Tolerance of Forage Grass to Abiotic Stresses by Melatonin Application: Effects, Mechanisms, and Progresses

Climate change related abiotic stress has been potentially impacting the quantity and quality of forage grass. Melatonin, a multifunctional molecule that has been found to be present in all plants examined to date, plays a crucial role in improving forage grass tolerance to both biotic and abiotic stresses. However, research on melatonin's role in forage grass is still developing. In this review, the effects of melatonin application on abiotic stress are the primary topic, and we try to find relative mechanisms. In order to determine whether melatonin has a good effect on forage grass, we compared and summarized the adapting ability of different forage grasses under abiotic stress after melatonin application in aspects of growth and development, photosynthesis, antioxidant systems, plant hormone interactions, and ion homeostasis. According to part of the data, we found that different forage grasses exhibited varying responses to endogenous melatonin content and exogenous melatonin dose applications. Meanwhile, the regulatory mechanisms of melatonin application include the expression of chlorophyll synthesis and degradation genes, electron transport and phosphorylation genes, stress regulation pathway genes, and plant hormone synthesis genes. We propose possible future studies that can further explore the metabolic pathways of melatonin and the molecular mechanisms of melatonin regulation of abiotic stress in forage grass. Specifically, research can focus on elucidating the signaling pathways, gene expression of regulatory networks, and interactions with other plant hormones. This will provide valuable theoretical and practical guidance for adapting to climate change and forage grass development.