Functional characterization of cinnamyl alcohol dehydrogenase and caffeic acid O-methyltransferase in Brachypodium distachyon

BMC Biotechnology

Research Article

Samuel P Hazen¹  Gina M Trabucco²  Dominick A Matos²  Scott J Lee³  Henry D Priest⁴  Todd C Mockler⁴  Gautam Sarath⁵  Aaron J Saathoff⁵ 

[1] Biology Department, University of Massachusetts 221 Morrill Science Center III, 01003, Amherst, MA, USA;Biology Department, University of Massachusetts 221 Morrill Science Center III, 01003, Amherst, MA, USA;Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA, USA;Biology Department, University of Massachusetts 221 Morrill Science Center III, 01003, Amherst, MA, USA;Plant Biology Graduate Program, University of Massachusetts, Amherst, MA, USA;The Donald Danforth Plant Science Center, St. Louis, MO, USA;USDA-ARS, Grain, Forage, and Bioenergy Research Unit, University of Nebraska-Lincoln, Lincoln, NE, USA;

关键词: Lignin;    Lignin Biosynthesis;    Cinnamyl Alcohol Dehydrogenase;    Empty Vector Control;    COMT Gene;   

DOI  :  10.1186/1472-6750-13-61

 received in 2013-05-20, accepted in 2013-06-11,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundLignin is a significant barrier in the conversion of plant biomass to bioethanol. Cinnamyl alcohol dehydrogenase (CAD) and caffeic acid O-methyltransferase (COMT) catalyze key steps in the pathway of lignin monomer biosynthesis. Brown midrib mutants in Zea mays and Sorghum bicolor with impaired CAD or COMT activity have attracted considerable agronomic interest for their altered lignin composition and improved digestibility. Here, we identified and functionally characterized candidate genes encoding CAD and COMT enzymes in the grass model species Brachypodium distachyon with the aim of improving crops for efficient biofuel production.ResultsWe developed transgenic plants overexpressing artificial microRNA designed to silence BdCAD1 or BdCOMT4. Both transgenes caused altered flowering time and increased stem count and weight. Downregulation of BdCAD1 caused a leaf brown midrib phenotype, the first time this phenotype has been observed in a C3 plant. While acetyl bromide soluble lignin measurements were equivalent in BdCAD1 downregulated and control plants, histochemical staining and thioacidolysis indicated a decrease in lignin syringyl units and reduced syringyl/guaiacyl ratio in the transgenic plants. BdCOMT4 downregulated plants exhibited a reduction in total lignin content and decreased Maule staining of syringyl units in stem. Ethanol yield by microbial fermentation was enhanced in amiR-cad1-8 plants.ConclusionThese results have elucidated two key genes in the lignin biosynthetic pathway in B. distachyon that, when perturbed, may result in greater stem biomass yield and bioconversion efficiency.

【 授权许可】

Unknown   
© Trabucco et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.