Wang Yu, Dou Ying, Wang Rui, Guan Xuelian, Hu Zenghui, Zheng Jian
College of Landscape Architecture, Beijing University of Agriculture, Beijing 102206, China.
College of Landscape Architecture, Beijing University of Agriculture, Beijing 102206, China; Beijing Collaborative Innovation Center for Eco-Environmental Improvement with Forestry and Fruit Trees, Beijing 102206, China.
Gene. 2017 Nov 30;635:16-23. doi: 10.1016/j.gene.2017.09.002. Epub 2017 Sep 7.
The flower color of Syringa oblata Lindl., which is often modulated by the flavonoid content, varies and is an important ornamental feature. Chalcone synthase (CHS) catalyzes the first key step in the flavonoid biosynthetic pathway. However, little is known about the role of S. oblata CHS (SoCHS) in flavonoid biosynthesis in this species. Here, we isolate and analyze the cDNA (SoCHS1) that encodes CHS in S. oblata. We also sought to analyzed the molecular characteristics and function of flavonoid metabolism by SoCHS1. We successfully isolated the CHS-encoding genomic DNA (gDNA) in S. oblata (SoCHS1), and the gene structural analysis indicated it had no intron. The opening reading frame (ORF) sequence of SoCHS1 was 1170bp long and encoded a 389-amino acid polypeptide. Multiple sequence alignment revealed that both the conserved CHS active site residues and CHS signature sequence were in the deduced amino acid sequence of SoCHS1. Crystallographic analysis revealed that the protein structure of SoCHS1 is highly similar to that of FnCHS1 in Freesia hybrida. The quantitative real-time polymerase chain reaction (PCR) performed to detect the SoCHS1 transcript expression levels in flowers, and other tissues revealed the expression was significantly correlated with anthocyanin accumulation during flower development. The ectopic expression results of Nicotiana tabacum showed that SoCHS1 overexpression in transgenic tobacco changed the flower color from pale pink to pink. In conclusion, these results suggest that SoCHS1 plays an essential role in flavonoid biosynthesis in S. oblata, and could be used to modify flavonoid components in other plant species.
紫丁香的花色常受类黄酮含量的调节，花色各异，是一项重要的观赏特征。查尔酮合酶（CHS）催化类黄酮生物合成途径中的第一步关键反应。然而，关于紫丁香CHS（SoCHS）在该物种类黄酮生物合成中的作用，人们了解甚少。在此，我们分离并分析了紫丁香中编码CHS的cDNA（SoCHS1）。我们还试图分析SoCHS1在类黄酮代谢中的分子特征和功能。我们成功分离出紫丁香中编码CHS的基因组DNA（gDNA）（SoCHS1），基因结构分析表明它没有内含子。SoCHS1的开放阅读框（ORF）序列长1170bp，编码一个389个氨基酸的多肽。多序列比对显示，SoCHS1推导的氨基酸序列中存在保守的CHS活性位点残基和CHS特征序列。晶体学分析表明，SoCHS1的蛋白质结构与小苍兰FnCHS1的蛋白质结构高度相似。通过定量实时聚合酶链反应（PCR）检测SoCHS1转录本在花朵及其他组织中的表达水平，结果显示其表达与花朵发育过程中的花青素积累显著相关。烟草的异位表达结果表明，转基因烟草中SoCHS1的过表达使花色从浅粉色变为粉色。总之，这些结果表明SoCHS1在紫丁香类黄酮生物合成中起关键作用，并且可用于修饰其他植物物种中的类黄酮成分。
