Zhang Weiwei, Xu Feng, Cheng Shuiyuan, Liao Yongling
College of Horticulture and Gardening, Yangtze University, Jingzhou, China.
School of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan, China.
Genes Genomics. 2018 Jan;40(1):49-61. doi: 10.1007/s13258-017-0609-5. Epub 2017 Sep 4.
Flavonoids are a group of metabolites in Ginkgo biloba thought to provide health benefits. R2R3-MYB transcription factors (TFs) play key roles in the transcriptional regulation of the flavonoid biosynthesis in plants. In this study, an R2R3-MYB transcription factor gene, GbMYBFL, was isolated from G. biloba and characterized. Results of bioinformatic analysis indicated that GbMYBFL is more closely related to the R2R3-MYB involved in flavonoid biosynthesis and displayed high similarity to MYB from other plants. The genmomic sequence of GbMYBFL had three exons and two introns, with its upstream sequence containing cis-acting regulatory elements Myb binding site, Myc recognition sites, and light, SA, MeJA responsive elements. Subcellular localization analysis indicates that GbMYBFL was located in the nucleus. Quantitative real-time PCR revealed that GbMYBFL was expressed in leaves, stems, roots, young fruits, male flower and female flower, and the level of transcription in male flower and leaves were higher than that in female flower, stems, roots, and young fruits. During G. biloba leaf growth, the transcription of GbMYBFL is positively correlated with the flavonoid content, suggesting that the GbMYBFL is involved in the flavonoid biosynthesis. Overexpression of GbMYBFL under the control of the CaMV35S promoter in Ginkgo callus notably enhanced the accumulation of flavonoids and anthocyanin compared with non-transformed callus. This finding suggested that GbMYBFL positively related to flavonoid biosynthesis, and the overexpression of GbMYBFL was sufficient to induce flavonoids and anthocyanin accumulation.
黄酮类化合物是银杏中的一组代谢产物，被认为对健康有益。R2R3-MYB转录因子在植物黄酮类生物合成的转录调控中起关键作用。在本研究中，从银杏中分离并鉴定了一个R2R3-MYB转录因子基因GbMYBFL。生物信息学分析结果表明，GbMYBFL与参与黄酮类生物合成的R2R3-MYB关系更为密切，与其他植物的MYB具有高度相似性。GbMYBFL的基因组序列有三个外显子和两个内含子，其上游序列包含顺式作用调控元件Myb结合位点、Myc识别位点以及光、水杨酸、茉莉酸甲酯响应元件。亚细胞定位分析表明GbMYBFL位于细胞核中。实时定量PCR显示，GbMYBFL在叶、茎、根、幼果、雄花和雌花中均有表达，雄花和叶中的转录水平高于雌花、茎、根和幼果。在银杏叶片生长过程中，GbMYBFL的转录与黄酮类化合物含量呈正相关，表明GbMYBFL参与了黄酮类生物合成。与未转化的愈伤组织相比，在CaMV35S启动子控制下在银杏愈伤组织中过表达GbMYBFL显著增强了黄酮类化合物和花青素的积累。这一发现表明GbMYBFL与黄酮类生物合成呈正相关，过表达GbMYBFL足以诱导黄酮类化合物和花青素的积累。
