Creeping bentgrass (Agrostis stolonifera), a widely used cool-season turfgrass, is highly susceptible to heat stress, which severely impairs its growth and physiological functions. In this study, two cultivars with contrasting heat tolerance, the heat-tolerant 13M and the heat-sensitive Seaside II (SII), were pretreated with diethyl aminoethyl hexanoate (DA-6) or distilled water and then exposed to either normal temperature or heat-stress conditions. Physiological traits and lipidomics were analyzed to investigate the regulatory role of DA-6 in lipid remodeling under high-temperature stress. Results showed that exogenous DA-6 application significantly mitigated physiological damage in both genotypes under heat stress. Under heat stress, compared with their corresponding untreated plants, DA-6 pretreatment increased the Fv/Fm by 15% in 13M and by 33% in SII; for the PIABS, DA-6 pretreatment increased it by 32% in 13M and by 55% in SII; for electrolyte leakage, DA-6 pretreatment reduced it by 24% in 13M and by 11% in SII. The analysis of lipidomics found that heat stress significantly reduced the accumulation of total lipids, phospholipids (PLs), glycolipids (GLs), and sphingolipids (SLs) in two genotypes, but under heat stress, 13M maintained significantly higher content of these lipids than SII. Exogenous DA-6 application significantly alleviated the heat-induced decline in photosynthesis-related glycolipids in SII. Specifically, MGDG, DGDG, and SQDG increased by 186%, 85%, and 32% in heat-stressed SII + DA-6, respectively, relative to heat-stressed SII without DA-6 pretreatment. In addition, DA-6 treatment also alleviated the heat-induced reduction in chloroplast- and mitochondria-associated lipids, including PG, LPG, and CL, in both genotypes. For heat-stressed 13M + DA-6, these lipids increased by 20%, 114%, and 22%, respectively, compared with heat-stressed 13M without DA-6 pretreatment; for heat-stressed SII + DA-6, they increased by 141%, 76%, and 184%, respectively, compared with heat-stressed SII without DA-6 pretreatment. These changes may contribute to improved stability of chloroplasts and mitochondria under heat stress. Furthermore, DA-6 application significantly promoted the accumulation of PC, PE, LPC, LPE, Cer, CerP, and Hex3Cer in both genotypes under heat stress. For 13M, the increases ranged from 18% to 120%; for SII, from 44% to 254%. In heat-stressed SII + DA-6 only, DA-6 also increased PA, PS, MLCL, DLCL, Hex1Cer, and Hex2Cer by 82%, 45%, 84%, 59%, 53%, and 41%, respectively, relative to heat-stressed SII without DA-6 pretreatment. These PLs and SLs are essential for maintaining plasma membrane integrity and mediating stress signal transduction. In addition, the application of DA-6 significantly reduced the heat-induced increase in unsaturation levels of total lipids in both genotypes, indicating that the DA-6 improved lipid saturation levels to better adapt to heat stress. Current findings demonstrated that the DA-6 application improved heat tolerance of creeping bentgrass associated with its regulation of lipid remodeling. Future investigations incorporating multi-omics approaches could comprehensively dissect the DA-6-induced signaling pathways and regulatory networks underlying heat-stress response in cool-season grass species.
Yin et al. (Tue,) studied this question.