Melatonin alleviates cold‐induced oxidative damage in maize seedlings by up‐regulating mineral elements and enhancing antioxidant activity

Abstract

Melatonin, known as an animal hormone and an antioxidant with a low molecular weight, is one of the most commonly used substances to improve plant resistance against various environmental stresses. However, there are no studies explaining the effects of melatonin on the relationship between defense system and mineral composition of plants under stressed and unstressed-conditions. The present study was conducted to investigate whether the mitigating effect of melatonin is associated with its modulating influence on the mineral elements of cold-stressed maize seedlings. The seedlings were treated with melatonin (1 mM) and cold stress (10/7°C) for 3 d separately and in combination. After 3 d, the seedlings were harvested to determine several physiological, biochemical, and molecular parameters. Melatonin application effectively mitigated the damages from cold stress, as demonstrated by higher relative water concentration, chlorophyll concentration and antioxidant enzyme activities (superoxide dismutase, guaiacol peroxidase, catalase, ascorbate peroxidase, and glutathione reductase), as well as lower superoxide, hydrogen peroxide, and malondialdehyde concentrations. Similarly, melatonin significantly ameliorated cold-induced reductions in the concentrations of potassium, phosphorus, sulfur, magnesium, iron, copper, manganese, and zinc. Besides, it further increased calcium and boron concentrations compared to cold stress alone. Our results reveal that melatonin has an important modulating influence on the mineral element composition of plants and mitigates cold stress through up-regulation of these elements and simultaneously enhanced antioxidant activity.

Postharvest exogenous melatonin treatment of strawberry reduces postharvest spoilage but affects components of the aroma profile

“…Calcium also plays an important role in cell wall structure and tissue firmness. Melatonin application led to a reduction in water loss and an increase in calcium content in maize seedlings under cold stress [18]. The weight loss and reduced decay elicited by melatonin treatment in chilled strawberry fruit shown here could therefore possibly be due to redistribution of the calcium in strawberry fruit tissue leading to less moisture loss.…”

Improved cold tolerance in Elymus nutans by exogenous application of melatonin may involve ABA-dependent and ABA-independent pathways

“…These observations indicate that melatonin might serve as a second messenger, activating downstream cold-responsive genes including EnCBF9, EnCBF14 , and EnCOR14a , and thus stimulating biosynthesis of cold-protecting compounds. Consequently, this contributes to the enhancement of cold tolerance in plants treated with exogenous melatonin and subjected to cold stress2331. Previous studies reported that both cold treatment and exogenous ABA treatment induce the expression of CBF1 and several COR genes in A. thaliana plants4344.…”

“…In recent years, melatonin has been found to be a ubiquitous modulator in multiple plant developmental processes, including flowering, promotion of photosynthesis, preservation of chlorophyll17, stimulation and regeneration of root system architecture18, delayed senescence of leaves19, and alleviation of oxidative damage induced by reactive oxygen species (ROS) and reactive nitrogen species (RNS)1720. Moreover, melatonin is involved in the regulation of various abiotic stresses, such as cold212223, salinity24, heavy metal25, herbicides26, and UV radiation27. The mechanisms of melatonin-mediated stress tolerance involve the activation of antioxidants biosynthesis and activities of antioxidant enzymes, as well as the direct scavenging of ROS following plant exposure to harsh environments282930.…”

“…Despite melatonin positively mediating plant responses to cold stress (e.g. via promoting seed germination in cucumber28, mitigating oxidative damage in maize seedlings23, and up-regulating the expression of cold-induced transcriptional activators including CBFs and zinc finger of Arabidopsis thaliana 6 (ZAT6)3031), the exact mechanism enabling these responses remain largely unknown.…”

Peer Review #1 of "Exogenous melatonin confers drought stress by promoting plant growth, photosynthetic capacity and antioxidant defense system of maize seedlings (v0.1)"

“…The leaf relative water concentration (RWC) was estimated by following Turk and Erdal (2015). The fresh weight (FW) of the seventh leaf was measured immediately after sample harvesting.…”