Characterization of Fusarium oxysporum f. sp. lini based on ITS and SSR Markers and identification of resistance of Indian Linseed (Linum usitatissimum L.) to Fusarium oxysporum f. sp. lini.

Different isolates of Fusarium oxysporum f. sp. lini (Fol) collected from seven linseedgrowing states in India were analyzed for their cultural characteristics, pathogenicity, and genetic diversity using ITS and SSR markers. The isolates exhibited varying colony colors (white, pink, purple) and textures (fluffy, appressed), with white being the most common. Pathogenicity tests on 52 linseed cultivars using a virulent isolate (Fol-4) revealed wilt incidence ranging from 2 to 87%, with RLC-92, RLC-148, RLC-133, Selection EC99001, and Binwa showing resistance. Further screening of 23 cultivars against six Fol isolates identified RLC-92, JLS-95, and RLC-148 as resistant across all tested isolates. ITS analysis generated a 650 bp amplicon, confirming 99-100% sequence identity with F. oxysporum (GenBank Accession Nos. ON714898 to ON714911). Genetic diversity analysis using cluster analysis, Jaccard's similarity coefficient, PCA, and SSR heatmap revealed two primary clusters with significant variability, with isolate Fol-13 emerging as a distinct outlier. These findings enhance the understanding of genetic variation in F. oxysporum f. sp. lini, aiding in disease resistance breeding and linseed wilt management strategies.