MARKERASSISTED BREEDING FOR BACTERIAL BLIGHT RESISTANCE IN PARENTAL LINES OF HYBRID RICE
S. Raghavendra Rao, M. Priyanka, M. Ajay Kumar, C. Ramanaiah, B. Yashwanth, K. Madan Mohan, B. Vidya Chandra, V. Venkateswarulu, D. Gandhi, N. Jagan Mohan Rao, G.V. Ramana Rao, M. Sai Murali Raj, M. Lalitha Shanti
GK5003 and GK5017 are the rice hybrids of Ganga Kaveri which are very popular with Indian farmers. In order to improve the performance of these hybrids under bacterial blight incidence, marker-assisted backcross breeding has been used to introgress Xa4, xa5, xa13 and Xa21 genes into the parental lines of these hybrids. Foreground as well as background selection using molecular markers was done to pick up target plants. Multiplexing of three bacterial blight resistance genes Xa4, xa13 and Xa21 was standardised and used in this study to screen large populations of maintainers and restorers. Seven isolates from different parts of the country were inoculated under artificial conditions to evaluate disease spectrum. In addition one very virulent isolate from Maruteru was used for field inoculations. The Xa21 entries in both hybrids showed moderate resistance, whereas the three gene and four gene combinations showed high level of resistance. Under field inoculated conditions at Kodakandla the three and four gene combinations exhibited significant yield 2 advantage over the original hybrids. Replicated yield trials were also conducted in the three states of Uttar Pradesh, Bihar and Chattisgarh which are the market segments of these hybrids. The value added hybrids were on par as compared to original with respect to agronomic and grain quality parameters. This work reports the successful application of marker assisted selection for introgression of disease resistance genes into the parental lines of hybrid rice.