title: Separation of genetic functions controlling organ identity in flowers.
abstract: Comparative studies on the ABC model of floral development have revealed extensive conservation of B and C class genes, but have failed to identify similar conservation for A class genes. Using a reverse genetic approach, we show that the previous inability to obtain Antirrhinum mutants corresponding to the A class gene AP2 of Arabidopsis reflects greater genetic redundancy in Antirrhinum . Antirrhinum has two genes corresponding to AP2, termed LIP1 and LIP2, both of which need to be inactivated to give a mutant phenotype. Analysis of interactions between LIP and class B/C genes shows that unlike AP2 in Arabidopsis, LIP genes are not required for repression of C in outer whorls of the flower. However, like AP2, LIP genes play a role in sepal, petal and ovule development, although some of their detailed effects are different, reflecting the diverse morphologies of Antirrhinum and Arabidopsis flowers. The dual functions for which AP2 is required in Arabidopsis are therefore separate in Antirrhinum, showing that the genetic basis of some aspects of organ identity have undergone major evolutionary change.
authors.affiliation: Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Keck
authors.forename: Paula
authors.initials: P
authors.lastname: McSteen
authors.forename: Rosemary
authors.initials: R
authors.lastname: Carpenter
authors.forename: Enrico
authors.initials: E
authors.lastname: Coen
mesh_terms: D000595:Amino Acid Sequence; D032161:Antirrhinum / Q000033:anatomy & histology / Q000235:genetics* / Q000502:physiology; D035264:Flowers / Q000033:anatomy & histology / Q000235:genetics* / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D017343:Genes, Plant; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D010641:Phenotype; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D016415:Sequence Alignment
chemical_list: D010940:Plant Proteins