Functional characterization of cinnamyl alcohol dehydrogenase and caffeic acid O-methyltransferase in Brachypodium distachyon
메타 데이터
바이오화학분류
바이오플라스틱
플라스틱
바이오정밀화학
용매
화학제품
연료
화장품용 기능성소재
계면활성제⁄증점제
의료용 화학소재
식품첨가제
논문
Functional characterization of cinnamyl alcohol dehydrogenase and caffeic acid O-methyltransferase in Brachypodium distachyon
학술지
BMC biotechnology
저자명
Trabucco, Gina M; Matos, Dominick A; Lee, Scott J; Saathoff, Aaron J; Priest, Henry D; Mockler, Todd C; Sarath, Gautam; Hazen, Samuel P
초록
<P><B>Background</B></P><P>Lignin is a significant barrier in the conversion of plant biomass to bioethanol. Cinnamyl alcohol dehydrogenase (CAD) and caffeic acid <I>O</I>-methyltransferase (COMT) catalyze key steps in the pathway of lignin monomer biosynthesis. Brown midrib mutants in <I>Zea mays</I> and <I>Sorghum bicolor</I> 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 <I>Brachypodium distachyon</I> with the aim of improving crops for efficient biofuel production.</P><P><B>Results</B></P><P>We developed transgenic plants overexpressing artificial microRNA designed to silence <I>BdCAD1</I> or <I>BdCOMT4</I>. Both transgenes caused altered flowering time and increased stem count and weight. Downregulation of <I>BdCAD1</I> caused a leaf brown midrib phenotype, the first time this phenotype has been observed in a C<SUB>3</SUB> plant. While acetyl bromide soluble lignin measurements were equivalent in <I>BdCAD1</I> downregulated and control plants, histochemical staining and thioacidolysis indicated a decrease in lignin syringyl units and reduced syringyl/guaiacyl ratio in the transgenic plants. <I>BdCOMT4</I> 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 <I>amiR</I>-<I>cad1</I>-<I>8</I> plants.</P><P><B>Conclusion</B></P><P>These results have elucidated two key genes in the lignin biosynthetic pathway in <I>B</I>. <I>distachyon</I> that, when perturbed, may result in greater stem biomass yield and bioconversion efficiency.</P>