The fruit of Lonicera caerulea L. is rich in anthocyanin, which has beneficial effects on human health. However, there is no research report on the regulation mechanism of anthocyanin synthesis in Lonicera caerulea L. TT8 gene-encoded protein belongs to bHLH transcription factor, and it has been reported to regulate anthocyanin synthesis. In the study, we cloned TT8 gene from Lonicera caerulea L. named “Berel” and transformed into tobacco (Nicotiana tabacum) to characterize its function. The open-reading frame of LcTT8 was 2049 bp, encoding a protein of 682 amino acids. The phylogenetic tree analysis showed that LcTT8 protein had the highest homology with TT8 in Paeonia suffruticosa. The analysis of expression in different tissues showed that the expression level of LcTT8 was higher in fruits than that in flowers, leaves, stems, and roots, and the expression level reached the peak at the early stage of fruit color change. The subcellular localization results showed that the LcTT8 protein was mainly localized in the nucleus. A total of ten LcTT8 overexpression transgenic tobacco were obtained. The ELISA results revealed that the anthocyanin content in the transgenic tobacco leaves was increased by 36.84% compared with the wild-type tobacco. The qPCR results showed that the overexpression of LcTT8 caused the up-expression of key genes of anthocyanin synthesis, including F3H, DFR, and ANS. Similarly, the enzyme activities of DFR and ANS were significantly increased in the transgenic lines (P < 0.05). Our research reveals the expression patterns and molecular characteristic of LcTT8 gene in anthocyanin synthesis, providing new possibilities for the breeding of blue honeysuckle and other fruit plants with high anthocyanin accumulation.

中文翻译：

---

Lonicera caerulea L. 转录因子 LcTT8 对花青素积累的调控。

Lonicera caerulea L.的果实富含花青素，对人体健康有益。但蓝花忍冬花色苷合成调控机制尚未见研究报道。TT8基因编码蛋白属于bHLH转录因子，有报道调控花色苷合成。在研究中，我们克隆了蓝花忍冬的TT8基因，命名为“Berel”，并转化到烟草（Nicotiana tabacum）中以表征其功能。LcTT8 的开放阅读框为 2049 bp，编码 682 个氨基酸的蛋白质。系统进化树分析表明，LcTT8蛋白与白芍中TT8的同源性最高。不同组织中的表达分析表明，LcTT8在果实中的表达水平高于在花、叶、茎和根中的表达水平，并且在果实颜色变化的早期表达水平达到高峰。亚细胞定位结果表明LcTT8蛋白主要定位于细胞核内。共获得10个LcTT8过表达转基因烟草。ELISA结果显示，与野生型烟草相比，转基因烟叶中的花青素含量增加了36.84%。qPCR结果表明，LcTT8的过表达导致花青素合成关键基因F3H、DFR和ANS的上调。同样，DFR 和 ANS 的酶活性在转基因株系中显着增加（P < 0.05）。我们的研究揭示了 LcTT8 基因在花青素合成中的表达模式和分子特征，