Elevating Air Temperature May Enhance Future Epidemic Risk of the Plant Pathogen Phytophthora infestans

Knowledge of pathogen adaptation to global warming is important for predicting future disease epidemics and food production in agricultural ecosystems; however, the patterns and mechanisms of such adaptation in many plant pathogens are poorly understood. Here, population genetics combined with physiological assays and common garden experiments were used to analyze the genetics, physiology, and thermal preference of pathogen aggressiveness in an evolutionary context using 140 Phytophthora infestans genotypes under five temperature regimes. Pathogens originating from warmer regions were more thermophilic and had a broader thermal niche than those from cooler regions. Phenotypic plasticity contributed -10-fold more than heritability measured by genetic variance. Further, experimental temperatures altered the expression of genetic variation and the association of pathogen aggressiveness with the local temperature. Increasing experimental temperature enhanced the variation in aggressiveness. At low experimental temperatures, pathogens from warmer places produced less disease than those from cooler places; however, this pattern was reversed at higher experimental temperatures. These results suggest that geographic variation in the thermal preferences of pathogens should be included in modeling future disease epidemics in agricultural ecosystems in response to global warming, and greater attention should be paid to preventing the movement of pathogens from warmer to cooler places.

Automated summary

Understanding pathogen adaptation to global warming is crucial for predicting disease epidemics and agricultural production in the future. This study used a combination of population genetics, physiological assays, and common garden experiments to analyze the genetic and physiological characteristics of 140 Phytophthora infestans genotypes under different temperature regimes. The results showed that pathogens from warmer regions had a higher thermal preference and broader thermal niche compared to those from cooler regions. Phenotypic plasticity played a more important role than genetic variance in determining aggressiveness. Experimental temperatures also influenced the expression of genetic variation and the association between pathogen aggressiveness and local temperature. These findings highlight the importance of including geographic variation in pathogen thermal preferences in modeling future disease epidemics in response to global warming.