Yu Tao, Li Geng, Dong Shuting, Liu Peng, Zhang Jiwang, Zhao Bin
State Key Laboratory of Crop Biology and College of Agronomy, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China.
BMC Plant Biol. 2016 Nov 4;16(1):241. doi: 10.1186/s12870-016-0878-1.
Grain development in maize is an essential process in the plant's life cycle and is vital for use of the plant as a crop for animals and humans. However, little is known regarding the protein regulatory networks that control grain development. Here, isobaric tag for relative and absolute quantification (iTRAQ) technology was used to analyze temporal changes in protein expression during maize grain development.
Maize grain proteins and changes in protein expression at eight developmental stages from 3 to 50 d after pollination (DAP) were performed using iTRAQ-based proteomics. Overall, 4751 proteins were identified; 2639 of these were quantified and 1235 showed at least 1.5-fold changes in expression levels at different developmental stages and were identified as differentially expressed proteins (DEPs). The DEPs were involved in different cellular and metabolic processes with a preferential distribution to protein synthesis/destination and metabolism categories. A K-means clustering analysis revealed coordinated protein expression associated with different functional categories/subcategories at different development stages.
Our results revealed developing maize grain display different proteomic characteristics at distinct stages, such as numerous DEPs for cell growth/division were highly expressed during early stages, whereas those for starch biosynthesis and defense/stress accumulated in middle and late stages, respectively. We also observed coordinated expression of multiple proteins of the antioxidant system, which are essential for the maintenance of reactive oxygen species (ROS) homeostasis during grain development. Particularly, some DEPs, such as zinc metallothionein class II, pyruvate orthophosphate dikinase (PPDK) and 14-3-3 proteins, undergo major changes in expression at specific developmental stages, suggesting their roles in maize grain development. These results provide a valuable resource for analyzing protein function on a global scale and also provide new insights into the potential protein regulatory networks that control grain yield and quality.
玉米籽粒发育是植物生命周期中的一个重要过程，对于将玉米作为动物和人类的作物使用至关重要。然而，关于控制籽粒发育的蛋白质调控网络，我们所知甚少。在此，采用相对和绝对定量等压标签（iTRAQ）技术分析玉米籽粒发育过程中蛋白质表达的时间变化。
使用基于iTRAQ的蛋白质组学对授粉后3至50天（DAP）的八个发育阶段的玉米籽粒蛋白质及蛋白质表达变化进行了研究。总体而言，共鉴定出4751种蛋白质；其中2639种被定量，1235种在不同发育阶段的表达水平显示至少1.5倍的变化，被鉴定为差异表达蛋白（DEP）。这些DEP参与了不同的细胞和代谢过程，优先分布于蛋白质合成/定位和代谢类别。K均值聚类分析揭示了不同发育阶段与不同功能类别/亚类相关的蛋白质表达协同情况。
我们的结果表明，发育中的玉米籽粒在不同阶段呈现出不同的蛋白质组特征，例如在早期阶段，大量参与细胞生长/分裂的DEP高度表达，而参与淀粉生物合成和防御/应激的DEP分别在中期和后期积累。我们还观察到抗氧化系统多种蛋白质的协同表达，这对于籽粒发育过程中活性氧（ROS）稳态的维持至关重要。特别是，一些DEP，如II类锌金属硫蛋白、丙酮酸磷酸双激酶（PPDK）和14-3-3蛋白，在特定发育阶段表达发生重大变化，表明它们在玉米籽粒发育中的作用。这些结果为在全球范围内分析蛋白质功能提供了宝贵资源，也为控制籽粒产量和品质的潜在蛋白质调控网络提供了新的见解。
