Screening of Restorable WA-CMS Rice Genotypes for Bacterial Blight (BB) Resistance

Aim: To screen and evaluate rice genotypes which were found to be having restorability for WA-CMS cytoplasm for their further use in the hybrid breeding program.

Study Design: Laboratory-experimental design was used in the study.

Place and Duration of the Study: The genotypes used in the study were comprised of promising lines from various experiments, local varieties and landraces, etc. The study was conducted during June 2017 to May 2018.

Methodology: In the present study, 55 rice lines which were found to have restorable capacity for WA-CMS system were screened for 4 Bacterial Blight resistance genes viz. Xa4, xa5, xa13, Xa21, against most prevalent races of the pathogen throughout the country, using PCR based molecular markers namely, MP1+MP2, xa5 multiplex, xa13 prom and pTA248, respectively.

Results: Bacterial Blight (BB) is considered to be one of the most important diseases of the rice crop. As hybrids are one of the most viable options to increase rice yields, the parental material used for the development of hybrids, must be having genes which show resistance against BB. Out of 55 restorer lines, 43 genotypes amplified for Xa4, 7 genotypes namely R. Bhagwati, IRBB5-9, Narendra Usar Dhan 3, Pratikhya, IR 88964-24-2-1-4, IR 94314-20-2-1B, HHZ 5-DT8-DT1-Y1 showed positive bands for xa5, 3 genotypes namely PAU 3220, N. Usar Dhan 3 and Pratikhya showed positive bands for xa13. However, only one genotype namely Pratikhya amplified for Xa21. In combinations, Narendra Usar Dhan 3 amplified for xa5 and xa13. Pratikhya was the only genotype found to have all 4 BB (Xa4, xa5, xa13, Xa21) resistance genes under consideration.

Conclusion: Genotypes having different BB resistant genes in combinations along with good capability of restoration for prevalent WA-CMS system can further be used as male parent in the hybrid breeding programme for development of BB resistant hybrids.