Evolutionary analysis of heterotrimeric G-protein function in plants

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Intellectual Merit: Heterotrimeric G-proteins consisting of Galpha, Gbeta and Ggamma subunits regulate some of the most important signaling pathways in eukaryotes. In metazoans, evolutionary diversification has led to the presence of a large number of G-proteins and associated components that regulate a multitude of signaling pathways with a high degree of specificity. In contrast, plants have a very limited number of G-proteins that integrate a plethora of signaling pathways to modulate overall growth and development. This observation has led to the hypothesis that the plant G-proteins have evolved differently from the metazoan G-proteins in accordance with the sedentary lifestyle of plants. Detailed studies of the structure/function attributes of plant G-proteins is currently mostly limited to Arabidopsis which restricts the knowledge of why and when during evolution the plant G-proteins emerged as modulators of multiple signals. It is also not known if the G-proteins have evolved to play critical roles in biological processes that are unique to specific plant lineages. Furthermore, the presence of certain unconventional G-protein components in plants suggests their role(s) in regulating novel, as yet unexplored G-proteins signaling mechanisms. The availability of fully sequenced genomes from a number of plant species at important evolutionary nodes and the PIs extensive experience working with G-protein signaling using complementary approaches including biochemical, molecular-genetics and genome/proteome-scale analyses, puts her in an excellent position to address some of the key questions related to the plant G-protein signaling. Towards this, important preliminary data have been generated related to G-proteins components and their activity from Arabidopsis, rice, soybean, Physcomitrella, Selaginella, Brachypodium and Aquilegia. This research has been developed with the overall objective to understand the functional evolution of the G-protein core components and their interaction in plants, and to infer the conventional and novel signaling mechanisms and their role in regulating signaling pathways involved in plant adaptation and yield. To accomplish this objective, following specific aims will be pursued: Aim 1. Biochemical characterization of the enzymatically active proteins of the G-protein complex in the context of their evolutionary diversification Aim 2. Evaluation of the role of G-proteins from across different taxa in regulating the signaling pathways important in the context of land plant evolution The material and intellectual resources generated from this research will be made publicly available through the Arabidopsis stock center and through our website. The long term benefits of the research include comprehensive knowledge of the evolution of G-protein components and signaling mechanisms in plants and their roles in regulating pathways controlling agronomically important traits. Broader Impact: This research addresses the fundamental aspects of plant signaling and evolution. Given the involvement of G-protein in regulating important agronomic traits such as seed development and physiology, abiotic stress tolerance and water use efficiency, the knowledge gained from this research will be useful for engineering important agricultural traits to the benefit of society. Moreover, the research specifically incorporates training for high-school students and teachers through the STARS program and undergraduate students through the REU program. The PI is actively involved in recruiting, mentoring and training of undergraduate students as a co-director of the Danforth Center REU program; and graduate students through her participation in Washington University plant biology recruitment, thesis committees and teaching. The proposed research offers multidisciplinary training to the post-docs in various aspects of modern plant biology. The PI is strongly committed to provide training and mentoring opportunities to post-docs to help them establish their independent careers. The PI is actively involved in developing scientific awareness in the local community through multiple volunteering programs offered at the Center, including participation in the ¡¥Ask a Plant Scientist¡¦ column and ¡¥Conversations¡¦ series, which offers an interactive session between local public and scientists.