Screening of recombinant inbred lines for resistance to bacterial leaf blight pathotypes in rice (Oryza sativa L.)

Sixteen recombinant inbred lines (RIL's) developed from the intra-specific cross between YH3 and AKDRMS 21-54 through Marker Assisted Pedigree Breeding Method were screened along with their parents and the checks, namely, BPT 5204, TN1 and Improved Samba Mahsuri (ISM) against the IxoPt-20 pathotype at the ICAR-Indian Institute of Rice Research (ICAR-IIRR), Hyderabad, Telangana, during Rabi season in 2021-22, and a new pathotype of Xanthomonas oryzae pv. oryzae causing bacterial leaf blight disease in rice at the Regional Agricultural Research Station (RARS), Maruteru during the Kharif season in 2022, to identify pathotype specific resistant sources. MorphoMolecular screening was adopted to evaluate the recombinant inbred lines over two locations in the consecutive seasons of Rabi season in 2021-22 and Kharif season in 2022. Based on percent diseased leaf area, the genotypes were scored and categorised as per the Standard Evaluation System (SES) scale provided by the International Rice Research Institute (IRRI). The results revealed all 16 RIL's to be either resistant (11) or moderately resistant (6) to the IxoPt-20 pathotype. However, only five RIL's were found to be resistant, while four RIL's were moderately resistant to the new virulent pathotype. Seven RIL's with resistant to moderately resistant reactions for the IxoPt-20 pathotype, showed moderately susceptible reactions for the new virulent pathotype. Among the resistant RIL's identified for each pathotype, BPT1901-72-10-6, BPT-1901-108-4-1, and BPT-1901-111-3-2 were found to be uniformly resistant, while BPT-1901-45-8-6 was uniformly moderately resistant to both IXoPt-20 and the new virulent pathotype at Hyderabad and Maruteru, respectively, indicating their potential as genetic stocks for the development of new cultivars resistant to bacterial leaf blight disease.