Diversity of resistance and virulence mechanisms in the rice/Rice yellow mottle virus pathosystem
H. PIDON (1), A. Pinel (2), E. Hébrard (2), S. Chéron (1), A. Ghesquière (1), L. Albar (1) (1) IRD, UMR DIADE, France; (2) IRD, UMR IPME, France

The Rice yellow mottle virus (RYMV, Sobemovirus) represents one of the major threats for rice cultivation in Africa and Madagascar. To understand the dialog between the host plant and the virus, we study resistance genes and their breakdown in this pathosystem. We already described two recessive resistance genes: a translation initiation factor eIF(iso)4G1 and a putative negative regulator of active defense mechanisms CPR5-1. By a genetic mapping approach on a plant carrying none of these two genes, we recently mapped in a 15kb interval the first dominant resistance gene against RYMV. The mapping region contains a CC-NBS-LRR gene, currently under validation. On the virus side, we characterized the resistance-breakdown by isolates representative of the RYMV diversity. An adaptation to the different host species seems to explain their ability to break or not the resistance genes. Moreover, we recently identified the three distinct viral determinants involved in the breakdown of these resistances by sequencing variants. Breakdowns of eIF(iso)4G2 and CPR5-1 require specific mutations in the viral VPg protein and protease, respectively. Recent results suggest that the breakdown of the dominant gene involves the coat protein. These results underline the diversity of mechanisms at work in this pathosystem, both from host and pathogen side, and will allow to optimize resistances deployment to achieve a better durability.

Abstract Number: P17-586
Session Type: Poster