Metabolomics and transcriptomics analyses revealed overexpression of TaMGD enhances wheat plant heat stress resistance through multiple responses

Monogalactosyldiacylglycerol (MGDG), as the primary lipid component of thylakoid membranes, has a significant part in plant growth and stress response. The current study employed two transgenic wheat lines (MG1516 and MG1314) overexpressing the MGDG synthase gene (TaMGD) and wild-type cv "JW1" to explore the function of TaMGD in response to high temperature stress during the anthesis stage of wheat. Under high-temperature stress, the overexpressed wheat lines exhibited higher grain weight, increased antioxidant enzyme activity, and lower H2O2 and malondialdehyde contents in leaves. Transcriptomic analysis suggests that overexpression of TaMGD influenced multiple metabolic pathways in response to high-temperature stress, including carbon metabolism, amino acid metabolism, photosynthesis, and lipid-related metabolism. Overall, 146 differentially expressed metabolites (DEMs) were identified in MG1516 and wild-type (WT) under heat stress, with MG1516 exhibiting a higher number of upregulated metabolites, particularly glycolipids, organic acids, and organic oxygen compounds. Furthermore, lipid content and unsaturation analysis revealed that the overexpressing wheat line had a higher lipid content and greater saturation than WT under heat stress. Our findings demonstrate that overexpression of TaMGD in wheat affects multiple metabolic pathways, including photosynthesis, carbon, and amino acid metabolism, in reply to high-temperature stress through the modification of cell membrane lipid content, fatty acid unsaturation and other factors.