title: Functional analysis of a cinnamyl alcohol dehydrogenase involved in lignin biosynthesis in wheat.
abstract: Cinnamyl alcohol dehydrogenase (CAD) catalyses the final step in the biosynthesis of monolignols. In the present study, a cDNA encoding a CAD was isolated from wheat, designated as TaCAD1. A genome-wide data mining in the wheat EST database revealed another 10 CAD-like homologues, namely TaCAD2 to TaCAD11. A phylogenetic analysis showed that TaCAD1 belonged to the bona fide CAD group involved in lignin synthesis. Two other putative CADs from the wheat genome (TaCAD2 and TaCAD4) also belonged to this group and were very close to TaCAD1, but lacked C-terminal domain, suggesting that they are pseudogenes. DNA gel blot analysis for the wheat genome showed two to three copies of CAD related to TaCAD1, but RNA gel blot analysis revealed only single band for TaCAD1, which was highly expressed in stem, with quite low expression in leaf and undetectable expression in root. The predicted three-dimension structure of TaCAD1 resembled that of AtCAD5, but two amino acid substitutions were identified in the substrate binding region. Recombinant TaCAD1 protein used coniferyl aldehyde as the most favoured substrate, also showed high efficiencies toward sinapyl and p-coumaryl aldehydes. TaCAD1 was an enzyme being pH-dependent and temperature-sensitive, and showing a typical random catalysing mechanism. At the milky stage of wheat, TaCAD1 mRNA abundance, protein level and enzyme activity in stem tissues were higher in a lodging-resistant cultivar (H4546) than in lodging-sensitive cultivar (C6001). These properties were correlated to the lignin contents and lodging indices of the two cultivars. These data suggest that TaCAD1 is the predominant CAD in wheat stem for lignin biosynthesis and is critical for lodging resistance.
authors.affiliation: Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, 20 Nanxin Cun, Xiangshan, Beijing, China. mqh@ibcas.ac.cn
authors.forename: Qing-Hu
authors.initials: QH
authors.lastname: Ma
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018744:DNA, Plant / Q000302:isolation & purification; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008031:Lignin / Q000096:biosynthesis*; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018547:Plant Stems / Q000201:enzymology; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D013696:Temperature; D014908:Triticum / Q000201:enzymology* / Q000235:genetics
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D011994:Recombinant Proteins; D008031:Lignin; D000429:Alcohol Oxidoreductases; C018656:cinnamyl alcohol dehydrogenase
references.citation: Plant Physiol. 1990 Jan;92(1):1-11
references.pmid: 16667228
references.citation: Plant Cell. 2001 Jul;13(7):1567-86
references.pmid: 11449052
references.citation: Plant J. 1998 Jun;14(5):545-53
references.pmid: 9675900
references.citation: J Mol Graph. 1996 Feb;14(1):51-5, 29-32
references.pmid: 8744573
references.citation: Planta. 2006 Dec;225(1):23-39
references.pmid: 16832689
references.citation: Genetics. 2009 Feb;181(2):783-95
references.pmid: 19087955
references.citation: Proc Natl Acad Sci U S A. 2004 Feb 10;101(6):1455-60
references.pmid: 14745009
references.citation: Plant Cell. 2005 Jul;17(7):2059-76
references.pmid: 15937231
references.citation: Plant Physiol. 2006 Mar;140(3):972-83
references.pmid: 16443696
references.citation: Org Biomol Chem. 2006 May 7;4(9):1687-97
references.pmid: 16633561
references.citation: J Exp Bot. 2007;58(8):2011-21
references.pmid: 17452751
references.citation: Plant Physiol. 1992 Apr;98(4):1364-71
references.pmid: 16668801
references.citation: Plant Mol Biol. 1999 Sep;41(2):279-91
references.pmid: 10579494
references.citation: Plant Physiol. 1994 Jan;104(1):75-84
references.pmid: 12232063
references.citation: Plant Physiol. 1996 Dec;112(4):1479-1490
references.pmid: 12226459
references.citation: Plant Mol Biol. 1993 Oct;23(1):145-56
references.pmid: 8219046
references.citation: Planta. 1992 Aug;188(1):48-53
references.pmid: 24178198
references.citation: Plant Physiol. 1992 Jan;98(1):12-6
references.pmid: 16668601
references.citation: Anal Biochem. 1976 May 7;72:248-54
references.pmid: 942051
references.citation: J Mol Evol. 1984-1985;21(3):259-69
references.pmid: 6100313
references.citation: Biochimie. 2008 Mar;90(3):515-24
references.pmid: 17976886
references.citation: Bioresour Technol. 2010 Apr;101(7):2311-6
references.pmid: 20004567
references.citation: Plant Physiol. 2009 Jun;150(2):584-95
references.pmid: 19363091
references.citation: Planta. 2005 Mar;220(5):678-88
references.pmid: 15452707
references.citation: Plant Mol Biol. 2009 Apr;69(6):685-97
references.pmid: 19116760
references.citation: Nucleic Acids Res. 1997 Sep 1;25(17):3389-402
references.pmid: 9254694
references.citation: J Exp Bot. 2009;60(9):2763-71
references.pmid: 19451187
references.citation: J Exp Bot. 2002 Aug;53(375):1723-34
references.pmid: 12147722
references.citation: Biol Chem. 2005 Jun;386(6):553-60
references.pmid: 16006242
references.citation: Phytochemistry. 2007 Jul;68(14):1957-74
references.pmid: 17467016
references.citation: Nucleic Acids Res. 1994 Nov 11;22(22):4673-80
references.pmid: 7984417
references.citation: Plant Physiol. 2003 Jun;132(2):848-60
references.pmid: 12805615