“…Ningxia, Guizhou, and Yunnan are among the top potato production regions in China, with >0.6 million annual hectares in each of the regions, whereas Fujian only grows ~1/10 acreage of each of the regions. The finding of the highest genetic variation in the P. infestans Avr4 gene from Fujian is unexpected but consistent with previous results derived from other effector genes (e.g., Avr2 and AVR3a), phenotypic traits (fungicide resistance and aggressiveness), and ecological data (e.g., growth rate and ultraviolet tolerance) of the pathogen (Qin et al, 2016;Yang et al, 2018Yang et al, , 2020Wu et al, 2019Wu et al, , 2020Lurwanu et al, 2021). Unlike Guizhou, Ningxia, Yunnan, and many other regions where well-established seed production systems can ensure the adequate supply for own use, potato in Fujian relies on imported seeds from other parts of China, increasing the chance of bringing novel variation into the region and supporting the theory that anthropogenic activities play a critical role in facilitating the evolution of plant pathogens in agricultural systems.…”