title: Melatonin promotes water-stress tolerance, lateral root formation, and seed germination in cucumber (Cucumis sativus L.).
abstract: A comprehensive investigation was carried out to determine the changes that occurred in water-stressed cucumber (Cucumis sativus L.) in response to melatonin treatment. We examined the potential roles of melatonin during seed germination and root generation and measured its effect on reactive oxygen species (ROS) levels, antioxidant enzyme activities, and photosynthesis. Melatonin alleviated polyethylene glycol induced inhibition of seed germination, with 100 μm melatonin-treated seeds showing the greatest germination rate. Melatonin stimulated root generation and vitality and increased the root:shoot ratio; therefore, melatonin may have an effect on strengthening cucumber roots. Melatonin treatment significantly reduced chlorophyll degradation. Seedlings treated with 100 μm melatonin clearly showed a higher photosynthetic rate, thus reversing the effect of water stress. Furthermore, the ultrastructure of chloroplasts in water-stressed cucumber leaves was maintained after melatonin treatment. The antioxidant levels and activities of the ROS scavenging enzymes, i.e., superoxide dismutase, peroxidase, and catalase, were also increased by melatonin. These results suggest that the adverse effects of water stress can be minimized by the application of melatonin.
authors: College of Agriculture and Biotechnology, China Agricultural University, Beijing, China School of Agriculture, Virginia State University, Petersburg, VA, USA.
authors: Na
authors: N
authors: Zhang
authors: Bing
authors: B
authors: Zhao
authors: Hai-Jun
authors: HJ
authors: Zhang
authors: Sarah
authors: S
authors: Weeda
authors: Chen
authors: C
authors: Yang
authors: Zi-Cai
authors: ZC
authors: Yang
authors: Shuxin
authors: S
authors: Ren
authors: Yang-Dong
authors: YD
authors: Guo
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D002736:Chloroplasts / Q000187:drug effects; D018553:Cucumis sativus; D018525:Germination / Q000187:drug effects*; D008550:Melatonin / Q000494:pharmacology*; D010788:Photosynthesis / Q000187:drug effects; D018517:Plant Roots / Q000502:physiology*; D011092:Polyethylene Glycols / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000378:metabolism; D012639:Seeds / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects*; D014867:Water
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D014867:Water; D011092:Polyethylene Glycols; D008550:Melatonin