Changes in melatonin content of pepper seeds during storage
Melatonin (N-acetyl-5-methoxytryptamine) is present in evolutionary distant organisms like bacteria, algae, invertebrates, vertebrates and plants. Melatonin may serve as a photoperiodic and circadian rhythm regulator as well as a universal antioxidant. Even though little is known about changes in seed melatonin content during short-term storage, there is no information available on the involvement of melatonin on seed aging and seasonal variation of seed melatonin content during long-term storage. The main aim of this research was to identify the changes in melatonin content of pepper seeds ('Yalova 341') stored for two years at two temperature regimes and to determine the possible effects of melatonin on the seed aging process. For this purpose, pepper seeds were treated with 0 or 250 µM melatonin for one day after which they were stored for up to two years under room temperature (25°C) or in the refrigerator (4°C). The effects of exogenous application of melatonin on seed aging and changes in melatonin content were assessed periodically with various tests and analyses. The results showed that seed melatonin content varied significantly during storage, reaching its peak in October and bottoming out in August during the course of the experiment. On the other hand, seed MDA and H2O2 contents were significantly higher and lower in October and August, respectively, and melatonin pre-treatment slightly improved seed germination performance during the course of the experiment. These results clearly indicate that the existing circannual rhythm in melatonin levels lasts longer than a year, presumably over the life of the seed albeit in a diminishing fashion.
Yakupoğlu, G., Köklü, Ş., Karaca, A., Düver, E., Klicic, A. and Korkmaz, A. (2020). Changes in melatonin content of pepper seeds during storage. Acta Hortic. 1273, 425-432
germination, seed storage, seasonal change, seed aging