Jasmonate-responsive expression of paclitaxel biosynthesis genes in Taxus cuspidata cultured cells is negatively regulated by the bHLH transcription factors TcJAMYC1, TcJAMYC2, and TcJAMYC4

Abstract

Taxus cell suspension culture is a sustainable technology for the industrial production of paclitaxel (Taxol®), a highly modified diterpene anti-cancer agent. The methyl jasmonate (MJ)-mediated paclitaxel biosynthetic pathway is not fully characterized, making metabolic engineering efforts difficult. Here, promoters of seven genes (TASY, T5αH, DBAT, DBBT, PAM, BAPT, and DBTNBT), encoding enzymes of the paclitaxel biosynthetic pathway were isolated and used to drive MJ-inducible expression of a GUS reporter construct in transiently transformed Taxus cells, showing that elicitation of paclitaxel production by MJ is regulated at least in part at the level of transcription. The paclitaxel biosynthetic pathway promoters contained a large number of E-box sites (CANNTG), similar to the binding sites for the key MJ-inducible transcription factor AtMYC2 from Arabidopsis thaliana. Three MJ-inducible MYC transcription factors similar to AtMYC2 (TcJAMYC1, TcJAMYC2, and TcJAMYC4) were identified in Taxus. Transcriptional regulation of paclitaxel biosynthetic pathway promoters by transient over expression of TcJAMYC transcription factors indicated a negative rather than positive regulatory role of TcJAMYCs on paclitaxel biosynthetic gene expression.

Comparison of elicitor-based effects on metabolic responses of Taxus × media hairy roots in perfluorodecalin-supported two-phase culture system

“…The results of current study are also supported by data obtained from transcript profiling experiments performed in cell suspension cultures of various Taxus spp. which points to and confirms the complex nature of yew metabolism regulation (Lenka et al 2012, 2015; Li et al 2012; Sun et al 2013). …”

“…In our study, the highest TXS gene expression was noted 2 days after elicitation in the KT roots, while in ATMA roots—12-h post-elicitation. This could indicate that the gene expression in various Taxus species is regulated also on the level of activation of different transcription factors which has been demonstrated recently by Lenka et al (2015) and Sun et al (2013) and the possible role of miRNAs was postulated (Sun et al 2013). The discrepancies detected between gene expression patterns in cell suspension and hairy root cultures could be also attributed to the different growth and differentiation regulatory programmes in undifferentiated cell suspension cultures and differentiated, organizing organs (Flores et al 1999).…”

“…Among them the TcERF12 acted as the repressor, while TcRF15 as an activator of TXS gene expression. Furthermore, Lenka et al (2015) reported that TcJAMYC1, TcJAMYC2 TcJAMYC4 transcription factors of T. cuspidata negatively regulates the promoters of BAPT and DBTNBT genes, whereas not affecting the activity of TXS gene. Nims et al (2006) first indicted that although the expression level of BAPT and DBTNBT genes did not exist 7-day post-MJ elicitation, the relevant enzyme activity may persist long after the quenching of genes expression.…”

Transcriptional regulation of artemisinin biosynthesis in Artemisia annua L.

“…Since AaWRKY1, AaERF1, AaERF2, AaORA, AabZIP1, and AabHLH1 transcript levels are increased by abiotic stress, such as ABA and JA, it is interesting to expand the network on how abiotic stress stimulates transcriptional levels of biosynthetic genes. The phytohormone jasmonates play an important role in regulating plant secondary metabolism, especially in medicinal plants [11,75], such as vinblastine biosynthesis in C. roseus [76], nicotine biosynthesis in N. tabacum [67], terpenoids biosynthesis in A. annua [77], Taxus chinensis [78], and Panax ginseng [75,79]. Nowadays, more and more researches in A. annua show that JA is one of the most effective phytohormones in promoting artemisinin accumulation [77,[80][81][82].…”

Transcriptional reprogramming strategies and miRNA-mediated regulation networks of Taxus media induced into callus cells from tissues

“…The roles of these TFs were analyzed here on the basis of studies on several known Taxus TFs [33][34][35][36]. TcERF15, TcMYC2a, TcJAMYC1/2/4, and TcWRKY1/ 8/20/26/47/52 were highly correlated with taxol biosynthesis genes with Pearson coefficients greater than 0.9 (Fig.…”