High‐temperature acclimation of photosystem <scp>II</scp> in land plants

Summary The effect of high temperature on plant performance and survival is a topic of great interest given the ongoing rise in global heatwave frequency, duration, and intensity. The temperature at which photosystem II (PSII) is disrupted is often used as a proxy for photosynthetic heat tolerance. Our current understanding of PSII heat tolerance is predominantly shaped by ‘snapshot’ measurements that capture heat tolerance at a single point in time. However, growing evidence of dynamic thermal acclimation of PSII raises questions about the accuracy of current estimates of photosynthetic heat tolerance based on snapshot measurements. We believe that failing to account for acclimation may result in the underestimation of PSII heat tolerance and that the extent of acclimation can be predicted from leaf economic traits, leaf habit, plant water use strategies, photosynthetic pathway, and habitat. We also explore efforts to use spectroscopy techniques to predict acclimation, and the biotic and abiotic factors that may influence these predictions. Finally, we provide recommendations for the future incorporation of PSII heat tolerance and acclimation into models of the thermal limits of plant performance.

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