title: The moss Funaria hygrometrica has cuticular wax similar to vascular plants, with distinct composition on leafy gametophyte, calyptra and sporophyte capsule surfaces.
abstract: Aerial surfaces of land plants are covered with a waxy cuticle to protect against water loss. The amount and composition of cuticular waxes on moss surfaces had rarely been investigated. Accordingly, the degree of similarity between moss and vascular plant waxes, and between maternal and offspring moss structure waxes is unknown. To resolve these issues, this study aimed at providing a comprehensive analysis of the waxes on the leafy gametophyte, gametophyte calyptra and sporophyte capsule of the moss Funaria hygrometrica
  
  
  
  Waxes were extracted from the surfaces of leafy gametophytes, gametophyte calyptrae and sporophyte capsules, separated by gas chromatography, identified qualitatively with mass spectrometry, and quantified with flame ionization detection. Diagnostic mass spectral peaks were used to determine the isomer composition of wax esters.
  
  
  
  The surfaces of the leafy gametophyte, calyptra and sporophyte capsule of F. hygrometrica were covered with 0·94, 2·0 and 0·44 μg cm(-2) wax, respectively. While each wax mixture was composed of mainly fatty acid alkyl esters, the waxes from maternal and offspring structures had unique compositional markers. β-Hydroxy fatty acid alkyl esters were limited to the leafy gametophyte and calyptra, while alkanes, aldehydes and diol esters were restricted to the sporophyte capsule. Ubiquitous fatty acids, alcohols, fatty acid alkyl esters, aldehydes and alkanes were all found on at least one surface.
  
  
  
  This is the first study to determine wax coverage (μg cm(-2)) on a moss surface, enabling direct comparisons with vascular plants, which were shown to have an equal amount or more wax than F. hygrometrica Wax ester biosynthesis is of particular importance in this species, and the ester-forming enzyme(s) in different parts of the moss may have different substrate preferences. Furthermore, the alkane-forming wax biosynthesis pathway, found widely in vascular plants, is active in the sporophyte capsule, but not in the leafy gametophyte or calyptra. Overall, wax composition and coverage on F. hygrometrica were similar to those reported for some vascular plant species, suggesting that the underlying biosynthetic processes in plants of both lineages were inherited from a common ancestor.
authors.affiliation: Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.
authors.forename: Lucas
authors.initials: L
authors.lastname: Busta
authors.affiliation: Department of Plant Biology, University of California - Davis, One Shields Ave., Davis, CA 95616, USA.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Budke
authors.affiliation: Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada reinhard.jetter@ubc.ca.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Jetter
mesh_terms: D000438:Alcohols / Q000737:chemistry; D019068:Bryopsida / Q000737:chemistry*; D004952:Esters / Q000737:chemistry; D005227:Fatty Acids / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D014885:Waxes / Q000737:chemistry*
chemical_list: D000438:Alcohols; D004952:Esters; D005227:Fatty Acids; D014885:Waxes
keywords: Cuticular wax; Funaria hygrometrica; bryophyte; calyptra; dehydration stress; esters; gas chromatography; leafy gametophyte; maternal protection; sporophyte; very-long-chain