title: Aberrant cell expansion in the elongation mutants of barley.
abstract: The elongation (elo) mutants of barley (Hordeum vulgare cv 'Himalaya') are a class of dwarf plants with defects affecting cell expansion. The phenotypes of mutants in three of the elo loci (elo1, elo2 and elo3) are recessive to the wild-type allele, and the mutations at elo-4 and elo-5 are semi-dominant. Allelism tests showed that elo1, elo2 and elo3 were at separate loci, and mapping data indicated that elo-5 was possibly allelic to either elo1 or elo2. A phenotype common to all elo mutants was the presence of short, radially swollen cells on the leaf epidermis, indicating a defect in longitudinal cell expansion. In three of the mutants, elo1, elo3 and elo5, this was accompanied by a twisting growth habit. Two of the mutations, elo2 and elo-5, affected cell division, with aberrant periclinal cell division resulting in the formation of increased cell layers in the leaf epidermis of elo2 and elo-5 homozygotes and in the aleurone layer of elo2 grains. Misplaced anticlinal divisions also occurred in the elo-5 leaf epidermis. Leaf cell walls of all elo lines contained less cellulose than the wild- type, and the cortical microtubules in elongating root epidermal cells in some elo lines were more randomly oriented than in the wild-type, consistent with the presence of radially swollen cells. We discuss possible functions for the Elo genes in primary cell wall synthesis.
authors.affiliation: Plant Cell Biology Research Centre and Australian Centre for Plant Functional Genomics, School of Botany, University of Melbourne, Parkville, VIC 3010, Australia.
authors.forename: Dyani
authors.initials: D
authors.lastname: Lewis
authors.forename: Antony
authors.initials: A
authors.lastname: Bacic
authors.forename: Peter M
authors.initials: PM
authors.lastname: Chandler
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Newbigin
mesh_terms: D000483:Alleles; D002455:Cell Division; D049108:Cell Enlargement; D002473:Cell Wall / Q000737:chemistry*; D002482:Cellulose / Q000032:analysis; D001467:Hordeum / Q000166:cytology / Q000235:genetics*; D008870:Microtubules / Q000648:ultrastructure; D009154:Mutation; D010641:Phenotype; D019441:Plant Epidermis / Q000166:cytology / Q000235:genetics; D018515:Plant Leaves / Q000166:cytology* / Q000235:genetics; D018517:Plant Roots / Q000166:cytology / Q000235:genetics
chemical_list: D002482:Cellulose