Diversity of magnaporthe oryzae isolates in Jammu, India: morphological and molecular perspectives

The present study aimed to determine the variability in the Magnapothe oryzae isolates associated with the rice blast from the Jammu region. Leaf blast samples were collected from the rice growing areas of five districts of Jammu division during Kharif 2018 and 2019, and morphological, pathological and molecular variations among the thirty isolates were investigated. The conidial length ranged between 8.67 and 15.51 μm, and the conidial breadth ranged between 3.22 and 7.73 μm in all the isolates. The maximum conidia size was recorded in isolate Po25 (13.80-15.51 × 6.20–7.73 μm), and it was the minimum in isolate Po5 (8.67–10.30 × 3.22–5.46 μm). The incubation period of all the M. oryzae isolates ranged from 5.9 to 8.6 days in different rice varieties. The molecular analysis using 25 SSR primer pairs revealed higher genetic variability in the 23 isolates of M. oryzae. Phylogenetic analysis based on similarity coefficient grouped the isolates into two major clusters, I and II, and four sub-clusters: IA, IB, IIA and IIB.