Morphological, pathogenic and molecular analysis of Bipolaris sorokiniana inciting spot blotch of barley in India

In India, spot blotch caused by Bipolaris sorokiniana is one of the most important diseases affecting barley crop and causes significant losses. With the present climate change scenario and cultivation of newer varieties, the present study aimed to characterize B . sorokiniana based on morphology, pathogenic, and cross-infectivity. Forty- five isolates were established from diseased samples collected from different hot spot locations of Uttar Pradesh and Bihar states in India and further confirmed with BLAST analysis using ITS region sequences. Morphological analysis revealed the highest mycelial growth (80.33 mm) in BS 36 (Varanasi, Uttar Pradesh) isolate and the lowest mycelial growth (19.33 mm) in BS 45 (Sultanpur, Uttar Pradesh) isolate after 15 DAI. The conidial length ranged from 74.58 μm to 42.05 μm, and the conidia width ranged from 22.94 μm to 12.18 μm across B . sorokiniana isolates. The highest sporulation (5.33 × 10 4 spores /ml) was observed in BS 32 isolate (Varanasi, Uttar Pradesh) and the lowest sporulation (0.73 × 10 4 spores /ml) was observed in BS 13 (Sultanpur, Uttar Pradesh). No correlation was found in the growth, sporulation, and pathogenic nature of B . sorokiniana . A total of 6 haplotypes were identified based on the ITS sequences with H_2 being the most predominant. The isolates (BS 52, BS 53, BS 54, and BS 55) from Samastipur, Bihar were highly pathogenic than other isolates. In cross-infectivity assays, B . sorokiniana isolate of barley was less virulent on wheat and B . sorokiniana isolate of wheat was highly virulent on barley. This study will help devise further management strategies against spot blotch of barley.