三色堇VwF3H基因启动子克隆及其功能分析

Cloning and functional analysis of the promoter of VwF3H gene in pansy( Viola×wittrockiana Gams)

  • 摘要: 【目的】 探究三色堇黄烷酮-3-羟化酶基因(VwF3H)启动子功能,并验证其与花青素相关MYB转录因子的互作关系,为揭示F3H基因在植物花青素合成过程中的调控机制提供参考依据。【方法】 以三色堇为研究材料,通过FPNI-PCR克隆VwF3H基因启动子序列,分析其功能元件、组织表达特异性及核心功能片段等,并通过酵母单杂交试验探究VwMYB27和VwMYB29能否与VwF3H基因启动子结合。【结果】 VwF3H基因启动子序列长2017 bp,含有较多光响应元件及激素响应元件;根据MYB等重要转录因子的位置,将其分为4段:VwF3H1(2017 bp)、VwF3H2(1353 bp)、VwF3H3(745 bp)和VwF3H4(446 bp)。VwF3H基因在三色堇花瓣中的相对表达量最高,显著高于根、茎和叶片中的相对表达量(P<0.05,下同)。VwF3H基因启动子全长具有较强的转录活性,缺失片段-2017~-1353 bp的VwF3HS2转录活性明显降低,缺失更多碱基的VwF3HS3和VwF3HS4则基本无转录活性,说明VwF3H基因启动子的高活性序列位于-2017~-1353 bp区域。VwF3H基因启动子在烟草叶片和花中启动GUS基因的能力不同,以花器官中的转录活性更强,说明VwF3H基因表达存在一定组织特异性;此外,VwF3H基因启动子在烟草中的转录活性明显低于CaMV35S启动子,但在三色堇中的转录活性明显高于CaMV35S启动子,推测VwF3H基因还存在物种偏好性,且更适合作为三色堇花瓣转化载体的启动子。VwF3H基因启动子的3-氨基-1,2,4-三唑(3-AT)自激活抑制浓度为250 mmol/L;VwMYB27与VwF3H基因启动子存在互作关系,而VwMYB29与VwF3H基因启动子无直接的互作关系。【结论】 VwF3H基因启动子在三色堇中具有较强的转录活性,其高活性序列位于-2017~-1353 bp区域;VwF3H基因启动子能与VwMYB27相互作用,而参与三色堇花瓣色斑的形成。

     

    Abstract: 【Objective】 To explore the function of the promoter of the flavanone-3-hydroxylase gene in pansy(Viola×wittrockiana Gams)(VwF3H) and verify its interaction with anthocyanin-related MYB transcription factors, which could provide reference for revealing the regulatory mechanism of F3H gene in the process of plant anthocyanin synthesis. 【Method】Using pansy as the research materials, the VwF3H gene promoter sequence was cloned by FPNI-PCR, and its functional elements, tissue expression specificity and core functional fragments were analyzed. Yeast one-hybrid assay was conducted to investigate whether VwMYB27 and VwMYB29 could bind to the VwF3H gene promoter. 【Result】 VwF3H gene promoter sequence was 2017 bp long and contained numerous light-responsive and hormone-responsive elements. Based on the positions of important transcription factors such as MYB, it was divided into 4 segments: VwF3H1(2017 bp), VwF3H2(1353 bp), VwF3H3(745 bp) and VwF3H4(446 bp). The relative expression of VwF3H gene was the highest in pansy petals, significantly higher than in roots, stems and leaves(P<0.05, the same below). The fulllength VwF3H gene promoter exhibited strong transcriptional activity. The transcriptional activity of VwF3HS2, with a deletion from-2017 to-1353 bp, was greatly reduced, while VwF3HS3 and VwF3HS4, with more bases deleted, showed almost no transcriptional activity, indicating that the high-activity sequence of the VwF3H gene promoter was located in the-2017 to-1353 bp region. The ability of the VwF3H gene promoter to drive GUS gene expression differed between tobacco leaves and flowers, with stronger transcriptional activity in floral organs, suggesting tissue-specific expression of VwF3H gene. Additionally, the transcriptional activity of VwF3H gene promoter in tobacco was significantly lower than that of the CaMV35S promoter, but it was significantly higher than that of the CaMV35S promoter in pansy, suggesting species preference of the VwF3H gene promoter and its suitability as a promoter for petal transformation vectors in pansy. The self-activation inhibition concentration of 3-amino-1,2,4-triazole(3-AT) for VwF3H gene promoter was 250 mmol/L. VwMYB27 interacted with VwF3H gene promoter, whereas VwMYB29 did not directly interact with it. 【Conclusion】 VwF3H gene promoter exhibits strong transcriptional activity in pansy, with its high-activity sequence located in the-2017 to-1353 bp region. VwF3H gene promoter interacts with VwMYB27 and is involved in the formation of petal color patterns in pansy.

     

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