Can the sex-specific molecular marker of Drepanocladus trifarius uncover gender in related species?

摘要

Unisexual bryophytes rarely exhibit readily discernible sexual dimorphism before sexual maturity (e.g. Goffinet, Buck & Shaw, 2008). In addition, a considerable number of species and many populations consist of non-expressing gametophytes only, bearing neither male or female inflorescenses (Longton & Schuster, 1983; Bisang & Hedena╯, 2005). Because of the difficulty to assess gender in nonfertile specimens, the study of sex-related questions has so far been mainly confined to sex-expressing individuals and species and to the reproductive phase of their life-cycles. Indirect approaches were used for gender identification in Plagiomnium affine (Funck) T.J.Kop. (Cronberg et al., 2003) and Hylocomium splendens (Hedw.) Schimp. (Rydgren, Cronberg & 豮land, 2006; Rydgren & 豮land, 2002). Newton (1971) was able to sex specimens of Plagiomnium undulatum (Hedw.) T.J.Kop. based on cytological evidence. Compared to flowering plants (for references, see Korpelainen, 2002), however, molecular sex markers have been discovered in only few bryophyte species to date, namely, in the liverworts Marchantia polymorpha L. (Okada et al., 2000; Yamato et al., 2007) and Sphaerocarpos texanus Aust. (McLetchie & Collins, 2002). McDaniel, Willis & Shaw (2007) presented a linkage map for the moss Ceratodon purpureus (Hedw.) Brid., which included a one gene-based sex marker. Recently, we developed a molecular sex marker and successfully characterized sex specific sequence differences in the moss Drepanocladus trifarius (F.Weber & D.Mohr) Broth. ex Paris (Pseudocalliergon trifarium (F.Weber & D.Mohr) Loeske; see Hedena¨ s & Rosborg, 2009) (Korpelainen et al., 2008). The female-specific DNA marker allows determination of gender in non-expressing gametophytes of D. trifarius (Hedena¨s et al., 2010). In this study, we investigate whether this marker can be used to determine sex in the three related species, D. lycopodioides (Brid.) Warnst., D. aduncus (Hedw.) Warnst. and Campylium stellatum (Hedw.) C.E.O.Jensen. All species are members of the Amblystegiaceae (Hedena¨ s & Vanderpoorten, 2007; Vanderpoorten et al., 2002) and occur in different kinds of wetlands (Hedena¨ s, 2003).