Ren Yifei, Liu Donglin, Zhao Weicheng, Wang Xinran, Cao Xiaoying, Wan Wen
School of Life Science, Jiangsu Normal University, Xuzhou, Jiangsu, 221116, People's Republic of China.
BMC Plant Biol. 2025 May 28;25(1):723. doi: 10.1186/s12870-025-06755-9.
Paclitaxel (Taxol) is an invaluable secondary metabolite extracted from Taxus species, wildly utilized in cancer therapeutics. Salicylic acid (SA), an important phytohormone, substantially elevates paclitaxel accumulation in Taxus cell suspension cultures. However, the molecular mechanisms governing SA-induced modulation of paclitaxel biosynthesis remain poorly elucidated. Our previous studies identified TcMYB73, an SA-responsive R2R3-MYB transcription factor (TF), which demonstrates a robust positive correlation with paclitaxel biosynthesis, implying its orchestrating role in this metabolic pathway.
Expression pattern analysis revealed that TcMYB73 displays predominant expression in lateral roots. Both overexpression and RNA interference (RNAi) of TcMYB73 demonstrated its regulatory function in modulating key paclitaxel biosynthetic genes, including taxadiene synthase (TASY), 10-deacetylbaccatin III-10-O-acetyltransferase (DBAT), and 3'-N-debenzoyl-2'-deoxytaxol-N-benzoyltransferase (DBTNBT). Transient TcMYB73 overexpression in Taxus chinensis (T. chinensis) needles induced 2.38-, 2.87-, and 1.79-fold increases in 10-DAB, baccatin III, and paclitaxel accumulation, respectively, compared to controls. Additionally, yeast one-hybrid (Y1H), Electrophoretic Mobility Shift Assay (EMSA), chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR), and dual-luciferase (Dual-LUC) assays verified that TcMYB73 directly binds to MYB recognition elements in the T10OH promoter, enhancing its transcription. Furthermore, TcWRKY33, a transcriptional activator of DBAT, functions as a positive regulator mediating SA signaling within the paclitaxel biosynthetic pathway. Subsequent investigations validated that TcMYB73 upregulates DBAT expression via direct transcriptional activation of TcWRKY33. Collectively, these results demonstrate that TcMYB73 transduces SA signals to T10OH and TcWRKY33, coordinately regulating paclitaxel biosynthesis through dual mechanisms: direct activation of biosynthetic genes and indirect modulation of upstream regulators.
Our results indicated that the SA-responsive R2R3-MYB TF, TcMYB73 transcriptionally governs paclitaxel biosynthesis in T. chinensis through direct activation the expression of the T10OH gene, and activating TcWRKY33 expression, thereby modulating DBAT expression. This study provides mechanistic insights into the role of TcMYB73 in mediating SA-induced transcriptional regulation of paclitaxel biosynthesis in Taxus species.
紫杉醇是从红豆杉属植物中提取的一种极为珍贵的次生代谢产物，广泛应用于癌症治疗。水杨酸（SA）作为一种重要的植物激素，可显著提高红豆杉细胞悬浮培养物中紫杉醇的积累量。然而，SA诱导紫杉醇生物合成调控的分子机制仍不清楚。我们之前的研究鉴定出了TcMYB73，一种SA响应型R2R3-MYB转录因子（TF），它与紫杉醇生物合成呈显著正相关，这表明它在该代谢途径中起调控作用。
表达模式分析表明，TcMYB73在侧根中优势表达。对TcMYB73进行过表达和RNA干扰（RNAi）实验，均证明了其对紫杉醇关键生物合成基因的调控功能，这些基因包括紫杉二烯合酶（TASY）、10-去乙酰巴卡亭III-10-O-乙酰转移酶（DBAT）和3'-N-去苯甲酰基-2'-脱氧紫杉醇-N-苯甲酰转移酶（DBTNBT）。与对照相比，在南方红豆杉针叶中瞬时过表达TcMYB73分别使10-去乙酰巴卡亭III、巴卡亭III和紫杉醇的积累量提高了2.38倍、2.87倍和1.79倍。此外，酵母单杂交（Y1H）、电泳迁移率变动分析（EMSA）、染色质免疫沉淀-定量PCR（ChIP-qPCR）和双荧光素酶（Dual-LUC）分析证实，TcMYB73直接结合T10OH启动子中的MYB识别元件，增强其转录。此外，DBAT的转录激活因子TcWRKY33作为一个正向调节因子，在紫杉醇生物合成途径中介导SA信号。随后的研究证实，TcMYB73通过直接转录激活TcWRKY33来上调DBAT的表达。总的来说，这些结果表明，TcMYB73将SA信号传递给T10OH和TcWRKY33，通过双重机制协调调控紫杉醇生物合成：直接激活生物合成基因和间接调节上游调节因子。
我们的结果表明，SA响应型R2R3-MYB转录因子TcMYB73通过直接激活T10OH基因的表达和激活TcWRKY33的表达，从而调节DBAT的表达，在转录水平上调控南方红豆杉中紫杉醇的生物合成。本研究为TcMYB73在介导SA诱导的红豆杉属植物紫杉醇生物合成转录调控中的作用提供了机制性见解。
