A Plant Natriuretic Peptide from Xanthomonas modifies host plant photosynthesis.

GARAVAGLIA, B.S.; GAROFALO, C.G.; ZIMARO, T.; DAURELIO, L. D.; GOTTIG, N.; GEHRING, C.; ORELLANO, E; JORGELINA OTTADO

Tucumán Argentina

Conferencia; XLV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Citrus canker, caused by Xanthomonas axonopodis pv. citri (Xac), is one of the most serious diseases affecting citrus production worldwide. The pathogen enters host plant tissues through stomatal openings and wounds and then colonizes the apoplast causing the break of the epidermis due to cell hyperplasia. The infection is visualized as raised lesions on leaves, fruits and stems. Xac contains a gene encoding a plant natriuretic peptide (PNP), not present in any other bacteria. PNPs are a class of extracellular, systemically mobile molecules that elicit a number of plant responses important in homeostasis and growth. We expressed and purified this bacterial PNP (XacPNP) and demonstrated that this protein alters physiological responses including stomatal opening in plants. To better characterize the role of XacPNP in the interaction with the plant we measured chlorophyll fluorescence parameters and water potential of citrus leaves infiltrated with recombinant purified XacPNP and demonstrated that the peptide improves both the photosynthesis efficiency and the hydration condition of the tissue. Moreover, when we analyzed enzymes involved in the photosynthetic process we observed increased expression levels of them in the presence of XacPNP purified protein. Our findings suggest that the pathogen uses this plant-like peptidic hormone to modulate the host metabolism to its own advantage.