Page 152 - 《广西植物》2025年第6期
P. 152
1 1 3 8 广 西 植 物 45 卷
Abstract: Anthocyanins are one of the key factors affecting the formation of ornamental value of Loropetalum chinense
var. rubrum. In order to investigate the molecular mechanisms of anthocyanin biosynthesis in L. chinense var. rubrumꎬ an
anthocyanin biosynthesis ̄related R2R3 ̄MYB geneꎬ named LcMYB113 with GenBank accession number OR344758ꎬ was
cloned from L. chinense var. rubrum. The deduced amino acid sequence of LcMYB113 gene was analyzed by
bioinformatics methods. The relative expression levels of LcMYB113 gene in leaves of L. chinense var. rubrum and
L. chinense were tested by real ̄time fluorescence quantitative RT ̄PCR method. The phenotypes of leaves and flowers of
transgenic tobacco lines were recorded. The relative expression levels of anthocyanin biosynthetic structural genes in
leaves of transgenic tobacco lines were examined. The results were as follows: (1) The open reading frame of LcMYB113
gene was 789 bp longꎬ encoding 262 amino acids. Multiple alignment analysis showed that the N ̄terminal of LcMYB113
contained a canonical R2R3 DNA binding domain and a bHLH transcript factor binding motif [D/ E]Lx [R/ K]x Lx
2 3 6
Lx R. Two anthocyanin biosynthesis activator characteristic motifs ANDV and [K/ R]P[Q/ R]P[Q/ R] were also found
3
in the amino acid sequence of LcMYB113. Phylogenetic tree analysis indicated that LcMYB113 was closely related to
anthocyanin specific R2R3 ̄MYB subfamily transcription factorsꎬ including PsMYB58 of Paeonia × suffruticosa and
VvMYBA1 of Vitis vinifera. (2) The anthocyanin content and relative expression level of LcMYB113 gene in leaves of
L. chinense var. rubrum were 7. 4 and 101 times that of L. chinense respectivelyꎬ which indicated that the relative
expression level of LcMYB113 gene was correlated with the anthocyanin content in leaves. (3) The LcMYB113 gene
overexpression vector was constructed and transformed into tobacco variety WS38. Heterologous expression of LcMYB113
gene in tobacco induced anthocyanin accumulation in leaves and flowers of transgenic lines. Further moreꎬ compared with
wide type tobacco lineꎬ transgenic lines had remarkably higher relative expression levels of anthocyanin biosynthetic
structural genesꎬ such as NtANSꎬ NtDFR and NtCHS. In summaryꎬ this research results indicate that LcMYB113 can
regulate the biosynthesis of anthocyaninꎬ and provide theoretical support for leaf color breeding of L. chinense var.
rubrum.
Key words: Loropetalum chinense var. rubrumꎬ anthocyaninꎬ LcMYB113ꎬ gene cloningꎬ real ̄time fluorescence
quantitative RT ̄PCR
红花檵木(Loropetalum chinense var. rubrum) 为 F3′H)、 二 氢 黄 酮 醇 4 ̄还 原 酶 ( dihydroflavonol 4 ̄
金缕梅科檵木属的多年生植物ꎬ树姿挺拔ꎬ枝条红 reductaseꎬ DFR )、 花 青 素 合 成 酶 ( anthocyanidin
褐色ꎬ花红叶艳ꎬ观赏性极佳ꎬ是原产于我国的特 synthaseꎬANS) 等 ( Li et al.ꎬ 2014ꎻ Chaves ̄Silva et
色观花观叶植物(董淑龙等ꎬ2022)ꎮ 此外ꎬ红花檵 al.ꎬ2018ꎻKhusnutdinov et al.ꎬ2021)ꎮ 在 植 物 中ꎬ
木适应性强、耐修剪、易于塑形ꎬ在长江流域及南 R2R3 ̄MYB 类转录因子被认为是调控花青苷生物
方地区常作为主要的彩叶观赏植物大量应用于城 合成结构基因表达的关键转录因子ꎬR2R3 ̄MYB
市道路、公园、社区等绿化中(张艺帆等ꎬ2022)ꎮ 能够结合花青苷生物合成结构基因的启动子区域
红花檵木作为我国特色的观花观叶园林绿化 并激活靶基因的表达ꎬ从而促进花青苷物质的积
植物(彭闰珉和于晓英ꎬ2012ꎻZhang et al.ꎬ2023)ꎬ 累ꎻ此外ꎬR2R3 ̄MYB 还能与 bHLH 及 WD40 形成
其花青苷物质类型及含量的差异是造成红花檵木 转录复合体共同调控花青苷物质的合成( Feller et
不同品种间叶色差异的基础ꎬ在红花檵木的叶片 al.ꎬ 2011ꎻ Liꎬ 2014ꎻ An et al.ꎬ 2020ꎻ Yan et al.ꎬ
中已经检测到 15 种花青苷物质ꎬ包括天竺葵素、 2021)ꎮ Wu 等(2022)研究表明ꎬR2R3 ̄MYBs 蛋白
矢车菊素、锦葵素等(陈倩如等ꎬ2021)ꎮ 已有研究 的 N 端 R2R3 DNA 结构域相对保守ꎬ而 C 端具有
表明ꎬ花青苷物质的生物合成依赖于多种结构酶 多样性ꎮ 基于拟南芥 R2R3 ̄MYB 蛋白 AtWER 的
类的 活 性ꎬ 包 括 苯 丙 氨 酸 解 氨 酶 ( phenylalanine 晶体结构分析ꎬ证明 R2R3 结构域形成 2 组各 3 个
ammonia lyaseꎬ PAL)、 查 尔 酮 合 成 酶 ( chalcone α 螺旋的结构ꎬ该结构域特异识别 DNA 序列 5′ ̄
synthaseꎬCHS)、查尔酮异构酶(chalcone isomeraseꎬ AACNGC ̄3′(Wang et al.ꎬ2020)ꎬ而 R3 结构中的
CHI)、 黄 烷 酮 3 ̄羟 化 酶 ( flavanone 3 ̄hydroxylaseꎬ RB 基序是识别 bHLH 的特征序列( Zimmermann et
F3H)、黄烷酮 3′ ̄羟化酶( flavanone 3′ ̄hydroxylaseꎬ al.ꎬ2004ꎻWang BH et al.ꎬ2022)ꎮ 在观赏植物中ꎬ

