Josefa Hernández-Ruiz - Department of Plant Biology (Plant Physiology), Faculty of Biology, University ofMurcia, Murcia, Spain
Marino B. Arnao - Department of Plant Biology (Plant Physiology), Faculty of Biology, University ofMurcia, Murcia, Spain

Melatonin is an indoleamine present in animals and other organisms. Its mainfunction inanimals where it acts as a hormone regulating circadian rhythms related processes is wellestablished. It was not until 1995 that this compound was detected in plants and, sincethen, interest clarifying their role has been increasing. This article describes the functionsthat 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 thatobserved for other plant hormones, such as auxin, to induce growth in stems and stimulaterooting. It is also able to delay senescence by protecting photosynthetic systems andprocesses. One of the most studied actions is its effect on biotic and abiotic stresses inthe 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 naturalantioxidant, although more recent data have demonstrate its role as a regulator at the levelof gene expression under certain conditions. This has given rise to the idea that it might beused as a natural biostimulating substance for treating field crops, for the phytoremediationof contaminated soils and as a nutraceutical compound

Plant StressSenescencePhytomelatoninMelatoninPlant Growth RegulatorsNutraceuticalAntioxidantsPhotosynthesis