The rice NLR heteropair RGA4/RGA5 confers resistance to bacterial blight and bacterial leaf streak diseases
M. HUTIN (1), S. Cesari (2), V. Chalvon (3), C. Michel (3), T. Tran (4), R. Koebnik (4), S. Boris (4), T. Kroj (3) (1) Cornell University, PPPMB, U.S.A.; (2) CSIRO, Australia; (3) INRA, France; (4) IRD, France; (5) IRD, France

Bacterial Blight (BB) and Bacterial Leaf Streak (BLS) are important rice diseases caused, respectively, by Xanthomonas oryzae pv. oryzae (Xoo) and pv. oryzicola (Xoc). In both bacteria, Transcription Activator-Like effectors (TALEs) are major virulence proteins that act by transactivating host genes downstream of Effector-Binding Elements (EBEs) bound in a sequence specific manner. Resistance to Xoo is mostly related to TALEs action, either by polymorphisms that prevent induction of susceptibility genes or by executor resistance genes with EBEs embedded in their promoter. For Xoc, no resistance genes are known in rice. We investigated if the recognition of effectors by nucleotide-binding leucine-rich repeat proteins (NLRs) is also able to stop BB and BLS. First, transgenic rice lines harboring the AVR1-CO39 effector gene from the rice blast fungus M. oryzae, under the control of an inducible promoter, were challenged with Xoo and Xoc strains carrying a TALE designed to activate this promoter. Induction of AVR1-CO39 expression triggers BB and BLS resistance when the corresponding Pi-CO39 resistance locus is present. In a second example, transactivation of an auto-active NLR by Xoo-delivered designer TALEs resulted in BB resistance, demonstrating that NLR-triggered immune responses efficiently control Xoo. This forms the foundation for future BB and BLS disease control strategies whereupon endogenous TALEs will target synthetic promoter regions of Avr or NLR executor genes.

Abstract Number: P17-537
Session Type: Poster