MYB4 is the best candidate transcription factor involved in pinosylvin stilbene biosynthesis in Pinus strobus L. cells by fungal elicitor treatment

Abstract Key message Dihydropinosylvin monomethyl ether (DPME) and pinosylvin monomethyl ether (PME) are pinosylvin derivatives that show high nematicidal activity against pine wood nematodes (PWNs). Here, we found that fungal elicitor treatment boosted the production of DPME and PME in cultured Pinus strobus L. cells and investigated the transcription factors (TFs) regulating the genes in the pinosylvin stilbenoid biosynthesis pathway. Context The discovery of TFs involved in the synthesis of DPME and PME provides an important clue to understanding the pinosylvin stilbenoid synthesis in pine plants. Aims We investigated the best fungal elicitor for the production of DPME and PME and the transcriptional activities of genes involved in PME and DPME biosynthesis in P. strobus L. cells after fungal elicitor treatment. Methods The content of DPME and PME in P. strobus cells was examined after treatment with fungal elicitors prepared from seven different species of fungi. Moreover, the role of fungal elicitors in the transcriptional activity of genes involved in DPME and PME biosynthesis was investigated by transcriptome analysis using RNA sequencing. Results Penicillium chrysogenum Thorn was the most efficient fungal elicitor for the production of DPME and PME in P. strobus cells among the other fungal species. The accumulation of DPME and PME in P. strobus cells after P. chrysogenum elicitor treatment increased 12. 7-fold and 23. 7-fold, respectively, compared to the control. Transcriptome analysis revealed that fungal elicitor treatment resulted in enhanced transcription of the PAL, 4CL, STS, PMT, and ACC genes, which are involved in PME and DPME biosynthesis. Some transcription factors belonging to the bHLH, MYB, WRKY, and ERF families showed a high transcription rate after fungal elicitor treatment. Conclusions We found that the fungal elicitor is a strong inducer of the accumulation of pinosylvin derivatives in the cells of P. strobus. We selected one unigene (c133966g3ᵢ1 in the MYB family) as the best candidate TF that regulates the DPME and PME biosynthesis in P. strobus by transcriptome analysis.