In Arabidopsis mature seeds, the onset of the embryo-to-seedling transition is nonautonomously controlled, being blocked by endospermic abscisic acid (ABA) release under unfavorable conditions. Whether the mature endosperm governs additional nonautonomous developmental processes during this transition is unknown. Mature embryos have a more permeable cuticle than seedlings, consistent with their endospermic ABA uptake capability. Seedlings acquire their well-sealing cuticles adapted to aerial lifestyle during germination. Endosperm removal prevents seedling cuticle formation, and seed reconstitution by endosperm grafting onto embryos shows that the endosperm promotes seedling cuticle development. Grafting different endosperm and embryo mutant combinations, together with biochemical, microscopy, and mass spectrometry approaches, reveal that the release of tyrosylprotein sulfotransferase (TPST)-sulfated CIF2 and PSY1 peptides from the endosperm promotes seedling cuticle development. Endosperm-deprived embryos produced nonviable seedlings bearing numerous developmental defects, not related to embryo malnutrition, all restored by exogenously provided endosperm. Hence, seedling establishment is nonautonomous, requiring the mature endosperm.

在拟南芥中在成熟的种子中，胚到幼苗过渡的开始是非自主控制的，在不利条件下会被胚乳脱落酸 (ABA) 释放所阻止。在这一转变过程中，成熟的胚乳是否控制着额外的非自主发育过程尚不清楚。成熟的胚胎具有比幼苗更具渗透性的角质层，这与它们的胚乳 ABA 吸收能力一致。幼苗在发芽期间获得了适合空中生活方式的密封良好的角质层。去除胚乳可防止幼苗表皮形成，通过胚乳嫁接到胚胎上的种子重建表明胚乳促进了幼苗表皮发育。嫁接不同的胚乳和胚胎突变体组合，结合生化、显微镜和质谱方法，揭示酪氨酰蛋白磺基转移酶 (TPST) 硫酸化 CIF2 和 PSY1 肽从胚乳的释放促进幼苗角质层发育。缺乏胚乳的胚胎会产生无法存活的幼苗，这些幼苗带有许多发育缺陷，与胚胎营养不良无关，所有这些都由外源提供的胚乳恢复。因此，幼苗的建立是非自主的，需要成熟的胚乳。