Population structure and genetic diversity of Botrychium pumicola (Ophioglossaceae) based on inter-simple sequence repeats (ISSR).

Species of Botrychium reproduce by spores that form subterranean gametophytes and a few, like B. pumicola, also reproduce asexually with subterranean sporophytic gemmae. The goal of this study was to examine the genetic diversity of B. pumicola populations and to better understand the role of gemmae. Ninety-nine individuals from three monitored populations were sampled. The technique of inter-simple sequence repeats (ISSR) produced 15 polymorphic loci and identified 71 ISSR genotypes. Sixteen of the ISSR genotypes were shared by more that one individual in a population, representing potential clones. Ten of the 16 shared genotypes were not limited to clusters of plants (groups of plants growing from the same point). The ten potential clones were disjunct (separated by other genotypes) and not in patches as might be expected for an underground propagule. There is a high probability that these shared genotypes arose from independent sexual events suggesting they were not clones. These results suggest that the long-distance dispersal of gemmae is at best a rare event.