Document Detail

Mutation of WRKY transcription factors initiates pith secondary wall formation and increases stem biomass in dicotyledonous plants.
MedLine Citation:
PMID:  21135241     Owner:  NLM     Status:  MEDLINE    
Stems of dicotyledonous plants consist of an outer epidermis, a cortex, a ring of secondarily thickened vascular bundles and interfascicular cells, and inner pith parenchyma cells with thin primary walls. It is unclear how the different cell layers attain and retain their identities. Here, we show that WRKY transcription factors are in part responsible for the parenchymatous nature of the pith cells in dicotyledonous plants. We isolated mutants of Medicago truncatula and Arabidopsis thaliana with secondary cell wall thickening in pith cells associated with ectopic deposition of lignin, xylan, and cellulose, leading to an ∼50% increase in biomass density in stem tissue of the Arabidopsis mutants. The mutations are caused by disruption of stem-expressed WRKY transcription factor (TF) genes, which consequently up-regulate downstream genes encoding the NAM, ATAF1/2, and CUC2 (NAC) and CCCH type (C3H) zinc finger TFs that activate secondary wall synthesis. Direct binding of WRKY to the NAC gene promoter and repression of three downstream TFs were confirmed by in vitro assays and in planta transgenic experiments. Secondary wall-bearing cells form lignocellulosic biomass that is the source for second generation biofuel production. The discovery of negative regulators of secondary wall formation in pith opens up the possibility of significantly increasing the mass of fermentable cell wall components in bioenergy crops.
Huanzhong Wang; Utku Avci; Jin Nakashima; Michael G Hahn; Fang Chen; Richard A Dixon
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2010-12-06
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  107     ISSN:  1091-6490     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-12-23     Completed Date:  2011-02-02     Revised Date:  2013-07-03    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  22338-43     Citation Subset:  IM    
Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA.
Data Bank Information
Bank Name/Acc. No.:
GENBANK/HM622066;  HM622067
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MeSH Terms
Arabidopsis / genetics,  growth & development*
Arabidopsis Proteins / genetics,  metabolism*
Base Sequence
Cell Wall / genetics,  metabolism*
Lignin / biosynthesis,  genetics
Medicago truncatula / genetics,  growth & development*
Molecular Sequence Data
Plant Stems / genetics,  growth & development*
Transcription Factors / genetics,  metabolism*
Reg. No./Substance:
0/Arabidopsis Proteins; 0/Transcription Factors; 11132-73-3/lignocellulose; 9005-53-2/Lignin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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