Codominant grasses differ in gene expression under experimental climate extremes in native tallgrass prairie.

Extremes in climate, such as heat waves and drought, are expected to become more frequent and intense with forecasted climate change. Plant species will almost certainly differ in their responses to these stressors. We experimentally imposed a heat wave and drought in the tallgrass prairie ecosystem near Manhattan, Kansas, USA to assess transcriptional responses of two ecologically important C grass species, and . Based on previous research, we expected that would regulate more genes, particularly those related to stress response, under high heat and drought. Across all treatments, showed greater expression of negative regulatory and catabolism genes while upregulated cellular and protein metabolism. As predicted, showed greater sensitivity to water stress, particularly with downregulation of non-coding RNAs and upregulation of water stress and catabolism genes. was less sensitive to drought although tended to respond with upregulation in response to drought versus which downregulated more genes under drier conditions. Surprisingly, only showed minimal gene expression response to increased temperature, while showed no response. Gene functional annotation suggested that these two species may respond to stress via different mechanisms. Specifically, tends to maintain molecular function while prioritizes avoidance. may strategize abscisic acid response and catabolism to respond rapidly to stress. These results have important implications for success of these two important grass species under a more variable and extreme climate forecast for the future.