Photosynthesis: temperature responses and enzyme performance in C3 and C4 plants

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Rising levels of atmospheric carbon-dioxide (CO2) since the industrial revolution have been linked to the climate warming of the last century. Temperature is one of the abiotic factors that severely impacts photosynthesis, the process by which plants harvest sunlight and use it to fix CO2 into carbohydrates. We have a good theoretical understanding of what limits photosynthesis at or below its optimum temperature in most cases, but there is considerable scientific debate about why photosynthesis declines in response to warm but non-lethal temperatures, and how plants adjust photosynthesis to different growth temperatures. The research proposed here will explore these questions using a variety of experimental approaches. The research program will also directly investigate the function of Rubisco, the enzyme that actually fixes CO2. Rubisco is the most abundant enzyme on Earth, but it is slow and inefficient in comparison to other enzymes. Moreover, its efficiency declines with increasing temperature. I will continue to characterize the biochemistry and structure of this enzyme, to better understand its performance, how it evolved, and how it responds to temperature. Understanding the response of photosynthesis to variation in atmospheric CO2 and temperature is a vital component of predicting the response of natural plant communities and agricultural species to global change.