A GLYCINE RICH PROTEIN IS INVOLVED IN XANTHOMONAS CITRI SUBSP. CITRI-PLANT INTERACTION

VRANYCH, CV; AINELEN PIAZZA; JORGELINA OTTADO; GOTTIG, N.

Cordoba

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

The Type III Secretion System (TTSS) is critical for pathogenicity andHypersensitive Response (HR) induction by phytopathogens asXanthomonas citri subsp. citri (Xcc): causal agent of citrus canker.HrpE protein is a principal component of TTSS and previously wecharacterized that this protein induces defense responses and HR inseveral plants. Moreover, by yeast two hybrid assays we had identifieda citrus Glycine Rich Protein (GRP) as a putative protein involved inHrpE recognition. Interestingly, GRPs have a key role in plant defensemechanisms in several plant species. In this work, BimolecularFluorescence Complementation assays confirmed HrpE-GRPinteraction in vivo. Also, we studied the response of HrpE in transgenicArabidopsis thaliana knock outs in a GRP endogenous gene that is theclosest homolog to the citrus GRP. These mutant GRP lines showedabsence or slight HR in leaves infiltrated with HrpE recombinantprotein compared to wild type plants. Furthermore, cell death, callosedeposition and the expression of defense genes as PR1 were decreasedin these transgenic lines treated with HrpE. These results suggest thatGRP is involved in HrpE recognition and signal transduction eventstriggering plant defenses against Xcc. Our results indicate for the firsttime a role of plant GRP in citrus canker disease. This study enhancesthe understanding of Xcc infection process.