The germination process of seeds is influenced by the interplay between two opposing factors: pectin methylesterase (PME) and pectin methylesterase inhibitor (PMEI), which collectively regulate patterns of pectin methylesterification. Despite the recognized importance of pectin methylesterification in seed germination, the specific mechanisms that govern this process remain unclear. In this study, we demonstrated that the overexpression of is associated with a decrease in PME activity and an increase in pectin methylesterification. This leads to the softening of the cell wall in seeds, which positively regulates cotton seed germination. AtPMEI19, the homologue in , plays a similar role in seed germination to GhPMEI53, indicating a conserved function and mechanism of PMEI in seed germination regulation. Further studies revealed that GhPMEI53 and AtPMEI19 directly contribute to promoting radicle protrusion and seed germination by inducing cell wall softening and reducing mechanical strength. Additionally, the pathways of ABA and GA in the transgenic materials underwent significant changes, suggesting that GhPMEI53/AtPMEI19-mediated pectin methylesterification serves as a regulatory signal for the related phytohormones involved in seed germination. In summary, GhPMEI53 and its homologs alter the mechanical properties of cell walls, influencing the mechanical resistance of the endosperm or testa. Moreover, they impact cellular phytohormone pathways (e.g., ABA, GA) to regulate seed germination. These findings enhance our understanding of pectin methylesterification in cellular morphological dynamics and signaling transduction, and contribute to a more comprehensive understanding of the PME/PMEI super-gene family in plants.

中文翻译：

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果胶甲酯酶抑制剂 GhPMEI53 和 AtPMEI19 通过调节棉花和拟南芥细胞壁可塑性来改善种子萌发

种子的发芽过程受到两个相反因素之间相互作用的影响：果胶甲酯酶（PME）和果胶甲酯酶抑制剂（PMEI），它们共同调节果胶甲酯化的模式。尽管人们认识到果胶甲基酯化在种子萌发中的重要性，但控制这一过程的具体机制仍不清楚。在这项研究中，我们证明 的过度表达与 PME 活性的降低和果胶甲基酯化的增加有关。这导致种子细胞壁软化，从而积极调节棉种子的发芽。AtPMEI19是GhPMEI53的同源物，在种子萌发中发挥着与GhPMEI53相似的作用，表明PMEI在种子萌发调控中具有保守的功能和机制。进一步的研究表明，GhPMEI53 和 AtPMEI19 通过诱导细胞壁软化和降低机械强度，直接促进胚根突出和种子萌发。此外，转基因材料中ABA和GA的途径发生了显着变化，表明GhPMEI53/AtPMEI19介导的果胶甲基酯化作用是参与种子萌发的相关植物激素的调节信号。总之，GhPMEI53 及其同系物改变细胞壁的机械特性，影响胚乳或种皮的机械阻力。此外，它们还影响细胞植物激素途径（例如 ABA、GA）来调节种子萌发。这些发现增强了我们对细胞形态动力学和信号转导中果胶甲酯化的理解，并有助于更全面地了解植物中的 PME/PMEI 超基因家族。