Molecular characterization of Erysiphe polygoni isolates on blackgram in Pudukottai district, Tamil Nadu

Blackgram (Vigna mungo L) is an important pulse crop in India, contributing significantly to dietary protein and nutritional security. Powdery mildew, caused by Erysiphe polygoni DC, is a major disease limiting blackgram productivity across diverse agroclimatic regions. This study investigated the pathogenic, morphological and molecular variability among ten naturally occurring E polygoni isolates collected from major blackgram growing areas of Tamil Nadu. The isolates showed noticeable variation in conidial size, hyphal growth, cleistothecia, asci and ascospore number, although traits such as ascus width and ascospore length remained relatively stable. ITSbased PCR amplification yielded a consistent ~ 630 bp fragment in all isolates, confirming species identity. Molecular analysis revealed high sequence similarity with only minor genetic differences among isolates. Overall, morphological variation was not closely associated with pathogenicity and ITS markers proved effective for species identification but limited for detecting intra-species diversity. The findings support improved pathogen characterization and provide useful information for developing durable powdery mildew resistance in blackgram.