Conservation Genetics of the Dixie Mountain Breadroot (Pediomelum piedmontanum), a rare and endangered legume from the Piedmont
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AbstractPediomelum piedmontanum, “Dixie Mt. Breadroot”, is a rare perennial legume endemic to the lower piedmont region of Georgia and South Carolina, with only three known populations. Previous research has explored local adaptations its unique substrates, serpentine and phyllite, and how metal tolerance contributes to its limited distribution. A different study, using tetrazolium chloride, revealed that only ~25% of phyllite seed is viable compared to about 95% seed viability in the serpentine population. We hypothesize that the phyllite plants are self-fertilizing before pollinators are present, creating an inbreeding depression and lower genetic variability. Populations with a relatively high genetic diversity are more able to adapt to new or sustained selective pressures. The CURS SSP investigated the conservation genetics and ecology of the three populations of P. piedmontanum. Nine Microsatellite markers, previously used by Ashely Egan in P. pariense, were implemented to determine the extent of genetic diversity of P. piedmontanum and its subsequent susceptibility to extinction. These genetic markers may also reveal evolutionary relationships between P. piedmontanum and closely related species, P. canescens, located in sandy habitats, and P. subcaule, an endemic to limestone. Currently, we have extracted 150 DNA samples from replicate leaves/plant/population. Gel electrophoresis of one of the markers “AG26” with DNA template from the serpentine population resulted in a ~500 bp fragment, which is vastly different than the expected 120 bp fragment observed in P. pariense. Further analyses will be required to determine the level of genetic variability in these populations. To determine the cause of seed inviability, we cross-pollinated tagged plants at a phyllite site. Cross-pollination should increase seed viability in the population compared to control plants. Population sizes and average number of inflorescences/plant were also measured. It appears that the one of phyllite populations is the largest of the three populations with ~ 600 plants. This large population contains little evidence of flowering within pockets of a forest. This indicates that these plants are reproducing asexually possibly from their large taproot, which suggests cloning and lower genetic variability in this forested phyllite population.
AffiliationDepartment of Biological Sciences
DescriptionPoster presentation given at the 2015 Summer Scholars Symposium