Title: Gene regulatory networks for lignin biosynthesis in switchgrass (Panicum virgatum )

Abstract

Summary Cell wall recalcitrance is the major challenge to improving saccharification efficiency in converting lignocellulose into biofuels. However, information regarding the transcriptional regulation of secondary cell wall biogenesis remains poor in switchgrass ( Panicum virgatum ), which has been selected as a biofuel crop in the United States. In this study, we present a combination of computational and experimental approaches to develop gene regulatory networks for lignin formation in switchgrass. To screen transcription factors ( TF s) involved in lignin biosynthesis, we developed a modified method to perform co‐expression network analysis using 14 lignin biosynthesis genes as bait (target) genes. The switchgrass lignin co‐expression network was further extended by adding 14 TF s identified in this study, and seven TF s identified in previous studies, as bait genes. Six TF s (Pv MYB 58/63, Pv MYB 42/85, Pv MYB 4, Pv WRKY 12, Pv SND 2 and Pv SWN 2) were targeted to generate overexpressing and/or down‐regulated transgenic switchgrass lines. The alteration of lignin content, cell wall composition and/or plant growth in the transgenic plants supported the role of the TF s in controlling secondary wall formation. RNA ‐seq analysis of four of the transgenic switchgrass lines revealed downstream targetmore » genes of the secondary wall‐related TF s and crosstalk with other biological pathways. In vitro transactivation assays further confirmed the regulation of specific lignin pathway genes by four of the TF s. Our meta‐analysis provides a hierarchical network of TF s and their potential target genes for future manipulation of secondary cell wall formation for lignin modification in switchgrass.« less

Authors:

Rao, Xiaolan ^[1]; Chen, Xin ^[2]; Shen, Hui ^[1]; Ma, Qin ^[3]; Li, Guifen ^[4]; Tang, Yuhong ^[5]; Pena, Maria ^[6]; York, William ^[6]; Frazier, Taylor P. ^[7]; Lenaghan, Scott ^[8]; Xiao, Xirong ^[9]; Chen, Fang ^[10]; Dixon, Richard A.  ^[10]

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+ Show Author Affiliations

1. BioDiscovery Institute and Department of Biological Sciences University of North Texas Denton TX USA, BioEnergy Science Center (BESC) Oak Ridge National Laboratory Oak Ridge TN USA
2. Center for Applied Mathematics Tianjin University Tianjin China
3. Department of Agronomy, Horticulture, and Plant Science and Department of Mathematics and Statistics South Dakota State University Brookings SD USA
4. Noble Research Institute Ardmore OK USA
5. BioEnergy Science Center (BESC) Oak Ridge National Laboratory Oak Ridge TN USA, Noble Research Institute Ardmore OK USA
6. BioEnergy Science Center (BESC) Oak Ridge National Laboratory Oak Ridge TN USA, Complex Carbohydrate Research Center and Department of Biochemistry and Molecular Biology University of Georgia Athens GA USA
7. Department of Plant Sciences University of Tennessee Knoxville TN USA
8. Department of Food Science University of Tennessee Knoxville TN USA
9. BioDiscovery Institute and Department of Biological Sciences University of North Texas Denton TX USA
10. BioDiscovery Institute and Department of Biological Sciences University of North Texas Denton TX USA, BioEnergy Science Center (BESC) Oak Ridge National Laboratory Oak Ridge TN USA, Center for Bioenergy Innovation (CBI) Oak Ridge National Laboratory Oak Ridge TN USA

Publication Date:

2018-09-17

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER). Biological Systems Science Division

OSTI Identifier:

1471144

Alternate Identifier(s):

OSTI ID: 1472152; OSTI ID: 1625926

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Published Article

Journal Name:

Plant Biotechnology Journal

Additional Journal Information:

Journal Name: Plant Biotechnology Journal Journal Volume: 17 Journal Issue: 3; Journal ID: ISSN 1467-7644

Publisher:

Wiley-Blackwell

Country of Publication:

United Kingdom

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; 09 BIOMASS FUELS; Biotechnology & Applied Microbiology; Plant Sciences; Bi-clustering algorithm; bioenergy crop; co-expression analysis; transcription factors; transgenic switchgrass; secondary cell wall biosynthesis