Li Xiao-Jing, Zhang Jie-Qiong, Wu Zi-Chen, Lai Biao, Huang Xu-Ming, Qin Yong-Hua, Wang Hui-Cong, Hu Gui-Bing
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China.
Physiological Laboratory for South China Fruits, College of Horticulture, South China Agricultural University, Guangzhou, China.
Physiol Plant. 2016 Feb;156(2):139-149. doi: 10.1111/ppl.12391. Epub 2015 Nov 2.
Anthocyanins generate the red color in the pericarp of Litchi chinensis. UDP-glucose: flavonoid 3-O-glycosyltransferase (UFGT, EC. 2.4.1.91) stabilizes anthocyanidin by attaching sugar moieties to the anthocyanin aglycone. In this study, the function of an UFGT gene involved in the biosynthesis of anthocyanin was verified through heterologous expression and virus-induced gene silencing assays. A strong positive correlation between UFGT activity and anthocyanin accumulation capacity was observed in the pericarp of 15 cultivars. Four putative flavonoid 3-O-glycosyltransferase-like genes, designated as LcUFGT1 to LcUFGT4, were identified in the pericarp of litchi. Among the four UFGT gene members, only LcUFGT1 can use cyanidin as its substrate. The expression of LcUFGT1 was parallel with developmental anthocyanin accumulation, and the heterologously expressed protein of LcUFGT1 displayed catalytic activities in the formation of anthocyanin. The LcUFGT1 over-expression tobacco had darker petals and pigmented filaments and calyxes resulting from higher anthocyanin accumulations compared with non-transformed tobacco. In the pericarp with LcUFGT1 suppressed by virus-induced gene silencing, pigmentation was retarded, which was well correlated with the reduced-LcUFGT1 transcriptional activity. These results suggested that the glycosylation-related gene LcUFGT1 plays a critical role in red color formation in the pericarp of litchi.
花青素在荔枝果皮中产生红色。尿苷二磷酸葡萄糖：类黄酮3 - O - 糖基转移酶（UFGT，EC. 2.4.1.91）通过将糖基部分连接到花青素苷元上来稳定花青素。在本研究中，通过异源表达和病毒诱导的基因沉默试验验证了一个参与花青素生物合成的UFGT基因的功能。在15个品种的果皮中观察到UFGT活性与花青素积累能力之间存在强正相关。在荔枝果皮中鉴定出四个假定的类黄酮3 - O - 糖基转移酶样基因，命名为LcUFGT1至LcUFGT4。在这四个UFGT基因成员中，只有LcUFGT1可以使用花青素作为其底物。LcUFGT1的表达与发育过程中的花青素积累平行，并且LcUFGT1的异源表达蛋白在花青素形成中表现出催化活性。与未转化的烟草相比，LcUFGT1过表达的烟草花瓣颜色更深，花丝和花萼有色素沉着，这是由于花青素积累更高所致。在通过病毒诱导的基因沉默抑制LcUFGT1的果皮中，色素沉着延迟，这与LcUFGT1转录活性降低密切相关。这些结果表明，与糖基化相关的基因LcUFGT1在荔枝果皮红色形成中起关键作用。
