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R2R3‐ MYB transcription factor MYB 6 promotes anthocyanin and proanthocyanidin biosynthesis but inhibits secondary cell wall formation in Populus tomentosa
Author(s) -
Wang Lijun,
Lu Wanxiang,
Ran Lingyu,
Dou Liwen,
Yao Shu,
Hu Jian,
Fan Di,
Li Chaofeng,
Luo Keming
Publication year - 2019
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14364
Subject(s) - phenylpropanoid , myb , arabidopsis , transcription factor , flavonoid biosynthesis , secondary cell wall , microbiology and biotechnology , biology , biochemistry , arabidopsis thaliana , cell wall , secondary metabolism , chemistry , botany , biosynthesis , gene expression , gene , transcriptome , mutant
Summary The secondary cell wall is an important carbon sink in higher plants and its biosynthesis requires coordination of metabolic fluxes in the phenylpropanoid pathway. In Arabidopsis ( Arabidopsis thaliana ), MYB 75 and the KNOX transcription factor KNAT 7 form functional complexes to regulate secondary cell wall formation in the inflorescence stem. However, the molecular mechanism by which these transcription factors control different branches of the phenylpropanoid pathway remains poorly understood in woody species. We isolated an R2R3‐ MYB transcription factor MYB 6 from Populus tomentosa and determined that it was expressed predominately in young leaves. Overexpression of MYB 6 in transgenic poplar upregulated flavonoid biosynthetic gene expression, resulting in significantly increased accumulation of anthocyanin and proanthocyanidins. MYB 6 ‐overexpression plants showed reduced secondary cell wall deposition, accompanied by repressed expression of secondary cell wall biosynthetic genes. We further showed that MYB 6 interacted physically with KNAT 7 and formed functional complexes that acted to repress secondary cell wall development in poplar and Arabidopsis. The results provide an insight into the transcriptional mechanisms involved in the regulation of the metabolic fluxes between the flavonoid and lignin biosynthetic pathways in poplar.