Self-incompatibility (SI) promotes outbreeding and prevents self-fertilization to promote genetic diversity in angiosperms. Several studies have been carried to investigate SI signaling in plants; however, protein phosphorylation and dephosphorylation in the fine-tuning of the SI response remain insufficiently understood. Here, we performed a phosphoproteomic analysis to identify the phosphoproteins in the stigma of self-compatible 'Westar' and self-incompatible 'W-3' Brassica napus lines. A total of 4109 phosphopeptides representing 1978 unique protein groups were identified. Moreover, 405 and 248 phosphoproteins were significantly changed in response to SI and self-compatibility, respectively. Casein kinase II (CK II) phosphorylation motifs were enriched in self-incompatible response and identified 127 times in 827 dominant SI phosphorylation residues. Functional annotation of the identified phosphoproteins revealed the major roles of these phosphoproteins in plant-pathogen interactions, cell wall modification, mRNA surveillance, RNA degradation, and plant hormone signal transduction. In particular, levels of homolog proteins ABF3, BKI1, BZR2/BSE1, and EIN2 were significantly increased in pistils pollinated with incompatible pollens. Abscisic acid and ethephon treatment partially inhibited seed set, while brassinolide promoted pollen germination and tube growth in SI response. Collectively, our results provided an overview of protein phosphorylation during compatible/incompatible pollination, which may be a potential component of B. napus SI responses.

中文翻译：

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甘蓝型油菜中相容和不相容授粉的磷酸化蛋白质组学比较分析。

自交不亲和性（SI）促进近亲繁殖，并防止自我受精从而促进被子植物的遗传多样性。已经进行了一些研究以调查植物中的SI信号传导；这些研究包括：然而，对SI应答的微调中的蛋白质磷酸化和去磷酸化仍然知之甚少。在这里，我们进行了磷酸化蛋白质组学分析，以鉴定自相溶的“ Westar”和自相溶的“ W-3”甘蓝型油菜的柱头中的磷酸化蛋白。共鉴定出代表1978个独特蛋白质组的4109个磷酸肽。此外，分别响应SI和自相容性，405和248磷蛋白发生了显着变化。酪蛋白激酶II（CK II）的磷酸化基序富含自身不相容反应，并在827个主要的SI磷酸化残基中鉴定出127次。鉴定出的磷蛋白的功能注释揭示了这些磷蛋白在植物-病原体相互作用，细胞壁修饰，mRNA监测，RNA降解和植物激素信号转导中的主要作用。特别是，在用不相容花粉授粉的雌蕊中，同源蛋白ABF3，BKI1，BZR2 / BSE1和EIN2的水平显着增加。脱落酸和乙烯利处理部分抑制了种子结实，而油菜素内酯则促进了花粉萌发和SI反应中的管生长。总的来说，我们的研究结果提供了相容/不相容授粉过程中蛋白质磷酸化的概述，这可能是B的潜在成分。