miR5298b regulated taxol biosynthesis by acting on TcNPR3, resulting in an alleviation of the strong inhibition of the TcNPR3-TcTGA6 complex in Taxus chinensis

• Published in: International journal of biological macromolecules Vol. 248; p. 125909
• Main Authors: Ying, Chen, Meng, Zhang, Wenli, Zhang, Yamin, Wang, Hua, Zhang, Liu, Yang, Longjiang, Yu, Chunhua, Fu
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.09.2023
• Subjects: miR5298b; Taxol biosynthesis; Taxus chinensis; TcNPR3; TGA; TcNPR3; Taxus chinensis; miR5298b; TGA; Taxol biosynthesis
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2023.125909

Taxol, a valuable but rare secondary metabolite of the genus Taxus, is an effective anticancer drug. Understanding the regulation of taxol biosynthesis may provide a means to increase taxol content. The microRNA miR5298b was found to promote the accumulation of taxol and upregulate several taxol biosynthesis genes, including DBAT, TASY, and T5H, as demonstrated by experiments using the overexpression and mimicry of transient leaves. Moreover, miR5298b cleaves the mRNA sequence of TcNPR3, a homolog of the salicylic acid receptor AtNPR3/4. Overexpression and knockdown by RNA interference of TcNPR3 confirmed that it repressed taxol biosynthesis. These results indicate that miR5298b enhances taxol biosynthesis via the cleavage of TcNPR3. Yeast two-hybrid bimolecular fluorescence complementation and pull-down assays revealed that TcTGA6, a TGA transcription factor, physically interacted with TcNPR3. Functional experiments showed that TcTGA6 negatively regulates taxol biosynthesis by directly combining with the TGACG motif in the promoters of TASY, T5H, and T10H. TcNPR3 enhances TcTGA6 inhibition Luciferase assays showed that miR5298b alleviated the repression of the TcNPR3–TcTGA6 complex. In summary, miR5298b can cleave TcNPR3, thereby alleviating the inhibition of the TcNPR3–TcTGA6 complex to upregulate taxol biosynthesis genes. •A novel microRNA regulator, miR5298b, could enhance taxol biosynthesis in Taxus chinensis•miR5298b could promote the degradation of TcNPR3, which was supposed to be a key component in SA signal transduction•TcNPR3 recruits and interacts with TcTGA6, a transcription factor that constitutes a protein complex with enhanced suppressive ability•miR5298b could alleviate the repressing ability of the TcNPR3-TcTGA6 complex•TcTGA6 regulates the downstream taxol biosynthesis genes by binding to the TGACG motif in the promoters of TASY, T5H, and T10H