Plants have a cuticular membrane (CM) and periderm membrane (PM), which act as barriers to terrestrial stresses. The CM covers primary organs with a continuous hydrophobic layer of waxes embedded in cutin, while the PM stacks with suberized cells outermost to the secondary tissues. The formation of native periderm is regulated by a postembryonic meristem phellogen that produces suberized phellem (cork) outwardly. However, the mechanism controlling phellogen differentiation to phellem remains to be clarified. Here, map-based cloning in a pear F1 population with segregation for periderm development in fruit skin facilitated the identification of an aspartic acid repeat deletion in Pyrus Periderm Programmed Cell Death 1.1 (PyPPCD1.1) that triggers phellogen activity for cork formation in pear russet fruit skin. PyPPCD1.1 showed preferential expression in pear fruit skin, and the encoded protein shares a structural similarity to that of the viral capsid proteins. Asp deletion in PyPPCD1.1 weakened its nuclear localization but increased its accumulation in the chloroplast. Both PyPPCD1.1 and its recessive allele directly interact with ADP-ribosylation factor 1 (ARF1). PyPPCD1.1 triggered PCD in an ARF1-dependent manner. Thus, this study identified the switch gene for PCD and periderm development and provided a new molecular regulatory mechanism underlying the development of this trait.

中文翻译：

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一种 ARF1 结合因子，可触发梨赤褐色果皮中的程序性细胞死亡和周皮发育。


植物有角质膜（CM）和周皮膜（PM），它们充当陆地胁迫的屏障。 CM 用嵌入角质中的连续疏水蜡层覆盖主要器官，而 PM 则与次生组织最外层的木栓化细胞堆叠在一起。原生周皮的形成受胚胎后分生组织胶原的调节，该胶原向外产生木栓化的木栓（软木）。然而，控制木栓原分化为木栓的机制仍有待阐明。在这里，在梨 F1 群体中进行基于图谱的克隆，并在果皮中进行周皮发育分离，促进了 Pyrus Periderm Programmed Cell Death 1.1 (PyPPCD1.1) 中天冬氨酸重复删除的鉴定，该删除触发了黄褐色梨木塞形成的 phellogen 活性水果皮。 PyPPCD1.1在梨果皮中优先表达，其编码的蛋白与病毒衣壳蛋白结构相似。 PyPPCD1.1 中的天冬氨酸缺失削弱了其核定位，但增加了其在叶绿体中的积累。 PyPPCD1.1 及其隐性等位基因都直接与 ADP-核糖基化因子 1 (ARF1) 相互作用。 PyPPCD1.1 以依赖于 ARF1 的方式触发 PCD。因此，本研究确定了 PCD 和周皮发育的开关基因，并提供了该性状发育的新分子调控机制。