Ethylene is one of the most important phytohormone in plants and plays a critical role during growth, development, maturity, and aging. The framework of the ethylene signaling pathway is well reported. Nevertheless, studies on Ethylene Insensitive 3 (EIN3), the downstream regulator of the ethylene signaling pathway, need to be investigated, especially in peach [Prunus persica (L.) Batsch]. In this study, we cloned PpEIN3 from peach and characterized it in tomato (Solanum lycopersicum L.). Our results depicted that the open‐reading frame of PpEIN3 was 1875 bp, encoding a protein with 624 amino acid residues that contained a conserved EIN3 domain, a highly conserved N‐terminal region, and seven DNA‐binding sites. PpEIN3 showed very close association with homologous EIN genes from apple (Malus domestica Borkh.) and grapevine (Vitis vinifera L.). All investigated EIN proteins shared similar domains and structures. The PpEIN3 promoter possessed several motifs related to hormones that affect fruit development and ripening. Spatial–temporal expression analysis revealed that PpEIN3 was expressed at high levels in the late stage of fruit development vs. the early stage. In transgenic tomato, PpEIIN3 showed overexpression and the key ethylene biosynthesis genes SlACO1, SlACS1, and SlSAMS1 were upregulated and promoted early maturation in fruit. By contrast, PpEIIN3 silencing delayed ripening and reduced SlEIN3 expression in tomato. The results confirmed that PpEIN3 is a positive regulator of the ethylene signal transduction pathway, which promoted fruit ripening. Our findings provide valuable insight to the roles in ethylene signal components in the modulation of peach fruit ripening.

中文翻译：

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番茄异位表达调控果实成熟过程中PpEIN3的特性与鉴定

乙烯是植物中最重要的植物激素之一，在生长，发育，成熟和衰老过程中起着至关重要的作用。乙烯信号传导途径的框架已被充分报道。尽管如此，仍需要对乙烯不敏感3（EIN3）（乙烯信号传导途径的下游调节剂）进行研究，尤其是在桃子中[ Prunus persica（L.）Batsch]。在这项研究中，我们克隆PpEIN3从桃和表征它在番茄（番茄L.）。我们的结果表明，PpEIN3的开放阅读框为1875 bp，编码具有624个氨基酸残基的蛋白质，其中包含一个保守的EIN3域，一个高度保守的N端区域和七个DNA结合位点。蛋白3与苹果（Malus domestica Borkh。）和葡萄（Vitis vinifera L.）的同源EIN基因紧密相关。所有研究的EIN蛋白都具有相似的结构域和结构。该PpEIN3子拥有有关影响果实发育和成熟激素的几个主题。时空表达分析表明，PpEIN3在果实发育的晚期相对于早期处于高水平表达。在转基因番茄中，PpEIIN3表现出过表达和关键的乙烯生物合成基因SlACO1，SlACS1和SlSAMS1被上调并促进了果实的早期成熟。相比之下，PpEIIN3沉默可延缓番茄的成熟并降低SlEIN3的表达。结果证实PpEIN3是乙烯信号转导途径的正调节剂，其促进果实成熟。我们的发现为乙烯信号成分在调节桃果实成熟中的作用提供了有价值的见解。