Phosphorus absorbed in the form of phosphate (H2PO4-) is an essential but limiting macronutrient for plant growth and agricultural productivity. A comprehensive understanding of how plants respond to phosphate starvation is essential to develop more phosphate-efficient crops. Here we employed label-free proteomics and phosphoproteomics to quantify protein-level responses to 48 h of phosphate versus phosphite (H2PO3-) resupply to phosphate-deprived Arabidopsis thaliana suspension cells. Phosphite is similarly sensed, taken up, and transported by plant cells as phosphate, but cannot be metabolized or used as a nutrient. Phosphite is thus a useful tool to delineate between non-specific processes related to phosphate sensing and transport, and specific responses to phosphorus nutrition. We found that responses to phosphate versus phosphite resupply occurred mainly at the level of protein phosphorylation, complemented by limited changes in protein abundance, primarily in protein translation, phosphate transport and scavenging, and central metabolism proteins. Altered phosphorylation of proteins involved in core processes such as translation, RNA splicing, and kinase signalling were especially important. We also found differential phosphorylation in response to phosphate and phosphite in 69 proteins, including splicing factors, translation factors, the PHT1;4 phosphate transporter and the HAT1 histone acetyltransferase potential phospho-switches signalling changes in phosphorus nutrition. Our study illuminates several new aspects of the phosphate-starvation response and identifies important targets for further investigation and potential crop improvement.

中文翻译：

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磷酸和亚磷酸酯差异影响拟南芥悬浮细胞培养的蛋白质组和磷酸蛋白质组

以磷酸盐（H2PO4-）形式吸收的磷是植物生长和农业生产力所不可或缺的重要营养素。全面理解植物如何应对磷饥饿问题，对于开发更具磷效率的作物至关重要。在这里，我们采用无标记的蛋白质组学和磷酸化蛋白质组学来量化蛋白质水平对48 h磷酸盐对亚磷酸盐（H2PO3-）再补充磷酸盐缺乏的拟南芥悬浮细胞的蛋白质水平响应。亚磷酸酯同样被植物细胞感应，吸收并作为磷酸盐运输，但不能被代谢或用作营养物质。因此，亚磷酸酯是一种有用的工具，可用于区分与磷酸盐感测和转运有关的非特异性过程，以及对磷营养的特异性反应。我们发现对磷酸盐和亚磷酸盐的再供应反应主要发生在蛋白质磷酸化的水平，辅之以蛋白质丰度的有限变化，主要是蛋白质翻译，磷酸盐转运和清除以及中央代谢蛋白质。涉及核心过程（例如翻译，RNA剪接和激酶信号转导）的蛋白质的磷酸化改变尤其重要。我们还发现了69种蛋白质，其中包括剪接因子，翻译因子，PHT1; 4磷酸转运蛋白和HAT1组蛋白乙酰转移酶潜在的磷酸开关，它们响应磷和亚磷酸的磷酸化差异，提示磷营养变化。