Characterization of Nothopassalora personata Causing Late Leaf Spot Disease in Peanut Across Major Peanut-Growing Regions of India

Peanut (Arachis hypogaea L.), also known as groundnut, is an important legume crop globally, serving as a key food and edible oil source for millions of people. Late leaf spot (LLS), caused by Nothopassalora personata (Berk. & M.A. Curtis) (syn. Cercosporidium personatum [Berk. & M.A. Curtis] Deighton), is the most destructive foliar fungal disease affecting peanuts, resulting in severe defoliation and yield losses of 40 to 90%. As a highly adaptable and evolving pathogen, N. personata rapidly develops new pathotypes, posing an ongoing threat to peanut crop. Monitoring the prevalence and genetic diversity of this pathogen in various agroecologies is requisite for tracking its spread and identifying areas of high risk. This study aimed to evaluate the disease severity and genetic diversity of N. personata across major peanut-growing regions in India. The survey revealed that disease severity (DS) ranged from 36.75 to 91.70%, with high humidity and moderate temperatures fostering disease progression. During the survey, the characteristic symptoms were observed, including dark brown lesions surrounded by chlorotic halos, advancing to necrosis and defoliation in severe cases. Forty isolates of N. personata were collected and identified through microscopic and molecular analysis using LSU-specific primers. Of these, five isolates (OD-8, KA-6, GJ-12, AP-3, and AP-4) exhibited high virulence in detached leaf assay. These results provide critical insights into the epidemiology of LLS, contributing to the development of effective disease forecasting models, which in turn guide targeted control measures. Further, whole-genome sequencing of N. personata isolates with different virulence patterns could identify key pathogenicity-related genes, paving the way for innovative control measures and the development of peanut varieties with enhanced resistance.