putative leucine-rich repeat receptor kinase, OsBRR1, is involved in rice blast resistance

Leucine-rich repeat receptor-like kinases (LRR-RLKs) comprise the largest subfamily of transmembrane receptor-like kinases in plants, and they regulate a wide variety of developmental and defense-related processes. In this study, RNA interference (RNAi) strategy was used to specifically knockdown 59 individual rice genes encoding putative LRR-RLKs, and a novel rice blast resistance-related gene (designated as OsBRR1) was identified by screening T₀ RNAi population using a weakly virulent isolate of Magnaporthe oryzae, Ken 54-04. Wild-type plants (Oryza sativa L. cv. 'Nipponbare') showed intermediate resistance to Ken 54-04, while OsBRR1 suppression plants were susceptible to Ken 54-04. Furthermore, OsBRR1-overexpressing plants exhibited enhanced resistance to some virulent isolates (97-27-2, 99-31-1 and zhong 10-8-14). OsBRR1 expression was low in leaves and undetectable in roots under normal growth conditions, while its transcript was significantly induced in leaves infected with the blast fungus (Ken 54-04) and was moderately affected by ABA, JA and SA treatment. Overexpression or RNAi suppression of OsBRR1 did not cause visible developmental changes in rice plants. These results indicate that OsBRR1 is involved in rice resistance responses to blast fungus and mediates resistance to rice blast.