Lipid storage in green tissues alters redox homeostasis, malate metabolism, phospholipids, and nitrogen partitioning in plants

In our previous research, we explored the ramifications of accumulating High Lipid levels in the green tissues of perennial ryegrass (Lolium perenne L., HL-Lp), revealing notable changes in gene transcripts associated with mitochondrial oxidative respiration and redox equilibrium. This study provides biochemical evidence of substantially altered redox components and investigates the broader metabolic consequences of lipid accumulation in vegetative tissues. To valid the observed changes in redox balance, we introduced a redox-sensitive GFP (Grx1roGFP2) into transgenic Nicotiana benthamiana (HL-Nb) and Arabidopsis thaliana (HL-At), demonstrating dose-dependent oxidative conditions in mature and senescing leaves of HL plants. We report that lipid accumulation in source tissues influences leaf malate, leaf pH, and phospholipid composition, with these effects being modulated by the form of nitrogen supplied. Our findings reveal that increased lipid biosynthesis imposes significant redox stress, necessitating compensatory adjustments in antioxidant pathways and malate metabolism. These insights highlight the metabolic trade-offs associated with lipid accumulation and provide a foundation for optimizing high-energy forage crops and renewable biomass sources. By elucidating the interplay between lipid metabolism, redox homeostasis, and nutrient partitioning, this study advances our understanding of plant metabolic engineering and its potential to enhance agricultural sustainability.