Melatonin inhibits seed germination by crosstalk with abscisic acid, gibberellin, and auxin in Arabidopsis

Seed germination, an important developmental stage in the life cycle of seed plants, is regulated by complex signals. Melatonin is a signaling molecule associated with seed germination under stressful conditions, although the underlying regulatory mechanisms are largely unknown. In this study, we showed that a low concentration (10 mu M or 100 mu M) of melatonin had no effect on seed germination, but when the concentration of melatonin increased to 500 mu M or 1000 mu M, seed germination was significantly inhibited in Arabidopsis. RNA sequencing analysis showed that melatonin regulated seed germination correlated to phytohormones abscisic acid (ABA), gibberellin (GA), and auxin. Further investigation revealed that ABA and melatonin synergistically inhibited seed germination, while GA and auxin antagonized the inhibitory effect of seed germination by melatonin. Disruption of the melatonin biosynthesis enzyme gene serotonin N-acetyltransferase (SNAT) or N-acetylserotonin methyltransferase (ASMT) promoted seed germination, while overexpression of ASMT inhibited seed germination. Taken together, our study sheds new light on the function and mechanism of melatonin in modulating seed germination in Arabidopsis.

Automated summary

Seed germination is an important developmental stage in seed plants, and is regulated by complex signals. Melatonin plays a role in inhibiting seed germination by regulating ABA, GA, and auxin pathways in Arabidopsis. Higher concentrations of melatonin inhibit seed germination, while ABA and melatonin synergistically inhibit seed germination.