R2R3-MYB transcription factors (TFs) are known to play a key role in regulating the expression of structural genes involved in plant flavonoid biosynthesis. However, the regulatory networks and related genes controlling isoflavonoid biosynthesis in soybean are poorly understood. We previously reported that ethephon application increases the production of isoflavonoids in soybean leaves. In this study, we attempted to identify a potential regulatory gene that positively controls isoflavonoid production in response to ethephon treatment in soybean (Glycine max L.). RNA sequencing (RNA-seq) revealed that ethephon application led to the upregulation of 22 genes, including the genes for R2R3-MYB TFs, related to isoflavonoid biosynthesis in soybean plants. Ethephon treatment highly induced the expression of GmMYB108, and its expression was exclusively enriched in flowers as determined using in silico and real-time quantitative PCR analyses. Furthermore, GmMYB108 overexpression resulted in an intense accumulation of anthocyanins as well as total flavonoid production in the leaf tissues of transgenic Arabidopsis plants. In addition, GmMYB108 overexpression increased the transcript levels of several genes involved in the biosynthesis of anthocyanins and their regulatory pathways in Arabidopsis. These results suggest that GmMYB108 is a potential positive regulator of the biosynthesis of flavonoids and anthocyanins in soybean flowers.

中文翻译：

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大豆花特异性R2R3-MYB转录因子基因GmMYB108诱导拟南芥花青素产生

已知 R2R3-MYB 转录因子 (TF) 在调节参与植物类黄酮生物合成的结构基因的表达中发挥关键作用。然而，人们对大豆中控制异黄酮类生物合成的调控网络和相关基因知之甚少。我们之前报道过乙烯利的应用增加了大豆叶中异黄酮类化合物的产量。在这项研究中，我们试图鉴定一种潜在的调控基因，该基因可以积极控制大豆（Glycine max L.）中乙烯利处理后异黄酮类化合物的产生。RNA 测序 (RNA-seq) 显示，乙烯利的应用导致 22 个基因上调，包括与大豆植物中异黄酮类生物合成相关的 R2R3-MYB TF 基因。乙烯利处理高度诱导 GmMYB108 的表达，并且根据计算机模拟和实时定量 PCR 分析确定，其表达仅在花中富集。此外，GmMYB108 过表达导致转基因拟南芥植物叶组织中花青素的大量积累以及总黄酮类化合物的产生。此外，GmMYB108 过表达增加了拟南芥中参与花青素生物合成及其调控途径的多个基因的转录水平。这些结果表明，GmMYB108 是大豆花中类黄酮和花青素生物合成的潜在正调节因子。