Role of Exogenous Melatonin in Plant Biotechnology: Physiological and Applied Aspects

Melatonin was discovered in plants in 1995, and so-called phytomelatonin. Its characteristic qualities as an antioxidant molecule and with amphiphilic nature make it an excellent candidate to use in plant biotechnological techniques. In plant physiology, melatonin has demonstrated with multiple studies great possibilities of application in crop improvement in aspects such as germination, rooting, plant growth, leaf-senescence, floration, fruit-set, parthenocarpy, fruit ripening and cut flower conservation, among others. In this work, we reviewed many studies on the possible role of melatonin to improve the different plant tissue culture goals, among them: the role of melatonin in callus culture induction and its effects in plant biomass production; the possible action of melatonin as an inductor or elicitor of different secondary metabolite generation in in vitro cultures; the interesting possibilities of melatonin as a protective agent (safener) against abiotic stressors present in in vitro cultures; the potential of melatonin in regulating plant organogenesis, modulating shooting/rooting responses; at last, the studies on the relevant role of melatonin in plant material cryopreservation and the improvement of cell transformation using A. tumefaciens have been discussed.