Functional complementation of rice blast resistance gene Pi-kh(Pi54) conferring resistance to diverse strains of Magnaporthe oryzae

Blast disease of rice, caused by Magnaporthe oryzae is an explosive disease that can spread rapidly in conducive conditions. R-gene mediated resistance offers an environmentally sustainable solution for management of this important disease of rice. We have earlier identified a unique R-gene of rice, on chromosome 11 of Oryza sativa ssp. indica cultivar Tetep. In this study we report functional validation of the Pi-k(h) (Pi54) gene using complementation assay. The blast resistance candidate gene Pi-e (Pi54) was cloned into a plant transformation vector and the construct was used to transform a japonica cultivar of rice Taipei 309, which is susceptible to M oryzae. Transgenic lines containing Pi-k(h) (Pi54) gene were found to confer high degree of resistance to diverse isolates of M oryzae. The callose deposition was analyzed and compared between the transgenic and non-transgenic rice plants and widespread deposition was observed at the infection sites in plants showing incompatible interaction. Successful complementation of Pi-k(h) (Pi54) gene confirmed that the gene is responsible for resistance to M oryzae in transgenic lines developed during this study. Expression analysis of the gene in resistant plants revealed that the gene is pathogen inducible in nature and is not expressed constitutively. Detection of callose deposition in resistant plants containing Pi-k(h) (Pi54) gene implicates its involvement in the initiation of defense response cascade.