背景:R2R3-MYB转录因子调节次级代谢,各种植物的胁迫反应和发育。葛根素是从葛根中分离出的生物活性成分和最丰富的次生代谢产物。葛根素的生物合成通过苯丙素途径和异黄酮途径进行,其中涉及9种关键酶。这些结构基因的表达在不同植物组织中的特定PtR2R3-MYB基因的控制下。然而,PtR2R3-MYB基因如何调节葛根素生物合成中的结构基因仍然难以捉摸。本研究挖掘了参与葛根素生物合成和对激素反应的PtR2R3-MYB基因。thomsonii.
结果:共鉴定出209个PtR2R3-MYB蛋白,其中根据拟南芥的系统发育拓扑和R2R3-MYB超家族的分类分为34个亚组。进一步的物理和化学特性,基因结构,和保守基序分析也用于进一步分析PtR2R3-MYB。结合葛根素含量和RNA-seq数据,推测PtR2R3-MYB基因和结构基因对葛根素生物合成的调控,因此,选择21个PtR2R3-MYB基因和25个结构基因进行验证基因表达,并使用qRT-PCR分析技术进一步探索其对MeJA和GSH治疗的反应。相关分析和顺式作用元件分析显示,6个PtR2R3-MYB基因(PtMYB039、PtMYB057、PtMYB080、PtMYB109、PMYB115和PtMYB138)和7个结构基因(PtHID2、PtHID9、PtIFS3、PtUGT069、Pt值得注意的是,经过MeJA和GSH治疗12-24小时,大多数候选基因的表达变化与葛根素生物合成的相关性一致,这也表明MeJA和GSH具有通过调节ZG11基因表达来介导葛根素生物合成的潜力。
结论:总体而言,这项研究提供了对PtR2R3-MYB的全面了解,并将为揭示葛根中PtR2R3-MYB基因的葛根素生物合成的转录调控和对植物激素的反应铺平道路。thomsonii.
BACKGROUND: R2R3-MYB transcription factors regulate secondary metabolism, stress responses and development in various plants. Puerarin is a bioactive ingredient and most abundant secondary metabolite isolated from Pueraria lobata. The biosynthesis of puerarin proceeds via the phenylpropanoid pathway and isoflavonoids pathway, in which 9 key enzymes are involved. The expression of these structural genes is under control of specific PtR2R3-MYB genes in different plant tissues. However, how PtR2R3-MYB genes regulates structural genes in puerarin biosynthesis remains elusive. This study mined the PtR2R3-MYB genes involved in puerarin biosynthesis and response to hormone in Pueraria lobata var. thomsonii.
RESULTS: A total of 209 PtR2R3-MYB proteins were identified, in which classified into 34 subgroups based on the phylogenetic topology and the classification of the R2R3-MYB superfamily in Arabidopsis thaliana. Furtherly physical and chemical characteristics, gene structure, and conserved motif analysis were also used to further analyze PtR2R3-MYBs. Combining puerarin content and RNA-seq data, speculated on the regulated puerarin biosynthesis of PtR2R3-MYB genes and structural genes, thus 21 PtR2R3-MYB genes and 25 structural genes were selected for validation gene expression and further explore its response to MeJA and GSH treatment by using qRT-PCR analysis technique. Correlation analysis and cis-acting element analysis revealed that 6 PtR2R3-MYB genes (PtMYB039, PtMYB057, PtMYB080, PtMYB109, PtMYB115 and PtMYB138) and 7 structural genes (PtHID2, PtHID9, PtIFS3, PtUGT069, PtUGT188, PtUGT286 and PtUGT297) were directly or indirectly regulation of puerarin biosynthesis in ZG11. It is worth noting that after MeJA and GSH treatment for 12-24 h, the expression changes of most candidate genes were consistent with the correlation of puerarin biosynthesis, which also shows that MeJA and GSH have the potential to mediate puerarin biosynthesis by regulating gene expression in ZG11.
CONCLUSIONS: Overall, this study provides a comprehensive understanding of the PtR2R3-MYB and will paves the way to reveal the transcriptional regulation of puerarin biosynthesis and response to phytohormone of PtR2R3-MYB genes in Pueraria lobata var. thomsonii.