The endosperm is a reproductive tissue supporting embryo development. In most flowering plants, the initial divisions of endosperm nuclei are not succeeded by cellularization; this process occurs only after a specific number of mitotic cycles have taken place. The timing of cellularization significantly influences seed viability and size. Previous research implicated auxin as a key factor in initiating nuclear divisions and determining the timing of cellularization. Here we uncover the involvement of a family of clustered auxin response factors (cARFs) as dosage-sensitive regulators of endosperm cellularization. cARFs, maternally expressed and paternally silenced, are shown to induce cellularization, thereby restricting seed growth. Our findings align with the predictions of the parental conflict theory, suggesting that cARFs represent major molecular targets in this conflict. We further demonstrate a recurring amplification of cARFs in the Brassicaceae, suggesting an evolutionary response to parental conflict by reinforcing maternal control over endosperm cellularization. Our study highlights that antagonistic parental control on endosperm cellularization converges on auxin biosynthesis and signalling.

胚乳是支持胚胎发育的生殖组织。在大多数开花植物中，胚乳核的初始分裂不会通过细胞化而成功。该过程仅在发生特定数量的有丝分裂周期后发生。细胞化的时间显着影响种子的活力和大小。先前的研究表明生长素是启动核分裂和决定细胞化时间的关键因素。在这里，我们揭示了一系列生长素反应因子（cARF）家族作为胚乳细胞化的剂量敏感调节剂的参与。 cARFs ，母系表达和父系沉默，被证明可以诱导细胞化，从而限制种子生长。我们的研究结果与父母冲突理论的预测一致，表明cARF代表了这种冲突中的主要分子靶标。我们进一步证明了十字花科中cARF的反复扩增，表明通过加强母体对胚乳细胞化的控制来应对亲本冲突的进化反应。我们的研究强调，对胚乳细胞化的拮抗亲本控制集中在生长素生物合成和信号传导上。