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Arabidopsis Genes (arabidopsi + gene)
Selected AbstractsThe timely deposition of callose is essential for cytokinesis in ArabidopsisTHE PLANT JOURNAL, Issue 1 2009Knut Thiele Summary The primary plant cell wall is laid down over a brief period of time during cytokinesis. Initially, a membrane network forms at the equator of a dividing cell. The cross-wall is then assembled and remodeled within this membrane compartment. Callose is the predominant luminal component of the nascent cross-wall or cell plate, but is not a component of intact mature cell walls, which are composed primarily of cellulose, pectins and xyloglucans. Widely accepted models postulate that callose comprises a transient, rapid spreading force for the expansion of membrane networks during cytokinesis. In this study, we clone and characterize an Arabidopsis gene, MASSUE/AtGSL8, which encodes a putative callose synthase. massue mutants are seedling-lethal and have a striking cytokinesis-defective phenotype. Callose deposition was delayed in the cell plates of massue mutants. Mutant cells were occasionally bi- or multi-nucleate, with cell-wall stubs, and we frequently observed gaps at the junction between cross-walls and parental cell walls. The results suggest that the timely deposition of callose is essential for the completion of plant cytokinesis. Surprisingly, confocal analysis revealed that the cell-plate membrane compartment forms and expands, seemingly as far as the parental wall, prior to the appearance of callose. We discuss the possibility that callose may be required to establish a lasting connection between the nascent cross-wall and the parental cell wall. [source] The Arabidopsis ARGOS-LIKE gene regulates cell expansion during organ growthTHE PLANT JOURNAL, Issue 1 2006Yuxin Hu Summary Cell expansion, and its coordination with cell division, plays a critical role in the growth and development of plant organs. However, the genes controlling cell expansion during organogenesis are largely unknown. Here, we demonstrate that a novel Arabidopsis gene, ARGOS-LIKE (ARL), which has some sequence homology to the ARGOS gene, is involved in this process. Reduced expression or overexpression of ARL in Arabidopsis results in smaller or larger cotyledons and leaves as well as other lateral organs, respectively. Anatomical examination of cotyledons and leaves in ARL transgenic plants demonstrates that the alteration in size can be attributed to changes in cell size rather than cell number, indicating that ARL plays a role in cell expansion-dependent organ growth. ARL is upregulated by brassinosteroid (BR) and this induction is impaired in the BR-insensitive mutant bri1, but not in the BR-deficient mutant det2. Ectopic expression of ARL in bri1,119 partially restores cell growth in cotyledons and leaves. Our results suggest that ARL acts downstream of BRI1 and partially mediates BR-related cell expansion signals during organ growth. [source] Multiple GUS expression patterns of a single Arabidopsis geneANNALS OF APPLIED BIOLOGY, Issue 1 2009Ekrem Dündar Abstract Ten independent transposant lines with gene or enhancer traps (ET) inserted into the same gene (At2g01170) were identified in Arabidopsis thaliana. Transposon insertions were confirmed for each line. Only three of five ET lines and only one of the five gene trap (GT) lines displayed uidA (GUS) staining. The GUS (,-glucuronidase) expression patterns of the ET lines were different in all three lines. In the GT line, the GUS expression was restricted to the vascular tissue under all conditions examined. The variation in ET GUS expression suggests that each ET was controlled by different enhancer elements or the different elements of the trapped locus may give rise to different GUS expression patterns. Of five GT lines, three have the GUS gene in the same orientation as the At2g01170 open reading frame, yet only one yielded GUS staining. Regardless of the insertion construct, only those transposants with an insertion at the 3, end of the gene yielded GUS staining. Some transposants displayed a longer root phenotype in the presence of kanamycin that was also observed in 3, insertion sites in At2g01170. Taken together, these data show that insertions in the 5, end of the gene disrupted expression and emphasise the complexity encountered with ET and GT constructs to characterise the expression patterns of genes of interest based solely on GUS expression patterns. [source] Genomics of cellulose biosynthesis in poplarsNEW PHYTOLOGIST, Issue 1 2004Chandrashekhar P. Joshi Summary Genetic improvement of cellulose production in commercially important trees is one of the formidable goals of current forest biotechnology research. To achieve this goal, we must first decipher the enigmatic and complex process of cellulose biosynthesis in trees. The recent availability of rich genomic resources in poplars make Populus the first tree genus for which genetic augmentation of cellulose may soon become possible. Fortunately, because of the structural conservation of key cellulose biosynthesis genes between Arabidopsis and poplar genomes, the lessons learned from exploring the functions of Arabidopsis genes may be applied directly to poplars. However, regulation of these genes will most likely be distinct in these two-model systems because of their inherent biological differences. This research review covers the current state of knowledge about the three major cellulose biosynthesis-related gene families from poplar genomes: cellulose synthases, sucrose synthases and korrigan cellulases. Furthermore, we also suggest some future research directions that may have significant economical impacts on global forest product industries. [source] Characterization of Arabidopsis genes involved in biosynthesis of polyamines in abiotic stress responses and developmental stagesPLANT CELL & ENVIRONMENT, Issue 11 2003K. URANO ABSTRACT To characterize the genes for enzymes involved in the biosynthesis of polyamines (PAs), their expression profiles were investigated and the levels of PAs in Arabidopsis thaliana quantified. In the Arabidopsis genome, eight genes involved in PAs biosynthesis were identified and the expression profiles of these genes were analysed, not only under abiotic stress to determine whether they were stress-inducible, constitutive, or stress-repressible, but also in various organs to show their tissue specificity. AtADC2 and AtSPMS mRNAs, encoding arginine decarboxylase and spermine synthase, clearly increased in response to NaCl and dehydration and abscisic acid treatments. Stress-inducible accumulation of AtADC2 mRNA correlated with putrescine (Put) accumulation under NaCl and dehydration treatments. In a cold condition, AtSAMDC2 mRNA increased significantly. AtADC2 and AtSAMDC2 mRNA were expressed in sexual organs such as flowers, buds and immature siliques. PAs also accumulated in sexual organs. These results suggest that the transcripts of eight genes involved in PA biosynthesis show different profiles of expression not only in response to environmental stress but also during plant development. [source] Characterization of a sub-family of Arabidopsis genes with the SPX domain reveals their diverse functions in plant tolerance to phosphorus starvationTHE PLANT JOURNAL, Issue 6 2008Ke Duan Summary Four genes of Arabidopsis (At5g20150, At2g26660, At2g45130 and At5g15330) encoding no conservative region other than an SPX domain (SYG1, Pho81 and XPR1) were named AtSPX1,AtSPX4. The various subcellular localizations of their GFP fusion proteins implied function variations for the four genes. Phosphate starvation strongly induced expression of AtSPX1 and AtSPX3 with distinct dynamic patterns, while AtSPX2 was weakly induced and AtSPX4 was suppressed. Expression of the four AtSPX genes was reduced to different extents in the Arabidopsis phr1 and siz1 mutants under phosphate starvation, indicating that they are part of the phosphate-signaling network that involves SIZ1/PHR1. Over-expression of AtSPX1 increased the transcript levels of ACP5, RNS1 and PAP2 under both phosphate-sufficient and phosphate-deficient conditions, suggesting a potential transcriptional regulation role of AtSPX1 in response to phosphate starvation. Partial repression of AtSPX3 by RNA interference led to aggravated phosphate-deficiency symptoms, altered P allocation and enhanced expression of a subset od phosphate-responsive genes including AtSPX1. Our results indicate that both AtSPX1 and AtSPX3 play positive roles in plant adaptation to phosphate starvation, and AtSPX3 may have a negative feedback regulatory role in AtSPX1 response to phosphate starvation. [source] Gene duplication, exon gain and neofunctionalization of OEP16 -related genes in land plantsTHE PLANT JOURNAL, Issue 5 2006Sinéad C. Drea Summary OEP16, a channel protein of the outer membrane of chloroplasts, has been implicated in amino acid transport and in the substrate-dependent import of protochlorophyllide oxidoreductase A. Two major clades of OEP16-related sequences were identified in land plants (OEP16-L and OEP16-S), which arose by a gene duplication event predating the divergence of seed plants and bryophytes. Remarkably, in angiosperms, OEP16-S genes evolved by gaining an additional exon that extends an interhelical loop domain in the pore-forming region of the protein. We analysed the sequence, structure and expression of the corresponding Arabidopsis genes (atOEP16-S and atOEP16-L) and demonstrated that following duplication, both genes diverged in terms of expression patterns and coding sequence. AtOEP16-S, which contains multiple G-box ABA-responsive elements (ABREs) in the promoter region, is regulated by ABI3 and ABI5 and is strongly expressed during the maturation phase in seeds and pollen grains, both desiccation-tolerant tissues. In contrast, atOEP-L, which lacks promoter ABREs, is expressed predominantly in leaves, is induced strongly by low-temperature stress and shows weak induction in response to osmotic stress, salicylic acid and exogenous ABA. Our results indicate that gene duplication, exon gain and regulatory sequence evolution each played a role in the divergence of OEP16 homologues in plants. [source] A collection of 11 800 single-copy Ds transposon insertion lines in ArabidopsisTHE PLANT JOURNAL, Issue 6 2004Takashi Kuromori Summary More than 10 000 transposon-tagged lines were constructed by using the Activator (Ac)/Dissociation (Ds) system in order to collect insertional mutants as a useful resource for functional genomics of Arabidopsis. The flanking sequences of the Ds element in the 11 800 independent lines were determined by high-throughput analysis using a semi-automated method. The sequence data allowed us to map the unique insertion site on the Arabidopsis genome in each line. The Ds element of 7566 lines is inserted in or close to coding regions, potentially affecting the function of 5031 of 25 000 Arabidopsis genes. Half of the lines have Ds insertions on chromosome 1 (Chr. 1), in which donor lines have a donor site. In the other half, the Ds insertions are distributed throughout the other four chromosomes. The intrachromosomal distribution of Ds insertions varies with the donor lines. We found that there are hot spots for Ds transposition near the ends of every chromosome, and we found some statistical preference for Ds insertion targets at the nucleotide level. On the basis of systematic analysis of the Ds insertion sites in the 11 800 lines, we propose the use of Ds -tagged lines with a single insertion in annotated genes for systematic analysis of phenotypes (phenome analysis) in functional genomics. We have opened a searchable database of the insertion-site sequences and mutated genes (http://rarge.gsc.riken.go.jp/) and are depositing these lines in the RIKEN BioResource Center as available resources (http://www.brc.riken.go.jp/Eng/). [source] | ||||||||||