Role of Non-Canonical pPLA-Mediated Acyl Hydrolysis in Plant Functional Morphology

Cereal plant inflorescence architecture affects flower density, seed numbers, and grain production. However, the mechanism that regulates inflorescence architecture remains largely unknown. This project addresses the molecular and signaling processes that modulate the reproductive structure and seed production. It investigates how a family of enzymes interacts with two types of proteins to affect their cellular activities and physiological functions. The results have the potential to discover a new regulatory nexus that modulates plant height, inflorescence architecture, and seed yield. The project will have broader impacts on science, education, and society. The research activities will provide opportunities for training and workforce development for students and researchers. Research findings from the proposed research have the potential to enhance crop functional structure and production for food, feed, fuel, and industrial feedstocks. The use of rice in the project further facilitates the knowledge translation to crop improvement, such as enhancing panicle density and grain yield. Thus, the proposed activities will advance the fundamental knowledge with potential applications for cereal crop improvement. The goal of this project is to understand how specific patatin-related phospholipase As (pPLAs) modulate plant height, reproductive architecture, and seed size. The hypotheses are that pPLAIIIs that contain a non-canonical esterase motif act through their unique enzymatic activities and interactions to affect the subcellular association and function of their interacting proteins mediating plant growth and structures. The specific aims are to determine: 1) the catalytic difference and substrate uses of pPLAIII and II; 2) the effect of pPLAs on S-acylation and membrane association of their interacting proteins; 3) the connection of pPLAIII with G protein signaling to cellulose synthase functions for anisotropic growth; and 4) the role of altered pPLAIII’s activity, subcellular interactions, and expression in panicle architecture and seed production. Multiple approaches, including mutagenesis, structural modeling, enzymology, lipidomics, genome-editing, cell biology, and organismal morphology, will be integrated to test the hypotheses and accomplish the goal. Completion of the research will fill critical knowledge gaps in the regulatory mechanism for cereal functional structures and test potential applications to enhance rice reproductive architecture. 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.