不同发育时期油桐种仁油体蛋白质组分析

目的 对油桐种仁不同生长时期的油体蛋白进行定量蛋白质组研究，鉴定油桐种仁油体蛋白质的组成，探讨不同生长时期种仁油体蛋白质组的表达差异。 方法 采用同位素标记相对和绝对定量（iTRAQ）技术提取3个不同生长时期的油桐种仁油体蛋白质组，质检合格的蛋白经酶解、iTRAQ标记后进行高效液相、质谱检测。利用Mascot软件对转换的二级质谱数据进行蛋白质鉴定，通过iTRAQ定量寻找差异表达蛋白，并对差异蛋白进行GO功能注释、KEGG代谢通路和聚类分析。 结果 在3个生长时期成熟油桐种仁油体亚细胞器中共鉴定出5632个蛋白，其中，2639个具有催化活性，401个蛋白质参与脂肪酸及油脂的合成与代谢。在种仁成熟的3个生长时期中，共有3430个油体蛋白的表达量发生了显著变化。油体差异蛋白的富集分析发现，具有催化活性这一分子功能的差异蛋白主要在油脂积累初期发生富集。在桐油和桐酸积累时期，参与脂肪酸代谢和油脂贮藏的酰基辅酶A氧化酶、DGA蛋白和油质蛋白（Oleosin）表达量显著上升，表明这些蛋白在调控桐油和桐酸的积累中可能发挥着关键作用。 结论 获得油桐种仁成熟过程中动态特异的油体蛋白质组表达谱，揭示油体蛋白质组的组成、主要调控桐油合成的关键酶和结构蛋白，为进一步研究油脂的合成与油体的装配等相关机制奠定了基础。

iTRAQ Quantitative Proteome Analysis of Kernel Oil Body in Different Growth Stages of Vernicia fordii

Objective iTRAQ (isobaric tags for relative and absolute quantitation) was performed on the proteome of kernel oil body in different growth stages of Vernicia fordii to identify the protein composition of the oil body and to explore the differentially expressed proteins in different growth periods. Method The proteomes of the oil body were extracted from V. fordii seed kernel at three different growth stages. Qualified proteomes were analyzed by LC-MS/MS (Liquid chromatography-mass spectrometry) after protease digestion and iTRAQ labeling. The obtained converted secondary mass spectrometry data were used for protein identification through Mascot software. Differentially expressed proteins were explored through iTRAQ quantification analysis. GO (Gene Ontology) function annotation, KEGG pathway and cluster analysis of differentially expressed proteins identified was further conducted. Result 5632 proteins were identified in the proteome of kernel oil body in three growth stages of V. fordii. Of them, 2639 proteins shared catalytic activity and 401 proteins involved in the synthesis and metabolism of fatty acids and fats. In the three growth stages of the kernel oil body, 3430 proteins were significantly differentially expressed. The GO enrichment analysis showed that the differentially expressed proteins with catalytic activity were mainly enriched in the OB1/OB2 stage rather than in the OB2/OB3 stage. During the accumulation period of tung oil and α-eleostearic acid, the acyl-CoA oxidase, GDA protein and oleosin, which involved in fatty acid metabolism and oil storage, exhibited significantly increased expression. It suggested that these proteins may play a key role in regulating the accumulation of tung oil and α-eleostearic acid. Conclusion The expression profiles of differentially expressed protein of kernel oil body in different growth stage were analyzed using iTRAQ method. The protein composition of the oil body was identified as well as the metabolic pathway and key functional genes involved fatty acid and lipid metabolism were explored. It is a crucial step for further study on the mechanism of oil synthesis and oil body assembly.