bluuebunny/crossref_metadata_2025_split huggingface dataset:
The promoter of the barley aleurone‐specific gene encoding a putative 7 kDa lipid transfer protein confers aleurone cell‐specific expression in transgenic rice
Authors: Kalla Roger , Shimamoto Ko , Potter Robert , Nielsen Peter Stein , Linnestad Casper , Olsen Odd‐Arne 
Published: March 2003

SummaryThis paper describes the aleurone‐specific gene Ltp2 from barley, which encodes a putative 7 kDa non‐specific lipid transfer protein. As shown by Northern and in situ hybridization analyses, the Ltp2 transcript is present in barley aleurone cells shortly after the initiation of aleurone cell differentiation. The expression of Ltp2 increases until grain mid‐maturity, but the mRNA is absent from mature grains. The Ltp2 transcript is undetectable in the embryo and vegetative tissues, confirming the aleurone specificity of the Ltp2 gene. The ability of the isolated 801 bp Ltp2 promoter to direct aleurone‐specific expression in immature barley grains is demonstrated by particle bombardment experiments. In these experiments, the activity of the Ltp2 promoter is 5% of the activity of the strong constitutive Actin1 promoter from rice, as quantified by GUS activity measurements. In stably transformed rice plants containing the Ltp2 promoter—Gus construct, the specificity of the Ltp2 promoter is confirmed in vivo by the presence of GUS activity exclusively in the aleurone layer. This study demonstrates the conserved nature of the regulatory signals involved in aleurone‐specific gene transcription in cereal grains.
Production of fertile transgenic maize plants by silicon carbide whisker‐mediated transformation
Authors: Frame Bronwyn R. , Drayton Paul R. , Bagnall Susan V. , Lewnau Carol J. , Bullock W. Paul , Wilson H. Martin , Dunwell James M. , Thompson John A. , Wang Kan 
Published: March 2003

SummaryA simple and inexpensive system for the generation of fertile, transgenic maize plants has been developed. Cells from embryogenic maize suspension cultures were transformed using silicon carbide whiskers to deliver plasmid DNA carrying the bacterial bar and uidA (gus) genes. Transformed cells were selected on medium containing the herbicide bialaphos. Integration of the bar gene and activity of the enzyme phosphinothricin acetyl transferase (PAT) were confirmed in all bialaphos‐resistant callus lines analysed. Fertile transgenic maize plants were regenerated. Herbicide spraying of progeny plants revealed that the bar gene was transmitted in a Mendelian fashion.
A mutant of Arabidopsis thaliana displaying altered patterns of cellulose deposition
Authors: Potikha Tamara , Delmer Deborah P. 
Published: March 2003

SummaryA homozygous recessive mutant of Arabidopsis thaliana has been selected which displays altered patterns of cellulose deposition. The mutant was selected because leaf and stem trichomes lacked the strong birefringence under polarized light which is characteristic of plant cells which contain highly ordered cellulose in their secondary cell walls. Compared with wild‐type A. thaliana, this mutant (designated tbr for trichome birefringence) also displays reduced birefringence in the xylem of the leaf. Direct chemical analyses of root, stem, and leaf tissues, including isolated leaf trichomes, support the conclusion that tbr is impaired in its ability to deposit secondary wall cellulose in specific cell types, most notably in trichomes where the secondary wall appears to be totally absent. Altered patterns of wound‐induced callose deposition in trichomes and surrounding cells is another trait which also co‐segregates with the tbr mutation.
The amylose content in rice endosperm is related to the post‐transcriptional regulation of the waxy gene
Authors: Wang Zong‐Yang , Zheng Fei‐Qin , Shen Ge‐Zhi , Gao Ji‐Ping , Snustad D. Peter , Li Min‐Gang , Zhang Jing‐Liu , Hong Meng‐Min 
Published: March 2003

SummaryThe waxy (Wx) gene of rice encodes a granule‐bound starch synthase (GBSS = waxy protein) required for the synthesis of amylose in endosperm. An analysis of Wx transcripts, Wx protein, and amylose content of 31 rice cultivars revealed that endosperm amylose and Wx protein contents are correlated with the ability of the cultivar to excise intron I from the leader sequence of the Wx transcript. Cultivars with high endosperm amylose content (group I) contain high levels of amylose, Wx protein, and the mature 2.3 kb Wx mRNA. Cultivars with intermediate amylose content (group II) produce substantial amounts of a large 3.3 kb Wx pre‐mRNA, with intron I still present, in addition to the mature Wx mRNA, and intermediate levels of Wx protein. Glutinous rice (group III cultivars) contains no amylose, no Wx protein, and no mature Wx mRNA; only the incompletely spliced 3.3 kb Wx pre‐mRNA is present in group III cultivars. Based on these results, it is hypothesized that the amylose content of rice endosperm is regulated at the level of Wx transcript processing, and, more specifically, at the stage of intron I excision from the Wx pre‐mRNA.
Identification of a methyl jasmonate‐responsive region in the promoter of a lipoxygenase 1 gene expressed in barley grain
Authors: Rouster Jacques , Leah Robert , Mundy John , Cameron‐Mills Verena 
Published: March 2003

SummaryA genomic DNA fragment was isolated containing 5′ upstream sequences and part of the open reading frame corresponding to the lipoxygenase 1 cDNA (LoxA) expressed in barley grains during development and germination. Lox1 transcription was shown to be methyl jasmonate (MeJA)‐ and wound‐inducible in leaves, but Lox1 transcripts were not detected in mildew‐infected leaves, although this is a commonly observed response to pathogenic attack in various plants. Transient gene expression assays were used to identify a promoter region involved in MeJA‐responsive expression. Analysis of 5′ and 3′ promoter deletions indicated that sequences between −363 and −294 conferred MeJA‐responsive expression. Deletions/replacements covering this part of the promoter further defined a MeJA‐responsive region between −331 and −291. Insertion of the region −328 to −293 into the constitutive CaMV 35S promoter conferred MeJA‐responsive expression. The 36 bp fragment contains the motif TGACG as inverted repeats, which has been previously identified as a binding site for bZIP transactivating factors. Site‐directed mutagenesis on these TGACG motifs abolished MeJA‐responsive expression, clearly identifying them as MeJA‐responsive elements. Sequence comparisons found no similar motif in other characterized promoters of MeJA‐inducible genes, but suggested a common spatial structure which may serve as a binding site for transacting factors involved in the MeJA signal transduction pathway.
Intra‐ and extracellular lipid composition and associated gene expression patterns during pollen development in Brassica napus
Authors: Piffanelli Pietro , Ross Joanne H.E. , Murphy Denis J. 
Published: March 2003

SummaryPollen development in angiosperms is regulated by the interaction of products contributed by both the gametophytic (haploid) and sporophytic (diploid) genomes. In entomophilous species, lipids are major products of both sporophytic and gametophytic metabolism during pollen development. Mature pollen grains of Brassica napus are shown to contain three major acyl lipid pools as follows: (i) the extracellular tryphine mainly consisting of medium‐chain neutral esters; (ii) the intracellular membranes, particularly endoplasmic reticulum, mainly containing phospholipids; and (iii) the intracellular storage lipids, which are mostly triacylglycerols. This paper reports on the kinetics of accumulation of these lipid classes during pollen maturation and the expression patterns of several lipid biosynthetic genes and their protein products that are differentially regulated in developing microspores/ pollen grains (gametophyte) and tapetal cells (sporophyte) of B. napus. Detailed analysis of three members of the stearoyl‐ACP desaturase (sad) gene family by Northern blotting, in situ hybridization and RT‐PCR showed that the same individual genes were expressed both in gametophytic and sporophytic tissues, although under different temporal regulation. In the tapetum, maximal expression of two marker genes for lipid biosynthesis (sad and ear) occurred at a bud length of 2–3 mm, and the corresponding gene products SAD and EAR were detected by Western blotting in 3–4 mm buds, coinciding with the maximal rates of tapetal lipid accumulation. These lipids are released following tapetal cell disintegration and are relocated to form the major structural component of the extracellular tryphine layer that coats the mature pollen grain. In contrast, in developing microspores/pollen grains, maximal expression of the lipid marker genes sad, ear, acp and cyb5 was at the 3–5 mm bud stages, with the SAD and EAR gene products detected in 4–7 mm buds. This pattern of expression coincided with accumulation of the intracellular storage and membrane lipid components of pollen. These results suggest that, although the same genes may be expressed in the sporophytic tapetal cells and in gametophytic tissues, they are regulated differentially leading to the production of the various contrasting lipidic structures that are assembled together to give rise to a viable, fertile pollen grain.
Developmental regulation of the gibberellin biosynthetic gene GA1 in Arabidopsis thaliana
Authors: Silverstone Aron L. , Chang Chien‐wei , Krol Elzbieta , Sun Tai‐ping 
Published: March 2003

SummaryThe GA1 gene of Arabidopsis thaliana encodes ent‐kaurene synthase A (KSA), which catalyzes the first committed step in the biosynthetic pathway of the plant hormone gibberellin (GA). Its location in the GA biosynthetic pathway has led to speculation that KSA regulation is one of the controlling steps. However, because KSA activity is so low that it is only measurable in Arabidopsis siliques, GA1 promoter‐GUS reporter gene fusions and quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) were used to examine the expression pattern of GA1. The results from this study indicate that GA1 gene expression is highly regulated during growth and development, and it is restricted to specific cell types at the sites of expression. GA1 promoter activity is highest in rapidly growing tissues, e.g. shoot apices, root tips, developing flowers and seeds. It is also active in the vascular tissue of some non‐growing organs, such as expanded leaves, suggesting that these leaves may be a site of GA synthesis for transport to other organs. It was also found that the first one or two introns in the GA1 gene are required for proper expression. Because of the high degree of regulation, GA1 may act as a gatekeeper, controlling the flow of metabolites into the GA biosynthetic pathway, while the levels of specific bioactive GAs are controlled by other downstream steps.
Physical mapping of the 5S ribosomal RNA genes in Arabidopsis thaliana by multi‐color fluorescence in situ hybridization with cosmid clones
Authors: Murata Minoru , Heslop‐Harrison J.S. , Motoyoshi Fusao 
Published: March 2003

SummaryThe 5S ribosomal RNA genes were mapped to mitotic chromosomes of Arabidopsis thaliana by fluorescence in situ hybridization (FISH). In the ecotype Landsberg erecta, hybridization signals appeared on three pairs of chromosomes, two of which were metacentric and the other acrocentric. Hybridization signals on one pair of metacentric chromosomes were much stronger than those on the acrocentric and the other pair of metacentric chromosomes, probably reflecting the number of copies of the genes on the chromosomes. Other ecotypes, Columbia and Wassilewskija, had similar chromosomal distribution of the genes, but the hybridization signals on one pair of metacentric chromosomes were very weak, and detectable only in chromosomes prepared from young flower buds. The chromosomes and arms carrying the 5S rDNA were identified by multi‐color FISH with cosmid clones and a centromeric 180 bp repeat as co‐probes. The metacentric chromosome 5 and its L arm carries the largest cluster of the genes, and the short arm of acrocentric chromosome 4 carries a small cluster in all three ecotypes. Chromosome 3 had another small cluster of 5S rRNA genes on its L arm. Chromosomes 1 and 2 had no 5S rDNA cluster, but they are morphologically distinguishable; chromosome 1 is metacentric and 2 acrocentric. Using the 5S rDNA as a probe, therefore, all chromosomes of A. thaliana could be identified by FISH. Chromosome 1 is large and metacentric; chromosome 2 is acrocentric carrying 18S‐5.8S‐25S rDNA clusters on its short arm; chromosome 3 is metacentric carrying a small cluster of 5S rDNA genes on its L arm; chromosome 4 is acrocentric carrying both 18S‐5.8S‐25S and 5S rDNAs on its short (L) arm; and chromosome 5 is metacentric carrying a large cluster of 5S rDNA on its L arm.
The plant 2‐Cys peroxiredoxin BAS1 is a nuclear‐encoded chloroplast protein: its expressional regulation, phylogenetic origin, and implications for its specific physiological function in plants
Authors: Baier Margarete , Dietz Karl‐Josef 
Published: March 2003

Summary2‐Cys peroxiredoxins constitute a family of enzymes which catalyze the transfer of electrons from sulfhydryl residues to peroxides and are ubiquitously distributed among all organisms. This paper characterizes the higher plant 2‐Cys‐peroxiredoxin BAS1. (i) Escherichia coli over‐expressing BAS1 exhibit increased tolerance for alkyl hydroperoxides in vivo. This result substantiates the peroxiredoxin function of BAS1. (ii) BAS1 protein is associated with the soluble chloroplast fraction of mesophyll protoplasts. Import and processing of in vitro‐transcribed and cell‐free translated BAS1 protein into isolated chloroplasts provides conclusive evidence that the plant‐specific N‐terminal extension of bas1 encodes the chloroplast import signal which targets the pre‐form of BAS1 to the chloroplast stroma where it is cleaved to its mature size. (iii) Genomic analysis reveals that the targeting signal is encoded by a separate exon in Arabidopsis thaliana. (iv) The amino acid sequence of the BAS1 core protein of higher plants has a higher degree of similarity to open reading frames in the genome of the bluegreen algae Synechochystis PCC sp. 6803 and in the plastome of the red algae Porphyra purpurea than to any other nuclear‐encoded 2‐Cys peroxiredoxin. Therefore, it is tempting to speculate that the chloroplast import signal was added to an ancestor gene of endosymbiotic origin in the course of plant evolution. (v) The bas1 gene expression is regulated under the control of the cellular redox state which is in accordance with the anti‐oxidant function of the enzyme. While oxidative stressors increased expression only slightly, antioxidants such as reduced thiols strongly suppressed the transcript level. The implications of these findings are discussed with respect to the possible physiological functions of BAS1.
Gating of epidermal plasmodesmata is restricted to the leading edge of expanding infection sites of tobacco mosaic virus (TMV)
Authors: Oparka K.J. , Prior D.A.M. , Cruz S. Santa , Padgett H.S , Beachy R.N. 
Published: March 2003

SummaryPlasmodesmatal gating in epidermal cells of Nicotianatabacum was examined in expanding infection sites of tobacco mosaic virus (TMV) expressing a fusion between the viral movement protein and the green fluorescent protein (MP‐GFP). The infection sites were circular in profile and within 3 days post‐inoculation had developed a brightly fluorescent leading edge, giving them a characteristic ‘halo’ shape. Co‐localization of MP‐GFP with callose demonstrated that nearly all epidermal cell plasmodesmata were targeted with MP‐GFP. The fusion protein was located in the centre of the plasmodesmal pore, between paired callose platelets. Increase in plasmodesmatal size exclusion limit, as determined by the passage of microinjected 10 kDa Texas Red dextran, was restricted predominantly to cells within the fluorescent halo, and was virtually absent from cells in the centre of the expanding infection site. The plasmodesmata of these cells, however, remained fluorescently labelled with MP‐GFP. Injections outside the fluorescent infection site failed to show movement of dextran, while dextran injected into cells at the leading edge moved inwards towards the centre of the lesion but not outwards into cells lacking GFP. Leaf incisions through cells ahead of the infection front halted the advance of the virus, indicating that virus replication was absent in non‐fluorescent cells outside the infection site. The data provide the first demonstration that within an expanding infection site plasmodesmatal gating is under temporal control.
Genotype and environment interact to control dormancy and differential expression of the VIVIPAROUS 1 homologue in embryos of Avena fatua
Authors: Jones H.D. , Peters N.C.B. , Holdsworth M.J. 
Published: March 2003

SummaryEmbryo dormancy is a reversible developmental state during which germination is repressed. In this study, inbred lines of Avena fatua were used to analyse the influence of genotype and environment on the dormant phenotype, and on expression of the homologue of the maize transcription factor VIVIPAROUS 1 (afVP 1). The cDNA for afVP 1 was cloned from mature embryos. Analysis of the predicted protein sequence revealed a high degree of similarity to other VP 1/ABI 3‐related transcription factors, in particular in four regions previously shown to be highly conserved, including the BR2 region that has been shown to interact with several classes of sequence‐specific DNA binding proteins. The potential of imbibed mature embryos for dormancy was analysed and shown to be determined primarily by genotype and secondarily by previous environmental experience of the mature seed acting on embryo genotype. Under all conditions studied, expression of afVP 1 and the A. fatua homologue of Em (shown in maize to be regulated by VP 1 during embryo maturation) were positively correlated with the dormant phenotype, whereas expression of A. fatua AMY‐related RNAs was negatively correlated with dormancy (in barley AMY 6–4 has been shown to be repressed by VP 1). Expression of afVP 1 RNA was also shown in the dry seed to be positively correlated with the length of time required for seeds of the inbred lines to after‐ripen. These results suggest new functions for the VP 1 transcription factor family in the control of dormancy‐related processes in embryo cells of mature seeds, and the up‐regulation of afVP 1 and afEm RNAs in the dormant state suggests that they are regulated by a switching mechanism in the mature seed that shows some aspects of reversibility.
A role for the vacuole in auxin‐mediated control of cytosolic pH by Vicia mesophyll and guard cells
Authors: Frohnmeyer Hanns , Grabov Alexander , Blatt Michael R. 
Published: March 2003

SummaryA role for cytosolic pH (pHi) in hormonal signalling and transport control in plants has long been mooted. Yet, while changes in pHi are a common consequence of hormonal stimuli in plant cells and contribute to hormonally evoked ion channel control, the origins of these changes remain unknown. To examine a possible role for the tonoplast and vacuolar compartment in these events, pHi was measured in the presence of auxins and during cytosolic H+ loading with weak acid in vacuolate and evacuolate protoplasts, both from mesophyll and guard cells of Vicia faba L. Evacuolate protoplasts were obtained following ultracentrifugation on Percoll gradients, and pHi of single protoplasts was recorded in both vacuolate and evacuolate preparations using fluorescence ratio microphotometry and the pH‐sensitive dye BCECF. External pH measurements indicated a roughly twofold increase in the rate of net H+ secretion in evacuolate compared with vacuolate protoplasts, and showed that evacuolate protoplasts retained the characteristic stimulation of H+ secretion in the presence of auxin. BCECF fluorescence recording gave resting pHi values near 7.5, and evacuolation had no significant effect on this parameter. Reversible decreases of 0.1–0.2 units in pHi were evoked in vacuolate protoplasts by 10 μM concentrations of the auxins 1‐naphthalene acetic acid and 3‐indoyl‐acetic acid, and not by the inactive (anti‐auxin) analogue 2‐naphthalene‐acetic acid. However, auxin treatments failed to evoke a change in pHi in all but one of 12 experiments with evacuolate protoplasts. Evacuolation also appeared to reduce the transient, dynamic H+ buffering capacity of the protoplasts in the face of acid pHi loads imposed by adding Na+‐butyrate to the bath. These results implicate the tonoplast or vacuolar compartment in short‐term pHi homeostasis and generation of hormonally evoked H+ signalling in plant cells; they also conform with the view that the decrease in pHiper se is not a primary determinant in the stimulation of H+ secretion by auxin.
A bifunctional oleate 12‐hydroxylase: desaturase from Lesquerella fendleri
Authors: Broun Pierre , Boddupalli Sekhar , Somerville Chris 
Published: March 2003

Summary LFAH12, an oleate 12‐hydroxylase gene from Lesquerella fendleri (L.) was isolated on the basis of nucleotide sequence similarity to an oleate hydroxylase gene from Ricinus communis (L.). Transgenic Arabidopsis plants containing the Lesquerella gene under transcriptional control of the cauliflower mosaic virus 35S promoter accumulated ricinoleic, lesquerolic and densipolic acids in seeds, but not in leaves or roots. However, hydroxylase activity was detectable in crude extracts of vegetative tissues. The discrepancy between the presence of activity and the lack of hydroxy fatty acids suggests selective removal and breakdown of hydroxy fatty acids in vegetative organs. High levels of LFAH12 mRNA accumulation did not lead to correspondingly high levels of protein accumulation, suggesting that accumulation of the hydroxylase may be controlled post‐transcriptionally. Expression of the L. fendleri gene in transgenic plants of a fad2 mutant of Arabidopsis, which is deficient in cytoplasmic oleate Δ12 desaturase activity, resulted in partial suppression of the mutant phenotype in roots. Thus, unlike the hydroxylase from R. communis, the L. fendleri enzyme has both hydroxylase and desaturase activities. Fusion of the 5′ flanking region of the LFAH12 gene to the β‐glucuronidase coding sequence resulted in a high level of early seed‐specific expression of β‐glucuronidase activity in transgenic Arabidopsis plants.
DET1 represses a chloroplast blue light‐responsive promoter in a developmental and tissue‐specific manner in Arabidopsis thaliana
Authors: Christopher David A. , Hoffer Paul H. 
Published: March 2003

SummaryThe chloroplast psbD‐psbC loci, which encode the D2 and CP43 subunits of the photosystem II reaction center, respectively, are regulated by a blue light‐responsive promoter (BLRP). It has recently been shown in barley seedlings that activation of psbD‐psbC transcription by blue light involves inhibition of a protein kinase that represses the BLRP in the dark. To elucidate further the photosensory pathways regulating the psbD BLRP, the effects of three nuclear mutations on the expression of the BLRP in chloroplasts of Arabidopsis thaliana were examined. The mutants used included the det1–1 and det1–6 alleles for the nuclear protein DET1, involved in repressing photomorphogenesis, and the cry1 gene for the blue light photoreceptor, cryptochrome (CRY1), involved in hypocotyl elongation. The BLRP was not significantly expressed in cotyledons of light‐grown wild‐type seedlings, unlike the light‐responsive expression of the chloroplast, psbA and rbcL, and nuclear, Lhcb and Chs, genes. Analysis of the mutants revealed that DET1 represses transcription from the BLRP in a developmental and tissue‐specific manner, which is unique from the effects that DET1 has on other light‐regulated promoters. In addition, the cry1 mutation did not reduce the expression of the BLRP in response to blue light. This suggests that the BLRP is regulated by a different photosensory system relative to CRY1. A model is proposed involving blue light, DET1 and phytochrome in regulating transcription from the psbD BLRP.