Xu Dongbin, Yuan Huwei, Tong Yafei, Zhao Liang, Qiu Lingling, Guo Wenbin, Shen Chenjia, Liu Hongjia, Yan Daoliang, Zheng Bingsong
State Key Laboratory of Subtropical Silviculture, Zhejiang A&F UniversityLinan, China.
Center for Cultivation of Subtropical Forest Resources, Zhejiang A&F UniversityLinan, China.
Front Plant Sci. 2017 Apr 27;8:676. doi: 10.3389/fpls.2017.00676. eCollection 2017.
Hickory (), a tree with high nutritional and economic value, is widely cultivated in China. Grafting greatly reduces the juvenile phase length and makes the large scale cultivation of hickory possible. To reveal the response mechanisms of this species to grafting, we employed a proteomics-based approach to identify differentially expressed proteins in the graft unions during the grafting process. Our study identified 3723 proteins, of which 2518 were quantified. A total of 710 differentially expressed proteins (DEPs) were quantified and these were involved in various molecular functional and biological processes. Among these DEPs, 341 were up-regulated and 369 were down-regulated at 7 days after grafting compared with the control. Four auxin-related proteins were down-regulated, which was in agreement with the transcription levels of their encoding genes. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the 'Flavonoid biosynthesis' pathway and 'starch and sucrose metabolism' were both significantly up-regulated. Interestingly, five flavonoid biosynthesis-related proteins, a flavanone 3-hyfroxylase, a cinnamate 4-hydroxylase, a dihydroflavonol-4-reductase, a chalcone synthase, and a chalcone isomerase, were significantly up-regulated. Further experiments verified a significant increase in the total flavonoid contents in scions, which suggests that graft union formation may activate flavonoid biosynthesis to increase the content of a series of downstream secondary metabolites. This comprehensive analysis provides fundamental information on the candidate proteins and secondary metabolism pathways involved in the grafting process for hickory.
山核桃是一种具有高营养价值和经济价值的树木，在中国广泛种植。嫁接极大地缩短了幼年期，使得山核桃的大规模种植成为可能。为了揭示该物种对嫁接的响应机制，我们采用基于蛋白质组学的方法来鉴定嫁接过程中嫁接部位差异表达的蛋白质。我们的研究鉴定出3723种蛋白质，其中2518种得到了定量。总共定量了710种差异表达蛋白质（DEPs），这些蛋白质参与了各种分子功能和生物学过程。在这些DEPs中，与对照相比，嫁接后7天有341种上调，369种下调。四种生长素相关蛋白下调，这与其编码基因的转录水平一致。京都基因与基因组百科全书（KEGG）分析表明，“类黄酮生物合成”途径和“淀粉与蔗糖代谢”均显著上调。有趣的是，五种类黄酮生物合成相关蛋白，即黄烷酮3-羟化酶、肉桂酸4-羟化酶、二氢黄酮醇4-还原酶、查尔酮合酶和查尔酮异构酶，显著上调。进一步的实验证实了接穗中总黄酮含量显著增加，这表明嫁接部位的形成可能激活类黄酮生物合成，以增加一系列下游次生代谢产物的含量。这项综合分析提供了关于山核桃嫁接过程中候选蛋白质和次生代谢途径的基础信息。
