Climate-mediated evolution of fungicide resistance: insights from interaction among Phytophthora infestans Cyt-b5, azoxystrobin and temperature

Understanding the spatial variation in the genetic base of fungicide resistance is essential to mitigate the intensifying threats of ongoing climate fluctuation and change to global food security. Phytophthora infestans, the causative agent of potato late blight, poses significant challenges to food security due to its rapid adaptation to climate cure and chemical controls. This study explores the role of environmental temperature in shaping the genetic diversity of the cytochrome b₅ (Cyt-b₅) gene and its association with fungicide tolerance in 96 P. infestans from seven different Chinese regions across three climatic zones that vary in their favorability for the development of late blight disease. Analysis of the 96 isolates revealed 13 polymorphic sites in Cyt-b₅, yielding nine nucleotide haplotypes and seven amino acid isoforms. Populations from warmer regions exhibited higher genetic diversity, correlating with local temperatures, while cooler regions showed monomorphic haplotypes. Although dependent on specific genotype and stress level, statistical links were observed between Cyt-b₅ diversity, both historical and experimental temperatures, and azoxystrobin tolerance, with reduced tolerance and enhanced Cyt-b₅ diversity occurring at higher temperatures. These findings underscore temperature as a key driver of genetic variation and suggest its complicated role in resistance dynamics. Warmer climates may enhance mutational diversity, pre-adapting pathogens to evade chemical controls, but also generate genetic load to constrain fitness. The study highlights the need for climate-smart resistance management strategies, integrating regional genetic monitoring and temperature-adjusted fungicide applications to mitigate resistance risks in a warming world.