Cen Huifang, Wang Tingting, Liu Huayue, Tian Danyang, Zhang Yunwei
College of Grassland Science and Technology, China Agricultural University, Beijing, 100193, China.
Plants (Basel). 2020 Feb 8;9(2):220. doi: 10.3390/plants9020220.
Alfalfa ( L.) is an important and widely cultivated forage grass. The productivity and forage quality of alfalfa are severely affected by salt stress. Melatonin is a bioactive molecule with versatile physiological functions and plays important roles in response to various biotic and abiotic stresses. Melatonin has been proven efficient in improving alfalfa drought and waterlogging tolerance in recent studies. In our reports, we applied melatonin exogenously to explore the effects of melatonin on alfalfa growth and salt resistance. The results demonstrated that melatonin application promoted alfalfa seed germination and seedling growth, and reduced oxidative damage under salt stress. Further application research found that melatonin alleviated salt injury in alfalfa plants under salt stress. The electrolyte leakage, malondialdehyde (MDA) content and HO content were significantly reduced, and the activities of catalase (CAT), peroxidase (POD), and Cu/Zn superoxide dismutase (Cu/Zn-SOD) were increased with melatonin pretreatment compared to control plants under salt stress with the upregulation of genes related to melatonin and antioxidant enzymes biosynthesis. Melatonin was also involved in reducing Na accumulation in alfalfa plants. Our study indicates that melatonin plays a primary role as an antioxidant in scavenging HO and enhancing activities of antioxidant enzymes to improve the salt tolerance of alfalfa plants.
紫花苜蓿（Medicago sativa L.）是一种重要且广泛种植的饲草。紫花苜蓿的生产力和饲草品质受到盐胁迫的严重影响。褪黑素是一种具有多种生理功能的生物活性分子，在应对各种生物和非生物胁迫中发挥重要作用。最近的研究表明，褪黑素在提高紫花苜蓿耐旱和耐涝性方面具有显著效果。在我们的报告中，我们通过外源施用褪黑素，探究其对紫花苜蓿生长和抗盐性的影响。结果表明，施用褪黑素促进了紫花苜蓿种子萌发和幼苗生长，并减轻了盐胁迫下的氧化损伤。进一步的应用研究发现，褪黑素减轻了盐胁迫下紫花苜蓿植株的盐害。与盐胁迫下的对照植株相比，经褪黑素预处理后，电解质渗漏率、丙二醛（MDA）含量和H₂O₂含量显著降低，过氧化氢酶（CAT）、过氧化物酶（POD）和铜/锌超氧化物歧化酶（Cu/Zn-SOD）的活性增加，同时与褪黑素和抗氧化酶生物合成相关的基因上调。褪黑素还参与减少紫花苜蓿植株中Na⁺的积累。我们的研究表明，褪黑素作为抗氧化剂，在清除H₂O₂和增强抗氧化酶活性方面发挥主要作用，从而提高紫花苜蓿植株的耐盐性。
