|Palmer, Nathan - Nate|
|BAIRD, LISA - University Of San Diego|
|TWIGG, PAUL - University Of Nebraska|
|CLEMENTE, THOMAS - University Of Nebraska|
Submitted to: Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2015
Publication Date: 1/30/2016
Publication URL: http://handle.nal.usda.gov/10113/61821
Citation: Scully, E.D., Gries, T.L., Sarath, G., Palmer, N.A., Sattler, S.E., Baird, L., Serapiglia, M., Dien, B.S., Boateng, A.A., Funnell-Harris, D.L., Twigg, P., Clemente, T.E. 2016. Overexpression of SbMyb60 impacts phenylpropanoid biosynthesis and alters secondary cell wall composition in sorghum bicolor. Plant Journal. 85:378-395.
Interpretive Summary: Lignin is the major structural component of plant cell walls whose presence and composition influences the usability of plant biomass for the production of biofuels and other natural products. In this study, a Myb transcription factor, SbMyb60 that activates synthesis.
Technical Abstract: The phenylpropanoid biosynthesis pathway that generates lignin subunits represents a significant target to alter the abundance and composition of lignin. The major regulators of phenylpropanoid metabolism are myb transcription factors, which have been shown to modulate secondary cell wall composition and regulate the synthesis of several other aromatic compounds, including anthocyanins and flavonoids. While negative regulators of phenylpropanoid biosynthesis have been identified in in several grass species, few positive regulators of this pathway have been identified in the C4 grasses, which are developed as dedicated bioenergy feedstocks. In this study, we investigated the role of SbMyb60 in lignin biosynthesis in sorghum (Sorghum bicolor), which is rapidly emerging as a drought-tolerant, high yielding biomass crop. Overexpression of this transcription factor in sorghum activated the monolignol biosynthesis pathway, and led to higher abundances of S-lignin, significant increases in the S/G ratio and increased lignin concentration in biomass. Overexpression of SbMyb60 also resulted in ectopic lignification in leaf midribs and elevated concentration of soluble phenolic compounds in biomass. Taken together, SbMyb60 is an activator of monolignol biosynthesis, whose overexpression is sufficient to induce the expression of nine monolignol biosynthetic genes in sorghum. SbMyb60 represents a tool to modify plant cell wall composition and the potential to improve biomass for renewable uses.