Development and Characterization of 12 Polymorphic Microsatellite Loci for Pityopsis graminifolia var. latifolia

Pityopsis graminifolia var. latifolia (narrowleaf silkplant), is an herbaceous perennial indigenous to northern Alabama and east Tennessee. Pityopsis graminifolia is a tetraploid (2n=4x=36) and is a sympatric species of the federally endangered plant P. ruthii, which grows along the Hiwassee and Ocoee Rivers in Polk County, Tennessee. Molecular markers to define genetic diversity within these species are necessary to determine population structure of these Pityopsis species along both river systems. To examine genetic diversity, we developed 12 polymorphic microsatellite loci from a small insert genomic library of P. graminifolia var. latifolia and characterized 87 individual plant samples. Additionally, 1 P. falcata and 12 P. ruthii individuals were characterized with these markers. PCR amplicons were separated utilizing the QIAxcel Capillary Electrophoresis System and binned into allelic classes. Pityopsis graminifolia var. latifolia, microsatellite loci were coded as binary data (presence/absence), and genetic diversity indices were calculated. Alleles per locus ranged from 4 to 21. Expected heterozygosity ranged from 0.076 to 0.145 and Shannon's Information Index ranged from 0.135 to 0.244. Seven of the 12 markers developed from P. graminifolia var. latifolia amplified P. ruthii samples. Additionally, the single sample of P. falcata amplified across six loci. Microsatellite loci can be used in further studies to analyze the genetic diversity and population structure of P. graminifolia var. latifolia and its relationship to other Pityopsis species, including the endangered species P. ruthii.