435 research outputs found
The Maize (Zea mays L.) Cat1 Catalase Promoter Displays Differential Binding of Nuclear Proteins Isolated from Germinated and Developing Embryos and from Embryos Grown in the Presence and Absence of Abscisic Acid
Dormancy and enzymatic activity of rice cultivars seeds stored in different environments
Multigene families encode the major enzymes of antioxidant metabolism in Eucalyptus grandis L
The Monofunctional Catalase KatE of Xanthomonas axonopodis pv. citri Is Required for Full Virulence in Citrus Plants
BACKGROUND: Xanthomonas axonopodis pv. citri (Xac) is an obligate aerobic phytopathogen constantly exposed to hydrogen peroxide produced by normal aerobic respiration and by the plant defense response during plant-pathogen interactions. Four putative catalase genes have been identified in silico in the Xac genome, designated as katE, catB, srpA (monofunctional catalases) and katG (bifunctional catalase). METHODOLOGY/PRINCIPAL FINDINGS: Xac catalase activity was analyzed using native gel electrophoresis and semi-quantitative RT-PCR. We demonstrated that the catalase activity pattern was regulated in different growth stages displaying the highest levels during the stationary phase. KatE was the most active catalase in this phase of growth. At this stage cells were more resistant to hydrogen peroxide as was determined by the analysis of CFU after the exposition to different H(2)O(2) concentrations. In addition, Xac exhibited an adaptive response to hydrogen peroxide, displaying higher levels of catalase activity and H(2)O(2) resistance after treatment with sub-lethal concentrations of the oxidant. In the plant-like medium XVM2 the expression of KatE was strongly induced and in this medium Xac was more resistant to H(2)O(2). A XackatE mutant strain was constructed by insertional mutagenesis. We observed that catalase induction in stationary phase was lost meanwhile the adaptive response to peroxide was maintained in this mutant. Finally, the XackatE strain was assayed in planta during host plant interaction rendering a less aggressive phenotype with a minor canker formation. CONCLUSIONS: Our results confirmed that in contrast to other Xanthomonas species, Xac catalase-specific activity is induced during the stationary phase of growth in parallel with the bacterial resistance to peroxide challenge. Moreover, Xac catalases expression pattern is modified in response to any stimuli associated with the plant or the microenvironment it provides. The catalase KatE has been shown to have an important function for the colonization and survival of the bacterium in the citrus plant during the pathogenic process. Our work provides the first genetic evidence to support a monofunctional catalase as a virulence factor in Xac
Evidence for nonrandom multiplicity of gene products in 22 plant genera
Correlations in the number (multiplicity) of molecular forms among 10 enzymes have been estimated from a sample of plants representing 22 genera. Significant correlations in multiplicity among some of the 10 enzyme systems suggest a nonrandom organization of variation in number of molecular forms. An analysis of the correlations among enzymes of a glycolytic and Krebs cycle subset supports the occurrence of patterns of influence on multiplicity which correspond to the known metabolic relatedness of the enzymes. We interpret these data as evidence for organization of enzyme multiplicity. This property may be of adaptive value to the species.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44173/1/10528_2004_Article_BF00485795.pd
Ethylene synthesis inhibition effects on oxidative stress and in vitro conservation of Lippia filifolia (Verbenaceae)
Gene diversity in grevillea populations introduced in Brazil and its implication on management of genetic resources.
A variabilidade isoenzimĂĄtica para seis populaçÔes de Grevillea robusta, oriundas de um teste de procedĂȘncias/progenies, implantado no delineamento em blocos casualizados com 5 plantas por parcela, no Sul do Brasil, Ă© descrita. A estrutura genĂ©tica da população foi analisada utilizando-se marcadores bioquĂmicos, aos 5 anos de idade, especificamente para os locos MDH-3, PGM-2, DIA-2, PO-1, PO-2, SOD-1, e SKDH-1. As procedĂȘncias do norte de ocorrĂȘncia natural (Rathdowney e Woodenbong) apresentaram divergĂȘncia genĂ©tica superior, em relação Ă mĂ©dia das progĂȘnies, considerando o nĂșmero de alelos por locus, (Ap), a riqueza alĂ©lica (Rs), a diversidade genĂ©tica de Nei (H), e o coeficiente de endogamia (f). A endogamia foi detectada em diversos graus. A testemunha comercial apresentou o maior coeficiente de endogamia, (f = 0,4448), comparativamente Ă mĂ©dia das procedĂȘncias (f = 0,2306), possivelmente devido Ă insuficiente amostragem populacional na regiĂŁo de origem (AustrĂĄlia). Apesar de sua ocorrĂȘncia natural restrita, observou-se correlação positiva entre divergĂȘncia genĂ©tica e distĂąncia geogrĂĄfica entre as populaçÔes originais. A distĂąncia genĂ©tica e anĂĄlise de cluster, baseada no modelo bayesiano, mostrou trĂȘs grupos de procedĂȘncias distintos: 1) Rathdowney- QLD e Woodenbong-QLD; 2) Paddy?s Flat-NSW; e 3) Mann River-NSW, Boyd River-NSW e a testemunha comercial (material utilizado no Brasil). O agrupamento da testemunha com as procedĂȘncias Mann River-NSW e Boyd River-NSW sugere um maior potencial das procedĂȘncias do norte para o melhoramento genĂ©tico visando Ă produção de madeira no Brasil, devido a sua elevada diversidade genĂ©tica e baixo coeficiente de endogamia
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