Phytomelatonin, an Interesting Tool for Agricultural Crops

Melatonin is an indoleamine present in animals and other organisms. Its main function in animals where it acts as a hormone regulating circadian rhythms related processes is well established. It was not until 1995 that this compound was detected in plants and, since then, interest clarifying their role has been increasing. This article describes the functions that have been identified so far in plants that might be of agronomic interest. As in animals, plant melatonin appears to have developed a type of hormonal function, similar to that observed for other plant hormones, such as auxin, to induce growth in stems and stimulate rooting. It is also able to delay senescence by protecting photosynthetic systems and processes. One of the most studied actions is its effect on biotic and abiotic stresses in the plant, such as drought, extreme temperature, chemical pollution, UV radiation, etc. Some of these functions could be explained by the fact that melatonin is a powerful natural antioxidant, although more recent data have demonstrate its role as a regulator at the level of gene expression under certain conditions. This has given rise to the idea that it might be used as a natural biostimulating substance for treating field crops, for the phytoremediation of contaminated soils and as a nutraceutical compound.