Beneficial effects of abscisic acid and melatonin in overcoming drought stress in cotton (Gossypium hirsutumL.)

Abstract

Pot experiments were performed to study the effects of abscisic acid (ABA) and melatonin (MT) on cotton drought tolerance and to explore their combined effects. ABA or MT spraying promoted water status and antioxidant capacity of drought-stressed leaves, which was conducive to scavenge ROS, finally increasing lint yield. However, the mitigation mechanisms of ABA and MT on drought were not identical, which were mainly manifested as: (1) ABA increased the relative water content (RWC) of drought-stressed leaves via, reducing water loss, but MT increased it via, promoting water uptake efficiency; (2) for enzymatic antioxidant system, ABA and MT might modulate different kinds of superoxide dismutase to catalyze the reduction of O 2 À under drought; and (3) for ascorbic acid (AsA)-glutathione (GSH) cycle, MT increased the glutathione reductase activity in drought-stressed leaves, but ABA did not. ABA + MT spraying led to higher leaf RWC and total antioxidant capacity than single hormone under drought, leading to a lower H 2 O 2 level. For the enzymatic antioxidant system, single hormone treatment affected Cu/ZnSOD or MnSOD expression, but ABA + MT upregulated both genes in drought-stressed leaves. Hormones combined application also had higher CAT expression than single hormone. For AsA-GSH cycle, ABA + MT had higher dehydroascorbic acid reductase activity than single hormone, resulting in higher AsA content. Moreover, hormones combined application caused higher ascorbate peroxidase activity than single hormone, suggesting that their combination synergistically improved the ability of AsA to eliminate ROS. All these confirmed that ABA plus MT had synergistic effects on improving crop drought resistance.

Exogenous Melatonin Reprograms the Rhizosphere Microbial Community to Modulate the Responses of Barley to Drought Stress

“…Enhanced antioxidant enzyme activities have been reported to be an important approach for exogenous melatonin-induced stress tolerance [ 49 ]. Melatonin can eliminate excess ROS accumulation by promoting the ascorbate–glutathione (AsA-GSH) cycle [ 50 , 51 ], which is consistent with this study where the activities of DHAR, GST, and MDHAR were significantly enhanced by melatonin in roots.…”

Melatonin Enhances Drought Tolerance in Rice Seedlings by Modulating Antioxidant Systems, Osmoregulation, and Corresponding Gene Expression

“…Interestingly, exogenous melatonin relieved the drought stress in rice seedlings by turning the originally yellowing and wilting leaves back to green, and by increasing the leaves’ RWC and the root-shoot ratio. Similar findings were also verified in drought-stressed cotton ( Gossypium hirsutum L.) [ 28 ] and potato ( Solanum tuberosum L.) [ 29 ].…”

Exogenous application of melatonin to mitigate drought stress-induced oxidative damage in Phoebe sheareri seedlings

“…This study found that melatonin treatment specifically scavenged drought-induced ROS (MDA and O 2 •− ) accumulation, thereby improving plant growth under drought conditions. Numerous studies supported our conclusions; for example, melatonin ameliorated maize seedling’s growth by improving drought tolerance and decreasing ROS ( Ahmad et al, 2021 ; Huang et al, 2019 ) as well as in cotton ( Gossypium hirsutum L.) ( Hu et al, 2021 ) and Tartary Buckwheat ( Fagopyrum tataricum (L.) Gaertn) ( Hossain et al, 2020 ). Melatonin alleviated the toxicity of nano plastics to wheat by activating the ROS scavenging system to maintain redox homeostasis and regulate the expression of aquaporin-related genes ( Li et al, 2021 ).…”