Lipidomics-based insights into the physiological mechanism of wheat in response to heat stress.

Lipids are the main components of plant cell biofilms and play a crucial role in plant growth, Understanding the modulation in lipid profiles under heat stress can contribute to understanding the heat tolerance mechanisms in wheat leaves. In the current study, two wheat cultivars with different heat tolerance levels were treated with optimum temperature (OT) and high temperature (HT) at the flowering stage, and the antioxidant enzyme activity in the leaves and the grain yield were determined. Further, lipidomics was studied to determine the changes in lipid composition in the leaves. The heat-tolerant cultivar ZM7698 exhibited higher antioxidant enzyme activity and lower malondialdehyde and HO contents. High-temperature stress led to the remodeling of lipid profile in the two cultivars. The relative proportion of digalactosyl diacylglycerol (DGDG) and phosphatidylinositol (PI) components increased in the heat-tolerant cultivar under high-temperature stress, while it was decreased in the heat-sensitive cultivar. The lipid unsaturation levels of sulfoquinovosyl diacylglycerol (SQDG), monogalactosyl monoacylglycerol (MGMG), and phosphatidic acid (PA) decreased significantly in the heat-tolerant cultivar under high-temperature stress. The increase in unsaturation of monogalactosyl diacylglycerol (MGDG) and phosphatidylethanolamine (PE) in the heat-tolerant cultivar under high-temperature stress was lower than in the heat-sensitive cultivar. In addition, a high sitosterol/stigmasterol (SiE/StE) ratio was observed in heat-tolerant cultivar under high-temperature stress. Taken together, these results revealed that a heat-tolerant cultivar could enhance its ability to resist heat stress by modulating the composition and ratio of the lipid components and decreasing lipid unsaturation levels in wheat.