Seed priming with melatonin: A promising approach to combat abiotic stress in plants

Abstract

Melatonin is an indolic compound derived from tryptophan and has an important role in the general processes of plants including germination, photosynthesis, circadian rhythms, flowering, senescence, and alleviating stress. Integrating melatonin application to agronomical practices reportedly provides numerous benefits. More particularly seed priming with melatonin has been shown to improve seed germination as well as improve resilience under adverse conditions. This review discusses in detail the studies showing elevated drought, salinity, heat, and heavy metal stress resistance as a result of melatonin seed priming. Differences in transcript and protein levels have been observed in plants/seedlings germinated via melatonin primed seeds, providing the foundation for further studies. Many pieces of research have also shown primed seeds possess a greater content of osmoprotectants, upregulation of energy-producing pathways, and an increase in protein content, which may lead to enhancing abiotic stress response in plants. The primary function attributed to melatonin is reactive oxygen species scavenging, which consequently leads to enhancing plant stress resistance against multiple stresses. Here, we highlight all the potential mechanisms involved in melatonin meditated induction of abiotic stress tolerance. We review the reports emphasizing the role played by melatonin under stress conditions in multiple crop species, the modification at genome, ribonucleic acid, and protein level involved, and the underlying mechanisms. Information provided here will be helpful to better understand the melatonin role in plants and its efficient exploration in the cropping system.