark(D) -grown PD broth cultures per lane was electrophoresed through a denaturing 1.2% agarose gel and transferred to nitrocellulose. Duplicate blots were probed with 3 P-labeled insert DNA from each of the cLEs (cLEl and cLE3 and cLE7) . Figure 2 is the genomic DNA sequence, cDNA sequence and the amino acid sequence for LE6-cfp. Figure 3 is an amino acid sequence for LE6-cfp showing a MacVector generated translation of the Open Reading Frame. Double underlined amino acid sequences are hydrophobic, alpha helical transmembrane regions as determined by Tmpred- Prediction of Transmembrane Regions and Orientations. Lower¬ case, bold letters represent the 19 amino acids comprising the motif associated with all known efflux drug resistance transporters. Figure 4 shows a comparative amino acid homology of the region surrounding the 19 amino acid motif as generated by a search of the BLAST peptide sequence databases. CmcT=cephamycin export protein from Norcardia lactamdurans; MmrB=methylenomycin resistance protein from Streptomyces coelicolor; TETr=tetracycline resistance protein from Aeromonas; MMrS=another methylenomycin resistance protein identical to MMrB; ToxA, HC=toxin resistance protein form CochlioJbolus carbonum; SGEl=crystal violet resistance protein from Saccharomyces cerevisiae; CFP=cercosporin facilitator protein (the protein of the instant invention) ; ActVA-1, ORF- 1=transmembrane protein of actinorhodin gene cluster from Streptomyces coelicolor; LmrA=lincomycin resistance protein from Escherichia coli ; QacA=antiseptic resistance protein from Staphylococcus aureus; TcmA=tetracenomycin resistance protein from Streptomyces glaucescens. Figure 5 shows a phylogenetic tree showing the relative relatedness among the LE6 protein and other drug transport proteins. Figure 6 is a MacVector hydrophilicity plot of the LE6 protein showing the position of the 19 amino acid motif relative to the entire sequence. Figure 7 depicts plant expression vector pB35S-LE6CFP which includes a 2.1kb Ba ΑI/Kpnl fragment comprising the entire length of LE6-cfp cDNA. Figure 8a is a graph showing time-course analysis of dry weight, cercosporin accumulation, and steady-state levels of RNA corresponding to the light-enhanced cDNAs cLE6 and cLE7 in wild -type strain PR. Figure 8b is a autoradiograph showing slot blot analysis of total RNA extracted from the samples used to generate the results shown in Figure 7a. Figure 9a depicts two different disrupted versions of the LE6 protein constructed and transformed in C. kikuchii PR as well as genomic LE6 (gLE6) . Figure 9b shows an autoradiogram of three disruptants containing a single copy of a disrupted version of the LE6 (cfp) gene. Lane 1 is wild-type strain PR, Lane 2 is Barl, Lane 3 is Bar2 and Lane 4 is Gus3. Figure 10 is a graph showing cercosporin production by disruptant transformants Barl, Bar2, Gus3 compared to wild-type Cercospora kikuchii PR grown in continuous light (PRLt) or continuous dark (PRDk) . Figure 11 is a graph showing cercosporin sensitivity of disruptant transformants Barl, Bar2, Gus3 compared to wild¬ type Cercospora kikuchii PR. All are grown in continuous light or continuous dark and levels are shown as percent of control radial growth. DETAILED DESCRIPTION OF THE INVENTION The isolation and cloning of a cDNA and its genomic DNA which is involved in cercosporin regulation according to the present invention enables the production of cercosporin- resistant plant varieties and cercosporin-susceptible Cercospora strains. Cercosporin allows the fungus to colonize and extract nutrients for growth and sporulation in infected plant tissues. Environmental conditions such as light intensity, temperature and nutrient relationships affect cercosporin production in culture. While temperature and growth medium composition affect the quantity of toxin produced, light appears to be the dominant regulatory cue (Jenns et al, Phytopathology, Volume 79, 213-219, 1989; Lynch et al, Trans. Br. Mycol. Soc, Volume 73, 311-327, 1979; all herein incorporated by reference) . This means that light should regulate certain genes that are involved in cercosporin metabolism. Light induction was used to isolate light-enhanced cDNAs by a subtractive hybridization technique (Maniatis et al, Molecular Cloning: A Laboratory Manual, pages 8.49 and 10.40- 10.43, 1989; herein incorporated by reference) . A cDNA library was constructed with the bacteriophage lambda vector lambda- ZAPII (Stratogene Cloning Systems, La Jolla, Calif.) by using poly-A + RNA isolated from light-grown, wild type Cercospora kikuchii PR. The library is maintained as a bacteriophage stock and infected into Escherichia coli XLl-blue cells (Stratogene Cloning Systems, La Jolla, Calif.) for screening. To isolate light-regulated cDNAs from this library, a subtracted probe is made from light-grown C. kikuchii poly-A + RNA and used to probe high-density plaque lifts. Single hybridizing plaques are isolated and converted into plasmids using a helper bacteriophage and an in vivo plasmid excision technique (Stratogene) . Inserts from these plasmids are then used to probe Northern (RNA) blots containing poly-A + RNA from light- and dark-grown C. kikuchii cultures. Six light-enhanced cDNA clones , cLEs, each of which hybridize to a single distinct mRNA band on Northern blots, are identified (Figure 1) . One of these cDNAs, LE6, shows enhanced transcript accumulation 20-fold higher in light and is correlated with the accumulation of cercosporin in culture and is nearly full length at 2.1 kb. The sequence of this cDNA (Figure 2) contains a putative open reading frame (ORF) of 1,818 base pairs that encodes a predominantly hydrophobic, cysteine-rich protein of 606 amino acids (pLE6) (Figure 2) with a molecular weight of 65,424 and an isoelectric point of 5.08. MacVector generated translation of the ORF shows sequences that are hydrophobic, alpha helical transmembrane regions, as determined by the Tmpred-Prediction of Transmembrane Regions and Orientation as seen in Figure 3 (Hofmann et al, Chem. Hoppe- Seyler, Volume 347, 166-176, 1993) . Kyte-Doolittle analysis of the protein indicates the pLE6 contains 12-13 transmembrane alpha helical regions. An amino acid sequence homology search has identified two regions of homology, GPVLGG and SWRWCLYINLPIG, to efflux-mediated resistance determinants, a subfamily of the major facilitator superfamily (Figure 4) . A comparative amino acid homology of the region surrounding this 19 amino acid motif was generated by a search of the BLAST peptide sequence databases (Figure 4) . Homology was found in the following efflux drug resistance transporters: CmcT, cephamycin export protein from Nocardia lactamdurans (Coque et al, EMBO J., Volume 12, 631-639, 1993) ; MmrB, methylenomycin resistance protein form Streptomyces coelicolor (Neal et al, Gene, Volume 58, 229-241, 1987); TETr, tetracycline resistance protein from Aeromonaε (Varela et al, Antimicrob. Agents Chemother., Volume 37, 1253-1258, 1993) ; MmrS, another methylenomycin resistance protein identical to MMrV; ToxA, HC toxin transport protein form Cochliobolus carbonum (J. Pitkin, Michigan State University, personal communication) ; SGE1, crystal violet resistance protein from Saccharomyces cereviseae (Eherhofer-Murray et al, Mol. Gen. Genet., Volume 244, 287-294, 1994) ; CFP (LE6) , cercosporin facilitator protein; ActVA-1, ORF-1, transmembrane protein of the actinorhodin gene cluster from Streptomyces coelicolor (Cavallero et al, Mol. Gen. Genet., Volume 230, 401-412, 1991); LmrA, lincomycin resistance protein from Streptomyces lincolnensis (Zhang et al, Molec. Microbiol., Volume 6, 2147-2157, 1992) ; EMRB, multidrug resistance protein from Escherichia coli (Lomovskaya et al , Proc. Natl. Acad. Sci., USA, Volume 89, 8938-8942, 1992) ; QacA, antiseptic resistance protein from Staphylococcus aureus (Tennent et al, J. Gen. Microbiol., Volume 135, 1-10, 1989) ; and TcmA, tetracenomycin resistance protein from Streptomyces glaucescens (Guilfoile et al, J. Bacteriol., Volume 174, 3651- 3658, 1992) . Figure 5 depicts a phylogenetic tree showing the relative relatedness among pLE6 and other drug transport proteins. The tree was constructed using the Unweighted Pair Group Method supplied by GeneWorks nucleic acid/protein analysis software (IntelliGenetics Inc, Mountain View, Calif.) . A MacVector hydrophilicity (inverse of hydropothy) plot indicates the position of the 19 amino acid motif relative to the entire sequence as being between amino acid 210 to amino acid 237 as shown in Figure 6. These data suggest that LE6 is responsible for the movement of cercosporin across the plasma membrane. Further analysis shows that this hydrophobic protein contains a region with significant amino acid sequence homology to both prokaryotic and yeast proteins involved in antibiotic resistance. Genomic Southern analysis shows that LE6cfp exists in the genomes of other phytopathogenic Cercospora species such as, for example, Cercospora beticola (Sugar beet), Cercospora nicotianae (tobacco) , and Cercospora zeae-maydis (corn) . Gene disruption of LE6 results in dramatically reduced cercosporin production in C. kikuchii grown in continuous light, loss of C. kikuchii pathogenicity on soybean, diminished transcript accumulation of another light-enhanced cDNA, an altered pigment accumulation profile, and substantial loss of auto-resistance to cercosporin. All this evidence indicates that pLE6 is responsible for moving cercosporin across the plasma membrane, i.e. that it is a membrane pump, to confer fungal resistance. This further indicates that it can be inserted into plant cells to make transgenic plants which are resistant to cercosporin. A cercosporin resistant transgenic plant is any transgenic plant that exhibits any level of cercosporin resistance as compared to the nontransformed plant. The DNA construct can be introduced into a plant using any method which provides for efficient transformation. Various methods for plant transformation include the use of Ti- or Ri-plasmids, DNA particle bombardment, micro injection, electroporation, liposome fusion, DNA bombardment, etc. See for example, Gordon-Kamm et all, The Plant Cell, Volume 2, 603-618, 1990; and Lowe et al, BIO/TECHNOLOGY, Volume 13, 677-682, 1995; all herein incorporated by reference. The plant tissue is genetically engineered with cDNA (LE6cfp) isolated from Cercospora kikuchii PR (C. kikuchii PR) and put into a plant expression vector such as, for example, pBIN/35S (Bevan, Nuc. Acids Res., Volume 12, 8711-8721. A 2.1 kb Ba HI/Kpnl fragment comprising the entire length of LE6(cfp)cDNA (Figure 2) was cloned into the polylinker site of the plant expression vector pBIN/35S as described by Bevan (supra) (Figure 7) . The following examples are intended only to further illustrate the invention and are not intended to limit the scope of the invention as described by the claims. EXAMPLE 1 Cercospora kikuchii PR was isolated from soybeans in Puerto Rico and was provided by J. B. Siclair, University of Illinois, Urbana, IL. Fungi are grown on potato dextraose medium (Difco Laboratories, Detroit, Michigan) in either liquid (PD) or agar-solidified (PDA) forms. Fungi cultured in liquid medium are grown in 50-ml volumes in 125-ml Erlenmeyer flasks on a rotary shaker (180 rpm) at 20°C under continuous white fluorescent light (approximately 15 microeinsteins m '2 s "1 or continuous dark. EXAMPLE 2 In order to isolate light-induced cDNAs, cultures of C. kikuchii PR are grown in either continuous white fluorescent light of approximately 15 microeinsteins "2 s "1 or continuous darkness either in potato dextrose (PD) broth (Difco Laboratories, Detroit, MI) or complete medium (CM) containing salts, yeast extract, and casamino acids (Jenns et al, supra) . The cultures are grown in shake culture (200 rpm) until early stationary phase. Five milliliter aliquots of culture (mycelium plus medium) are blended for 30 seconds in a Waring blender with 5 ml of distilled water. The resulting slurry is used to determine cercosporin concentration as described by Jenns et al (Phytopathology, Volume 79, 213-219, 1989; supra) . Dry weights are determined after lyophilization. EXAMPLE 3 In order to extract RNA and construct a cDNA library, mycelia are harvested from the liquid cultures, described in Example 2 above, by vacuum filtration through Miracloth, frozen in liquid nitrogen, and lyophilized. Lyophilized tissue is refrozen in liquid nitrogen and ground to a powder in a mortar and pestle prechilled with liquid nitrogen. Total RNA is extracted as described in Williamson et al (Plant Physiol., Volume 88, 1002-1007, 1988; herein incorporated by reference) . Poly(A) + RNA is extracted from total RNA by oligo(dT) cellulose chromatography as described by Maniatis et al (supra , pages 8.49 and 10.40-10.43; herein incorporated by reference) . RNA extracted from light-grown cultures, described in Example 1, is used to construct a cDNA library with the bacteriophage lambda vector lambda ZAPII (Stratagene) by using poly(A) + RNA isolated from the light-grown C. kikuchii PR. It is maintained as a bacteriophage stock and infected into Escherichia coli XL1 blue cells (Stratagene) for screening. EXAMPLE 4 To obtain cDNA clones from the cDNA library constructed from light-grown C. kikuchii poly(A) + , a subtractive hybridization technique is used as described by Maniatis et al (pages 8.49 and 10.40-10.43, supra) . First-strand cDNA is synthesized from light-grown C. kikuchii poly(A) + RNA by using [α- 32 P]dCTP. Dark-grown C. Ji uchii poly(A) + RNA is biotinylated and hybridized to the first-strand light-enhanced cDNA and hybrids and nonhybridized dark-grown C. kikuchii poly(A)+RNA are subtracted from the mixture with strepavidin as described by Sive et al (Nucleic Acids Res., Volume 16, 10937, 1988; herein incorporated by reference) . The procedure is repeated twice. After two rounds of subtraction, the remaining light-enhanced cDNA is labeled with [α- 32 P] dCTP by random hexamer priming as described by Feinberg et al (Anal. Biochem., Volume 132, 6-13, 1983; herein incorporated by reference) and this is used to probe duplicate plaque lifts, as described by Maniatis et al (pages 10.40-10.43, supra), containing the light-enhanced cDNA library. Hybridizing areas containing multiple plaques are subsequently plaque purified and the cloned DNA is converted into plasmid DNA by using a helper bacteriophage (Stratagene) and an in vivo plasmid excision technique (Stratagene, herein incorporated by reference) . EXAMPLE 5 To isolate specific clones for which corresponding mRNAs exhibit enhanced accumulation in the light, 2 μg samples of glyoxylated poly(A) + RNA are electrophoresed under denaturing conditions through a 1.2% agarose gel as described by Maniatis et al ( supra) and transferred to nitrocellulose. For slot blot analysis, either 10- or 20-μg samples are applied to nitrocellulose with a Schleicher & Schuell Minifold II . Hybridizations are performed in a 50% formamide buffer at 42° C with insert DNA from the plasmids described above in Example 4 labeled to a high specific activity with [α "3 P] dCTP by random hexamer labeling as described by Feinberg et al (supra) . The probe is removed from the slot blots after hybridization by washing in 0.1 X SSC (1 X SSC is 0.15 M NaCl plus 0.015 M sodium citrate) -0.1% sodium dodecyl sulfate at 95°C. The blots are then hybridized with a Neurospora crassa probe consisting of rDNA (genes coding for rRNA) as described by Russell et al (Mol. Gen. Gent., Volume 196, 275-282, 1984; herein incorporated by reference) . Theses control hybridizations verify that all the samples within a slot blot are equally loaded. To quantitate intensity of slot blot hybridization, the autoradiographs are analyzed by laser scanning densitometry. Six light-enhanced cDNA clones (cLEs) , cLEland cLE3-cLE7, each of which hybridize to a single distinct mRNA band on Northern blots, were identified (Figure 1) . The lengths of these transcripts range from approximately 0.8 to 6.0 kb, while the lengths of the cDNA inserts range from approximately 0.8 to 2.4 kb. Two of the cDNA clones are nearly full length, while the others range from approximately 32 to 79% of the lengths of their respective mRNAs. No transcripts for cLE6 are detected in dark-grown C. kikuchii poly(A) + RNA. MRNAs for the other light-enhanced sequences are detected at various levels in the dark-grown C. kikuchii poly(A) + RNA. These six cloned DNAs are converted into plasmid DNA by using a helper bacteriophage and an in vivo plasmid excision technique CStratogene, supra) to form plasmid pcLEl and pcLE3-pcLE7, especially CLE6-CFP, which are then infected into Escherichia coli XL1 Blue (Stratagene) cells to maintain. EXAMPLE 6 To determine the relationship between toxin synthesis and expression of the light-enhanced cDNAs in C. kikuchii PR, the kinetics of transcript and toxin accumulation are compared. Samples are collected at 24 hour intervals from a single large PD broth culture. Aliquots are used for toxin analysis as described by Jenns et al (supra) , and the remaining culture is recovered and lyophilized for dry weight determination and RNA extraction. Transcript accumulation is assessed by slot blot analysis of total RNA from all samples except the day one sample, which yielded too little tissue for RNA extraction. Signal intensities are quantitated by laser scanning densitometry. The onset of toxin accumulation occurs dramatically between days 2 and 3, lagging behind the onset of logarithmic growth by at least about 24 hours (Figure 8a ) . Transcripts for both cLE6 and cLE7 exhibit accumulation kinetics identical to that of the toxin (Figure 8b) ; i.e., each also increased dramatically between days 2 and 3. Between days 2 and 3, cercosporin levels increased from undetectable to approximately 29 nmol/mg of fungal tissue (dry weight) , while steady-state RNA levels for cLE6 and cLE7 increased approximately 16- and 4- fold, respectively. Transcripts for the other cLEs are already present at higher levels than those for cLE6 and cLE7 on day 2. They did not, however, show any marked change in steady-state level during the course of the experiment (data not shown) . Of the six cLEs, cLE6 exhibits the most striking relationship to cercosporin production. In PR, accumulation of cLE6 transcripts in the light is increased by approximately 20- fold over transcript accumulation in the dark. EXAMPLE 7 Fungal transformations were conducted as described by Upchurch et al (Applied and Environmental Microbiology, Volume 60 (12), 4592-45951994; herein incorporated by reference) . Transformants were grown on plates containing regeneration medium supplemented with lOμM bialaphos. This allows for the selection of fungal colonies which have integrated a copy of the Jbar gene from Streptomyces hygroscopicus into their genome. Putative transformants were transferred to bialaphos- containing media for several generations to ensure stability of the marker. EXAMPLE 8 The LE6cfp gene is contained within genomic clone gLE6. This 6.5kb JEcoRI genomic DNA fragment is used to construct deletion clones. The plasmid pCFP ΔBAR was constructed by deletion of a 2.5kb Clal/Hindlll fragment from gLE6 followed by ligation of the 3. lkb Clal/Hindlll Jbar "expression unit" subcloned from the plasmid pNBl (Upchurch, 1994, herein incorporated by reference) . The ar gene confers resistance to the herbicide bialaphos (Straubinger et al,Fungal Genet. Newsl., Volume 39, 82-83, 1992; herein incorporated by reference) . The plasmid pCFP GUS was constructed by excising the 6.5kb EcoRI fragment from the gLE6 plasmid. The purified insert DNA was highly diluted and exposed to T4 DNA ligase allowing it to circularize in a head-to-tail orientation. Immediately following heat inactivation of the ligase the sample was restricted with Hindlll, thus causing the gLE6 insert DNA to remain in the head-to-tail orientation with Hindlll ends. The appropriate size head-to-tail construct was gel purified and ligated in the Hindlll digested 7.lkb plasmid pNOM102 (Roberts et al, Curr. Genet., Volume 15, 177-180, 1989; herein incorporated by reference) . Transformations were performed as described above in Example 7 and transformants selected on regeneration medium amended with bialaphos. Southern analysis utilized .EcoRI digested genomic DNA and radiolabeled gLE6 insert DNA as well as the Jbar and uidA genes to determine the number and locations of insertion events. Two different disrupted versions of the LE6cfp gene were constructed and transformed into C. kikuchii PR as described above and are depicted in Figure 9a. The number and position of insertion events was evaluated by Southern hybridization analysis of twelve bialaphos-resistant transformants of each type of disruptant. Of those colonies analyzed, three were shown to contain a single copy of a disrupted version of the LE6cfp gene (Figure 9b) . The disruptants containing pLE6CFPDBar are denoted Barl and Bar2 and that containing a single copy of pLE6CFP GUS is labeled Gus3. Northern analysis was performed to assure that the disruption of the native Lecfp gene had blocked its transcription. No hybridization was shown when Barl and Bar2 total RNA was probed with LE6cfp, but a minimal signal was detected in steady state RNA isolated from Gus3 (data not shown) . EXAMPLE 9 Levels of cercosporin produced by disruptant transgenic C. kikuchii are determined by taking 10ml aliquots of fungal liquid cultures (mycelia plus medium) . The aliquots are blended in a Waring blender and treated with one volume of 5N KOH as described by Jenns et al (supra) and clarified by centrifugation. Cercosporin concentrations are determined spectrophotometrically from the A 4β0 and the molar extinction coefficient of 23,300 for cercosporin in base (Jenns et al, supra) . Samples of lyophilized mycelia are weighed in order to express cercosporin concentration as nmol/mg dry wt. Disruptant transformants Barl, Bar2, and Gus3 are tan in color, rather than bright red, when grown in PD medium. The levels of cercosporin in the transformant fungi are shown Figure 10. The levels of cercosporin production in Barl, Bar2, and Guε3 were drastically lower than that of wild-type strain PR. Cercosporin production by Barl was measured at approximately 3% of wild-type, Bar2 at approximately 6%, and Gus3 accumulated approximately 5% of light-grown PR levels. The levels are significantly lower than values routinely obtained for PR cultures grown in the dark. These measurements are consistent with the levels observed by thin-layer chromatographic separation (data not shown) . EXAMPLE 10 To determine autoresistance of the transgenic fungi to cercosporin, C. . iJuchii PR and the disruptant transformants are tested for inhibition of radial growth on agar. Fungal plugs (5mm) are inoculated onto divided petri plates with the PDA medium on one half of each plate amended by the addition of a cercosporin stock solution to give a final concentration of lOmM as outlined by Daub et al (Phytopathology, Volume 77, 1515-1520, 1987; herein incorporated by reference) . Since the cercosporin stock is prepared in acetone, the second half of each plate is amended with an equal volume of acetone. Plates are maintained at 25°C under continuous fluorescent light (80 microeinsteins "2 s "1 ) , and radial growth is measured 3 and 4 days after inoculation. Wild-type Cercospora kikuchii shows only slight growth inhibition when grown in the presence of cercosporin (Daub et al, In R. Heitz et al (ed.) , Light activated Pesticides, American Chemical Society, Washington, D.C, pages 271-280, 1987, herein incorporated by reference) . The relative growth of wild-type and disruptant C. kikuchii is evaluated in the presence of cercosporin. Disruptants Barl and Bar2 exhibited the greatest sensitivity to cercosporin, with average percent growth inhibitions of approximately 48 and 52, respectively (Figure 11) . The other transformant, Gus3, also has average percent growth inhibition of 48. The LE6cfp disruptant strains are dramatically more sensitive to cercosporin than wild-type PR. EXAMPLE 11 The aggressiveness of C. -ciJuαhii transformants in planta is determined by leaf inoculation of greenhouse grown 5-week- old soybean (Glycine max L.) cultivar Lee-68 plants. Fungal inoculum is prepared by blending approximately 0.5 g (fresh weight) of washed, dark-grown mycelia of each strain in 20 ml of sterile water in a sterile Waring blender as described by Upchurch et al (Appl. Environ. Microbiol., Volume 57, 2940- 2945, 1991, herein incorporated by reference) . Mycelial suspensions are then atomized onto the underside of the leaves until inoculum runoff is acheived. Plants are covered with plastic bags for an initial 48 hour period in reduced light to maintain humidity for infection. Lesion formation is monitored over a 14-day period. Five plants are inoculated with each fungal strain tested and the entire experiment was repeated. Thirty soybean trifoliate leaf panels (90 separate leaves) were examined in the two inoculation experiments. Irregularly shaped 2-8 mm spreading lesions with necrotic centers were observed on the upper surfaces of the Lee-68 cultivar plants 7 days after inoculation with the wild-type isolate PR. Only pinpoint flecks were observed infrequently on leaves inoculated with the LE6 disruptant Barl, Bar2, and Gus3 indicating the decreased aggressiveness of these mutants compared to the wild¬ type. No lesions were detected on plants that were mock inoculated with a water control. This decrease in aggressiveness in the disruptant fungi appears to caused by the decrease in cercosporin production in these fungi. It has been shown that cercosporin is a critical pathogenicity factor in the infection of soybean by C. kikuchii (Upchurch, 1991, supra) . Since the experiments show that the concentration of cercosporin produced by these fungal strains is much less than wild-type levels, it would be expected that these fungi would be less aggressive. In addition to decreased aggressiveness, these disruptant fungi may have decreased fitness in their natural environment since they have an increased sensitivity to their own toxin, although environmental fitness has not been tested. The foregoing detailed description is for the purpose of illustration. Such detail is solely for that purpose and those skilled in the art can make variations therein without departing from the spirit and scope of the invention. SEQUENCELISΗNG (1) GENERAL INFORMATION: (i) APPLICANT: The United States of America, As Represented by the Secretary of Agriculture and North Carolina State University (ii) TITLE OF INVENTION: Fungal Gene Encoding Resistance to the Phytotoxin Cercosporin (iii) NUMBER OF SEQUENCES: 3 (iv) CORRESPONDENCE ADDRESS: (A) ADDRESSEE: USDA-ARS-OTT (B) STREET: Room 407, BLDG. 005, BARC-W (C) CITY: Beltsville (D) STATE: Maryland (E) COUNTRY: USA (F) ZIP: 20705 (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: (C) CLASSIFICATION: (viii) ATTORNEY/AGENT INFORMATION: (A) NAME: Poulos, Gail E. (B) REGISTRATION NUMBER: 36,327 (C) REFERENCE/DOCKET NUMBER: 0045.96 (ix) TELECOMMUNICATION INFORMATION: (A) TELEPHONE: 301-504-5302 (B) TELEFAX: 301-504-5060 (2) INFORMATION FOR SEQ ID NO:l: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 2192 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (iii) HYPOTHETICAL: NO (iv) ANTI-SENSE: NO (vi) ORIGINAL SOURCE: (A) ORGANISM: Cercospora kikuchii (B) STRAIN: PR (ix) FEATURE: (A) NAME/KEY: intron (B) LOCATION: 746..798 (ix) FEATURE: (A) NAME/KEY: intron (B) LOCATION: 1199..1248 (ix) FEATURE: (A) NAME/KEY: intron (B) LOCATION: 1459..1507 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:l: GCCGTCGAAT GAGTTCCCTC ATAGCAGTCT GGACCGGCTA CTTTCCATAC ATTGACAATG 60 ACGAGCCCAG CGCGATCAAC GCATACTGAT ACAGAGTCTC ACGACGTCGT AAAGAGCGAC 120 TCGGAATCGA AACTGGAACT GGAGCACAGC GATTCGGATA ATCAAGATGA GAAGTCCAAC 180 GCTAAGTTGG CGGAACGTCC TGAAGCCAAG CCAGAAGAAG ATGAAGAACT CAATGATCAA 240 GGCGAGAGGT ACATCTGCGG CTGGCCTCTG GTATTTCTCT TGTTAGCCAT GGTCTCCACA 300 GTCTTCATTG TCGCTTTGAG CAACACCATC ATCAGCACAG CAATCCCGGC CATCACAACA 360 GCGTTCAATA GTACCCGAGA TATTGGCTGG TACAACTCTG GAGAAGCTCT TGCAGCCACT 420 GCCTTCCAAC TACCTTTCGG GCGAGCGTAT CTCTTGATGG ACCTGAAGTG GACTTTCCTC 480 GTCTCACTGG CCTTATATCT GATCGGCAGC CTGATCTGTG GTGTGGCAAA CTCTTCTGAG 540 CTTCTCATTT TTGGCCGATC GATTGCAGGA GTTGGCAACG CTGGCGTCTT CGCTGGCGTG 600 TTCATCATTA TTGCTCGAAA CGTTCCTCTG CGGAAACGCA CTTTATGCTG GATTGGTTGG 660 AGCGACTTTT GCCATTGCTG CTGTGCTGGA CCTGTCCTGG GTGGTATCTT TACTGACCGT 720 ATTAGCTGGA GGTGGTGTTT GTACAGTAAG TCTCTAGAAC CCGTGCACTT TATTCCGTTC 780 ATTGACACTT TTCAACAGTT AACCTGCCTA TCGGAGCTGT ACGTGTCGCA ATCATCATAT 840 TCCTCCTTCC ATCTCGTCCT GGCGAAAAGG CAGCAGAAGT CAAGGACCTG TCCTGGTGGC 900 AGTTCTTCCT AAAGCTCAAT CCTTTTGGGT CGGCTCTCCT ACTCGGTTCC CTGACGTGCT 960 TTTTCCTCGC CCTACAGTGG GGCGGCGGCG AATACCGTTG GAGTGCTGGT CGTGTCGTTG 1020 CTGTACTGGT GGTCTTCGCC GTCAGCTTCA TCGGATGGCT GGTTCTGCAA TACTTCCAAG 1080 GCGACGAAGC CACACTGCCA TTTAACGTTG CAAAACAGCG TACCGTTGGT GGTGCCTCTA 1140 TCTACACTCT GCATCTGAGC GCCGCATTTG GACTCGTCAT ATACTATCTG CCTCTCTGGT 1200 GAGTTGATTC ATGAGCATGC ACTGGGCTCA CGAACTGACA TTATGAAGGT TTCAAGCAGT 1260 ACGATCTGAC AGTGCCGAAG CTGCTGGTCT CAAGCAACTT GGCATCGTCA TCTCGCTCAC 1320 TCTCTCGTCA ATTGCAGCTG GCGGTGCTGT TGTAAAAATA GGATATTACT ATCCTTTCAT 1380 TTACGCCGGA ACGGTCTTAT GCAGCATCGG CTCTGGCTTG CTTTACACGA TCACACTCGA 1440 TACACCGCAA TGGGATATGT AAGTAATCGA GCTCCGACTG AATTTGAACA TTTCTAACGC 1500 ATGACAGTAT CGGTTATTCG ATCGTATTCG CCATTGGAAT CGGCGTCAGT CTCGAGCAAT 1560 CCAACGTTGC TGTCCAGACT GTCCTGCCCG ATGCTCAGAT ACCAGCAGGA ACAAGCTTGG 1620 TTCTGTTCGT CCGACTACTT GGATCAGCAA TCCCCGGACC CATCGGACAG AGTGTACTCC 1680 AGACAACACT TGCCAGTAGG CTAGGGACTG AGGTCGCAGA GCAAGCATAT GGTGGTACCG 1740 GAGCAACTGA AATCCGCTCA AAGCTCGACA ACATTTTTGG AGCTGGCACA CCTGAAGCTC 1800 GAGATGCCCT TGACGCTTTC AACGATTCTG TGACGAAGAT CTTCATGGTC GCAATCATAG 1860 TCTCATGTCT GAGTGCGCTG CCTCTTCCCC TCATCGAGCT CAAGAGCGTC AAGCGTGAGA 1920 AACGAGACAA CGAAGACGCC AAAGAAGGCA AGAAAACTAA TGGGACGACG CGTGAGATAG 1980 AAGATCCAGA GAAGGGGCAG AGTGCAGAGA TCGTGGGCAA AGCAGTGTGA GATGTGGCAT 2040 CAGACCGAGC GACGATTTTA TAGACATTGT AGCGAGCTGT TACGACTAAC GCATGTACCC 2100 AACAGAGTGT GTGGCTCAGA GGCAATAGAG CTTTGACGAC ATAATAAACC AAGAATTTTA 2160 ATGGCTACGA GTCCTCTCAA AACCTCGCCG GA 2192 (2 ) INFORMATION FOR SEQ ID NO:2 : (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1893 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA (iii) HYPOTHETICAL: NO (iv) ANTI-SENSE: NO (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2: CATACATTGA CAATGACGAG CCCAGCGCGA TCAACGCATA CTGATACAGA GTCTCACGAC 60 GTCGTAAAGA GCGACTCGGA ATCGAAACTG GAACTGGAGC ACAGCGATTC GGATAATCAA 120 GATGAGAAGT CCAACGCTAA GTTGGCGGAA CGTCCTGAAG CCAAGCCAGA AGAAGATGAA 180 GAACTCAATG ATCAAGGCGA GAGGTACATC TGCGGCTGGC CTCTGGTATT TCTCTTGTTA 240 GCCATGGTCT CCACAGTCTT CATTGTCGCT TTGAGCAACA CCATCATCAG CACAGCAATC 300 CCGGCCATCA CAACAGCGTT CAATAGTACC CGAGATATTG GCTGGTACAA CTCTGGAGAA 360 GCTCTTGCAG CCACTGCCTT CCAACTACCT TTCGGGCGAG CGTATCTCTT GATGGACCTG 420 AAGTGGACTT TCCTCGTCTC ACTGGCCTTA TATCTGATCG GCAGCCTGAT CTGTGGTGTG 480 GCAAACTCTT CTGAGCTTCT CATTTTTGGC CGATCGATTG CAGGAGTTGG CAACGCTGGC 540 GTCTTCGCTG GCGTGTTCAT CATTATTGCT CGAAACGTTC CTCTGCGGAA ACGCACTTTA 600 TGCTGGATTG GTTGGAGCGA CTTTTGCCAT TGCTGCTGTG CTGGACCTGT CCTGGGTGGT 660 ATCTTTACTG ACCGTATTAG CTGGAGGTGG TGTTTGTACA TTAACCTGCC TATCGGAGCT 720 GTACGTGTCG CAATCATCAT ATTCCTCCTT CCATCTCGTC CTGGCGAAAA GGCAGCAGAA 780 GTCAAGGACC TGTCCTGGTG GCAGTTCTTC CTAAAGCTCA ATCCTTTTGG GTCGGCTCTC 840 CTACTCGGTT CCCTGACGTG CTTTTTCCTC GCCCTACAGT GGGGCGGCGG CGAATACCGT 900 TGGAGTGCTG GTCGTGTCGT TGCTGTACTG GTGGTCTTCG CCGTCAGCTT CATCGGATGG 960 CTGGTTCTGC AATACTTCCA AGGCGACGAA GCCACACTGC CATTTAACGT TGCAAAACAG 1020 CGTACCGTTG GTGGTGCCTC TATCTACACT CTGCATCTGA GCGCCGCATT TGGACTCGTC 1080 ATATACTATC TGCCTCTCTT GGTTTCAAGC AGTACGATCT GACAGTGCCG AAGCTGCTGG 1140 TCTCAAGCAA CTTGGCATCG TCATCTCGCT CACTCTCTCG TCAATTGCAG CTGGCGGTGC 1200 TGTTGTAAAA ATAGGATATT ACTATCCTTT CATTTACGCC GGAACGGTCT TATGCAGCAT 1260 CGGCTCTGGC TTGCTTTACA CGATCACACT CGATACACCG CAATGGGATA TTATCGGTTA 1320 TTCGATCGTA TTCGCCATTG GAATCGGCGT CAGTCTCGAG CAATCCAACG TTGCTGTCCA 1380 GACTGTCCTG CCCGATGCTC AGATACCAGC AGGAACAAGC TTGGTTCTGT TCGTCCGACT 1440 ACTTGGATCA GCAATCCCCG GACCCATCGG ACAGAGTGTA CTCCAGACAA CACTTGCCAG 1500 TAGGCTAGGG ACTGAGGTCG CAGAGCAAGC ATATGGTGGT ACCGGAGCAA CTGAAATCCG 1560 CTCAAAGCTC GACAACATTT TTGGAGCTGG CACACCTGAA GCTCGAGATG CCCTTGACGC 1620 TTTCAACGAT TCTGTGACGA AGATCTTCAT GGTCGCAATC ATAGTCTCAT GTCTGAGTGC 1680 GCTGCCTCTT CCCCTCATCG AGCTCAAGAG CGTCAAGCGT GAGAAACGAG ACAACGAAGA 1740 CGCCAAAGAA GGCAAGAAAA CTAATGGGAC GACGCGTGAG ATAGAAGATC CAGAGAAGGG 1800 GCAGAGTGCA GAGATCGTGG GCAAAGCAGT GTGAGATGTG GCATCAGACC GAGCGACGAT 1860 TTTATAGACA TTGTAGCGAG CTGTTACGAC TAA 1893 (2) INFORMATION FOR SEQ ID NO:3: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 606 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (iii) HYPOTHETICAL: YES (iv) ANTI-SENSE: NO (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3: Met Thr Ser Pro Ala Arg Ser Thr His Thr Asp Thr Glu Ser His Asp 1 5 10 15 Val Val Lys Ser Asp Ser Glu Ser Lys Leu Glu Leu Glu His Ser Asp 20 25 30 Ser Asp Asn Gin Asp Glu Lys Ser Asn Ala Lys Leu Ala Glu Arg Pro 35 40 45 Glu Ala Lys Pro Glu Glu Asp Glu Glu Leu Asn Asp Gin Gly Glu Arg 50 55 60 Tyr Ile Cys Gly Trp Pro Leu Val Phe Leu Leu Leu Ala Met Val Ser 65 70 75 80 Thr Val Phe Val Phe Ile Val Ala Leu Ser Asn Thr Ile Ile Ser Thr 85 90 95 Ala Ile Pro Ala Ile Thr Thr Ala Phe Asn Arg Asp Ile Gly Trp Tyr 100 105 110 Asn Ser Gly Glu Ala Leu Ala Ala Thr Ala Phe Gin Leu Pro Phe Gly 115 120 125 Arg Ala Tyr Leu Leu Met Asp Leu Lys Trp Thr Phe Leu Val Ser Leu 130 135 140 Ala Leu Tyr Leu Ile Gly Ser Leu Ile Cys Gly Val Ala Asn Ser Ser 145 150 155 160 Glu Leu Leu Ile Phe Gly Arg Ser Ile Ala Gly Val Gly Asn Ala Gly 165 170 175 Val Phe Ala Gly Val Phe Ile Ile Ile Ala Arg Asn Val Pro Leu Arg 180 185 190 Lys Arg Thr Leu Cys Trp Ile Gly Trp Ser Asp Phe Cys His Cys Cys 195 200 205 Cys Ala Gly Pro Val Leu Gly Gly Ile Phe Thr Asp Arg Ile Ser Trp 210 215 220 Arg Trp Cys Leu Tyr Ile Asn Leu Pro Ile Gly Ala Val Arg Val Ala 225 230 235 240 lie Ile Ile Phe Leu Leu Pro Ser Arg Pro Gly Glu Lys Ala Ala Glu 245 250 255 Val Lys Asp Leu Ser Trp Trp Gin Phe Phe Leu Lys Leu Asn Pro Phe 260 265 270 Gly Ser Ala Leu Leu Leu Gly Ser Leu Thr Cys Phe Phe Leu Ala Leu 275 280 285 Gin Trp Gly Gly Gly Glu Tyr Arg Trp Ser Ala Gly Arg Val Val Ala 290 295 300 Val Leu Val Val Phe Ala Val Ser Phe Ile Gly Trp Leu Val Leu Gin 305 310 315 320 Tyr Phe Gin Gly Asp Glu Ala Thr Leu Pro Phe Asn Val Ala Lys Gin 325 330 335 Arg Thr Val Gly Gly Ala Ser Ile Tyr Thr Leu His Leu Ser Ala Ala 340 345 350 Phe Gly Leu Val Ile Tyr Tyr Leu Pro Leu Trp Phe Gin Ala Val Arg 355 360 365 Ser Asp Ser Ala Glu Ala Ala Gly Leu Lys Gin Leu Gly Ile Val Ile 370 375 380 Ser Leu Thr Leu Ser Ser Ile Ala Ala Gly Gly Ala Val Val Lys Ile 385 390 395 400 Gly Tyr Tyr Tyr Pro Phe Ile Tyr Ala Gly Thr Val Leu Cys Ser Ile 405 410 415 Gly Ser Gly Leu Leu Tyr Thr Ile Thr Leu Asp Thr Pro Gin Trp Asp 420 425 430 Ile Ile Gly Tyr Ser Ile Val Phe Ala Ile Gly Ile Gly Val Ser Leu 435 440 445 Glu Gin Ser Asn Val Ala Val Gin Thr Val Leu Pro Asp Ala Gin Ile 450 455 460 Pro Ala Gly Thr Ser Leu Val Leu Phe Val Arg Leu Leu Gly Ser Ala 465 470 475 480 Ile Pro Gly Pro Ile Gly Gin Ser Val Leu Gin Thr Thr Leu Ala Ser 485 490 495 Arg Leu Gly Thr Glu Val Ala Glu Gin Ala Tyr Gly Gly Thr Gly Ala 500 505 510 Thr Glu Ile Arg Ser Lys Leu Asp Asn Ile Phe Gly Ala Gly Thr Pro 515 520 525 Glu Ala Arg Asp Ala Leu Asp Ala Phe Asn Asp Ser Val Thr Lys Ile 530 535 540 Phe Met Val Ala Ile Ile Val Ser Cys Leu Ser Ala Leu Pro Leu Pro 545 550 555 560 Leu Ile Glu Leu Lys Ser Val Lys Arg Glu Lys Arg Asp Asn Glu Asp 565 570 575 Ala Lys Glu Gly Lys Lys Thr Asn Gly Thr Thr Arg Glu Ile Glu Asp 580 585 590 Pro Glu Lys Gly Gin Ser Ala Glu Ile Val Gly Lys Ala Val 595 600 605 INDICATIONS RELATING TO A DEPOSITED MICROORGANISM (PCT Rule 13 bis) A. The indications made below relate to the microorganism referred to in the descπption on page 5 , line 9-14 B. IDENTIFICATION OF DEPOSIT Further deposits are identified on an additional sheet j | Name of depositary institution Amencan Type Culture Collection Address of depositary institution (including postal code and country) 12301 Parklawn Drive Rockville, Maryland 20852 US Date of deposit Accession Number March 15, 1996 ATCC 97482 C. ADDITIONAL INDICATIONS (leave blank if not applicable) This information is continued on an additional sheet | | 1 microorganism is disclosed in the specification. In respect to those designations in which a European Patent is sought a sample of the deposited microorganism will be made available until the publication or the mention of the grant of the European patent or until the date on which the application has been refused or withdrawn or is deemed to be withdrawn, only the issue of such a sample to an expert nominiated by the person requesting the same (Rule 28(4) EPC). D. DESIGNATED STATES FOR WHICH INDICATIONS ARE MADE (if the indications are not for all designated States) E. SEPARATE FURNISHING OF INDICATIONS (leave blank if not applicable) The indications listed below will be submitted to the International Bureau later (specify the general nature of the indications e g , "Accession Number of Deposit") For International Bureau use only D This sheet was received by the Intemationai Bureau on- Authorized officer Form PCT/RO/134 (July 1992) Legalsofl 1995 Form PCTM5

Claims: We claim : 1. An isolated DNA sequence capable of conferring cercosporin resistance to plants. 2. An isolated DNA sequence for the expression of a cercosporin membrane pump protein. 3. A vector containing a DNA sequence which confers a major level of cercosporin resistance to cercosporin producing Cercospora fungi . 4. A transformed cell comprising a region encoding for the production of SEQ ID NO. 3. 5. The transformed cell of claim 4 wherein the cell is a prokaryotic cell. 6. An isolated protein capable of conferring cercosporin resistance to plants. 7. An isolated protein which confers a major level of cercosporin resistance to cercosporin producing Cercospora fungi. 8. A plant transformation vector containing a DNA sequence for the expression of cercosporin. 9. A transgenic plant comprising a genome which containβ genetic material for the expression of a heterologous Cercospora kikuchii membrane pump protein.

Inventors: CALLAHAN TERRENCE M, EHRENSHAFT MARILYN, UPCHURCH ROBERT G, CALLAHAN, TERRENCE, M., EHRENSHAFT, MARILYN, UPCHURCH, ROBERT, G.
Applicants: UNIV NORTH CAROLINA, US AGRICULTURE, NORTH CAROLINA STATE UNIVERSITY, THE UNITED STATES OF AMERICA, REPRESENTED BY THE SECRETARY OF AGRICULTURE
Application year: 1997
Main classification: C12N5
IPC codes: C07K14, C12N15