In the cells of a plant, lipids form membranes that separate the cell from its environment and compartments within the cell from one another. These lipids also have crucial metabolic and signaling functions that are only now being established. As plants develop and are exposed to environmental signals, membrane lipids are extensively chemically modified. Recent advances in lipid analysis have revealed that addition of a fatty acid to a membrane lipid, called polar lipid head-group acylation, is a major modification process, but relatively little is known about this process or its physiological significance. This project will address the hypothesis that head-group acylation of lipids functions to improve plant adaptation to environmental stress. To identify the role of head-group acylation when plants are under stress, genes encoding enzymes responsible for head-group-acylated lipid metabolism will be identified. By examining plants that are missing these genes and enzymes, in comparison to plants that contain them, the functions of membrane lipid head-group acylation in plant stress responses will be determined. These activities will identify metabolic steps with potential to enhance stress tolerance in plants and improve agricultural productivity and quality. Relevant data will be integrated into a plant functional genomic knowledge base. Further, the work will provide interdisciplinary training in biostatistics, chemistry, and biology to postdoctoral trainees, and it will broaden the participation of underrepresented groups in research through collaboration with a faculty mentor and undergraduate student at historically black Langston University.
This project aims to improve current understanding of the role of membrane lipid modification in producing and maintaining complex cell membranes, and influencing organismal performance. In the context of whole glycerolipidomes, new mass spectrometry-based approaches will be used to identify and characterize changes in lipid head-group acylation in response to a biotic stress, Pseudomonas syringae infection, and an abiotic stress, phosphate deficiency. To identify the gene product(s) responsible for head-group acylation, the lipid profiles of knockout mutants of candidate genes will be obtained and compared to the lipid profiles of wild-type plants. Data from functional analysis of the knockout mutants under stress will be correlated with lipid levels, providing additional information about the roles of head-group acylation in plant function. The effects of application of acylated head groups or head-group acylated lipids to plants also will be tested. Lipid profiling and functional data will be integrated into a novel metabolic database to expand knowledge of metabolic networks.
