Phytomelatonin: assisting plants to survive and thrive.
This review summarizes the advances that have been made in terms of the identified functions of melatonin in plants. Melatonin is an endogenously-produced molecule in all plant species that have been investigated. Its concentration in plant organs varies in different tissues, e.g., roots versus leaves, and with their developmental stage. As in animals, the pathway of melatonin synthesis in plants utilizes tryptophan as an essential precursor molecule. Melatonin synthesis is inducible in plants when they are exposed to abiotic stresses (extremes of temperature, toxins, increased soil salinity, drought, etc.) as well as to biotic stresses (fungal infection). Melatonin aids plants in terms of root growth, leaf morphology, chlorophyll preservation and fruit development. There is also evidence that exogenously-applied melatonin improves seed germination, plant growth and crop yield and its application to plant products post-harvest shows that melatonin advances fruit ripening and may improve food quality. Since melatonin was only discovered in plants two decades ago, there is still a great deal to learn about the functional significance of melatonin in plants. It is the hope of the authors that the current review will serve as a stimulus for scientists to join the endeavor of clarifying the function of this phylogenetically-ancient molecule in plants and particularly in reference to the mechanisms by which melatonin mediates its multiple actions.
Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA. reiter@uthscsa.edu.
Russel J
RJ
Reiter
Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA. tan@uthscsa.edu.
Dun-Xian
DX
Tan
Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA. LunaZhou00@163.com.|Department of Occupational Health, Third Military Medical University, Chongqing 400038, China. LunaZhou00@163.com.
Zhou
Z
Zhou
Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering, University of Sao Paolo, Pirassununga 13635-900, Brazil. helenacruz@usp.br.
Maria Helena Coelho
MH
Cruz
Department of Human Anatomy and Histology University of Zaragoza, Zaragoza E-50009, Spain. lfuentes@unizar.es.
Lorena
L
Fuentes-Broto
Departamento de Quimica Universidad Autonoma Metropolitana-Iztapalapa, Mexico CP09340, Mexico. agalano@prodigy.net.mx.
Annia
A
Galano
D008550:Melatonin / Q000378:metabolism* / Q000494:pharmacology; D010802:Phylogeny; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018521:Plant Physiological Phenomena / Q000187:drug effects; D010940:Plant Proteins / Q000378:metabolism* / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D013312:Stress, Physiological; D014364:Tryptophan / Q000378:metabolism
D010940:Plant Proteins; D014364:Tryptophan; D008550:Melatonin