title: PtoMYB156 is involved in negative regulation of phenylpropanoid metabolism and secondary cell wall biosynthesis during wood formation in poplar.
abstract: Some R2R3 MYB transcription factors have been shown to be major regulators of phenylpropanoid biosynthetic pathway and impact secondary wall formation in plants. In this study, we describe the functional characterization of PtoMYB156, encoding a R2R3-MYB transcription factor, from Populus tomentosa. Expression pattern analysis showed that PtoMYB156 is widely expressed in all tissues examined, but predominantly in leaves and developing wood cells. PtoMYB156 localized to the nucleus and acted as a transcriptional repressor. Overexpression of PtoMYB156 in poplar repressed phenylpropanoid biosynthetic genes, leading to a reduction in the amounts of total phenolic and flavonoid compounds. Transgenic plants overexpressing PtoMYB156 also displayed a dramatic decrease in secondary wall thicknesses of xylem fibers and the content of cellulose, lignin and xylose compared with wild-type plants. Transcript accumulation of secondary wall biosynthetic genes was down-regulated by PtoMYB156 overexpression. Transcriptional activation assays revealed that PtoMYB156 was able to repress the promoter activities of poplar CESA17, C4H2 and GT43B. By contrast, knockout of PtoMYB156 by CRISPR/Cas9 in poplar resulted in ectopic deposition of lignin, xylan and cellulose during secondary cell wall formation. Taken together, these results show that PtoMYB156 may repress phenylpropanoid biosynthesis and negatively regulate secondary cell wall formation in poplar.
authors.affiliation: Key Laboratory of Eco-environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China.
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.affiliation: Key Laboratory of Eco-environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Eco-environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China.
authors.forename: Lingyu
authors.initials: L
authors.lastname: Ran
authors.affiliation: Key Laboratory of Eco-environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China.
authors.forename: Chaofeng
authors.initials: C
authors.lastname: Li
authors.affiliation: Key Laboratory of Eco-environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China.
authors.forename: Di
authors.initials: D
authors.lastname: Fan
authors.affiliation: Key Laboratory of Eco-environments of Three Gorges Reservoir Region, Ministry of Education, Institute of Resources Botany, School of Life Sciences, Southwest University, Chongqing 400715, China.
authors.forename: Keming
authors.initials: K
authors.lastname: Luo
mesh_terms: D002473:Cell Wall / Q000235:genetics / Q000378:metabolism*; D002482:Cellulose / Q000096:biosynthesis; D018506:Gene Expression Regulation, Plant; D008031:Lignin / Q000096:biosynthesis; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D032107:Populus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D015533:Transcriptional Activation; D014934:Wood / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D014990:Xylans / Q000096:biosynthesis
chemical_list: D010940:Plant Proteins; D014990:Xylans; D002482:Cellulose; D008031:Lignin