Marker-assisted selection for biotic stress (Bacterial leaf blight and gall midge) tolerance in Bc4F4 generation of rice (Oryza sativa L.)

Bacterial blight (BB) of rice caused by the pathogen Xanthomonas oryzae pv. oryzae and the insect gall midge (GM) (Orseolia oryzae) are two major limitations of rice production. The present study was carried out to improve CO 43 a popular variety of Tamil Nadu for BB and GM resistance through marker assisted backcross breeding. Two sets of genes Xa21 and xa13 for bacterial blight resistance and Gm1 and Gm4 for gall midge resistance were used for this study. A total of 95 plants in BC₄F₄ generation were genotyped with SSR markers RM1328, RM22550, xa13 prom and pTA248 for the genes Gm1, Gm4, xa13 and Xa21 respectively. Artificial screening for bacterial blight screening was conducted in glass house condition and gall midge screening was conducted in the field condition. The lines selected for bacterial blight and gall midge resistance genes recorded a high level of resistance than the recurrent parent CO43.