Characterization and development of 14 microsatellite markers for mountain stewartia (Stewartia ovata): an uncommon, Appalachian-endemic member of the tea family

Abstract

ABSTRACT Mountain stewartia [Stewartia ovata (Cav.) Weatherby] is a rare, endemic understory tree native to the southeastern U.S.A. While found only in microsites across southeastern Appalachia, the species distribution spans from northern Alabama and Georgia to southern Kentucky and Virginia. However, most occurrences have been recorded in Tennessee. While recent distribution surveys and habitat suitability modeling conducted for this species have improved our understanding of the environmental parameters that constitute its fundamental niche, the ecological profile of S. ovata remains poorly understood. Consequently, its rarity has raised concerns as to the long-term resilience of this species in the wild. Faced with these challenges, the assessment of existing genetic diversity in S. ovata through genetically informative molecular resources is critical to understanding the adaptive potential and ecological resilience of the species. Microsatellites are cost-efficient molecular tools capable of addressing these concerns by elucidating trends in population structure, population demography, and inbreeding. To increase the available genetic resources for S. ovata, we screened 105 microsatellite loci for their suitability to assess these population features using capillary gel electrophoresis. The utility of these markers was evaluated by assessing polymorphism information content (PIC) and population statistics, which yielded 14 highly polymorphic microsatellite markers. These markers displayed an average PIC of 0.695 (PIC range of 0.538–0.851), which supports their ability to capture fine-scale genetic diversity within the species. We also report a low average observed heterozygosity of 0.375 (versus an expected heterozygosity of 0.645) among screened loci, which reinforces the need for broader genetic diversity assessments within this species.