Metabolic Regulation and Lipidomic Remodeling in Relation to Spermidine-induced Stress Tolerance to High Temperature in Plants

Abstract

Beneficial effects of spermidine (Spd) on alleviating abiotic stress damage have been explored in plants for hundreds of years, but limited information is available about its roles in regulating lipids signaling and metabolism during heat stress. White clover (Trifolium repens) plants were pretreated with 70 μM Spd and then subjected to high temperature (38/33 °C) stress for 20 days. To further investigate the effect of Spd on heat tolerance, transgenic Arabidopsis thaliana overexpressing a TrSAMS encoding a key enzyme involved in Spd biosynthesis was exposed to high temperature (38/33 °C) stress for 10 days. A significant increase in endogenous Spd content in white clover by exogenous application of Spd or the TrSAMS overexpression in Arabidopsis thaliana could effectively mitigate heat-induced growth retardation, oxidative damage to lipids, and declines in photochemical efficiency and cell membrane stability. Based on the analysis of metabolomics, the amino acids and vitamins metabolism, biosynthesis of secondary metabolites, and lipids metabolism were main metabolic pathways regulated by the Spd in cool-season white clover under heat stress. Further analysis of lipidomics found the TrSAMS-transgenic plants maintained relatively higher accumulations of total lipids, eight phospholipids (PC, phosphatidylcholine; PG, phosphatidylglycerol; PS, phosphatidylserine; CL, cardiolipin; LPA, lysophosphatidic acid; LPC, lyso phosphatidylcholine; LPG, lyso phosphatidylglycerol; and LPI, lyso phosphatidylinositol), one glycoglycerolipid (DGDG, digalactosyl diacylglycerol), and four sphingolipids (Cer, ceramide; CerG2GNAc1, dihexosyl N-acetylhexosyl ceramide; Hex1Cer, hexosyl ceramide; and ST, sulfatide), higher ratio of DGDG: monogalactosyl diacylglycerol (MGDG), and lower unsaturation level than wild-type Arabidopsis thaliana in response to heat stress. Spd-induced lipids accumulation and remodeling could contribute to better maintenance of membrane stability, integrity, and functionality when plants underwent a long period of heat stress. In addition, the Spd significantly up-regulated PIP2 and PA signaling pathways, which was beneficial to signal perception and transduction for stress defense. Current findings provide a novel insight into the function of Spd against heat stress through regulating lipids signaling and reprograming in plants.

Isolation and Characterization of the Sulfate Transporter Gene Family and Its Expression Pattern in Response to Selenium and Abiotic Stress in Walnuts (Juglans regia L.)

“…Throughout the growth and development of walnuts, they are frequently exposed to diverse abiotic stress conditions, drought, low temperatures, high temperatures, and other adverse environments that can impact their growth [8,[21][22][23]. At present, the research and development of selenium-rich products is more and more extensive; by exogenous spraying, selenium can be rapidly enriched in plants.…”

“…In Arabidopsis thaliana, AtSULTR2;1 has been identified as regulating protein activity, while AtSULTR3;1 has been found to participate in the transportation of SO 4 2− in plants [19,20]. The SULTR genes play a positive role in participating in the stress response under heavy metal, drought, and low-and high-temperature environments [8,[21][22][23]. By enhancing the transport of sulfate, the synthesis of glutathione and glucosinolate can be promoted, improving the tolerance of plants in abiotic stress environments [24].…”