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ARS Home » Midwest Area » Columbia, Missouri » Plant Genetics Research » Research » Publications at this Location » Publication #406107

Research Project: Improving Soybean Seed Composition, Plant Productivity, and Resilience to Climate Change Through Biological Network Modification

Location: Plant Genetics Research

Title: Arabidopsis acyl carrier protein 4 and rhomboid like 10 act independently in chloroplast phosphatidic acid assembly

Author
item XU, YANG - Michigan State University
item COOK, RON - Michigan State University
item KAMBHAMPATI, SHRIKAAR - Donald Danforth Plant Science Center
item Morley, Stewart
item FROEHLICH, JOHN - Michigan State University
item Allen, Douglas - Doug
item BENNING, CHRISTOPH - Michigan State University

Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: In plant cells, lipids can be produced using similar biochemical pathways but involving different substrates and taking place in one of several subcellular locations. The generation of lipids is necessary to form membranes that segregate compartments within a cell that enable it to function correctly for plant growth. In addition, lipids are energy dense and understanding lipid production can be important for the production of biofuels that are an important part of a sustainable economy. In the current studies, mutants in one of the lipid biosynthetic pathways were used to study lipid production. The investigations included measurement of lipids and metabolites involved in lipid biosynthesis. The studies identified important roles for genes involved in lipid pathways and that affect the final lipid composition. Such studies are important because they contribute to our understanding of plant cellular lipid metabolism and provide inspiration for how plants might be rationally engineered to augment biomass and in particular lipid profiles.

Technical Abstract: Acyl Carrier Protein (ACP) 4 is the most abundant ACP isoform in Arabidopsis leaves and acts as scaffold for de novo fatty acid biosynthesis and as substrate for acyl-ACP utilizing enzymes. Recently, ACP4 was found to interact with a protein designated plastid rhomboid like (RBL) 10 and affects chloroplast monogalactosyldiacylglycerol (MGDG) biosynthesis, but the mechanisms remain largely unknown. Here, we generated and characterized acp4 rbl10 double mutants as a means of exploring how ACP4 and RBL10 influence chloroplast lipid metabolism. Alterations in the content and molecular species of chloroplast lipids such as MGDG and phosphatidylglycerol (PG) were observed in the acp4 and rbl10 mutants, which are likely associated with the changes in the size and profiles of diacylglycerol (DAG), phosphatidic acid (PA) and acyl-ACP precursor pools. ACP4 was found to determine the size and profile of the acyl-ACP pool and to interact with acyl-ACP utilizing enzymes, likely contributing to chloroplast fatty acid biosynthesis and assembly. RBL10 appears to be involved in the conversion of PA to DAG precursors for MGDG biosynthesis as evidenced by the increased 34:x PA and decreased 34:x DAG in the rbl10 mutant and the slow turnover of radiolabeled PA in isolated chloroplasts fed with [14C] acetate. Interestingly, the impaired PA turnover in rbl10 was partially rescued in the acp4 rbl10 double mutant. Apparently, removing ACP4 changes the PA pools sufficiently to facilitate the subsequent turnover. Collectively, this study shows that ACP4 and RBL10 affect chloroplast lipid biosynthesis by modulating substrate precursor pools.