Melatonin (N-acetyl-5-methoxytryptamine) is a well-known animal hormone that is involved in many biological processes including sleep, circadian rhythms, antioxidative activity, and immunological enhancement. However, melatonin is not only found exclusively in animals, but is ubiquitously identified in plants in the last 20 years. The well-known beneficial effects of melatonin on human health and the abundance of melatonin in popular beverages and crops may encourage the daily consumption of these products. 

Bermudagrass [Cynodon dactylon (L). Pers.] is a warm-season turfgrass cultivated  worldwide. The improvement of its abiotic stress resistance is very important for grass engineering. Previous study has showed melatonin’s benifical role in some plant development and various stress responses, however, the endogenous melatonin concentration and the possible role of melatonin in response to abiotic stress in bermudagrass is largely unknown. 

Prof. CHAN Zhulong and Dr. SHI Haitao from Wuhan Botanical Garden made comparative physiological, metabolomic, and transcriptomic analyses to reveal mechanisms of improved abiotic stress resistance in bermudagrass by exogenous melatonin. 

In this study, they found that salt, drought, and cold stress induced the endogenous melatonin level in bermudagrass; exogenous melatonin application improved salt, drought, and freezing stress resistance in bermudagrass. Moreover, exogenous melatonin treatment revealed that exogenous application of melatonin modulated abiotic stress-triggered reactive oxygen species (ROS) accumulation and related oxidative damage in bermudagrass. Metabolic and transcriptomic analyses indicated that melatonin affected the express of many genes involved in plant defense and these changes might contribute to the enrichment of stress-related gene ontology (GO) term. Additionally, exogenous melatonin treatment had significant effects on various signalling pathways, as well as the concentrations of 54 metabolites including amino acids, organic acids, sugars and sugar alcohols. 

This study provides the first evidence of the exogenous melatonin’s protective roles in the bermudagrass response to abiotic stresses, which involves the activation of antioxidants, modulation of metabolic homeostasis, and extensive transcriptional reprogramming. 

This research entitled “Comparative physiological, metabolomic, and transcriptomic analyses reveal mechanisms of improved abiotic stress resistance in bermudagrass [Cynodon dactylon(L). Pers.] by exogenous melatonin” was published in Journal of Experimental Botany (doi: 10.1093/jxb/eru373).