A Glycine Rich Protein Is Involved In Xanthomonas citri subsp. citri- Plant Interaction

PIAZZA, A.; VRANYCH, C.V.; GOTTIG, N.; OTTADO, J.

Córdoba

Congreso; LII Reunión Anual de la Sociedad Argentina de Bioquímica y Biología Molecular; 2016

Sociedad Argentina de Bioquímica y Biología Molecular

The Type III Secretion System (TTSS) is critical for pathogenicity and Hypersensitive Response (HR) induction by phytopathogens as Xanthomonas citri subsp. citri (Xcc): causal agent of citrus canker. HrpE protein is a principal component of TTSS and previously we characterized that this protein induces defense responses and HR in several plants. Moreover, by yeast two hybrid assays we had identified a citrus Glycine Rich Protein (GRP) as a putative protein involved in HrpE recognition. Interestingly, GRPs have a key role in plant defense mechanisms in several plant species. In this work, Bimolecular Fluorescence Complementation assays confirmed HrpE-GRP interaction in vivo. Also, we studied the response of HrpE intransgenic Arabidopsis thaliana knock outs in a GRP endogenous gene that is the closest homolog to the citrus GRP. These mutant GRP lines showed absence or slight HR in leaves infiltrated with HrpE recombinant protein compared to wild type plants. Furthermore, cell death, callose deposition and the expression of defense genes as PR1 were decreased in these transgenic lines treated with HrpE. These results suggest that GRP is involved in HrpE recognition and signal transduction events triggering plant defenses against Xcc. Our results indicate for the first time a role of plant GRP in citrus canker disease. This study enhances the understanding of Xcc infection process.