title: Overexpression of SbMyb60 impacts phenylpropanoid biosynthesis and alters secondary cell wall composition in Sorghum bicolor.
abstract: The phenylpropanoid biosynthetic pathway that generates lignin subunits represents a significant target for altering the abundance and composition of lignin. The global regulators of phenylpropanoid metabolism may include MYB transcription factors, whose expression levels have been correlated with changes in secondary cell wall composition and the levels of several other aromatic compounds, including anthocyanins and flavonoids. While transcription factors correlated with downregulation of the phenylpropanoid biosynthesis pathway have been identified in several grass species, few transcription factors linked to activation of this pathway have been identified in C4 grasses, some of which are being developed as dedicated bioenergy feedstocks. In this study we investigated the role of SbMyb60 in lignin biosynthesis in sorghum (Sorghum bicolor), which is a drought-tolerant, high-yielding biomass crop. Ectopic expression of this transcription factor in sorghum was associated with higher expression levels of genes involved in monolignol biosynthesis, and led to higher abundances of syringyl lignin, significant compositional changes to the lignin polymer and increased lignin concentration in biomass. Moreover, transgenic plants constitutively overexpressing SbMyb60 also displayed ectopic lignification in leaf midribs and elevated concentrations of soluble phenolic compounds in biomass. Results indicate that overexpression of SbMyb60 is associated with activation of monolignol biosynthesis in sorghum. SbMyb60 represents a target for modification of plant cell wall composition, with the potential to improve biomass for renewable uses.
authors.affiliation: Grain, Forage, and Bioenergy Research Unit, USDA-ARS, Lincoln, NE, 68583, USA.|Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA.
authors.forename: Erin D
authors.initials: ED
authors.lastname: Scully
authors.affiliation: Grain, Forage, and Bioenergy Research Unit, USDA-ARS, Lincoln, NE, 68583, USA.
authors.forename: Tammy
authors.initials: T
authors.lastname: Gries
authors.affiliation: Grain, Forage, and Bioenergy Research Unit, USDA-ARS, Lincoln, NE, 68583, USA.
authors.forename: Gautam
authors.initials: G
authors.lastname: Sarath
authors.affiliation: Grain, Forage, and Bioenergy Research Unit, USDA-ARS, Lincoln, NE, 68583, USA.
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Palmer
authors.affiliation: Department of Biology, Shiley Center for Science and Technology, University of San Diego, San Diego, CA, 92110, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Baird
authors.affiliation: Agricultural Research Service, United States Department of Agriculture (USDA-ARS), Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA, 19038, USA.
authors.forename: Michelle J
authors.initials: MJ
authors.lastname: Serapiglia
authors.affiliation: National Center for Agricultural Utilization Research, USDA-ARS, 1815 North University Street, Peoria, IL, 61604, USA.
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Dien
authors.affiliation: Agricultural Research Service, United States Department of Agriculture (USDA-ARS), Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA, 19038, USA.
authors.forename: Akwasi A
authors.initials: AA
authors.lastname: Boateng
authors.affiliation: Department of Agronomy and Horticulture, Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, 68588, USA.
authors.forename: Zhengxiang
authors.initials: Z
authors.lastname: Ge
authors.affiliation: Grain, Forage, and Bioenergy Research Unit, USDA-ARS, Lincoln, NE, 68583, USA.|Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA.
authors.forename: Deanna L
authors.initials: DL
authors.lastname: Funnell-Harris
authors.affiliation: Biology Department, University of Nebraska-Kearney, Kearney, NE, 68849, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Twigg
authors.affiliation: Department of Agronomy and Horticulture, Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, 68588, USA.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Clemente
authors.affiliation: Grain, Forage, and Bioenergy Research Unit, USDA-ARS, Lincoln, NE, 68583, USA.|Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA.
authors.forename: Scott E
authors.initials: SE
authors.lastname: Sattler
mesh_terms: D018533:Biomass; D002473:Cell Wall / Q000378:metabolism*; D015536:Down-Regulation; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D008031:Lignin / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D020005:Propanols / Q000378:metabolism*; D045868:Sorghum / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D020005:Propanols; D014157:Transcription Factors; C439395:1-phenylpropanol; D008031:Lignin
keywords: C4 grass; bioenergy; lignin; monocot; monolignol; transgenic