Lipid composition remodeling plays a critical role during the differential responses of leaves and roots to heat stress in bermudagrass

Heat stress is one of the most detrimental abiotic stresses to impede plant growth and development. Previous studies found that plant roots were more sensitive to heat stress than leaves. However, the underlying mechanisms remain unclear. The objective of this study was to determine whether the differential responses of leaves and roots to heat stress were associated with membrane lipid reprogramming under heat stress. Bermudagrass (Cynodon transvaalensis × C. dactylon) was subjected to control (35/30 °C day/night) or heat stress (45/40 °C day/night) in growth chambers. Phenotype and physiological indexes of bermudagrass were observed and measured at 0, 12, and 24 d and lipidomic analysis was conducted at 24 d of heat stress. After 12 d of heat stress, roots exhibited worse phenotypes with higher decline in biomass and increase in both electrolyte leakage and malondialdehyde compared to leaves. Lipidomic analysis showed that leaves have more stable membrane structures than roots in response to heat stress, which was attributed to the up-regulation of phosphatidylglycerol, monogalactosyl diacylglycerol, digalactosyl diacylglycerol, phosphatidic acid, phosphatidylinositol, and saturated and low unsaturated phosphatidylcholine and phosphatidylethanolamine, as well as the down-regulation in polyunsaturated phosphatidylcholine and phosphatidylethanolamine in leaves, therefore resulting in the greater heat tolerance in leaves than roots. These results indicated that the differential responses of leaves and roots to heat stress were involved in the membrane lipid remodeling.