Human activities are increasing atmospheric carbon dioxide (CO2) levels. Elevated CO2 decreases the concentration of mineral nutrients and protein in plant leaves, and it increases leaf temperatures. Also, increases in CO2 may be partly responsible for recent increases in global temperatures, which are predicted to increase further in this century. Thus, in the future, plants, and particularly leaves, will experience higher temperatures. Unfortunately, photosynthesis, which occurs mostly in leaves, is among the most sensitive of plant processes to heat stress, so increases in heat stress will decrease plant growth and survival. However, the effects of high CO2 on the tolerance of photosynthesis to heat stress are not understood. Further, effects of high CO2 on production of heat-shock proteins (HSPs) have not been examined, yet HSPs are principle cellular adaptations to heat stress in nearly all organisms, and HSPs play prominent roles in protection of photosynthesis during heat stress.

As with most proteins, HSP production in plants is limited by the cellular concentration of mineral nutrients and total protein, and any decreases in HSP content will decrease the protection of photosynthesis during heat stress by HSPs. Thus, we hypothesize that HSP production will decrease at high CO2, and this will negatively affect plant and photosynthetic tolerance to heat stress. We further hypothesize that high-CO2 decreases in HSPs will vary predictably among different categories of plants and under different nutrient and growth-temperature conditions. We will test these specific hypotheses in this research project.

This research addresses problems that are currently important to both science and society. The project will increase the understanding of how CO2 affects plant tolerance to heat stress, which will become more common in the future (e.g., How will human-driven increases in CO2 affect the heat tolerance of crops and native vegetation? Will different types of plants be affected to the same extent? Will differential effects on thermotolerance contribute to changes in the survival of species, and hence biodiversity?). This research will also be useful in improving crop heat tolerance via biotechnology or breeding.

This project is a collaboration between investigators at a Ph.D.-granting and an undergraduate institution. Both principal investigators have strong records of involving undergraduate students, women, and minorities in their research programs, and in integrating NSF-funded research into their teaching, and this will continue with the proposed project. Thus, this project will advance discovery while promoting teaching and training, and will increase participation of under-represented groups.

National Science Foundation (NSF)
Division of Integrative Organismal Systems (IOS)
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Irwin Forseth
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Washington and Lee University
United States
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