Characterization of a bacterial plant natriuretic peptide-like in plants.

FICARRA, F.A.; BETIANA S. GARAVAGLIA; GOTTIG, N.; JORGELINA OTTADO

Congreso; XLVIII Reunión Anual de SAIB; 2012

The bacterial citrus pathogen, Xanthomonas axonopodis pv. citri, contains a gene encoding a plant natriuretic peptide (PNP)-like protein (XacPNP) that shares significant sequence similarity and identical domain organization with PNPs. These peptides are extracellular, systemically mobile molecules that are able to elicit a number of plant responses important in homeostasis and growth. It has been shown that purified XacPNP, as well as PNPs, alters physiological responses including stomatal opening and photosynthetic efficiency. Also, it has been shown that XacPNP expression is induced upon infection, and lesions caused by a XacPNP mutant are more severe than those of wild-type strain, suggesting that XacPNP enables the pathogen to modify host homeostasis with the aim of creating favorable conditions to its own survival. To study the physiological processes in which PNPs are involved we obtained Arabidopsis thaliana transgenic lines that overexpress XacPNP. These lines showed higher sensitivity to saline stress compared to wild type. In order to further characterize the role of PNPs in plants and get closer to the mechanism of action of PNPs, we obtained A. thaliana lines that express a version of XacPNP fused to the green fluorescent protein and observed that this hormone-like peptide is associated to plant cell membranes, giving support to the proposal of this peptide as a hormone.