State Key Laboratory of Biotechnology of Shannxi Province, Key Laboratory of Resource Biology and Biothchnology in Western China (Ministry of Education), College of Life Science, Northwest University, Xi'an 710069, China.
Molecules. 2018 Jun 29;23(7):1580. doi: 10.3390/molecules23071580.
Melatonin (-acetyl-5-methoxytryptamine, MT) is a molecule with pleiotropic effects including antioxidant activity, regulated plant growth, development, and reduced environmental stress in plants. However, only a few studies have analyzed the effect of exogenous MT on drought stress in naked oat seedlings. Therefore, in this study, we studied the effects of exogenous MT on the antioxidant capacity of naked oat under drought stress to understand the possible antioxidant mechanism. The results showed that a pretreatment of 100 μM MT reduced the hydrogen peroxide (H₂O₂) and superoxide anion (O•) contents. MT also enhanced superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) activities in the leaves of naked oat seedlings under 20% PEG-6000 drought stress. MT upregulated the expression levels of the mitogen-activated protein kinases (MAPKs) and , and the transcription factor (TF) genes (except for ), , , and increased in drought with MT pretreatment seedlings when compared with seedlings exposed to drought stress alone. These data indicated that the MT-mediated induction of the antioxidant response may require the activation of reactive oxygen species (ROS) and MAPK, followed by triggering a downstream MAPK cascade such as Asmap1 and Aspk11, to regulate the expression of antioxidant-related genes. This study demonstrated that MT could induce the expression of MAPKs and TFs and regulate the expression of downstream stress-responsive genes, thereby increasing the plant’s tolerance. This may provide a new idea for MT modulation in the regulation of plant antioxidant defenses. These results provide a theoretical basis for MT to alleviate drought stress in naked oat.
褪黑素（-乙酰-5-甲氧基色胺，MT）是一种具有多种作用的分子，包括抗氧化活性、调节植物生长、发育和减轻植物环境压力。然而，只有少数研究分析了外源性 MT 对裸燕麦幼苗干旱胁迫的影响。因此，在本研究中，我们研究了外源性 MT 对干旱胁迫下裸燕麦抗氧化能力的影响，以了解可能的抗氧化机制。结果表明，100μM MT 预处理降低了过氧化氢（H₂O₂）和超氧阴离子（O•）的含量。MT 还增强了 20%PEG-6000 干旱胁迫下裸燕麦幼苗叶片中超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）的活性。MT 上调了丝裂原激活蛋白激酶（MAPKs）和转录因子（TFs）基因的表达水平（除了 、 、 、 ），与单独暴露于干旱胁迫的幼苗相比，用 MT 预处理的幼苗在干旱条件下这些基因的表达增加。这些数据表明，MT 介导的抗氧化反应的诱导可能需要活性氧（ROS）和 MAPK 的激活，随后触发 MAPK 级联反应，如 Asmap1 和 Aspk11，以调节抗氧化相关基因的表达。本研究表明，MT 可以诱导 MAPKs 和 TFs 的表达，调节下游应激响应基因的表达，从而提高植物的耐受性。这可能为 MT 调节植物抗氧化防御提供了新的思路。这些结果为 MT 缓解裸燕麦干旱胁迫提供了理论依据。
