Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Education Ministry, School of Landscape Architecture, Beijing Forestry University, Beijing, 100083, China.
Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Education Ministry, School of Landscape Architecture, Beijing Forestry University, Beijing, 100083, China.
Plant Sci. 2021 Dec;313:111094. doi: 10.1016/j.plantsci.2021.111094. Epub 2021 Oct 18.
Anthocyanins are important flavonoid pigments involved in the colouring of flowers and fruits. They are synthesized on the cytoplasmic surface of the endoplasmic reticulum and transported into the vacuole for storage. Previous reports have suggested that glutathione S-transferase (GST) is involved in anthocyanin transport. However, due to the limitation of plant materials, most GSTs only participate in the cyanidin or delphinidin transport pathway. Here, an anthocyanin-related GST, ScGST3, was identified from the transcriptome of cineraria. The expression pattern of ScGST3 was highly consistent with anthocyanin accumulation in ray florets. Molecular complementation of Arabidopsis tt19 indicated that the overexpression of ScGST3 restores the anthocyanin-deficient phenotype of the mutant. Virus-induced gene silencing (VIGS) of ScGST3 in carmine and blue cineraria leaves could inhibit anthocyanin accumulation, further confirming the function of ScGST3 in anthocyanin accumulation. In vitro assays showed that ScGST3 increases the water solubility of cyanidin-3-O-glucoside (C3G) and delphinidin-3-O-glucosid (D3G). In addition, we also identified two anthocyanin-related MYB transcription factors, ScMYB3 and ScMYB6. The expression pattern of these two genes was also highly consistent with anthocyanin accumulation. Faded abaxial leaf phenotypes were observed after the silencing of ScMYB3 and ScMYB6, and the expression levels of partial structural genes were repressed. Based on the results from dual-luciferase assays and yeast one-hybrid assays, ScMYB3 can activate the promoter of ScGST3. Collectively, the transcription of ScGST3 is regulated by ScMYB3, which plays an important role in the transport of C3G and D3G in cineraria.
花青苷是一种重要的类黄酮色素，参与花和果实的颜色形成。它们在粗面内质网的细胞质表面合成，并被运输到液泡中储存。先前的报告表明，谷胱甘肽 S-转移酶（GST）参与花青苷的运输。然而，由于植物材料的限制，大多数 GST 仅参与飞燕草色素或天竺葵色素的运输途径。在这里，从瓜叶菊转录组中鉴定出一个与花青苷相关的 GST，ScGST3。ScGST3 的表达模式与射线花瓣中花青苷的积累高度一致。ScGST3 在拟南芥 tt19 中的分子互补表明，ScGST3 的过表达恢复了突变体中缺乏花青苷的表型。在胭脂红和蓝色瓜叶菊叶片中通过病毒诱导的基因沉默（VIGS）抑制 ScGST3 的表达可以抑制花青苷的积累，进一步证实了 ScGST3 在花青苷积累中的作用。体外实验表明，ScGST3 增加了飞燕草素-3-O-葡萄糖苷（C3G）和天竺葵素-3-O-葡萄糖苷（D3G）的水溶性。此外，我们还鉴定了两个与花青苷相关的 MYB 转录因子，ScMYB3 和 ScMYB6。这两个基因的表达模式也与花青苷的积累高度一致。ScMYB3 和 ScMYB6 沉默后，叶片下表皮褪色表型出现，部分结构基因的表达水平受到抑制。基于双荧光素酶报告基因和酵母单杂交实验的结果，ScMYB3 可以激活 ScGST3 的启动子。总之，ScGST3 的转录受 ScMYB3 调控，在瓜叶菊中 C3G 和 D3G 的运输中发挥重要作用。
