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

Abstract

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.

Evaluating the contribution of historical and contemporary temperature to the oospore production of self‐fertile Phytophthora infestans

“…The quadratic model based on the data generated from the five experimental temperatures predicts that the average optimal temperature of oospore production is ~21°C, which is similar to the optimal temperatures for P. infestans infection and potato growth. The model also reveals that oospore production shares thermal profile (spectrum and shape) with potato growth and P. infestans infection, but skewing towards higher temperatures (Figure 3 , Wu et al., 2022 ; Yang et al., 2016 ). Taken together, these results indicate that the temperatures required for P. infestans to produce oospores are much higher than reported (Cohen et al., 1997 ; Turkensteen et al., 2000 ).…”

“…The thermal reaction norm of oospore production in each isolate was fitted to a second‐order polynomial distribution using the values generated in the five experimental temperatures. The resulting norms were used to estimate minimum temperature (OT min ), optimum temperature (OT opt ), maximum temperature (OT max ), temperature breadth (OT b ) and maximum oospore production (MNO) as described previously (Wu et al., 2022 ; Yang et al., 2016 ). Briefly, OT max and OT min of oospore production were estimated from the thermal reaction norm by setting the quadratic equation to zero and then solving it.…”

Fitness difference between two synonymous mutations of Phytophthora infestans ATP6 gene

“…Aggressiveness of the isolates was measured as the area under the disease progress curve (AUDPC; [ 54 ] according to the following formula [ 55 ].…”

“…Leaves and lesion areas were photographed between the second and fifth days after inoculation and quantified electronically using Assess image analysis software [ 57 ]. Detailed protocols for experimental measurements of metabolic rate, temperature sensitivity, azoxystrobin tolerance and aggressiveness can be found in previous publications [ 25 , 29 , 55 ].…”

Survival of Phytophthora cryptogea and Phytophthora cactorum in Commercial Potting Substrates for Eucalyptus globulus Plants

“…These recent advances bode well for the future development of a coordinated strategy for the early detection of Phytophthora pathogens in plant nurseries globally. There are many aspects to consider, not least the geographic variations in the thermal preferences of pathogens [20] and the effect of drought [21]. In the study by Wu et al, it was concluded that greater attention should be paid to preventing the movement of pathogens from warmer to cooler places [20].…”