College of Agronomy, Anhui Agricultural University, Hefei, China.
Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China.
Plant Biol (Stuttg). 2020 Jul;22(4):679-690. doi: 10.1111/plb.13093. Epub 2020 Mar 23.
Melatonin has emerged as an essential molecule in plants, due to its role in defence against metal toxicity. Aluminium (Al) and cadmium (Cd) toxicity inhibit rapeseed seedling growth. In this study, we applied different doses of melatonin (50 and 100 µm) to alleviate Al (25 µm) and Cd (25 µm) stress in rapeseed seedlings. Results show that Al and Cd caused toxicity in rapeseed seedling, as evidenced by a decrease in height, biomass and antioxidant enzyme activity. Melatonin increased the expression of melatonin biosynthesis-related Brassica napus genes for caffeic acid O-methyl transferase (BnCOMT) under Al and Cd stress. The genes BnCOMT-1, BnCOMT-5 and BnCOMT-8 showed up-regulated expression, while BnCOMT-4 and BnCOMT-6 were down-regulated during incubation in water. Melatonin application increased the germination rate, shoot length, root length, fresh and dry weight of seedlings. Melatonin supplementation under Al and Cd stress increased superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, proline, chlorophyll and anthocyanin content, as well as photosynthesis rate. Both Cd and Al treatments significantly increased hydrogen peroxide and malondialdehyde levels in rapeseed seedlings, which were strictly counterbalanced by melatonin. Analysis of Cd and Al in different subcellular compartments showed that melatonin enhanced cell wall and soluble fractions, but reduced the vacuolar and organelle fractions in Al- and Cd-treated seedlings. These results suggest that melatonin-induced improvements in antioxidant potential, biomass, photosynthesis rate and successive Cd and Al sequestration play a pivotal role in plant tolerance to Al and Cd stress. This mechanism may have potential implications in safe food production.
褪黑素已成为植物中一种重要的分子，因为它在抵御金属毒性方面发挥作用。铝 (Al) 和镉 (Cd) 毒性抑制油菜幼苗生长。在这项研究中，我们应用不同剂量的褪黑素（50 和 100µm）来缓解油菜幼苗的 Al（25µm）和 Cd（25µm）胁迫。结果表明，Al 和 Cd 对油菜幼苗造成毒性，表现在高度、生物量和抗氧化酶活性降低。褪黑素在 Al 和 Cd 胁迫下增加了与褪黑素生物合成相关的 Brassica napus 基因咖啡酸-O-甲基转移酶（BnCOMT）的表达。基因 BnCOMT-1、BnCOMT-5 和 BnCOMT-8 表现出上调表达，而 BnCOMT-4 和 BnCOMT-6 在水孵育期间下调表达。褪黑素的应用增加了种子的发芽率、苗高、根长、鲜重和干重。在 Al 和 Cd 胁迫下补充褪黑素增加了超氧化物歧化酶、过氧化氢酶、过氧化物酶、抗坏血酸过氧化物酶、脯氨酸、叶绿素和花青素含量以及光合作用速率。Cd 和 Al 处理显著增加了油菜幼苗中的过氧化氢和丙二醛水平，而褪黑素则严格平衡了这两种物质。对不同亚细胞区室中的 Cd 和 Al 分析表明，褪黑素增强了细胞壁和可溶部分，但减少了 Al 和 Cd 处理的幼苗中的液泡和细胞器部分。这些结果表明，褪黑素诱导的抗氧化能力、生物量、光合作用速率和连续 Cd 和 Al 螯合的提高在植物对 Al 和 Cd 胁迫的耐受性中起着关键作用。这种机制可能对安全食品生产具有潜在意义。
