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  • Botany & Plant Biology 2007 - Abstract Search
    Carbon dioxide levels in the troposphere are expected to steadily increase ca 50 from present levels in less than fifty years The amount of ozone is also expected to increase over this time Most agricultural regions in the United States are exposed to elevated levels of ozone sometime during the growing season Previous work showed that increased ozone levels have detrimental effects on many crop plants Soybeans Glycine max are especially sensitive to elevated levels of ozone and show significant yield loss when continuously exposed to above ambient levels of ozone Unlike CO 2 trophospheric levels of ozone fluctuate daily so that soybeans are exposed to varying levels of this ROS throughout the growing season We are particularly interested in understanding how increasing levels of tropospheric ozone effect soybeans To this end we measured the gene expression levels of Ascorbate Peroxidase APX1 an enzyme involved in the antioxidant defense system in soybean plants exposed to elevated ozone 20 above ambient elevated CO 2 550 ppm both elevated ozone and CO 2 or ambient conditions Soybeans were grown under field conditions at the SoyFACE field site in Champaign Illinois Leaf samples were collected five times throughout the growing season We used

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=2239 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    turgor The adjustment of water transport is fundamental to plant adaptation to many challenging environmental conditions The discovery of aquaporins as membrane channels facilitating water transfer and recent insights into their gating properties have opened new avenues for elucidating regulation mechanisms at a molecular level But their significance for whole plant adaptation remains poorly documented This work aims to integrate advances in molecular biology of aquaporin gating with whole plant hydraulics and hydraulically controlled processes Particularly the significance of aquaporin gating in roots for stomatal functioning and growth of leaves was investigated We induced aquaporin gating in maize roots by acid load H 2 O 2 and anoxia Under all these conditions aquaporin gating decreases cell turgor in the leaf elongation zone and dramatically reduced leaf growth However these effects could only be observed when the plant transpired substantially attributing a critical role for aquaporins under high evaporative demand Negligible effects of aquaporin gating on transpiration were observed indicating that aquaporin gating does not induce stomatal closure Overall we show that aquaporin gating modifies the hydraulic architecture of the whole plant with consequences for plant growth but not for transpiration Turgor measurements demonstrate that leaf growth responses to aquaporin gating

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=899 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    flowering plant genus Aquilegia have undergone a very recent adaptive radiation and present a unique opportunity to investigate the molecular genetic changes underlying adaptations Species in this genus have spectacularly different floral morphologies with specializations to different pollinators In addition species differ radically in their habitats ranging from coastal forests to desert springs to the high alpine Because species in the genus are cross compatible it should be possible to dissect the genetic basis for essentially any trait in any species Currently a diverse array of molecular genomic tools are being created for Aquilegia These include ESTs 85 000 genetic and physical maps BAC end sequencing and gene silencing through VIGS We have already used some of these resources to investigate the molecular basis of convergent evolution for floral color and found strong evidence for convergence at the molecular level These resources have also led to investigations of the evolutionary origins of a novel floral organ staminodia At a broader phylogenetic scale comparative genomic studies will be particularly amenable because Aquilegia is a member of the basal eudicot family Ranunculaceae which is nearly equidistant between the eudicot model systems such as Arabidopsis and the monocot model systems such as rice

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=2262 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    13 16 25 Unable to connect to database 13 16 25 SQL Statement is null or not a SELECT 13 16 25 Abstract Detail Plant Pathogen Interactions Peethambaran Bela 1 Wang Lin 2 Mitra Raka 2 Botanga Chris 2 Qi Yiping 2 Glazebrook Jane 2 Arabidopsis 14 3 3 nu is involved in defense against Pseudomonas syringae Plants have evolved complex and sophisticated mechanisms to survive attack by microbial pathogens In response to pathogen exposure multiple host signaling networks are activated resulting in the differential expression of hundreds of plant genes In order to identify host genes that are required for pathogen defense we have used a reverse genetics approach involving the inactivation of pathogen induced plant genes Using microarray experiments we identified a set of Arabidopsis thaliana genes that are transcriptionally induced in response to Pseudomonas syringae Psm4326 We determined whether inactivation of each gene by a T DNA insertion resulted in enhanced disease susceptibility to P syringae From this screening we identified a 14 3 3 nu protein that is required for defense against P syringae We are currently conducting functional analyses on this protein to better understand the role of 14 3 3 proteins in disease signaling

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=1117 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    Participates in Both Cytoplasmic and Nuclear Processes ADFs modulate rates of actin polymerization and depolymerization by severing actin filaments and enhancing actin filament turnover Higher plant genomes contain at least four ancient classes of ADF genes This study examines one member of the ADF family in Arabidopsis ADF9 Although microarray gene expression data is available for ADF9 little is known about the functions of the protein encoded by this gene ADF9 promoter GUS reporter fusions showed that ADF9 was constitutively expressed with the highest levels in fast expanding tissues such as the apical meristem root tip and callus Expression of the GUS reporter gene was greatly increased in the root tip meristem trichomes and shoot apical meristem in response to various hormonal treatments To gain insight into possible gene functions we analyzed two ADF9 T DNA insertion mutants The knockout and knockdown mutants adf9 1 and adf9 2 had a 99 fold and 2 fold reduction in transcript levels respectively Compared to wild type the mutant plants were smaller in size flowered early and had an increased number of primary inflorescences and longer branches An ADF9 expression clone complemented all the adf9 1 mutant phenotypes In addition we found that

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=324 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    3 Arabidopsis APP1 is a rate limiting component of Auxin signalling required for activation of DR5 like Auxin response elements Arabidopsis APP1 is a membrane associated soluble aminopeptidase with activity against N terminal Arg Pro Leu Tyr X Pro Trp residues APP1 is a single copy gene and was originally isolated by its weak affinity for the auxin transport inhibitor 1 Naphthylphthalamic acid NPA Enzymatic activity of APP1 is partially inhibited by NPA and the similar auxin transport inhibitor DCPFA although activation is seen at higher NPA concentrations Mutations in APP1 result in drastically reduced growth Overexpression results in increased growth enhanced lateral root formation and decreased seed set Treatment of app1 with auxin does not restore growth Treatment of APP1 overexpressors with NPA restores wild type growth APP1 expression is induced by auxin wounding and jasmonic acid However IAA treatment upto 500nM decreases APP1 protein levels indicating enhanced turnover but increases then after upto 5μM tested APP1 exhibits affinity for WPP peptide motifs and binds diprolyl motifs in AUX IAA proteins with relatively high affinity in vivo and in vitro at different auxin gradients for IAA1 and IAA7 Binding severly decreases when iaa7 diprolyl mutant peptides are substituted in the pulldowns but is auxin independent when the iaa1 mutant used DR5 GUS activity and transcription are barely detectable in the app1 knockout mutant background even after auxin treatment analogous to DR5 Juglone treatment Juglone and MG132 enhances AtAPP1 interaction in the pull down assays Increase APP1 activity results in ectopic DR5 GUS expression in the enhanced Tyr AP activity atapp1 5 mutant background However app1 mutants exhibit no detectable alterations in auxin accumulation or transport These results suggest that activation of DR5 like auxin response elements by Auxin Response Factors requires APP1 dependent degradation of Aux IAA repressor proteins

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=694 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    Arabidopsis APP1 is a rate limiting component of Auxin signalling required for activation of DR5 like Auxin response elements Arabidopsis APP1 is a membrane associated soluble aminopeptidase with activity against N terminal Arg Pro Leu Tyr X Pro Trp residues APP1 is a single copy gene and was originally isolated by its weak affinity for the auxin transport inhibitor 1 Naphthylphthalamic acid NPA Enzymatic activity of APP1 is partially inhibited by NPA and the similar auxin transport inhibitor DCPFA although activation is seen at higher NPA concentrations Mutations in APP1 result in drastically reduced growth Overexpression results in increased growth enhanced lateral root formation and decreased seed set Treatment of app1 with auxin does not restore growth Treatment of APP1 overexpressors with NPA restores wild type growth APP1 expression is induced by auxin wounding and jasmonic acid However IAA treatment upto 500nM decreases APP1 protein levels indicating enhanced turnover but increases then after upto 5μM tested APP1 exhibits affinity for WPP peptide motifs and binds diprolyl motifs in AUX IAA proteins with relatively high affinity in vivo and in vitro at different auxin gradients for IAA1 and IAA7 Binding severly decreases when iaa7 diprolyl mutant peptides are substituted in the pulldowns but is auxin independent when the iaa1 mutant used DR5 GUS activity and transcription are barely detectable in the app1 knockout mutant background even after auxin treatment analogous to DR5 Juglone treatment Juglone and MG132 enhances AtAPP1 interaction in the pull down assays Increase APP1 activity results in ectopic DR5 GUS expression in the enhanced Tyr AP activity atapp1 5 mutant background However app1 mutants exhibit no detectable alterations in auxin accumulation or transport These results suggest that activation of DR5 like auxin response elements by Auxin Response Factors requires APP1 dependent degradation of Aux IAA repressor proteins These

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=424 (2016-02-01)
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  • Botany & Plant Biology 2007 - Abstract Search
    2 binding proteins encoded in the Arabidopsis genome are predicted to mediate cellular responses to Ca 2 fluctuations In the present work we find two related putative Ca 2 sensors CML23 and CML24 regulate the transition to flowering The cml24 4 allele behaves as a loss of function and causes late flowering specifically under long days indicating the CML24 is required for proper functioning of the photoperiod pathway Conversely cml24 2 with a substitution of a conserved amino acid in an EF hand Ca 2 binding motif flowers early Opposing phenotypes suggest that CML24 can act as a switch in the photoperiod pathway regulating flowering transition Based on quantitative RT PCR we place CML24 function upstream of Constans CO cml24 4 has reduced CO expression cml24 2 has elevated CO expression Mutants harboring loss of function alleles of both CML24 and the closely related paralog CML23 are also defective in the autonomous pathway regulating flowering transition cml23 cml24 double mutants have elevated Flowering Locus C FLC expression and flower late under all photoperiods Both single and double mutants respond normally to gibberellin and vernalization These roles for CML23 and CML24 in regulating flowering transition may link circadian and light regulated

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=494 (2016-02-01)
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