Abstract: Melatonin is an indoleamine growth hormone with multiple biological functions,as well as has an ability to regulate defense responses in plants under stress of adversity. The present study was conducted to explore the effects of exogenous melatonin on the phenotype,physiological indicators,enzyme activities and their related genes in oats (Avena sativa L.) seedlings under salt stress. This study was conducted in an artificial climate chamber and cultured by root irrigation to compare the changes in phenotypic indicators,osmotic regulatory substances,degree of membrane lipid peroxidation,antioxidant system activity,and expression levels of genes related to enzymes encoding antioxidants in 'Baiyan7' under the seven treatments of the single salt stress and combined treatment with salt and melatonin.The results showed that compared with salt stress,the plant height and root length of 'Baiyan 7' seedlings were significantly increased after the addition of exogenous melatonin,the membrane damage caused by oxidative stress was reduced,the expression level of lipoxygenase-related genes LOX was down-regulated,while osmotic imbalance was effectively alleviated;in terms of scavenging reactive oxygen species,the expression of related genes encoding antioxidant enzymes was up-regulated,the enzyme activity was significantly increased,and the activity of antioxidant system was significantly enhanced,which was most suitable at the added concentration of 150 μmol ·L^-1.These results suggest that exogenous melatonin has an important role in alleviating salt stress to oats seedlings.

Key words: Oat, Exogenous melatonin, Antioxidant system

摘要： 褪黑素作为一种吲哚胺类生长激素，具有多种生物学功能，能够调节植物的逆境胁迫中的防御反应。为探究外源褪黑素对盐胁迫下耐盐饲用燕麦(Avena sativa L.)幼苗'白燕7号'的表型和生理的调节作用。本研究在人工气候室进行，采用根灌水培培养，比较在单独盐胁迫和盐与褪黑素复合处理下，'白燕7号'表型指标、渗透调节物质、膜脂过氧化程度、抗氧化系统活性、编码抗氧化物酶相关基因的表达量变化。研究结果表明：与盐胁迫处理相比，添加外源褪黑素后'白燕7号'幼苗的株高和根长显著增高，氧化胁迫造成的膜损伤减轻，且脂氧合酶相关基因LOX表达水平下调，同时渗透失衡得到有效缓解；在清除活性氧方面，编码抗氧化物酶的相关基因表达量上调，酶活性显著提高，抗氧化系统活性显著提升，外源褪黑素最为适宜的浓度为150 μmol·L^-1。这些结果说明外源褪黑素在缓解燕麦盐胁迫方面起重要作用。

关键词: 燕麦, 外源褪黑素, 抗氧化系统