Longitudinal Changes of Transcriptional Levels of bHLH, MYB and WD40 and Their Relationships with Total Anthocyanin Contents in the Green-purple Aerial Stems of Panax notoginseng

PurposeTo explore the longitudinal changes of the transcriptional levels of the basic helix-loop-helix gene (bHLH), v-myb myeloblastosis viral oncogene homolog gene (MYB) and WD40 gene (WD40) of Panax notoginseng and their correlations with the total anthocyanin contents (TACs) in the green purple aerial stems of P. notoginseng.

MethodsThe stems of the green purple aerial stemmed plants with an average height of about 18 cm of the one-year-old P. notoginseng were evenly divided into 18 segments. The transcriptional levels of the bHLH, MYB and WD40 and the TACs were determined by using quantitative real-time PCR (qRT-PCR) and spectrophotometry, respectively.

ResultsFrom the tops to the bases of the green purple stems of P. notoginseng, the longitudinal changes of the transcriptional levels of the bHLH, MYB and WD40 of P. notoginseng roughly displayed a “muti-peaked”, “W-shape” and “W+inversed V-shape” curves, respectively, the highest transcriptional levels of the three transcription factor genes (TFs) appeared at the segment 7, 10 and 7, respectively, and the differences of the levels of the three TFs among the different segments reached the significant, extremely significant and extremely significant levels, respectively. Whereas, the longitudinal changes of the TACs exhibited a “single peaked” curve as a whole, the highest TAC emerged at the segment 8, and the differences of the TACs among the different segments reached the extremely significant level. The transcriptional levels of the three TFs were all positively correlated with the TACs, the corresponding correlation coefficients were as: MYB>bHLH>WD40.

ConclusionsFor the anthocyanin synthesis in the green purple stems of the one-year-old P. notoginseng, the differential contributions of the three TFs were as: MYB>bHLH>WD40.This study could provide a reference for the investigations of the transcriptional regulation of the anthocyanin synthesis in the aerial stems of P. notoginseng.