Pathological and multi locus sequence analysis in Bipolaris sorokiniana inciting spot blotch of wheat reveals the predominant virulent haplotypes in India

Abstract

Globally, a significant portion of wheat yield is impacted by Bipolaris sorokiniana, incitant of spot blotch disease. The current study aimed to unravel the diversity and virulence of B. sorokiniana in climate change scenarios. In total, 40 B. sorokiniana isolates were established based on the molecular and morphological traits which revealed BS-21 (Pusa, Bihar), BS-27, BS-33 (Sultanpur, UP), and BS-34 (Varanasi, UP) exhibited the highest mycelial growth (90 mm) at 15 DAI. The pathogen population is distributed in two major types, white/greenish black colonies (45%) and brown/dull black suppressed growth (10%). The maximum sporulation was in Pusa, Bihar isolates and the minimum sporulation was in Vidisha, MP isolates (BS-8 and BS-1). BS-21 exhibited the highest ADI (87.97%) while BS-10 showed the lowest ADI (6.86%). Upon phylogenetic analysis, the BS isolates were grouped into six clades using the multigene analysis using TEF1α, GAPDH, RPB2, BT, and ITS. The BS isolates from Ujjain, Kanpur and Panipat showed nucleotide variations in SCD1 gene, correlating with a significant reduction in pathogenicity. BRN1 gene was highly conserved among all the BS isolates. Among BS isolates, Pusa, and Bihar BS isolates were highly pathogenic. The virulence analysis for the SCD1 gene was correlated with pathogenicity. The highly virulent isolates were linked to the two most predominant haplotypes viz., Hap_2 and Hap_4 was identified from the virulence loci analysis. The present study will enhance our comprehension of B. sorokiniana’s pathogenesis and offer valuable perspectives for managing wheat spot blotch.