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  • Botany & Plant Biology 2007 - Abstract Search
    stress signaling pathways Plants encounter a combination of environmental stress conditions and to response they often utilize overlapping signaling pathways In this regard scaffold proteins are uniquely poised to integrate signals from multiple pathways by bringing interacting signaling components to proximity Scaffold protein RACK1 in metazoan mediates diverse signaling pathways and is reported to interact with more than 70 diverse proteins Loss of function alleles of three rack1 genes in Arabidopsis implicate the proteins in diverse environmental stress signaling pathways The proteins can potentially dimerize and higher levels of homo hetrodimerization were observed under water stress conditions Site directed mutagenesis in the potential sumoylation site abolished dimerization Split ubiquitin cDNA library screen identified two RACK1 interacting clones in photorespiration and UV B stress response pathways The interactions are confirmed by one to one bait prey split ubiquitin assay and by co immunoprecipitation The rack1a mutants withstand diverse environmental conditions like drought elevated temperature high intensity light and oxidative stresses significantly better than the WT plants as measured by the chlorophyll fluorescence in dark and light adapted leaves Fv Fm Especially the lower non photochemical quenching of chlorophyll fluorescence Fm Fm Fm in the mutants under oxidative stress imply that the

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=397 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    diverse environmental stress signaling pathways Plants encounter a combination of environmental stress conditions and to response they often utilize overlapping signaling pathways In this regard scaffold proteins are uniquely poised to integrate signals from multiple pathways by bringing interacting signaling components to proximity Scaffold protein RACK1 in metazoan mediates diverse signaling pathways and is reported to interact with more than 70 diverse proteins Loss of function alleles of three rack1 genes in Arabidopsis implicate the proteins in diverse environmental stress signaling pathways The proteins can potentially dimerize and higher levels of homo hetrodimerization were observed under water stress conditions Site directed mutagenesis in the potential sumoylation site abolished dimerization Split ubiquitin cDNA library screen identified two RACK1 interacting clones in photorespiration and UV B stress response pathways The interactions are confirmed by one to one bait prey split ubiquitin assay and by co immunoprecipitation The rack1a mutants withstand diverse environmental conditions like drought elevated temperature high intensity light and oxidative stresses significantly better than the WT plants as measured by the chlorophyll fluorescence in dark and light adapted leaves Fv Fm Especially the lower non photochemical quenching of chlorophyll fluorescence Fm Fm Fm in the mutants under oxidative stress imply

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=666 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    Abstract Detail Tropisms Tseng Tong Seung 1 Briggs Winslow R 2 Arabidopsis Ser Thr protein phosphatase 2A dephosphorylates PHOTOTROPIN 2 PHOT2 We found that the regulatory A1 subunit of protein phosphatase 2A PP2A interacts with PHOTOTROPIN 2 PHOT2 in yeast and in in vitro pull down assays The null mutation of PP2AA1 rcn1 ROOTS CURL IN NAPHTHYLPHTHALAMIC ACID 1 lowers the activity of PP2A to 40 60 of that of the wild type Using a phot1 5 rcn1 double mutant we found both earlier development of phototropic curvature and greater sensitivity at low fluence rates of the double mutant than the single phot1 5 mutant harboring normal RCN1 We reasoned that impaired dephosphorylation of PHOT2 might result in longer activation state for the photoreceptor and the increased photosensitivity for phototropism We found that the phosphorylation state of PHOT2 in the rcn1 mutant background was prolonged compared to PHOT2 in the wild type RCN1 background Preliminary experiments with the phot2 1 rcn1 double mutant showed that rcn1mutation has very little or no effect on the phototropic responses mediated by PHOT1 Also the rcn1 mutation did not prolong the phosphorylation state of PHOT1 suggesting that the Ser Thr PP2A activity mediated through

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=955 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    development and important for seed thermotolerance Heat shock protein 70s Hsp70s have been shown to function in protein folding protein translocation and stress responses in almost all organisms and all subcellular compartments However the function of plastid stromal Hsp70s in higher plants are still uncertain Genomic surveys revealed that there are two putative stromal Hsp70s in Arabidopsis which were denoted cpHsc70 1 and cpHsc70 2 In this study we show that cpHsc70 1 and cpHsc70 2 could indeed be imported into the chloroplast stroma Their corresponding T DNA insertion knockout mutants were isolated and designated as Δ cphsc70 1 and Δ cphsc70 2 Δ cphsc70 1 mutant plants exhibited variegated cotyledons malformed leaves growth retardation and impaired root growth In contrast no visible phenotype was observed in the Δ cphsc70 2 mutant plants under normal growth conditions However no Δ cphsc70 1 Δ cphsc70 2 double mutant could be obtained suggesting that the double mutation is lethal and stromal Hsp70s are essential for plant development When analyzed using in vitro protein import assays isolated Δ cphsc70 2 chloroplasts had normal protein import ability compared to the wild type chloroplasts while reduced import was observed in chloroplasts isolated from 7 d

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=2498 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    Yoo Chan Yul 2 Kim Woe Yeon 3 Hyun Youbong 4 Somers David E 3 Lee Ilha 4 Yun Dae Jin 5 Bressan Ray A 2 Hasegawa Paul M 2 Arabidopsis SUMO E3 ligase AtSIZ1 modulates FLD activity through SUMO modification This study establishes that loss of function siz1 mutations siz1 2 and siz1 3 cause substantial early flowering under short days which is suppressed by expressing SIZ1 siz1 mutations down regulate expression of FLOWERING LOCUS C FLC compared to wild type and partially suppress late flowering of FRI Col plant These results indicate that SIZ1 represses transition to flowering and promotes expression of FLC Genetic and molecular analyses of double mutants show that the early flowering phenotype and down regulated FLC transcript level caused by siz1 mutation are suppressed by mutations to autonomous floral promotion pathway gene FLOWERING LOCUS D FLD indicating that SIZ1 functions upstream of FLD within the autonomous pathway FLD is sumoylated in wild type but to a less extent in siz1 2 FLD has three predicted sumoylation motifs and mutations to lysine residues in these FLDK3R abolish SUMO modification of the protein These results indicate that SIZ1 facilitates SUMO conjugation to sumoylation motif s of FLD Expression of FLDK3R sumoylation defective reduces acetylation status of histone H4 in FLC chromatin relative to the expression of native FLD These results indicate that SIZ1 mediated SUMO modification of FLD represses its activity to facilitate deacetylation of histones in FLC chromatin and implicate sumoylation as a post translational control process of the autonomous floral promotion pathway The siz1 plant accumulates higher level of salicylic acid SA and expression of nahG protein in siz1 SA deficient plant strongly suppressed early flowering phenotype of siz1 This result suggests that SIZ1 may negatively regulate SA dependent stress induced flowering under non

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=2664 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    Takeda Yoshimitsu 2 Suzuki Go 4 Kawagishi Kobayashi Makiko 3 Watanabe Masao 2 Arabidopsis thaliana 3 ketoacyl ACP synthase2 AtKAS2 gene is required for embryogenesis The 3 ketoacyl ACP synthase KAS enzyme creates new carbon carbon bonds by carrying out Claisen condensation which consists of three steps The fatty acid biosynthesis 1 fab1 mutant of Arabidopsis thaliana is partially deficient in activity of Arabidopsis thaliana 3 ketoacyl ACP synthase2 AtKAS2 so we have used T DNA insertion mutant of AtKAS2 to study possible role of the AtKAS2 in plant development To obtain homozygous plants of the atkas2 mutant line the isolated heterozygous plant was allowed to self pollinate Despite extensive screening no homozygous mutant plants were identified by segregation analysis of progeny derived from atkas2 heterozygotes We couldn t find atkas2 homozygous mutant adult plants in heterozygous mutant progeny AtKAS2 gene was shown to be expressed in various plant organs except for root and highly expressed in silique The fusion of GUS to the AtKAS2 promoter demonstrated that the promoter was active in a ovule Phenotypic analysis showed that disruption of the AtKAS2 by T DNA insertion caused embryo lethality and the development of the embryos was arrested at the

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=2588 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    18 34 Unable to connect to database 13 18 34 SQL Statement is null or not a SELECT 13 18 34 Abstract Detail Growth and Vegetative Development Ingram Paul 1 Malamy Jocelyn 2 Arabidopsis thaliana mutants with altered root system plasticity during mild osmotic stress The post embryonic addition of lateral roots is modulated by changes in several environmental cues yet little is known about the molecular pathways that mediate these plastic responses We have focused our attention on the affects of water availability or osmotic stress on root plasticity in the model flowering plant Arabidopsis thaliana When Arabidopsis accession Columbia Col 7 seedlings are grown on agar plates containing osmotica lateral root formation is repressed This establishes a nice assay to look for mutants that are capable of forming lateral roots under these repressive conditions Activation tagged lines generated by Detlef Weigel in the Col 7 background are available and represent an excellent resource for screening due to the possibility of isolating both dominant and recessive mutants Segregating activation tagged lines were screened on plates containing osmotica and thirteen potential mutants were identified with increased lateral root development Further characterization of the mutants and progress toward gene identification will

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=2128 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    T cell receptor mediated signal transduction in mammals These proteins are ubiquitous in all organisms from bacteria to animals and plants Plants have a great number of immunophilins but no immune system what is their role in plants Plant immunophilins are found in multiple developmental processes The membrane bound FK506 binding FKBP immunophilin TWISTED DWARF1 TWD1 regulates the polar export of auxin by ABC transporters PGP1 and PGP19 Knock outs of TWD1 in Arabidopsis result in dwarfism and disorientated growth Is regulation of polar auxin transport a common function for TWD1 in plants A phylogenetic approach of cross species complementation of knock out mutants will be used to determine the function of TWD1 orthologs The goal is to elucidate the role of TWD1 in plant development Arabidopsis twd1 mutants are a test system for functional complementation by transformation with TWD1 orthologs from other species Depending on amino acid aa alterations acquired during evolution a more or less complete functional complementation of twd1 phenotype should be visible Sequence comparisons of the different proteins will reveal which aa positions are altered and which alterations are essential for complete complementation Likewise aa alterations without effects will also be identified Together with protein structure

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=905 (2016-02-01)
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