Geographic Distribution and Genetic Diversity of Podosphaera xanthii in Pakistan

Background and Objective: Podosphaera xanthii is one of the most commonly occurring powdery mildew pathogens, with a broad host range and wide distribution. Despite its prevalence, an updated record of its host plants in Pakistan was lacking. This study aimed to update the host range of P. xanthii based on recent surveys, confirm its occurrence through morphological and molecular analyses, and highlight its diversity and regional spread in Pakistan. Materials and Methods: Field surveys were conducted across five regions of Pakistan Battagram, Fairy Meadows, Khanspur, Mansehra, and Swat between 2022 and 2024. Infected plant samples were collected and analyzed morphologically, focusing on both anamorphic and teleomorphic stages. Molecular confirmation was done through sequencing of the internal transcribed spacer (ITS) region. Descriptive statistics were used to report host range diversity and geographic occurrence. Results: A total of ten plant species were confirmed as hosts of P. xanthii, based on morphological characteristics and ITS-based molecular validation. Among these, members of the Asteraceae family were dominant. The fungus was found in all surveyed regions, indicating a wide ecological range and adaptability. The simultaneous observation of both reproductive stages supports its active and persistent lifecycle across diverse climatic zones. Conclusion: This study provides an updated account of P. xanthii host plants in Pakistan, confirming its widespread occurrence and significant diversity. The findings underscore the need for targeted management strategies to mitigate its impact, especially on susceptible plant families like Asteraceae.