title: Agravitropic mutants of the moss Ceratodon purpureus do not complement mutants having a reversed gravitropic response.
abstract: New mutants of the moss Ceratodon purpureus have been isolated, which showed abnormal gravitropic responses. The apical cells of protonemal filaments of wild-type strains respond to gravity by growing upwards and are well aligned to the gravity vector. This response only occurs in darkness. Mutants show a range of phenotypes. Some are insensitive to gravity, showing symmetrical growth, while others align to the gravity vector but orient growth downwards. A further class grows in darkness as though it were in light, showing insensitivity to gravity and continued chlorophyll synthesis. Somatic hybrids between mutants and wild-type strains and between pairs of mutants have been selected using transgenic antibiotic resistance as selective markers. Hybrids between wild-type strains and all of the mutants have a wild-type phenotype, and so all mutants therefore have recessive phenotypes. Mutants comprise three complementation groups. One group has a single member, while another has three members. The third has at least 16 members and shows a complex pattern of complementation consistent with a single gene product functioning in both orientation and alignment to gravity, as well as contributing more than one subunit to the mature product.
authors.affiliation: Centre for Plant Sciences, University of Leeds, Leeds LS2 9JT, UK. d.j.cove@leeds.ac.uk
authors.forename: David J
authors.initials: DJ
authors.lastname: Cove
authors.forename: Ralph S
authors.initials: RS
authors.lastname: Quatrano
mesh_terms: D019068:Bryopsida / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D003624:Darkness; D005816:Genetic Complementation Test / Q000379:methods*; D005820:Genetic Testing; D018522:Gravitropism / Q000502:physiology*; D006824:Hybridization, Genetic; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D011523:Protoplasts / Q000378:metabolism