The Coat Protein I (COPI) complex is a seven-subunit coatomer complex consisting of the α, β, β′, γ, δ, ε, and ζ proteins. In Arabidopsis thaliana, COPI is required for retrograde transport from the Golgi to the endoplasmic reticulum, Golgi maintenance, and cell plate formation. During compatible pollination, vesicle recruitment to the pollen contact point is required for pollen hydration and pollen tube penetration. Here, to identify other aspects of trafficking involved in the acceptance of compatible pollen by stigmatic papillae and to determine their roles in compatible pollination, we characterized knockout lines of several isoforms of the COPI complex, including α1-COP, γ-COP, and ε-COP. Specifically, we characterized pollen grain adherence, pollen tube penetration, and seed set in the mutants. Of the mutant lines examined, α1-cop had the most severe phenotypes, including altered compatible pollen grain adherence and tube germination and reduced seed set, whereas the other lines had milder phenotypes but visibly retarded compatible pollen acceptance. This is the first study demonstrating that COPI complex subunits are required for the acceptance of compatible pollen.

中文翻译：

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早熟拟南芥中兼容的花粉粒需要COPI复合同工型。

外壳蛋白I（COPI）复合物是由亚蛋白，β，β'，γ，δ，ε和ζ蛋白组成的七亚基涂层复合物。在拟南芥中从高尔基体向内质网逆行运输，高尔基体维持和细胞板形成需要COPI。在相容性授粉过程中，需要将囊泡募集到花粉接触点以进行花粉水合作用和花粉管穿透。在这里，为了确定由柱状乳头接受相容花粉所涉及的贩运的其他方面，并确定它们在相容授粉中的作用，我们表征了COPI复合物的几种同工型的敲除谱线，包括α1-COP，γ-COP和ε -警察。具体来说，我们表征了突变体中的花粉粒粘附，花粉管穿透和结实。在检查的突变株中，α1 - cop具有最严重的表型，包括改变的相容性花粉粒附着力和管萌发，减少结实，而其他品系具有较轻的表型，但明显阻碍了相容性花粉的接受。这是第一项研究，证明接受兼容花粉需要COPI复合亚基。