De-etiolation consists of a series of developmental and physiological changes that a plant undergoes in response to light. During this process light, an important environmental signal, triggers the inhibition of mesocotyl elongation and the production of photosynthetically active chloroplasts, and etiolated leaves transition from the “sink” stage to the “source” stage. De-etiolation has been extensively studied in maize (Zea mays L.). However, little is known about how this transition is regulated. In this study, we described a quantitative proteomic and phosphoproteomic atlas of the de-etiolation process in maize. We identified 16,420 proteins in proteome, among which 14,168 proteins were quantified. In addition, 8746 phosphorylation sites within 3110 proteins were identified. From the combined proteomic and phosphoproteomic data, we identified a total of 17,436 proteins. Only 7.0% (998/14,168) of proteins significantly changed in abundance during de-etiolation. In contrast, 26.6% of phosphorylated proteins exhibited significant changes in phosphorylation level; these included proteins involved in gene expression and homeostatic pathways and rate-limiting enzymes involved in photosynthetic light and carbon reactions. Based on phosphoproteomic analysis, 34.0% (1057/3110) of phosphorylated proteins identified in this study contained more than 2 phosphorylation sites, and 37 proteins contained more than 16 phosphorylation sites, indicating that multi-phosphorylation is ubiquitous during the de-etiolation process. Our results suggest that plants might preferentially regulate the level of posttranslational modifications (PTMs) rather than protein abundance for adapting to changing environments. The study of PTMs could thus better reveal the regulation of de-etiolation.
黄化苗的复绿过程是植物为响应光照经历的一系列发育和生理过程。在整个过程中，植物需要快速响应光信号并完成光形态建成，使黄化叶片复绿并实现由“库”阶段向“源”阶段的转换。在玉米中，复绿过程已得到很充分的研究，但是对“库-源”转换的调控研究较少。在本研究中，我们描述了玉米复绿过程的定量蛋白质组和磷酸化蛋白质组图谱，提供了迄今为止最全面的玉米复绿叶片中蛋白质丰度和磷酸化的动态分析。我们结合2D-HPLC-MS/MS测序和3D-HPLC-MS/MS深度测序，共鉴定到16,420个蛋白，其中14168实现定量分析。另外，通过磷酸化富集结合HPLC-MS/MS测序分析，鉴定到3110个蛋白上的8746个磷酸化位点，其中1507个蛋白存在三个以上的磷酸化位点，表明蛋白的多磷酸化修饰在复绿过程中普遍存在。对蛋白质组和磷酸化修饰组学数据深入挖掘发现，仅有7%（998）的蛋白在复绿过程中蛋白量发生显示变化，而超过26%的磷酸化蛋白的磷酸化水平在复绿过程中受到调控。大量磷酸化蛋白的多个位点的磷酸化水平在黄化苗复绿过程中发生动态而复杂的变化，暗示植物可能通过精细调控蛋白的复杂磷酸化修饰响应光环境变化。我们的结果表明，相较于调控蛋白量的变化，调节翻译后修饰变化是植物应对周围环境因素变化时更为有效的手段。





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