Bacterial Leaf Blight Resistance Gene, Xa33 in Rice : Identification and genetic characterization of new Bacertial Leaf Blight (BLB) resistance gene in Rice

Rice (Oryza sativa L.) is the principal food crop of the world. To meet the increasing food demands for the future, concerted efforts are required to increase the rice productivity and minimize production losses due to biotic stresses afflicting rice, Bacterial Leaf Blight (BLB) is an important disease that causes significant yield reduction worldwide. Broadening of the genetic base for identification and transfer of genes for BLB resistance from wild relatives of rice is an important strategy in resistance breeding programs across the world. In the present study, a novel, dominant BLB resistance gene Xa33 has been identified from O. nivara, tagged and fine mapped on Chr. 7 using SSR markers RMWR7.1 and RMWR7.6. It is the first dominant gene mapped on Chr. 7 and second gene derived from wild rice, O. nivara. The gene is introgressed into the elite fine-grained high yielding cultivar Samba Mahsuri (BPT5204) through marker-assisted backcross breeding. Further, putative candidate genes which could be possibly associated with Xa33 encoded function have also been identified.