College of Horticulture, South China Agricultural University, Guangzhou, China.
Physiol Plant. 2024 Nov-Dec;176(6):e14633. doi: 10.1111/ppl.14633.
Anthocyanins are important secondary metabolites in plants. After the formation of anthocyanidins, Flavonoid 3-O-glucosyltransferase (3GT) mediated glycosylation first occurs at the C-3 site, forming a stable anthocyanin 3-O-glucoside. Several studies have investigated the function of 3GT using biochemical methods. However, it is necessary to provide further genetic evidence for the role of Ph3GT in petunia (Petunia hybrida). In addition, there is no information regarding the subcellular localization of Ph3GT and the regulation of transcription factors on Ph3GT. In this study, the full-length Ph3GT gene from petunia (Petunia hybrida) was isolated. We found that Ph3GT is localized in the cytoplasm. Ph3GT exhibited high expression levels in the corollas during the coloring period of petunia flowers. VIGS-mediated Ph3GT silencing resulted in a lighter corolla color and a significant decrease in the anthocyanin content in six petunia cultivars. The silencing of Ph3GT affected the expression levels of eight key genes in the anthocyanin synthesis pathway. Additionally, dual luciferase and yeast one-hybrid assays showed that R2R3-MYB transcription factor PhAN2 directly regulates the transcript of Ph3GT.
花色素苷是植物中重要的次生代谢物。在花色素苷形成后，类黄酮 3-O-葡萄糖基转移酶（3GT）首先介导在 C-3 位发生糖基化，形成稳定的花色素苷 3-O-葡萄糖苷。已有几项研究使用生化方法研究了 3GT 的功能。然而，需要进一步提供遗传证据来证明 Ph3GT 在矮牵牛（Petunia hybrida）中的作用。此外，关于 Ph3GT 的亚细胞定位和转录因子对 Ph3GT 的调控，尚无相关信息。在本研究中，从矮牵牛中分离出全长 Ph3GT 基因。我们发现 Ph3GT 定位于细胞质中。Ph3GT 在矮牵牛花朵的着色期表现出高水平的表达，在花瓣中表达量最高。VIGS 介导的 Ph3GT 沉默导致六个矮牵牛品种的花瓣颜色变浅，花色素苷含量显著下降。Ph3GT 的沉默影响了花色素苷合成途径中八个关键基因的表达水平。此外，双荧光素酶和酵母单杂交测定表明 R2R3-MYB 转录因子 PhAN2 直接调控 Ph3GT 的转录本。
