Diethyl aminoethyl hexanoate mitigates drought-stimulated leaf senescence via the regulation of water homeostasis, chlorophyll metabolism, and antioxidant defense in creeping bentgrass

Abstract

Diethyl aminoethyl hexanoate (DA-6) is involved in the regulation of adaptive response of plants to unfavorable environmental conditions. The objective of this experiment was to examine whether the DA-6 pretreatment could effectively alleviate drought-triggered leaf senescence and oxidative injury to creeping bentgrass. Plants were exogenously irrigated with or without DA-6 (0.4 mM·L−1) before being subjected to PEG-induced drought stress for 9 d. Drought stress resulted in significant growth retardation, Chl loss, and decreases in leaf relative water content, water use efficiency, photochemical efficiency, and net photosynthetic rate, but significantly enhanced oxidative damage. Exogenous DA-6 markedly alleviated symptoms of drought stress by improving water homeostasis, ROS scavenging, Chl biosynthesis, and photosynthesis. In contrast to untreated plants, the DA-6-pretreated creeping bentgrass demonstrated significantly higher transcript levels of genes related to rubisco activity (AsRuBisCo), and Chl biosynthesis (AsMg-CHT, AsPBGD, AsPOR, and AsCHLH), but lower transcript levels of Chl degradation-related genes (AsPAO, AsCLH, and AsPPH), and senescence-associated genes (Asl20 and Ash36), thereby decreasing leaf senescence and ameliorating photosynthetic performance under drought stress. Moreover, DA-6 also significantly promoted activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase, hence efficiently diminishing drought-stimulated oxidative damage. The current study supplies important information about DA-6-regulated growth and drought tolerance associated with osmotic adjustment, antioxidant defense, photosynthetic function, and Chl metabolism in cool-season turfgrass species.