Morpho-molecular delineation of rice germplasm for leaf blast resistance under intermediate hill ecology of UT of J&K India

Leaf blast of rice, caused by the fungus Pyricularia oryzae, is a highly destructive disease that severely affects rice production in India, including the intermediate hill ecology of the Union Territory (UT) of Jammu and Kashmir (J&K). This region, rich in rice diversity, cultivates a variety of primitive and improved rice cultivars. In this study, rice germplasm lines were collected from the Poonch, Rajouri, and Udhampur districts of Jammu province, UT of J&K, and characterized for leaf blast resistance using morpho-molecular markers. These lines were evaluated during the Kharif season of 2022 at the Regional Agriculture Research Station in Rajouri under natural field conditions using the Standard Evaluation System scale as reported by IRRI (Standard evaluation system for rice, INGER Genetic Resources Centre, Manila, 1996) and gene-specific primers targeting five resistance genes: Pi1, Pi2, Pi9, Pi54, and Pita. Phenotypic screening revealed significant variation among the germplasm lines. Molecular characterization indicated the presence of the Pi2 gene or its allelic variant in four germplasm lines, Pi9 gene in three lines, Pi1 gene in one line, and Pi54 gene in six lines, while Pita gene was not detected in any lines. Notably, germplasm lines GP 6 (Pi2 and Pi9), GP 10 (Pi9 and Pi54), and GP 11 (Pi9 and Pi5) possessed two resistance genes or their allelic variants. These lines require further validation for their potential use in breeding programs.