College of Agriculture, Nanjing Agricultural University, Nanjing, China.
Physiol Plant. 2021 Dec;173(4):2041-2054. doi: 10.1111/ppl.13550. Epub 2021 Sep 18.
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 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 O 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.
采用盆栽试验研究了脱落酸（ABA）和褪黑素（MT）对棉花抗旱性的影响，并探讨了它们的协同作用。ABA 或 MT 喷施促进了干旱胁迫叶片的水分状况和抗氧化能力，有利于清除 ROS，最终增加了皮棉产量。然而，ABA 和 MT 缓解干旱的机制并不相同，主要表现为：（1）ABA 通过减少水分损失来提高干旱胁迫叶片的相对含水量（RWC），而 MT 通过提高吸水效率来提高 RWC；（2）对于酶促抗氧化系统，ABA 和 MT 可能通过调节不同类型的超氧化物歧化酶来催化 O 在干旱下的还原；（3）对于抗坏血酸（AsA）-谷胱甘肽（GSH）循环，MT 提高了干旱胁迫叶片中的谷胱甘肽还原酶活性，但 ABA 没有。ABA+MT 喷施在干旱下比单激素处理具有更高的叶片 RWC 和总抗氧化能力，导致较低的 H₂O 水平。对于酶促抗氧化系统，单激素处理影响 Cu/ZnSOD 或 MnSOD 的表达，但 ABA+MT 在干旱胁迫叶片中上调了这两个基因。激素联合处理的 CAT 表达也高于单激素处理。对于 AsA-GSH 循环，ABA+MT 具有比单激素更高的脱氢抗坏血酸还原酶活性，导致更高的 AsA 含量。此外，激素联合处理的抗坏血酸过氧化物酶活性高于单激素处理，表明它们的组合协同提高了 AsA 消除 ROS 的能力。所有这些都证实了 ABA 与 MT 联合使用对提高作物抗旱性具有协同作用。
