Bao Changjian, Niu Mengyang, Liu Ze, Wu Yukun, Cao Beier, Zhou Min, Yuan Xingxing, Jia Li, Cui Jin, Shen Zhenguo, Su Nana
College of Life Sciences, Nanjing Agricultural University, Nanjing, China.
Jiangsu Key Laboratory for Horticultural Crop Genetic Improvement, Institute of Industrial Crops, Jiangsu Academy of Agricultural Sciences, Nanjing, China.
Planta. 2025 Jul 31;262(3):70. doi: 10.1007/s00425-025-04785-z.
VrANR and VrMYB90 were identified by transcriptome between 'Sulv1' and 'M0313'. VrMYB90 acted upstream of VrANR by binding to the promoter of VrANR and inhibiting the expression of VrANR, thus regulating negatively the biosynthesis of proanthocyanins. Anthocyanin reductase (ANR), the enzyme responsible for converting anthocyanidins to their corresponding 2,3-cis-flavan-3-ols, which is crucial to balance the anthocyanins and proanthocyanidins (PAs) level. In this study, significant differences were observed in the contents of anthocyanins and PA between the two cultivars. We identified a structural gene VrANR and a MYB transcription factor VrMYB90 that acts upstream of VrANR based on transcriptomic data analysis. Both of the two factors played key roles in PA accumulation in mung bean. Overexpressing VrANR in mung bean hairy roots led to a higher PA accumulation when compared with empty vector. Furthermore, overexpression VrANR in the Arabidopsis ban (anr) mutants increased PA content while reducing anthocyanin levels. Yeast-one-hybridization, β-glucuronidase (GUS) assay and dual-luciferase (LUC) reporter assays revealed that VrMYB90 (a positive regulator in anthocyanin) could bind to the VrANR promoter to repress its expression and then repress PA synthesis. Determination of transcript level of VrANR in VrMYB90 transgenic mung bean also proved that VrMYB90 inhibited the expression of VrANR. Above all, our present results suggested that VrMYB90 can repress the transcription of VrANR to play a negative role in the PAs accumulation in mung bean. These findings enriched our understanding in the regulatory network of PAs in mung bean.
通过对‘Sulv1’和‘M0313’进行转录组分析鉴定出了VrANR和VrMYB90。VrMYB90通过与VrANR的启动子结合并抑制VrANR的表达，在VrANR的上游发挥作用，从而对原花青素的生物合成起负调控作用。花青素还原酶（ANR）负责将花青素转化为相应的2,3-顺式黄烷-3-醇，这对于平衡花青素和原花青素（PAs）水平至关重要。在本研究中，观察到两个品种之间花青素和PA含量存在显著差异。基于转录组数据分析，我们鉴定出一个结构基因VrANR和一个在VrANR上游起作用的MYB转录因子VrMYB90。这两个因子在绿豆PA积累中都发挥着关键作用。与空载载体相比，在绿豆毛状根中过表达VrANR导致更高的PA积累。此外，在拟南芥ban（anr）突变体中过表达VrANR增加了PA含量，同时降低了花青素水平。酵母单杂交、β-葡萄糖醛酸酶（GUS）分析和双荧光素酶（LUC）报告基因分析表明，VrMYB90（花青素的正调控因子）可以与VrANR启动子结合以抑制其表达，进而抑制PA合成。对VrMYB90转基因绿豆中VrANR转录水平的测定也证明VrMYB90抑制了VrANR的表达。综上所述，我们目前的结果表明VrMYB90可以抑制VrANR的转录，从而在绿豆PA积累中发挥负作用。这些发现丰富了我们对绿豆中PA调控网络的理解。
