背景回顾：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. 

提出问题：Whether the mature endosperm governs additional nonautonomous developmental processes during this transition is unknown. 

结果1-幼苗角质层比胚胎封闭性好：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. 

结果2-胚乳作用于幼苗角质层形成：Endosperm removal prevents seedling cuticle formation, and seed reconstitution by endosperm grafting onto embryos shows that the endosperm promotes seedling cuticle development. 

结果3-胚胎中硫酸化的CIF2和PSY1作用于幼苗角质层形成：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. 

结果4-缺乏胚乳造成的胚胎-幼苗转变发育缺陷与营养无关：Endosperm-deprived embryos produced nonviable seedlings bearing numerous developmental defects, not related to embryo malnutrition, all restored by exogenously provided endosperm. 

结论：Hence, seedling establishment is nonautonomous, requiring the mature endosperm.

 摘 要 

在拟南芥成熟的种子中，胚胎向幼苗的转变起始是非自主性控制的，在不适宜的环境条件下会被胚乳中的ABA释放所阻断。在这个转变过程中，成熟的胚乳是否会影响其它的非自主性发育进程还不清楚。成熟胚胎的角质层要比幼苗的更具渗透性，与其胚乳的ABA吸收能力相一致。幼苗在萌发过程中，建立了封闭良好的角质层以适应地表暴露在空气中的生活方式。胚乳移除会阻碍幼苗角质层的形成，通过将胚乳移接到胚胎上重建种子表明胚乳确实促进了幼苗的角质层发育。作者进一步通过移接不同的胚乳和胚胎突变体组合，通知结合生物化学、显微观察和质谱分析，发现来自胚乳中被酪氨酰蛋白磺基转移酶TPST硫酸化的CIF2和PSY1多肽促进幼苗角质层的发育。缺少胚乳的胚胎形成的幼苗存在许多发育缺陷，不能存活，这些缺陷与胚胎营养不良无关，并且通过外源提供胚乳能够修复所有的缺陷。因此，幼苗的建立是非自主性的，并且需要成熟的胚乳。

 通讯作者 

** Luis Lopez-Molina **