Page 128 - 《广西植物》2025年第5期
P. 128

9 3 2                                  广  西  植  物                                         45 卷
                 Abstract: R2R3 ̄MYB transcription factor plays an important role in plant growth and developmentꎬ stress responseꎬ and
                 secondary metabolism. In order to explore the temporal and spatial expression pattern of R2R3 ̄MYB transcription factors
                 in Pseudostellaria heterophylla and screen R2R3 ̄MYB transcription factors involved in the regulation of heterophyllin B
                 biosynthesisꎬ 15 R2R3 ̄MYB transcription factors were identified from P. heterophylla based on the full ̄length
                 transcriptome database. Their physicochemical propertiesꎬ conserved motifs and phylogenetic relationships were analyzed
                 by bioinformatics methodsꎬ and their tissue expression and abscisic acid induced expression patterns were studied by
                 qRT ̄PCR. The results were as follows: (1) A total of 15 PhR2R3 ̄MYB protein subcells were predicted to locate in cell
                 nucleusꎬ and most of them were hydrophilic unstable proteins. By constructing phylogenetic tree with Arabidopsis
                 thaliana R2R3 ̄MYB proteinꎬ PhR2R3 ̄MYB proteins could be divided into eight subgroupsꎬ of which six subgroups can
                 be clustered with A. thaliana R2R3 ̄MYB transcription factors respectively. ( 2) PhR2R3 ̄MYB gene had tissue
                 expression specificity in Pseudostellaria heterophyllaꎬ and two of the genesꎬ PhMYB4 and PhMYB8ꎬ were highly
                 expressed in phloem of tuberous root. Correlation analysis showed that expression of PhMYB4 and PhMYB8 genes were
                 significantly positively correlated with heterophyllin B content and prePhHB gene expression in P. heterophyllaꎬ
                 suggesting that PhMYB4 and PhMYB8 might be involved in the regulation of heterophyllin B biosynthesis in P.
                 heterophylla. (3) PhMYB4 and PhMYB8 genes were differentially expressed in response to ABA treatment for different
                 time. The expression of PhMYB4 gene decreased firstꎬ then increased and then decreasedꎬ while the expression of
                 PhMYB8 gene was inhibited with ABA treatmentꎬ indicating that both PhMYB4 and PhMYB8 genes respond to ABA
                 signal. This study will lay a foundation for further investigation of the function of PhR2R3 ̄MYB genesꎬ and also provides
                 a theoretical reference for revealing the mechanism of R2R3 ̄MYB transcription factors involved in the regulation of
                 heterophyllin B biosynthesis.
                 Key words: Pseudostellaria heterophyllaꎬ R2R3 ̄MYB transcription factorꎬ heterophyllin Bꎬ bioinformatics analysisꎬ
                 expression analysis


                太子参为石竹科植物孩儿参( Pseudostellaria                  生物合成的转录调控研究尚未见报道ꎮ
            heterophylla)的干燥块根ꎬ具有益气健脾、生津润肺                         转录因子( transcription factorꎬTF) 是一类调节
            的功效ꎬ临床上用于脾虚体倦、食欲不振、病后虚                             蛋白ꎬ通过直接或间接地与靶基因启动子区的顺
            弱等病症ꎮ 太子参主要活性成分有环肽、皂苷、多                            式作用元件结合来调节靶基因的转录表达ꎮ MYB
            糖等 化 学 物 质ꎮ 现 代 药 理 研 究 认 为 环 肽 B                  转录因子是目前植物中功能多样、分布广泛的转
            (heterophyllin B) 具有促进血管新生、抑制酪氨酸                   录因子家族之一ꎬ可以调控植物的生长发育、次生
            酶活性、抗炎等作用ꎬ具有较高的药用开发价值                              代谢及逆境响应等过程( 张弛等ꎬ2020ꎻ段童瑶等ꎬ
            (Yang et al.ꎬ 2018ꎻ 李 军 等ꎬ 2019ꎻ Deng et al.ꎬ      2020)ꎮ 根据 MYB 结构域的数目ꎬ可以将其分为 4
            2022)ꎮ 但是ꎬ太子参中环肽 B 的含量并不高ꎬ限                        类ꎬ即 1R ̄MYB、 R2R3 ̄MYB、 3R ̄MYB 和 4R ̄MYB
            制了其开发利用ꎮ 随着组学技术的发展ꎬ在解析                             (牛义岭等ꎬ2016)ꎮ R2R3 ̄MYB 转录因子在植物
            太子参中环肽 B 生物合成途径的基础上ꎬ挖掘太                            次生代谢的调控过程中发挥重要作用ꎮ 例如:丹
            子参中环肽 B 生物合成相关的调控因子并解析其                            参 SmMYB98 可以通过激活丹参酮和丹酚酸生物

            调控机制是提高环肽 B 含量的有效手段ꎮ Zheng                         合成通路上关键酶编码基因的表达来调控丹参酮
            等(2019)研究表明ꎬ环肽 B 是由线性前体肽经酶                         和丹酚酸的生物合成( Hao et al.ꎬ 2020)ꎻ三七中

            催化形成的环状化合物ꎬ其中 prePhHB 是环肽 B                        的 PnMYB1 调控三七皂苷的生物合成( 雷君等ꎬ
            的前体肽编码基因ꎬ是环肽 B 生物合成途径中的                            2022)ꎻ 红 豆 杉 中 的 R2R3 ̄MYB 转 录 因 子———
            关键酶编码基因ꎮ 虽然环肽 B 的生物合成途径在                           TcMYB29a 通过脱落酸介导的紫杉醇积累信号通
            逐步被解析ꎬ但是关于环肽 B 生物合成的调控研                            路促进紫杉醇在红豆杉细胞中的积累( Cao et al.ꎬ
            究还较少ꎮ 现有研究显示ꎬ水分胁迫、氮代谢及植                            2022)ꎮ 许文彦(2011) 研究表明ꎬABA 可以增加
            物激素 ABA 等均会影响环肽 B 的积累( 许文彦ꎬ                        太子参组织培养丛生芽中环肽 B 的积累ꎬ但是关
            2011ꎻ韦德群ꎬ2019ꎻ刘洋等ꎬ2024)ꎬ但关于环肽 B                    于 R2R3 ̄MYB 转录因子是否调控太子参次级代谢
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