Development of microsatellite markers for Croomia japonica and cross-amplification in its congener

Croomia is a small monocotyledonous genus with eastern Asian–eastern North American floristic disjunction. The Croomia species are endangered and in urgent need of conservation. In this study, we report the development and characterization of 11 polymorphic compound microsatellite markers from Croomia japonica. Moreover, transferability and polymorphism of these primers was tested across Croomia heterosepala and Croomia pauciflora. All of them were transferable and polymorphic in these species. The number of alleles per locus ranged from 2 to 14 (mean: 7.7), 2 to 20 (mean: 7.3) and 2 to 16 (mean: 8.2), while the observed (and expected) heterozygosities ranged from 0.053 to 1.000 (0.053–0.918), 0.000 to 1.000 (0.656–0.945) and 0.190 to 0.905 (0.251–0.937) in populations of C. japonica, C. heterosepala and C. pauciflora, respectively. Most loci in the Croomia populations deviated significantly from the HWE expectations. Significant heterozygosity deficiency was found but no bottleneck was detected in Croomia. These polymorphic markers will be useful tool to study the genetic diversity and the population genetic structure, evolution of Croomia species and for establishment of effective conservation strategies.