title: Overexpression of KNAT1 in lettuce shifts leaf determinate growth to a shoot-like indeterminate growth associated with an accumulation of isopentenyl-type cytokinins.
abstract: Leaves are specialized organs characterized by defined developmental destiny and determinate growth. The overexpression of Knotted1-like homeobox genes in different species has been shown to alter leaf shape and development, but a definite role for this class of genes remains to be established. Transgenics that overexpress Knotted1-like genes present some traits that are characteristic of altered cytokinin physiology. Here we show that lettuce (Lactuca sativa) leaves that overexpress KNAT1, an Arabidopsis kn1-like gene, acquire characteristics of indeterminate growth typical of the shoot and that this cell fate change is associated with the accumulation of specific types of cytokinins. The possibility that the phenotypic effects of KNAT1 overexpression may arise primarily from the modulation of local ratios of different cytokinins is discussed.
authors.affiliation: Istituto di Biochimica ed Ecofisiologia Vegetali del Consiglio Nazionale delle Richerche, via Salaria km 29,300-00016 Monterotondo Scalo, Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Frugis
authors.forename: D
authors.initials: D
authors.lastname: Giannino
authors.forename: G
authors.initials: G
authors.lastname: Mele
authors.forename: C
authors.initials: C
authors.lastname: Nicolodi
authors.forename: A
authors.initials: A
authors.lastname: Chiappetta
authors.forename: M B
authors.initials: MB
authors.lastname: Bitonti
authors.forename: A M
authors.initials: AM
authors.lastname: Innocenti
authors.forename: W
authors.initials: W
authors.lastname: Dewitte
authors.forename: H
authors.initials: H
authors.lastname: Van Onckelen
authors.forename: D
authors.initials: D
authors.lastname: Mariotti
mesh_terms: D029681:Arabidopsis Proteins; D003583:Cytokinins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D007150:Immunohistochemistry; D018545:Lactuca / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D009024:Morphogenesis; D010641:Phenotype; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000254:growth & development; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D018547:Plant Stems / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D010970:Plastocyanin
chemical_list: D029681:Arabidopsis Proteins; D003583:Cytokinins; D018398:Homeodomain Proteins; C092212:KNAT1 protein, Arabidopsis; C095848:Kn1 protein, plant; D010940:Plant Proteins; D010970:Plastocyanin