RUI: Role of Rubisco Activase Gene Regulation in Acclimation of Photosynthesis to Heat Stress

Grinnell College, Grinnell IA

Investigators

Abstract

High temperature inhibition of photosynthesis is recognized as a primary limitation to the growth and productivity of plants in both agricultural and natural environments. With global temperatures predicted to rise, research aimed at understanding and reducing plant susceptibility to heat stress is likely to have a significant impact on future crop yields. Heat stress appears to inhibit photosynthesis primarily by impairing the activity of Rubisco during the rate-limiting step of carbon assimilation in plants. Rubisco relies on an enzyme called activase to maintain its functional potential. During periods of heat stress, activase loses its ability to sustain Rubisco activity, resulting in decreased rates of photosynthesis and plant growth. There is substantial evidence that photosynthesis can acclimate to long term heat stress and that activase may play a central role in the acclimatory response. However, the basis for heat acclimation of photosynthesis is largely undefined. The current project builds on recent work supporting the involvement of activase gene regulation in the acclimation response. The focus of this research is to address specific questions regarding activase gene expression and protein regulation in plants exposed to elevated temperatures, and to begin to define the role of these regulatory processes in acclimation of photosynthesis to heat stress. Specifically, the project addresses the hypothesis that activase regulation during heat stress is influenced by genetic elements in its 3'-untranslated region, and seeks to evaluate activase protein turnover properties in vivo using a unique approach. Knowledge of the regulatory processes that support activase gene and protein expression during heat stress will greatly facilitate the design of effective strategies to promote heat stress tolerance of photosynthesis in plants, including important crop species. This project will be carried out at Grinnell College in close partnership with a diverse group of undergraduate research students who will participate at all levels in the gathering, analysis and communication of the results of the study. By providing independent research opportunities within a biology curriculum centered on inquiry-based skills, this project will maintain the institution's proven tradition of integrating scientific research into a broad and consequential liberal arts education.