Host plant and arbuscular mycorrhizal fungi show contrasting responses to temperature increase: Implications for dioecious plants

Abstract

Individual plants live in complex environments where they interact with other organisms such as herbivores, pollinators, fungi and pathogens. The influence of rising temperature on biotic interactions has begun to receive attention, and is an important research frontier currently. However, the belowground interactions with organisms such as arbuscular mycorrhizal (AM) fungi have received little attention so far. In this study, we investigated the response of the dioecious plant Antennaria dioica and its AM fungi to increased temperature in a controlled environment simulating the period of growth of A. dioica in central Finland. Specifically, we evaluated the effect of rising temperature on plant survival, growth, flowering and physiology in plants growing with or without AM fungi. Overall, increased temperature had a positive effect on plant survival, but a negative effect on the growth and flowering compared with the control temperature, while it did not affect the physiological parameters analyzed. Females suffered more of rising temperature in terms of reduced flowering, but a larger proportion of plants survived compared to males. In contrast, the rising temperature had positive effects on the frequency of AM fungal colonization in roots regardless of sex, but sex-specific differences were observed in the amount of extraradical hyphae and the number of spores produced. These findings suggest than the sexes in dioecious species and their associated fungi respond differently to increasing temperature. If rising temperature affects host plants and symbionts in a contrasting way, a potential functional mismatch might appear.