Resistance against herbicide isoxaben and cellulose deficiency caused by distinct mutations in same cellulose synthase isoform CESA6.
Isoxaben is a pre-emergence herbicide that inhibits cellulose biosynthesis in higher plants. Two loci identified by isoxaben-resistant mutants (ixr1-1, ixr1-2, and ixr2-1) in Arabidopsis have been reported previously. IXR1 was recently shown to encode the cellulose synthase catalytic subunit CESA3 (W.-R. Scheible, R. Eshed, T. Richmond, D. Delmer, and C. Somerville [2001] Proc Natl Acad Sci USA 98: 10079-10084). Here, we report on the cloning of IXR2, and show that it encodes another cellulose synthase isoform, CESA6. ixr2-1 carries a mutation substituting an amino acid close to the C terminus of CESA6 that is highly conserved among CESA family members. Transformation of wild-type plants with the mutated gene and not with the wild-type gene conferred increased resistance against the herbicide. The simplest interpretation for the existence of these two isoxaben-resistant loci is that CESA3 and CESA6 have redundant functions. However, loss of function procuste1 alleles of CESA6 were previously shown to have a strong growth defect and reduced cellulose content in roots and dark-grown hypocotyls. This indicates that in these mutants, the presence of CESA3 does not compensate for the absence of CESA6 in roots and dark-grown hypocotyls, which argues against redundant functions for CESA3 and CESA6. Together, these observations are compatible with a model in which CESA6 and CESA3 are active as a protein complex.
Desprez
Thierry
T
Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique, 78026 Versailles cedex, France.
Vernhettes
Samantha
S
Fagard
Mathilde
M
Refrégier
Guislaine
G
Desnos
Thierry
T
Aletti
Estelle
E
Py
Nicolas
N
Pelletier
Sandra
S
Höfte
Herman
H
D051696:Activating Transcription Factors; D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins; D001549:Benzamides / Q000494:pharmacology*; D002482:Cellulose / Q000378:metabolism*; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance / Q000235:genetics; D015870:Gene Expression; D005838:Genotype; D005936:Glucans / Q000378:metabolism; D005964:Glucosyltransferases / Q000235:genetics* / Q000378:metabolism; D006540:Herbicides / Q000494:pharmacology*; D018546:Hypocotyl / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008031:Lignin / Q000378:metabolism; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010641:Phenotype; D010802:Phylogeny; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D029702:Schizosaccharomyces pombe Proteins; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014170:Transformation, Genetic
D051696:Activating Transcription Factors; D029681:Arabidopsis Proteins; D001549:Benzamides; D004268:DNA-Binding Proteins; D005936:Glucans; D006540:Herbicides; D007527:Isoenzymes; C097701:Pcr1 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; C057467:isoxaben; D002482:Cellulose; D008031:Lignin; C048306:callose; C420969:CESA8 protein, Arabidopsis; D005964:Glucosyltransferases; C457769:PRC1 protein, Arabidopsis; C028634:cellulose synthase (UDP-forming)