No abstract

To combat the dreaded diseases in rice like bacterial blight and blast, host plant resistance has been advocated as a sustainable method. Through the present study, we have successfully incorporated three major bacterial blight (BB) resistance genes viz., Xa21, xa13 and xa5 into NLR3449, a high yielding, blast resistant, fine-grain type popular rice variety through marker-assisted backcross breeding. Foreground selection was carried out using PCR based, gene-specific markers viz., pTA248 (Xa21), xa13prom (xa13) and xa5FM (xa5) at each generation of backcrossing, while 127 polymorphic SSR markers spanning on 12 chromosomes were used for background selection and backcrossing was limited to two rounds. At BC2F1 generation, a single plant (NLR-87-10) with 89.9% recovery and possessing all the three bacterial blight resistance genes was forwarded to BC2F2 generation. A solitary BC2F2 plant viz., NLR-87-10-106 possessing all the three resistance genes and > 90% genome recovery was identified and advanced through selfing till BC2F4 generation by adopting pedigree method. Three best lines at BC2F4 lines, possessing high level of resistance against bacterial blight and blast and equivalent or superior to NLR 34449 in terms of yield, grain quality and agro-morphological traits have been identified and advanced for multi-location trials.