archive-org.com » ORG » B » BOTANYCONFERENCE.ORG

Total: 597

Choose link from "Titles, links and description words view":

Or switch to "Titles and links view".
  • Botany & Plant Biology 2007 - Abstract Search
    Rebecca 1 Mason Michael 1 Mathews Dennis 2 Palmer Christine 1 Argyros D Aaron 1 Rashotte Aaron 3 Kieber Joseph 3 Schaller G Eric 4 Arabidopsis type B response regulators in cytokinin signaling Type B Arabidopsis Response Regulators ARR s are transcription factors that act as positive regulators of the two component cytokinin signaling pathway in Arabidopsis To characterize their role in plant growth and development we isolated T DNA insertion alleles in type B ARR s and constructed higher order mutant combinations Single mutants were similar to wild type in phenotype but higher order mutants showed increasing insensitivity to exogenously applied cytokinin The most pronounced phenotype was found in an arr1 10 12 triple null mutant which shows almost complete insensitivity to high levels of exogenously applied cytokinins The triple mutant exhibits reduced stature due to decreased cell division in the shoot sensitivity to light altered chlorophyll and anthocyanin concentrations and an aborted primary root with protoxylem but no metaxylem Microarray analysis was used to determine the changes in expression that take place as a result of type B ARR action and how other transcription factors such as the Cytokinin Response Factors CRF s act in tandem with the

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=2676 (2016-02-01)
    Open archived version from archive


  • Botany & Plant Biology 2007 - Abstract Search
    the key topics of plant development Several mutants altered in root development and root system architecture were isolated after screening of more than 17 000 M2 plants of EMS mutagenized Arabidopsis thaliana The mutants preliminarily called sr short roots with determinate growth and dg determinate growth have alterations in primary root growth Both mutants showed disorganization in the root apical meristem occurring within the first week of growth The primary root mersitem became completely exhausted between 13 and 16 days after germination in these mutants Root architecture was abnormal in both mutants Many short pericycle cells adjacent to the protoxylem were found in sr indicating alterations in lateral root initiation The mutant forms many short lateral roots The morphogenesis of the lateral root primordium in sr is also altered In dg apparently lateral root development is unaltered However this mutant forms extra numerous adventitious roots unusually spaced the feature that alters significantly the root architecture This mutant is delayed in many developmental aspects including flowering time Genetic analysis proved that both sr and dg are monogenic recessive mutations Genetic mapping using SSLP markers are in progress For the moment SR is mapped on the lower arm of chromosome 4 and

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=1241 (2016-02-01)
    Open archived version from archive

  • Botany & Plant Biology 2007 - Abstract Search
    Conservation Biology of Eastern Tallgrass Prairie Integrating Issues of Management and Restoration for the 21st Century Miller Michael 1 Bever James 2 Fitzsimons Michael 3 Arbuscular mycorrhizal fungal diversity and niche differences across tallgrass prairie restorations and prairie remnants We believe to better understand and manage natural plant communities it is thus important to identify those mechanisms that determines the distribution and diversity of arbuscular mycorrhizal fungi AMF Over the last 20 years we have been investigating the relationship of AMF with tallgrass prairie plant community dynamics in the Chicago region Although these studies have found a positive relationship between plant species and mycorrhizal fungal species richness little information exists for those factors that govern AMF community composition By using the Fermilab prairie restorations we find that three niche axis appear to control AMF composition these being plant identity soil composition and successional status or disturbance history We also find the influences of soils and plant identity on AMF composition operate at different spatial scales local and plot level respectively This finding indicates that coexistence of multiple AMF is made possible through niche partitioning among any or all three of these axes Our studies of Chicago area prairie remnants also

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=2020 (2016-02-01)
    Open archived version from archive

  • Botany & Plant Biology 2007 - Abstract Search
    involved in PCD remodeling of lace place leaves The lace plant Aponogeton madagascariensis uses programmed cell death PCD during leaf development in a quite different way than other plants PCD remodels the leaves of the lace plant forming a lattice pattern of equidistantly positioned perforations at a set time in development Therefore lace plant is an attractive model system for studying developmentally regulated PCD in plants In this system discrete populations of cells undergo a disruption of cytoplasmic streaming and loss of anthocyanin indicators of tonoplast rupture as well as DNA degradation and other cytoplasmic changes such as formation of vesicles shrinkage and invagination of the membrane and degradation of other organelles Concurrently adjacent cells are unaffected by these processes and develop normally Unlike many other forms of plant PCD cell wall degradation is a key event in lace plant PCD and is required for formation of the open perforations in the leaf blade An ethylene biosynthesis inhibitor significantly inhibited perforation formation in cultured lace plant and detached leaves The absence of perforation formation in leaves of whole plants and in detached leaves treated with the ethylene biosynthesis inhibitor AVG suggests ethylene may be an initial trigger in developmentally regulated

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=533 (2016-02-01)
    Open archived version from archive

  • Botany & Plant Biology 2007 - Abstract Search
    the first of two photosynthetic reactions that convert sunlight into chemical energy Native PSII is a supercomplex consisting of core and light harvesting chlorophyll proteins Although the structure of PSII has been resolved by x ray crystallography the mechanism underlying its assembly is poorly understood Here we report that an immunophilin of the chloroplast thylakoid lumen is required for accumulation of the PSII supercomplex in Arabidopsis thaliana The immunophilin FKBP20 2 belongs to the FK 506 binding protein FKBP subfamily that functions as peptidyl prolyl isomerases PPIases in protein folding FKBP20 2 has a unique pair of cysteines at the C terminus and was found to be reduced by thioredoxin Trx itself reduced by NADPH by means of NADP Trx reductase The FKBP20 2 protein which contains only two of the five amino acids required for catalysis showed a low level of PPIase activity that was unaffected on reduction by Trx Genetic disruption of the FKBP20 2 gene resulted in reduced plant growth consistent with the observed lower rate of PSII activity determined by fluorescence using leaves and oxygen evolution using isolated chloroplasts Analysis of isolated thylakoid membranes with blue native gels and immunoblots showed that accumulation of the PSII

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=2671 (2016-02-01)
    Open archived version from archive

  • Botany & Plant Biology 2007 - Abstract Search
    Arabidopsis metabolism and growth revealed by the low oil 1 mutant that corresponds to ATP Phosphoribosyl Transferase 1 a key enzyme of histidine biosynthesis Amino acid sensory mechanisms are known to coordinate metabolism and growth in microbes and animals However evidence for their existence in plants has been elusive In a genetic screen for Arabidopsis seed oil and protein deposition mutants the low oil 1 loo1 was isolated and map based gene cloning identified a missense mutation in the first histidine biosynthetic enzyme ATP phosphoribosyl transferase 1 ATP PRT1 The loo1 mutant exhibited development and growth defects throughout the entire lifespan The severely retarded root elongation of loo1 seedlings was rescued by supplemental histidine in the growth medium Transcript and metabolite profiling and real time RT PCR revealed a global integrated response involving primary metabolic pathways storage protein pathways phytohormone pathways and stress pathways Consistent with gene expression and metabolomic data loo1 seedling growth and seed germination exhibited altered responses to ABA and sugar We propose that the level of histidine modulates various plant functions by acting as a direct signal and by modifying secondary signals including phytohormones and metabolites The existence of a regulatory response to the level of

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=725 (2016-02-01)
    Open archived version from archive

  • Botany & Plant Biology 2007 - Abstract Search
    growth revealed by the low oil 1 mutant that corresponds to ATP Phosphoribosyl Transferase 1 a key enzyme of histidine biosynthesis Amino acid sensory mechanisms are known to coordinate metabolism and growth in microbes and animals However evidence for their existence in plants has been elusive In a genetic screen for Arabidopsis seed oil and protein deposition mutants the low oil 1 loo1 was isolated and map based gene cloning identified a missense mutation in the first histidine biosynthetic enzyme ATP phosphoribosyl transferase 1 ATP PRT1 The loo1 mutant exhibited development and growth defects throughout the entire lifespan The severely retarded root elongation of loo1 seedlings was rescued by supplemental histidine in the growth medium Transcript and metabolite profiling and real time RT PCR revealed a global integrated response involving primary metabolic pathways storage protein pathways phytohormone pathways and stress pathways Consistent with gene expression and metabolomic data loo1 seedling growth and seed germination exhibited altered responses to ABA and sugar We propose that the level of histidine modulates various plant functions by acting as a direct signal and by modifying secondary signals including phytohormones and metabolites The existence of a regulatory response to the level of histidine was further

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=477 (2016-02-01)
    Open archived version from archive

  • Botany & Plant Biology 2007 - Abstract Search
    Elizabeth 7 A relationship between structural features and lily pollen tube adhesion activity of SCA Stigma style Cysteine rich Adhesin isoforms Lily pollen tubes grow adhering to an extracellular matrix produced by the transmitting tract epidermis in a hollow style SCA a small 9 4 kDa and basic protein and low esterified pectin were previously identified to be involved in the pollen tube adhesion event However its mode of action is unknown We purified three SCA isoforms with a partial separation from the lily stigma in serial size exclusion column fractions SCA1 9370 Da SCA2 9384 Da SCA3 9484 Da Peptide sequencing analysis allowed us to determine two amino acid variations in SCA3 compared to SCA1 Arg26 and Ala71 For SCA2 however there are more sequence variations yet to be identified Our structural homology and molecular dynamics MD modeling results show that SCA isoforms have the typical structure of the plant non specific lipid transfer protein nsLTP family a globular shape of the orthogonal 4 helix bundle architecture four disulfide bonds a hydrophobic core an internal hydrophobic and solvent inaccessible cavity and a long C terminal tail in random coil conformations Arg26 in SCA3 replacing Gly26 in SCA1 is predicted to cause structural changes that result in a significantly reduced volume for the internal hydrophobic cavity in SCA3 The volume of the internal cavity fluctuates slightly during the MD simulation but overall SCA1 displays a larger cavity than SCA3 SCA1 displays the highest activity in the in vitro pollen tube adhesion assay amongst the SCA isoforms No differences were found amongst SCAs in a binding assay with pectin The correlation between the larger size of the hydrophobic cavity in SCA1 and its higher adhesion activity suggests that the structure of this isoform which is the most abundant in the pistil

    Original URL path: http://2007.botanyconference.org/engine/search/index.php?func=detail&aid=1279 (2016-02-01)
    Open archived version from archive