Participacon de XacPNP en la cancrosis de los citricos

GARAVAGLIA BS; FICARRA FA; ZIMARO T; GAROFALO CG; LUDIVINE T; GEHRING C; ORELLANO EG; GOTTIG N; OTTADO J

La Plata, Argentina

Congreso; XVIII Reunion Argentina de Fisiologia Vegetal; 2010

Sociedad Argentina de Fisiología Vegetal

Xanthomonas citri pv. citri, the bacteria responsible for citrus canker posses a biological active plant natriuretic peptide (PNP)-like protein, not present in any other bacteria. PNPs are a class of extracellular, systemically mobile peptides that elicit a number of plant responses important in homeostasis and growth. Previously, we showed that a Xanthomonas citri pv. citri mutant lacking the PNP-like protein XacPNP produced more necrotic lesions in citrus leaves than wild type infections and suggested a role for XacPNP in the regulation of host homeostasis. Here we have analyzed the proteome modifications observed in citrus leaves infected with the wild type and XacPNP deletion mutant bacteria. While both of them cause downregulation of enzymes related to photosynthesis as well as chloroplastic ribosomal proteins, proteins related to defense responses are up-regulated. However, leaves infiltrated with the XacPNP deletion mutant show a more pronounced decrease in photosynthetic proteins while no reduction in defense related proteins as compared to the wild-type pathogen. On the other hand, we analyzed the citrus leaves proteome treated with recombinant XacPNP. This work suggests that XacPNP serves the pathogen to maintain host photosynthetic efficiency during pathogenesis. We therefore conclude that XacPNP counteracts the shut-down of host photosynthesis during infection and in that way maintains the tissue in better conditions, suggesting that the pathogen has adapted a host gene to modify its natural host and render it a better reservoir for prolonged bacterial survival and thus for further colonization.