The R2R3-MYB Factor FhMYB5 From Freesia hybrida Contributes to the Regulation of Anthocyanin and Proanthocyanidin in Biosynthesis
The R2R3-MYB Factor FhMYB5 From Freesia hybrida Contributes to the Regulation of Anthocyanin and Proanthocyanidin in Biosynthesis
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小苍兰中的 R2R3-MYB 因子 FhMYB5 有助于调节花青素和原花青素的生物合成
DOI：
10.3389/fpls.2018.01935
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发表时间：
2019-01-07
影响因子：
5.6
通讯作者：
Gao, Xiang
中科院分区：
文献类型：
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作者：
Li, Yueqing;Shan, Xiaotong;Gao, Xiang
黄酮类化合物是植物和人体重要的营养物质。与单子叶植物相比，双子叶植物花色素苷和原花色素（PA）生物合成的转录调控被广泛研究。在这项研究中，我们的特点是功能的R2 R3-MYB基因FhMYB 5从单子叶开花植物鸢尾科，小苍兰杂交。多重序列比对和系统发育分析表明，FhMYB 5与葡萄藤VvMYB 5 b亚支聚为一个。相关性分析表明，FhMYB 5的时空表达模式与小苍兰花色素苷和PA的积累规律一致。此外，小苍兰原生质体中的瞬时转染测定揭示了晚期类黄酮生物合成基因（例如，DFR和LDOX）被单独的FhMYB 5略微上调，而当FhMYB 5与两个Illf Glade bHLH基因FhTT 8L和FhGL 3L中的任一个共感染时，早期和晚期生物合成基因都被显著激活。此外，通过将FhMYB 5与上述bHLH基因中的任一个共转染到表达由小苍兰启动子驱动的GUS报告基因的原生质体中，进一步证实了这些结果。此外，FhMYB 5在烟草和拟南芥中的过表达还能显著上调参与总黄酮途径的基因的表达。FhMYB 5基因在小苍兰类黄酮代谢途径中发挥重要作用。这些结果表明，与类黄酮生物合成相关的MYB调控因子在被子植物中具有功能保守性。
The flavonoids are important and nourishing compounds for plants and human. The transcription regulation of anthocyanin and proanthocyanidin (PA) biosynthesis was extensively studied in dicot compared with monocot plants. In this study, we characterized the functionality of an R2R3-MYB gene FhMYB5 from the monocotyledonous flowering plant of Iridaceae, Freesia hybrida. Multiple sequence alignment and phylogenetic analysis implied that FhMYB5 was clustered into grapevine VvMYB5b subclade. Correlation analysis indicated that the spatio-temporal expression patterns of FhMYB5 coincided well with anthocyanin and PA accumulations in Freesia per se. Furthermore, transient transfection assays in Freesia protoplasts revealed that the late flavonoid biosynthetic genes (e.g., DFR and LDOX) were slightly up-regulated by FhMYB5 alone, whereas both early and late biosynthetic genes were significantly activated when FhMYB5 were co-infected with either of the two Illf Glade bHLH genes, FhTT8L and FhGL3L. Moreover, these results were further confirmed by co-transfection of FhMYB5 with either of the bHLH genes aforementioned into protoplasts expressing GUS reporter gene driven by Freesia promoters. In addition, the overexpression of FhMYB5 in tobacco and Arabidopsis could also significantly up-regulate the expression of genes participating in the general flavonoid pathway. In conclusion, FhMYB5 was proved to function in the general flavonoid pathway in Freesia. The results implied a function conservation of flavonoid biosynthesis related MYB regulators in angiosperm plants.