DcMYB6和DcbHLH1在紫胡萝卜肉质根花青苷合成中的作用

项目名称： DcMYB6和DcbHLH1在紫胡萝卜肉质根花青苷合成中的作用

项目编号： No.31501775

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 农业科学

项目作者： 徐志胜

作者单位： 南京农业大学

项目金额： 20万元

中文摘要： 紫胡萝卜在进化史上比其他颜色胡萝卜出现的要早。紫胡萝卜肉质根富含花青苷，而其他颜色胡萝卜肉质根则基本不合成花青苷。在我们早期的研究结论中，推测可能因转录因子的差异造成了许多参与花青苷合成的结构基因在紫色和非紫色胡萝卜中表达差异显著。.在植物中，MYB、bHLH和WD40转录因子常形成蛋白复合体直接调控花青苷途径中结构基因的表达。在前期工作中，基于我们建立的胡萝卜全基因组和转录组数据库中的信息，通过基因序列同源性比对和表达量分析，筛选出DcMYB6和DcbHLH1基因，其表达与花青苷合成呈现正相关。而将DcMYB6转入拟南芥中表达，植株呈紫色。本项目拟将DcMYB6和DcbHLH1转入非紫色胡萝卜中过量表达，并在紫色胡萝卜中分别敲除这两个基因，研究其对花青苷合成的调控。并通过对启动子的研究，分析DcMYB6和DcbHLH1在紫色和非紫色胡萝卜中差异表达的原因。通过本研究，初步阐明转录因子调控胡萝卜花青苷合成的分子机制，为胡萝卜在颜色方向的育种提供重要的理论基础，具有实际的应用价值。

中文关键词： 胡萝卜；花青苷；MYB；bHLH；转录因子

英文摘要： Purple carrots (Daucus carota L.) are thought to be much older than the non-purple carrots. Purple carrots accelerate extremely high content of stable anthocyanins in the taproots while non-purple carrots do not. In previous study, we speculated that many structural genes involved in the anthocyanins biosynthesis showed high expression levels in purple carrots but no or scarce expression levels in non-purple carrots was possibly caused by activation or inactivation of regulator genes. .In higher plants, MYB–bHLH–WD40 protein complexes directly regulate the structural genes involved in anthocyanins biosynthesis. Based on the sequences of MYB, bHLH, and WD40 genes that regulate anthocyanins biosynthesis in other higher plants, we found several MYB, bHLH, and WD40 genes from carrots with BLAST search tool in the CarrotDB website in the primary study. Among these genes, two genes named DcMYB6 and DcbHLH1 showed high expression levels in purple carrots but no or scarce expression levels in non-purple carrots. We also demonstrated that overexpression of DcMYB6 in transgenic Arabidopsis generated a deep purple color in leaves, stems, roots, and seeds. In this project, DcMYB6 and DcbHLH1 will be transformed into non-purple carrots for overexpression and inactivated in the purple carrots using a CRISPR/Cas9 system, to determine whether DcMYB6 and DcbHLH1 regulate anthocyanins biosynthesis in carrots or not. The promoters of DcMYB6 and DcbHLH1 from the purple and non-purple carrots will also be cloned and analyzed to figure out the different expression levels of DcMYB6 and DcbHLH1 between purple and non-purple carrots. The molecular mechanism of anthocyanins biosynthesis regulated by transcription factors in the purple carrots will be preliminary elucidated in this project, which will also promote breeding of carrots with different colors.

英文关键词： Carrot;Anthocyanin;MYB;bHLH;Transcription factor