Melatonin in flowering, fruit set and fruit ripening.

KEY MESSAGE: Melatonin induces a delay in flowering stabilizing DELLA proteins and also promotes the transcription of FLC. In fruit set, melatonin is able to induce parthenocarpy. Melatonin promotes ripening and retards senescence of fruits. Melatonin is an animal hormone involved in many regulatory processes such as those related to sleep. Melatonin was discovered in plants in 1995 and is called phytomelatonin. Also in plants, a great variety of physiological processes have been described in which melatonin plays a role. In plants, melatonin is mainly involved in stress situations but also in germination, plant growth, rhizogenesis, senescence and as a protector agent improving important processes such as photosynthesis, CO2 uptake, cell water economy and primary and secondary metabolism. Melatonin has been related to changes in the majority of plant hormones. Many revisions of stress situations have been published. However, melatonin and plant reproductive development have been poorly studied. The aim of this review is to provide an overview of works related to flowering, fruit set and development, including parthenocarpy and fruit ripening/senescence, and the role played by melatonin in the same.