title: The Decreased apical dominance1/Petunia hybrida CAROTENOID CLEAVAGE DIOXYGENASE8 gene affects branch production and plays a role in leaf senescence, root growth, and flower development.
abstract: Carotenoids and carotenoid cleavage products play an important and integral role in plant development. The Decreased apical dominance1 (Dad1)/PhCCD8 gene of petunia (Petunia hybrida) encodes a hypothetical carotenoid cleavage dioxygenase (CCD) and ortholog of the MORE AXILLARY GROWTH4 (MAX4)/AtCCD8 gene. The dad1-1 mutant allele was inactivated by insertion of an unusual transposon (Dad-one transposon), and the dad1-3 allele is a revertant allele of dad1-1. Consistent with its role in producing a graft-transmissible compound that can alter branching, the Dad1/PhCCD8 gene is expressed in root and shoot tissue. This expression is upregulated in the stems of the dad1-1, dad2, and dad3 increased branching mutants, indicating feedback regulation of the gene in this tissue. However, this feedback regulation does not affect the root expression of Dad1/PhCCD8. Overexpression of Dad1/PhCCD8 in the dad1-1 mutant complemented the mutant phenotype, and RNA interference in the wild type resulted in an increased branching phenotype. Other differences in phenotype associated with the loss of Dad1/PhCCD8 function included altered timing of axillary meristem development, delayed leaf senescence, smaller flowers, reduced internode length, and reduced root growth. These data indicate that the substrate(s) and/or product(s) of the Dad1/PhCCD8 enzyme are mobile signal molecules with diverse roles in plant development.
authors.affiliation: HortResearch, Private Bag 92169, Mt. Albert, Auckland, New Zealand.
authors.forename: Kimberley C
authors.initials: KC
authors.lastname: Snowden
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Simkin
authors.forename: Bart J
authors.initials: BJ
authors.lastname: Janssen
authors.forename: Kerry R
authors.initials: KR
authors.lastname: Templeton
authors.forename: Holly M
authors.initials: HM
authors.lastname: Loucas
authors.forename: Joanne L
authors.initials: JL
authors.lastname: Simons
authors.forename: Sakuntala
authors.initials: S
authors.lastname: Karunairetnam
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Gleave
authors.forename: David G
authors.initials: DG
authors.lastname: Clark
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Klee
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D002338:Carotenoids / Q000378:metabolism; D004251:DNA Transposable Elements / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D049308:Dioxygenases / Q000235:genetics; D035264:Flowers / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008969:Molecular Sequence Data; D009154:Mutation; D032306:Petunia / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development*; D010641:Phenotype; D010802:Phylogeny; D018515:Plant Leaves / Q000254:growth & development; D018517:Plant Roots / Q000254:growth & development; D030821:Plants, Genetically Modified; D017386:Sequence Homology, Amino Acid
chemical_list: D004251:DNA Transposable Elements; D018744:DNA, Plant; D002338:Carotenoids; D049308:Dioxygenases