Abstract
Melatonin (N-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 (O2−•) 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) Asmap1 and Aspk11, and the transcription factor (TF) genes (except for NAC), WRKY1, DREB2, and MYB 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.
Highlights
Naked oat (Avena nuda L.) is an annual herbaceous crop in the family Poaceae
The growth naked oat seedlings wasofinhibited by drought stress, Stress and 100 μM MT promoted
The growth of naked oat seedlings was inhibited by drought stress, and 100 μM MT promoted weight, and plant growth dry weight of 1naked seedlings inhibited, but that response was alleviated seedling (Figures and 2).oat
Summary
Naked oat (Avena nuda L.) is an annual herbaceous crop in the family Poaceae. Naked oat is a high nutritional value cereal [1] and is a unique food crop in Chinese alpine regions. . Membrane lipid peroxidation which further actstress as inducers or production activatorsofto activate response gene expression, thereby enhancing is triggered when the balance between ROS accumulation and the free radical scavenging systems is stress tolerance [9]. Mechanisms have developed in plants to combatto adverse conditionsChanges (the main factor that limitsconditions activate the plant’s internal antioxidant system to maintain and balance normal physiological plant productivity), which can prevent harmful damage [5], and the antioxidant system is one of the reactions, best ways plants stress. Oat seedlings under drought stress were treated with MT to study the effects of MT on antioxidant enzyme activities and the expression levels of related resistance genes in leaves. Effect of Spraying 100 μM MT on Leaves of Naked Oat Seedlings under Drought Stress
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