During the process of fertilization of sexually reproducing organisms, maternal and paternal gametes, egg and sperm respectively, fuses together to give rise to the zygote. Differently from animal, in flowering plants the so-called double fertilization involves a second female gamete, the central cell, from which originates the endosperm, a triploid and ephemeral tissue that nurtures and sustains the growth of the embryo. The fusion of the paternal and maternal gametes generates a series of dramatic events, including the re-activation of the cell cycle that is, somehow, strongly inhibited before fertilization to avoid premature division. Genetic evidences show that both parents exert a tight control over cell cycle progression: the mother reins cell division in the seeds, whereas the father provokes the opposite. The lack of this control then has dramatic and conflicting effects as the development of seed-like structure from unfertilized ovules, or suicidal cell divisions as result of unbalanced DNA content after fertilization. The molecular mechanisms underlying these processes are yet to be fully understood. I will present some of our recent data about the characterization of such mechanisms, showing how maternal factors keep female gametes quiescent, and how paternally-derived signals trigger cell cycle progression specifically at fertilization. https://www.botinst.uzh.ch/en/research/embryology/simonini.html