Acetyl-Proteomic Profiling of Sorghum bicolor Seedlings after Chitin Treatment Reveals the Involvement of Acetylated Chlorophyll a/b Binding Proteins in the Innate Immune Response

Plant pathogen-associated molecular pattern-triggered immunity (PTI) is affected by post-translational modifications, but the role of acetylation in the PTI responses of Sorghum bicolor remains unclear. In this study, a comprehensive acetyl-proteomic analysis was performed on sorghum seedlings treated with chitin based on label-free protein quantification. Chitin rapidly induced 15 PTI-related genes and 5 defense enzymes. Acetylation was upregulated in sorghum after the chitin treatment, and 579, 895, and 929 acetylated proteins, peptides, and sites, respectively, were identified using high-performance liquid chromatography-tandem mass spectrometry. Acetylation and expression of chlorophyll a/b binding proteins (Lhcs) were significantly upregulated, and they were localized in chloroplasts. Additionally, we found that the expression of Lhcs in vivo enhanced chitin-mediated acetylation. The findings of this study provide a comprehensive assessment of the lysine acetylome in sorghum and a foundation for future study into the regulatory mechanisms of acetylation during chlorophyll synthesis.植物病原相关分子模式触发的免疫（Plant pathogen-associated molecular pattern-triggered immunity, PTI）会受到翻译后修饰的调控，但乙酰化在高粱（Sorghum bicolor）PTI响应中的作用仍不明确。本研究基于无标记蛋白质定量技术，对经几丁质处理的高粱幼苗开展了全面的乙酰化蛋白质组学分析。几丁质可快速诱导15个PTI相关基因及5种防御酶的表达。经几丁质处理后，高粱体内的乙酰化水平显著上调；本研究通过高效液相色谱-串联质谱共鉴定得到579个乙酰化蛋白质、895条乙酰化肽段以及929个乙酰化位点。叶绿素a/b结合蛋白（Lhcs）的乙酰化修饰与表达水平均显著上调，且该类蛋白定位于叶绿体中。此外，本研究发现体内Lhcs的表达可增强几丁质介导的乙酰化过程。本研究的结果为高粱赖氨酸乙酰化组提供了全面的解析，并为后续研究乙酰化在叶绿素合成过程中的调控机制奠定了基础。