Birch (Betula platyphylla) contains triterpenoids with anti-HIV and
anti-tumor activities. However, the natural amount of these triterpenoids is
low, and their chemical synthesis, costly. Transcription factors, such as
the bHLH (basic helix-loop-helix), can regulate metabolite pathways, and
improve yield. Thus, transcription factors can potentially improve
production of birch triterpenoids.

The team of Jing Yin from Northeast Forestry University in China studied two
genes, BpMYC4 and BpbHLH9, which encode bHLH transcription factors in birch.
The expressions of BpMYC4 and BpbHLH9 were found to be increased with
treatments of abscisic acid, methyl jasmonate, and gibberellin while it is
decreased by ethephon treatment.

The BpbHLH9 gene was then attached to an improved promoter and introduced to
birch. Compared to wild types, the resulting transgenic birch exhibited
upregulated expression of genes related to triterpenoid synthesis.

These findings will be the groundwork for the development of birch
accessions with improved triterpenoid production.

[bmcplantbiol.biomedcentral.com]