College of Grassland Science and Technology, Sichuan Agricultural University, Chengdu 611130, China.
Institute of Turfgrass Science, Beijing Forestry University, Beijing 100083, China.
Int J Mol Sci. 2022 Oct 13;23(20):12247. doi: 10.3390/ijms232012247.
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 () 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 overexpressing a 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 overexpression in 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 -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 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.
多胺（Spd）在缓解非生物胁迫损伤方面对植物的有益作用已被研究了数百年，但关于其在热胁迫下调节脂质信号和代谢中的作用的信息有限。用 70 μM Spd 预处理白三叶草（）植株，然后用高温（38/33°C）胁迫处理 20 天。为了进一步研究 Spd 对耐热性的影响，过表达参与 Spd 生物合成的关键酶的转基因（）在高温（38/33°C）胁迫下暴露 10 天。外源施用 Spd 或在 中过表达可有效减轻热诱导的生长迟缓、脂质氧化损伤以及光化学效率和细胞膜稳定性下降，从而导致白三叶草内源 Spd 含量显著增加。基于代谢组学分析，在冷季型白三叶草中，Spd 在热胁迫下主要调节氨基酸和维生素代谢、次生代谢物合成和脂质代谢。脂质组学进一步分析发现，-转基因植物保持相对较高的总脂质、八种磷脂（PC、磷脂酰胆碱；PG、磷脂酰甘油；PS、磷脂酰丝氨酸；CL、心磷脂；LPA、溶血磷脂酸；LPC、溶血磷脂酰胆碱；LPG、溶血磷脂酰甘油；和 LPI、溶血磷脂酰肌醇）、一种糖脂（DGDG、二半乳糖基二酰基甘油）和四种神经酰胺（Cer、神经酰胺；CerG2GNAc1、二己糖基-N-乙酰己糖基神经酰胺；Hex1Cer、己糖神经酰胺；和 ST、硫酸神经酰胺）的积累，DGDG:MGDG 的比值较高，不饱和程度较低，对热胁迫的反应比野生型更好。Spd 诱导的脂质积累和重塑有助于在植物经历长时间热胁迫时更好地维持膜稳定性、完整性和功能。此外，Spd 显著上调了 PIP2 和 PA 信号通路，这有利于对信号的感知和转导，以进行应激防御。目前的研究结果为 Spd 通过调节植物中的脂质信号和重编程来抵抗热应激提供了新的见解。
