title: Novel localization of callose in the spores of Physcomitrella patens and phylogenomics of the callose synthase gene family.
abstract: OBJECTIVE
  Callose involvement in spore development is a plesiomorphic feature of land plants. Correlated light, fluorescence and immuno-electron microscopy was conducted on the developing spores of Physcomitrella patens to probe for callose. Using a bioinformatic approach, the callose synthase (PpCalS) genes were annotated and PpCalS and AtCalS gene families compared, testing the hypothesis that an exine development orthologue is present in P. patens based on deduced polypeptide similarity with AtCalS5, a known exine development gene.
  
  
  METHODS
  Spores were stained with aniline blue fluorescent dye. Capsules were prepared for immuno-light and immuno-electron microscopy by gold labelling callose epitopes with monoclonal antibody. BLAST searches were conducted using the AtCalS5 sequence as a query against the P. patens genome. Phylogenomic analysis of the CalS gene family was conducted using PAUP (v.4.1b10).
  
  
  RESULTS
  Callose is briefly present in the aperture of developing P. patens spores. The PpCalS gene family consists of 12 copies that fall into three distinct clades with AtCalS genes. PpCalS5 is an orthologue to AtCalS5 with highly conserved domains and 64 % similarity of their deduced polypeptides.
  
  
  CONCLUSIONS
  This is the first study to identify the presence of callose in moss spores. AtCalS5 was previously shown to be involved in pollen exine development, thus making PpCalS5 a suspect gene involved in moss spore exine development.
authors.affiliation: Department of Plant Biology-6509, Southern Illinois University, Carbondale, IL 62901, USA. renzlab@siu.edu
authors.forename: Scott
authors.initials: S
authors.lastname: Schuette
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Wood
authors.forename: Matt
authors.initials: M
authors.lastname: Geisler
authors.forename: Jane
authors.initials: J
authors.lastname: Geisler-Lee
authors.forename: Roberto
authors.initials: R
authors.lastname: Ligrone
authors.forename: Karen S
authors.initials: KS
authors.lastname: Renzaglia
mesh_terms: D000595:Amino Acid Sequence; D019068:Bryopsida / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D023281:Genomics; D005936:Glucans / Q000378:metabolism*; D005964:Glucosyltransferases / Q000737:chemistry / Q000235:genetics*; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D016415:Sequence Alignment; D013170:Spores / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure
chemical_list: D005936:Glucans; C048306:callose; D005964:Glucosyltransferases; C020570:1,3-beta-glucan synthase