Characterization of seven (CTT)n microsatellite loci in the Pyrenean endemic Borderea pyrenaica (Dioscoreaceae). Remarks on ploidy level and hybrid origin assessed through allozymes and microsatellite analyses.

We present the identification and characterization of
microsatellite loci in the Pyrenean endemic Borderea
pyrenaica Mie´ geville (Dioscoreaceae). Seven microsatellite
loci were isolated from a (CTT)n-enriched partial genomic
library. Electropherograms patterns suggest that B. pyrenaica
is a tetraploid species, as is its congener B. chouardii. One
microsatellite locus was monomorphic, whereas the remaining
ones presented from 2 to 10 alleles when analyzed in
a sample of 60 individuals. Microsatellites have revealed
higher levels of genetic variability than those in previous
studies based on allozymes. Levels of genetic diversity are
discussed in terms of tetrasomic (autotetraploidy) or
duplicated disomic (allotetraploidy) modes of allele segregation.
According to the first hypothesis, mean levels of genetic
variability (Hmin–Hmax) range between 0.36 and 0.41,
whereas, according to the second hypothesis, the 7 primer
pairs amplified 11 chromosomal loci, and mean levels of
observed and expected heterozygosities were 0.217 and
0.229, respectively, and did not differ significantly from HW
expectations. These results suggest a hybrid allopolyploid
origin for the Borderea taxa.