TcMYC2a, a Basic Helix–Loop–Helix Transcription Factor, Transduces JA-Signals and Regulates Taxol Biosynthesis in Taxus chinensis

Abstract

The multitherapeutic taxol, which can be obtained from Taxus spp., is the most widely used anticancer drug. Taxol biosynthesis is significantly regulated by jasmonate acid (JA), one of the most important endogenous hormones in land plants. Nevertheless, the JA-inducing mechanism remains poorly understood. MYC2 is one of the key regulators of JA signal transfer and the biosynthesis of various secondary metabolites. Here, TcMYC2a was identified to contain a basic helix–loop–helix (bHLH)-leucine zipper domain, a bHLH-MYC_N domain, and a BIF/ACT-like domain. TcMYC2a was also found to bind with TcJAZ3 in yeast, which was a homolog of Arabidopsis JASMONATE ZIM-domain JAZ proteins, indicating that TcMYC2a had a similar function to AtMYC2 of JA signal transduction. TcMYC2a was able to affect the expression of GUS reporter gene by binding with the T/G-box, G-box, and E-box, which were the key cis-elements of TASY and TcERF12/15 promoter. TcMYC2a overexpression also led to significantly increased expression of TASY, tat, dbtnbt, t13h, and t5h genes. Additionally, TcERF15, which played the positive role to regulate tasy gene, was up-regulated by TcMYC2a. All these results revealed that TcMYC2a can regulate taxol biosynthesis either directly or via ERF regulators depending on JA signaling transduction.

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.…”

“…The tissues and callus cells were firstly grinding with liquid Nitrogen, then taxanes were extracted using the method described previously [54]. And the quantitative analysis was conducted using HPLC as the previous reports [36].…”

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 ( Figure 7b, Additional file 17).…”

“…The tissues and callus cells were firstly grinding with liquid Nitrogen, then taxanes were extracted using the method described previously [54]. And the quantitative analysis was conducted using HPLC as the previous reports [36]. Transcriptional alterations in callus cells Total six samples from two groups were highthroughput sequenced.…”

Genome-Wide Characterization and Analysis of bHLH Transcription Factors Related to Crocin Biosynthesis in Gardenia jasminoides Ellis (Rubiaceae)

“…The genome-wide identification and analysis of bHLH TFs have been reported in many plants, such as Arabidopsis thaliana [15], Oryza sativa [16], Solanum lycopersicum [17], Brassica rapa [18], Salvia miltiorrhiza [19], Panax ginseng [20], Vitis vinifera [21], Malus domestica [22], and Arachis hypogaea [23]. bHLH TFs can bind to E-box (5 ′ -CANNTG-3 ′ ), MYCATRD22 (5′-CACATG-3′), T/G-box (5′-AACGTG-3′), or G-box (5′-CACGTG-3′) elements to regulate gene expression [24][25][26]. Based on transcriptome analysis of C. sativus, many transcription factors including two bHLH members were selected to be involved in the crocin biosynthesis and accumulation [27].…”