Genome regulatory mechanisms mediating abscisic acid stress hormone response and stomatal aperture control in plants

Plants have evolved sophisticated mechanisms to survive and reproduce in a changing and frequently stressful environment. For example, plants control the aperture size of microscopic leaf pores known as stomata to balance the absorption of carbon dioxide (CO2) into the leaf, essential for photosynthesis with the loss of water out of the leaf to the surrounding atmosphere. This regulation is essential for plant survival during periods of stress, including drought and high temperatures. Specialized leaf cells called guard cells control the opening and closing of stomatal pores. This research program will identify the genetic pathways controlling guard cell function and determine how these pathways promote stress tolerance in fruit plants. Discoveries from this research could inform strategies to improve environmental stress tolerance in crops, a major focus of biotechnology. This project will help build the scientific workforce by providing advanced training in plant biology and genetics at the undergraduate and graduate levels. Additionally, the project will advance pre-college STEM education in collaboration with a STEM educator training program and implement a research experience program for teachers and student-teachers. Finally, to enhance research access, the principal investigator has partnered with a local high school to provide early research experiences to students through a formalized internship. Guard cells must integrate distinct environmental signaling pathways with opposing physiological consequences. For example, the plant drought stress hormone abscissic acid (ABA) and high concentrations of atmospheric CO2 ([CO2]) trigger stomatal closure to minimize water loss, while low [CO2] and light trigger stomatal opening to support photosynthesis. The mechanisms responsible for such signal integration are only poorly understood. Furthermore, atmospheric [CO2] is higher today than at any point in the last 3 million years and is predicted to double in the coming century. Understanding the genetic pathways mediating stomatal control by [CO2] and ABA is of fundamental importance to plant biology. Research in the model plant Arabidopsis thaliana has uncovered critical genes controlling stomatal movements; however, it is unclear if these pathways are conserved in fruit crops. Therefore, the principal investigator’s research group has initiated a research program investigating stomatal physiology and genetics in the emerging model fruit plant Fragaria vesca (diploid strawberry). Our program will combine cell-type specific genomics approaches and plant physiological studies to analyze the genetic pathways controlling stomatal physiology in F. vesca. Preliminary studies have observed robust stomatal responses to changes in atmospheric [CO2] and to ABA application in F. vesca and identified putative orthologs of the key Arabidopsis stomatal signaling genes. This project will build on these results and investigate the gene regulatory networks active in F. vesca guard cells using guard cell specific genomics approaches. Furthermore, detailed genetic and physiological studies will determine the functions and conservation of putative stomatal signaling genes in F. vesca. This research program will discover the genetic mechanisms underlying stomatal responses in strawberry plants and potentially advance efforts to improve stomatal traits in fruit crops. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.