title: Brassinosteroids control the proliferation of leaf cells of Arabidopsis thaliana.
abstract: The growth of leaves in the model plant, Arabidopsis thaliana (L.) Heynh., is determined by the extent of expansion of individual cells and by cell proliferation. Mutants of A. thaliana with known defects in the biosynthesis or perception of brassinosteroids develop small leaves. When the leaves of brassinosteroid-related mutants, det2 (de-etiolated2 = cro1) and dwf1 (dwarf1 = cro2) were compared to wild-type plants, an earlier cessation of leaf expansion was observed; a detailed anatomical analysis further revealed that the mutants had fewer cells per leaf blade. Treatment of the det2 mutants with the brassinosteroid, brassinolide, reversed the mutation and restored the potential for growth to that of the wild type. Restoration of leaf size could not be explained solely on the basis of an increase in individual cell volume, thus suggesting that brassinosteroids play a dual role in regulating cell expansion and proliferation.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Tokyo, 113-0033 Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Nakaya
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tsukaya
authors.forename: Noriaki
authors.initials: N
authors.lastname: Murakami
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kato
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D060406:Brassinosteroids; D002455:Cell Division / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D002777:Cholestanols / Q000494:pharmacology*; D009154:Mutation; D010641:Phenotype; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects / Q000254:growth & development*; D013260:Steroids, Heterocyclic / Q000494:pharmacology*
chemical_list: D060406:Brassinosteroids; D002777:Cholestanols; D010937:Plant Growth Regulators; D013260:Steroids, Heterocyclic; C023623:brassinolide