MEASURING HEAT TOLERANCE IN A STERILIZING “ANTHER-SMUT” PATHOGEN OF WILD PLANTS

Increasing temperatures can alter host–pathogen interactions, with the outcome depending on the relative heat tolerance of both species. We asked how increasing temperatures affect life history traits of the herbaceous plant Silene latifolia and its fungal pathogen Microbotryum lychnidis-dioicae, which causes a sterilizing, “anther-smut” disease. We measured the effect of temperature on the ability of Microbotryum to grow in vitro, infect hosts, and sporulate in the field. We found that the multiple life history stages of the pathogen were suppressed by high temperatures (30°C), while survival and flowering of the host were not, predictive of a future decline in disease.