Modified expression of ZmMYB167 in Brachypodium distachyon and Zea mays leads to increased cell wall lignin and phenolic content

• Published in: Scientific reports Vol. 9; no. 1; pp. 8800 - 12
• Main Authors: Bhatia, Rakesh, Dalton, Sue, Roberts, Luned A., Moron-Garcia, Odin M., Iacono, Rosario, Kosik, Ondrej, Gallagher, Joe A., Bosch, Maurice
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19.06.2019; Nature Publishing Group
• Subjects: 45/77; 631/449/2491/2046; 631/449/447/2311; 631/449/448/1365; 631/61/447/2311; 82/16; 96/106; Amino Acid Sequence; Biofuels; Biomass; Biosynthesis; Brachypodium - genetics; Brachypodium - growth & development; Cell Wall - metabolism; Cell walls; Coumaric acid; Ferulic acid; Gene Expression Regulation, Plant; Genetic engineering; Grasses; Humanities and Social Sciences; Lignin; Lignin - metabolism; multidisciplinary; p-Coumaric acid; Phenolic compounds; Phenols; Phenols - metabolism; Phenotype; Phenotypes; Plant biomass; Plant growth; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - metabolism; Plants, Genetically Modified; Propanols - metabolism; Science; Science (multidisciplinary); Solubility; Sugar; Sugars - metabolism; Transcription factors; Zea mays; Zea mays - genetics
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-45225-9

One of the challenges to enable targeted modification of lignocellulosic biomass from grasses for improved biofuel and biochemical production lies within our limited understanding of the transcriptional control of secondary cell wall biosynthesis. Here, we investigated the role of the maize MYB transcription factor ZmMYB167 in secondary cell wall biosynthesis and how modified ZmMYB167 expression in two distinct grass model species affects plant biomass and growth phenotypes. Heterologous expression of ZmMYB167 in the C 3 model system Brachypodium led to mild dwarf phenotypes, increased lignin (~7% to 13%) and S-lignin monomer (~11% to 16%) content, elevated concentrations of cell wall-bound p -coumaric acid (~15% to 24%) and reduced biomass sugar release (~20%) compared to controls. Overexpression of ZmMYB167 in the C 4 model system Zea mays increased lignin (~4% to 13%), p -coumaric acid (~8% to 52%) and ferulic acid (~13% to 38%) content but did not affect plant growth and development nor biomass recalcitrance. Taken together, modifying ZmMYB167 expression represents a target to alter lignin and phenolic content in grasses. The ZmMYB167 expression-induced discrepancies in plant phenotypic and biomass properties between the two grass model systems highlight the challenges and opportunities for MYB transcription factor-based genetic engineering approaches of grass biomass.