Han Qiao-Hong, Huang Bo, Ding Chun-Bang, Zhang Zhong-Wei, Chen Yang-Er, Hu Chao, Zhou Li-Jun, Huang Yan, Liao Jin-Qiu, Yuan Shu, Yuan Ming
College of Life Sciences, Sichuan Agricultural UniversityYa'an, China.
College of Resources, Sichuan Agricultural UniversityChengdu, China.
Front Plant Sci. 2017 May 11;8:785. doi: 10.3389/fpls.2017.00785. eCollection 2017.
Melatonin (-acetyl-5-methoxytryptamine) plays important role in multiple plant developmental processes and stress responses. We investigated the possible mediatory role of melatonin in growth, photosynthesis, and the response to cold stress in rice by using three different experiments: soaking seed; immersing roots, and spraying to leaves with 0, 20, or 100 μM melatonin. After 6 days of cold stress, the growth of rice seedlings was significantly inhibited, but this inhibition was alleviated by exogenous melatonin. Furthermore, exogenous melatonin pretreatment alleviated the accumulation of reactive oxygen species, malondialdehyde and cell death induced by cold stress. Melatonin pretreatment also relieved the stress-induced inhibitions to photosynthesis and photosystem II activities. Further investigations showed that, antioxidant enzyme activities and non-enzymatic antioxidant levels were increased by melatonin pretreatments. The treatment methods of seed soaking and root immersion were more effective in improving cold stress resistance than the spraying method. The results also indicated the dose-dependent response of melatonin on rice physiological, biochemical, and photosynthetic parameters.
褪黑素（N-乙酰-5-甲氧基色胺）在多种植物发育过程和应激反应中发挥重要作用。我们通过三项不同实验研究了褪黑素在水稻生长、光合作用及对冷胁迫响应中的可能介导作用：种子浸泡；根部浸泡；以及用0、20或100 μM褪黑素喷施叶片。冷胁迫6天后，水稻幼苗生长受到显著抑制，但外源褪黑素缓解了这种抑制。此外，外源褪黑素预处理减轻了冷胁迫诱导的活性氧、丙二醛积累及细胞死亡。褪黑素预处理还缓解了胁迫诱导的对光合作用和光系统II活性的抑制。进一步研究表明，褪黑素预处理提高了抗氧化酶活性和非酶抗氧化水平。种子浸泡和根部浸泡处理方法在提高抗冷性方面比喷施方法更有效。结果还表明褪黑素对水稻生理、生化和光合参数具有剂量依赖性响应。
