AUTHOR=Kim Yi Rae , Han Jung Yeon , Choi Yong Eui 

TITLE=A Pinus strobus transcription factor PsbHLH1 activates the production of pinosylvin stilbenoids in transgenic Pinus koraiensis calli and tobacco leaves

JOURNAL=Frontiers in Plant Science

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1342626

DOI=10.3389/fpls.2024.1342626

ISSN=1664-462X

ABSTRACT=<p>Transcription factors (TFs) play an important role in regulating the biosynthesis of secondary metabolites. In <italic>Pinus strobus</italic>, the level of methylated derivatives of pinosylvin is significantly increased upon pine wood nematode (PWN) infection, and these compounds are highly toxic to PWNs. In a previous study, we found that the expression of a basic helix-loop-helix TF gene, <italic>PsbHLH1</italic>, strongly increased in <italic>P. strobus</italic> plants after infection with PWNs. In this study, we elucidated the regulatory role of the <italic>PsbHLH1</italic> gene in the production of methylated derivatives of pinosylvin such as pinosylvin monomethyl ether (PME) and dihydropinoylvin monomethyl ether (DPME). When <italic>PsbHLH1</italic> was overexpressed in <italic>Pinus koraiensis</italic> calli, the production of PME and DPME was significantly increased. Overexpression of the stilbene synthase (<italic>PsSTS</italic>) and pinosylvin methyl transferase (<italic>PsPMT</italic>) genes, known as key enzymes for the biosynthesis of methylated pinosylvins, did not change PME or DPME production. Moreover, PME and DPME were not produced in tobacco leaves when the <italic>PsSTS</italic> and <italic>PsPMT</italic> genes were transiently coexpressed. However, the transient expression of three genes, <italic>PsSTS</italic>, <italic>PsPMT</italic>, and <italic>PsbHLH1</italic>, resulted in the production of PME and DPME in tobacco leaves. These results prove that <italic>PsbHLH1</italic> is an important TF for the pinosylvin stilbene biosynthesis in pine plants and plays a regulatory role in the engineered production of PME and DPME in tobacco plants.</p>