title: Cloning and characterization of irregular xylem4 (irx4): a severely lignin-deficient mutant of Arabidopsis.
abstract: A severe lignin mutant, irx4, has been identified in Arabidopsis thaliana as a result of its collapsed xylem phenotype. In contrast to previously described irx mutants, irx4 plants have 50% less lignin than wild-type plants, whilst the cellulose and hemicellulose content remained unchanged. These alterations in the composition of irx4 secondary cell walls had a dramatic effect on the morphology and architecture of the walls, which expand to fill most of the cell, and also on the physical properties of irx4 stems. Further analysis indicated that the irx4 mutation occurred in a cinnamoyl-CoA reductase (CCR) gene within a highly conserved intron splice site sequence of intron 2. As a result, CCR mRNA transcripts were incorrectly spliced. Transgenic plants expressing an IRX3 promoter-CCR cDNA construct were used to generate a series of plants with varying degrees of lignin content in order to assess the role of lignin content in determining the physical properties of Arabidopsis stems.
authors.affiliation: School of Biological Sciences, 3.614 Stopford Building, University of Manchester, Manchester M13 9PT, UK.
authors.forename: L
authors.initials: L
authors.lastname: Jones
authors.forename: A R
authors.initials: AR
authors.lastname: Ennos
authors.forename: S R
authors.initials: SR
authors.lastname: Turner
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000235:genetics*; D000483:Alleles; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D001696:Biomechanical Phenomena; D002473:Cell Wall / Q000737:chemistry / Q000648:ultrastructure; D002482:Cellulose / Q000096:biosynthesis; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D005816:Genetic Complementation Test; D008031:Lignin / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D009005:Monosaccharides / Q000032:analysis; D009154:Mutation; D010641:Phenotype; D010802:Phylogeny; D010940:Plant Proteins; D018547:Plant Stems / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011134:Polysaccharides / Q000096:biosynthesis; D022821:RNA Splice Sites / Q000235:genetics; D012333:RNA, Messenger; D018749:RNA, Plant
chemical_list: D009005:Monosaccharides; D010940:Plant Proteins; D011134:Polysaccharides; D022821:RNA Splice Sites; D012333:RNA, Messenger; D018749:RNA, Plant; C007916:hemicellulose; D002482:Cellulose; D008031:Lignin; D000445:Aldehyde Oxidoreductases; C019904:cinnamoyl CoA reductase