Functional Analysis of Cellulose Synthase CesA4 and CesA6 Genes in Switchgrass (Panicum virgatum) by Overexpression and RNAi-Mediated Gene Silencing

Frontiers in Plant Science

Holly L. Baxter¹  Wegi A. Wuddineh¹  Mitra Mazarei¹  C. Neal Stewart¹  Yunqiao Pu²  Mi Li²  Keonhee Kim³  Nicole Labbé³  Debra Mohnen⁴  Ajaya K. Biswal⁴  Xianzhi Meng⁵  Arthur J. Ragauskas⁵  Geoffrey B. Turner⁷  Robert W. Sykes⁷  Mark F. Davis⁷  Zeng-Yu Wang⁸  Michael K. Udvardi⁸  Ji-Yi Zhang⁸ 

[1] BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, United States;Biosciences Division, Joint Institute for Biological Science, Oak Ridge National Laboratory, Oak Ridge, TN, United States;Center for Renewable Carbon, University of Tennessee, Knoxville, Knoxville, TN, United States;Complex Carbohydrate Research Center, University of Georgia, Athens, GA, United States;Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Knoxville, TN, United States;Department of Plant Sciences, University of Tennessee, Knoxville, Knoxville, TN, United States;National Renewable Energy Laboratory, Golden, CO, United States;Noble Research Institute, Ardmore, OK, United States;

关键词: cellulose synthase;    switchgrass;    overexpression;    RNAi-gene silencing;    PvCesA4;    PvCesA6;   

DOI  :  10.3389/fpls.2018.01114

来源: DOAJ

【 摘 要 】

Switchgrass (Panicum virgatum L.) is a leading lignocellulosic bioenergy feedstock. Cellulose is a major component of the plant cell walls and the primary substrate for saccharification. Accessibility of cellulose to enzymatic breakdown into fermentable sugars is limited by the presence of lignin in the plant cell wall. In this study, putatively novel switchgrass secondary cell wall cellulose synthase PvCesA4 and primary cell wall PvCesA6 genes were identified and their functional role in cellulose synthesis and cell wall composition was examined by overexpression and knockdown of the individual genes in switchgrass. The endogenous expression of PvCesA4 and PvCesA6 genes varied among including roots, leaves, stem, and reproductive tissues. Increasing or decreasing PvCesA4 and PvCesA6 expression to extreme levels in the transgenic lines resulted in decreased biomass production. PvCesA6-overexpressing lines had reduced lignin content and syringyl/guaiacyl lignin monomer ratio accompanied by increased sugar release efficiency, suggesting an impact of PvCesA6 expression levels on lignin biosynthesis. Cellulose content and cellulose crystallinity were decreased, while xylan content was increased in PvCesA4 and PvCesA6 overexpression or knockdown lines. The increase in xylan content suggests that the amount of non-cellulosic cell wall polysaccharide was modified in these plants. Taken together, the results show that the manipulation of the cellulose synthase genes alters the cell wall composition and availability of cellulose as a bioprocessing substrate.

【 授权许可】

Unknown