Evaluating the effectiveness of blast resistance genes under diverse altitudinal conditions of Western Himalayas

Rice is a predominant cereal crop of Kashmir, is cultivated in diverse agro-ecological situations 146 extending from the subtropical area (<1000 m amsl) of Jammu, through the temperate valley to cold high altitudes regions (1650-2400 m amsl) of Kashmir valley but is seriously affected by rice blast disease that limits its production. Disease management through genetic resistance is a durable, economic and eco-friendly and safe approach. More than 100 genes have been reported for rice blast resistance. A set of monogenic lines having only a single resistance gene in a Japonica-type variety Lijianxintuanheigu (LTH) background are being used world over as donors for rice breeding programmes and for pathological studies. Presently eighteen LTH monogenic lines were evaluated at two hotspot locations of Khudwani (1560msl) and Larnoo (2200msl) during the years 2018, 2020 and 2021. Further, the lines were validated for the presence of genes using gene specific and linked markers. Three rice lines S2 (IRBLb-1t13/CO1), S34 (IRBLzt-T) and S45 (IRBL9-W) harbouring the genes Pib, Pizt and Pi9 respectively exhibited resistance reaction at both the locations. Nine rice lines S- 5(IRBLk-ka-co) Pik, S-24 (IRBLa-A) Pia, S-27 (IRBLi-F5-) Pik, S- 28(IRBLks-s) Piks, S-29 (IRBLk-ka) Pik, S-33 (IRBLz5-CA) Piz5, S- 36(IRBLta-CT2) Pita, S-50(IRBLta2-Pi) Pita2, S-52 (IRBLta-CP1) Pita were found to be susceptible at Khudwani which represents the valley plains. All the lines except, S-27(IRBLi-F5-) Pik, S-50(IRBLta2-Pi) Pita2, S-52 (IRBLta-CP1) Pita showed resistance reaction at Larnoo which represents the high-altitude rice ecology. The above sets of lines were also screened under controlled epiphytotic conditions using a virulent isolate from Larnoo location. Lines S-50 (IRBLta2-Pi) Pita2, and S-52 (IRBLta-CP1) Pita, displayed susceptible score of 5 which is in conformity with the field screening results under Larnoo conditions. The information generated on the effectiveness of the genes can be utilized to frame a strategy aimed at the introgression of genetic resistance in high yielding and adapted rice varieties for Western Himalayas.