title: OUROBOROS is a master regulator of the gametophyte to sporophyte life cycle transition in the brown alga Ectocarpus.
abstract: The brown alga Ectocarpus siliculosus has a haploid-diploid life cycle that involves an alternation between two distinct generations, the sporophyte and the gametophyte. We describe a mutant, ouroboros (oro), in which the sporophyte generation is converted into a functional, gamete-producing gametophyte. The life history of the mutant thus consists of a continuous reiteration of the gametophyte generation. The oro mutant exhibited morphological features typical of the gametophyte generation and accumulated transcripts of gametophyte generation marker genes. Genetic analysis showed that oro behaved as a single, recessive, Mendelian locus that was unlinked to the IMMEDIATE UPRIGHT locus, which has been shown to be necessary for full expression of the sporophyte developmental program. The data presented here indicate that ORO is a master regulator of the gametophyte-to-sporophyte life cycle transition and, moreover, that oro represents a unique class of homeotic mutation that results in switching between two developmental programs that operate at the level of the whole organism.
authors.affiliation: Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, 29682 Roscoff Cedex, France.
authors.forename: Susana M
authors.initials: SM
authors.lastname: Coelho
authors.forename: Olivier
authors.initials: O
authors.lastname: Godfroy
authors.forename: Alok
authors.initials: A
authors.lastname: Arun
authors.forename: Gildas
authors.initials: G
authors.lastname: Le Corguillé
authors.forename: Akira F
authors.initials: AF
authors.lastname: Peters
authors.forename: J Mark
authors.initials: JM
authors.lastname: Cock
mesh_terms: D001483:Base Sequence; D004171:Diploidy; D018507:Gene Expression Regulation, Developmental; D055993:Germ Cells, Plant / Q000254:growth & development / Q000378:metabolism; D006238:Haploidy; D006720:Homozygote; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D000459:Phaeophyceae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D012333:RNA, Messenger