INVESTIGADORES
OTTADO Jorgelina
congresos y reuniones científicas
Título:
EXPRESSION PROFILES OF CATALASE GENES IN THE PHYTOPATHOGEN Xanthomonas axonopodis PV citri
Autor/es:
TONDO, M.; JORGELINA OTTADO; ORELLANO, E
Lugar:
Villa Carlos Paz
Reunión:
Congreso; XLIV Reunión Anual de la Sociedad Argentina de Bioquímica y Biología Molecular; 2008
Resumen:
Xanthomonas axonopodis pv. citri (Xac) is a Gram-negative
obligate aerobic bacterium that infects citrus plants. Pathogenic
bacteria are usually exposed to H O produced either by normal 2 2
aerobic metabolism or as a part of the plant defense response against
microbial invasion. In order to survive and colonize plant tissues
Xac must overcome H O toxicity, and catalases are enzymes 2 2
employed for its detoxification. We determined Xac catalase
activity in different growth phases and observed that it was higher in
stationary-phase compared to early-exponential phase. This was
consistent with the capacity of cultures to resist H O . Semi- 2 2
quantitative RT-PCR analysis showed that three catalase genes are
expressed in Xac during growth in rich media. The genes srpA and
katG are expressed throughout all phases of growth whereas katE
transcripts are only detected as cells enter the stationary phase. We
also analyzed the expression profiles of catalase genes in Xac
cultures grown in standard media and in XVM2, suspected to mimic
the environment of plant intercellular spaces. We found that mRNA
levels of katE are significantly higher in XVM2, which could
account for the higher catalase activity previously observed in this
media. Our results suggest that KatE may be the major catalase
induced in Xac in starvation conditions and in the environment
found during plant-pathogen interactions.