Temperature sensitivity of plant disease resistance

Plants, like animals, have a complex immune system to fend off potential invaders, but their immune responses are very sensitive to the environment. Even small, non-stressful increases in temperature can negatively impact the plant’s ability to fend off pathogens. We use several independent temperature sensitive cases of plant autoimmunity in Arabidopsis thaliana, which constitutively signal as if they have been attacked, to understand why the plant immune system is sensitive to shut-down by elevated temperature and how the threshold is set (since we know from the literature that the temperature thresholds vary among species and correlate with climate of origin). This work will touch upon two broader questions: How plants adapt in the long term to habitats with distinct temperatures, and how plants may respond and adapt in the context of short term climate change.

Ben Hunter, a postdoctoral scientist in the lab, is using genetics and chemical interventions to understand how the plant immune system is tuned to features of a plant’s physical habitat, particularly temperature. In the process, he is also exploring the similarities and differences in molecular mechanisms underlying these cases. So far, he has screened a large number of candidate mutations in defense-related pathways and other candidate pathways. He has identified numerous genes that are involved in tuning the threshold and signaling strength of immune responses in these cases of plant autoimmunity. He has also ruled out two commonly assumed mechanisms of temperature-sensitivity.

This figure shows a hybrid necrosis case published in Bomblies et al 2007, PLoS Biology. The parents are at the left and right, and all plants are the same age. These plants were grown at 16°C; hybrids are almost completely normal at 23°C.