外源褪黑素对铜胁迫下大豆幼苗生长及生理特性的影响

Effects of exogenous melatonin on seedling growth and physiological characteristics of soybean under copper stress

【目的】研究在铜(Cu)胁迫下,褪黑素对大豆Glycine max(Linn.)Merr.生理特性的影响,为缓解重金属胁迫提供一定的参考。【方法】采用盆栽试验,选用Cu敏感品种‘桂早1号’和耐Cu品种‘巴西13’,在0.5 mmol·L^(−1) Cu胁迫下,施用100μmol·L^(−1)褪黑素,探究褪黑素对大豆生理指标(根长、株高、鲜质量、叶绿素相对含量和Cu含量),超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性,丙二醛(MDA)、可溶性糖和可溶性蛋白含量的影响。【结果】Cu胁迫下喷施100μmol·L^(−1)褪黑素显著提高了2个大豆品种的根长、株高、鲜质量和叶绿素相对含量。Cu胁迫下施用褪黑素显著降低2个品种地上部、地下部Cu含量,‘桂早1号’降低25.01%、18.40%,‘巴西13’降低26.84%、20.28%。Cu胁迫下施用褪黑素,‘桂早1号’的地上部POD活性和‘巴西13’的地下部CAT活性显著提高,分别为56.84%和48.35%;‘桂早1号’和‘巴西13’地上部SOD活性分别显著提高19.07%和7.30%;地上部MDA含量分别显著减少8.05%和26.56%。单施褪黑素和Cu胁迫下施用褪黑素对2个品种可溶性蛋白含量无显著影响;而Cu胁迫下施用褪黑素,‘桂早1号’和‘巴西13’地上部可溶性糖含量分别显著提高149.70%和58.75%。【结论】适宜浓度的褪黑素可以通过提高植株抗氧化酶活性,抑制膜脂氧化,减少对Cu的吸收和增加渗透调节物质等方式缓解Cu胁迫对大豆生长发育的影响。

【Objective】The effects of melatonin on the physiological properties of soybean(Glycine max(Linn.)Merr.)under copper(Cu)stress were investigated to provide some reference for the mitigation of heavy metal stress.【Method】In a pot experiment,the Cu-sensitive variety‘GuiZao 1’and the Cu-tolerant variety‘Brazil 13’were selected and applied with 100μmol·L^(−1) melatonin under 0.5 mmol·L^(−1) Cu stress to explore the effects of melatonin on soybean physiological indicators(root length,plant height,fresh weight,relative chlorophyll content and Cu content),superoxide dismutase(SOD),catalase(CAT),peroxidase(POD)activities,malondialdehyde(MDA),soluble sugar and soluble protein contents.【Result】Application of 100μmol·L^(−1) melatonin under Cu stress increased the root length,plant height,fresh weight and relative chlorophyll content of both soybean varieties.The Cu contents in shoots and roots of both varieties were significantly reduced by melatonin treatment under Cu stress by 25.01%and 18.40%(‘GuiZao 1’),26.84%and 20.28%(‘Brazil 13’),respectively.By applying melatonin under Cu stress,‘GuiZao 1’had a significant increase of POD activity in shoots by 48.35%,and‘Brazil 13’had a significant increase of CAT activity in roots by 56.84%;‘GuiZao 1’and‘Brazil 13’had significantly higher SOD activities in shoots by 19.07%and 7.30%,respectively;MDA content in shoots was significantly reduced by 8.05%and 26.56%.In the single application or mixed application under Cu stress,melatonin had no significant effect on the soluble protein contents of the two varieties.The amounts of soluble sugar in shoots of‘GuiZao 1’and‘Brazil 13’increased by 149.70%and 58.75%in the mixed application treatment under Cu stress.【Conclusion】The appropriate concentrations of melatonin can mitigate the effects with Cu stress on soybean growth and development by improving antioxidant enzyme activity,inhibiting membrane lipid oxidation,reducing Cu uptake and increasing osmoregulatory substances.