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Atlanta, GA, United States

Pandey M.,Texas Tech University | Pandey M.,Molecular Research LP | Richards M.,Atlanta Botanical Garden | Sharma J.,Texas Tech University
Genetica | Year: 2015

We investigated the patterns of genetic diversity and structure in seven disjunct populations of a rare North American orchid, Cypripedium kentuckiense by including populations that represented the periphery and the center of the its range. Eight nuclear and two chloroplast microsatellites were used. Genetic diversity was low across the sampled populations of C. kentuckiense based on both nuclear (average An = 4.0, Ho = 0.436, He = 0.448) and cpDNA microsatellites (average An = 1.57, Nh = 1.57 and H = 0.133). The number of private alleles ranged from one to four per population with a total of 17 private alleles detected at five nuclear microsatellites. One private allele at one cpDNA microsatellite was also observed. Although the absolute values for nuclear microsatellite based population differentiation were low (Fst = 0.075; ϕPT = 0.24), they were statistically significant. Pairwise Fst values ranged from 0.038 to 0.123 and each comparison was significant. We also detected isolation by distance with nDNA microsatellites based on the Mantel test (r2 = 0.209, P = 0.05). STRUCTURE analysis and the neighbor joining trees grouped the populations similarly whereby the geographically proximal populations were genetically similar. Our data indicate that the species is genetically depauperate but the diversity is distributed more or less equally across its range. Population differentiation and isolation by distance were detectable, which indicates that genetic isolation is beginning to manifest itself across the range in this rare species. © 2015, Springer International Publishing Switzerland.

Cruse-Sanders J.M.,Atlanta Botanical Garden | Parker K.C.,University of Georgia | Friar E.A.,500 N College Ave | Friar E.A.,National Science Foundation | And 5 more authors.
Ecology and Evolution | Year: 2013

Microsatellite markers (N = 5) were developed for analysis of genetic variation in 15 populations of the columnar cactus Stenocereus stellatus, managed under traditional agriculture practices in central Mexico. Microsatellite diversity was analyzed within and among populations, between geographic regions, and among population management types to provide detailed insight into historical gene flow rates and population dynamics associated with domestication. Our results corroborate a greater diversity in populations managed by farmers compared with wild ones (HE = 0.64 vs. 0.55), but with regional variation between populations among regions. Although farmers propagated S. stellatus vegetatively in home gardens to diversify their stock, asexual recruitment also occurred naturally in populations where more marginal conditions have limited sexual recruitment, resulting in lower genetic diversity. Therefore, a clear-cut relationship between the occurrence of asexual recruitment and genetic diversity was not evident. Two managed populations adjacent to towns were identified as major sources of gene movement in each sampled region, with significant migration to distant as well as nearby populations. Coupled with the absence of significant bottlenecks, this suggests a mechanism for promoting genetic diversity in managed populations through long distance gene exchange. Cultivation of S. stellatus in close proximity to wild populations has led to complex patterns of genetic variation across the landscape that reflects the interaction of natural and cultural processes. As molecular markers become available for nontraditional crops and novel analysis techniques allow us to detect and evaluate patterns of genetic diversity, genetic studies provide valuable insights into managing crop genetic resources into the future against a backdrop of global change. Traditional agriculture systems play an important role in maintaining genetic diversity for plant species. © 2013 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

Miller D.L.,University of Georgia | Miller D.L.,University of Tennessee at Knoxville | Hill R.L.,Atlanta Botanical Garden | McGuire J.L.,University of Georgia | Yabsley M.J.,University of Georgia
EcoHealth | Year: 2013

The interactive effects of environmental stressors and emerging infectious disease pose potential threats to stream salamander communities and their headwater stream ecosystems. To begin assessing these threats, we conducted occupancy surveys and pathogen screening of stream salamanders (Family Plethodontidae) in a protected southern Appalachians watershed in Georgia and North Carolina, USA. Of the 101 salamanders screened for both chytrid fungus (Batrachochytrium dendrobatidis) and Ranavirus, only two exhibited low-level chytrid infections. Prevalence of Ranavirus was much higher (30.4% among five species of Desmognathus). Despite the ubiquity of ranaviral infections, we found high probabilities of site occupancy (≥0.60) for all stream salamander species. © 2013 International Association for Ecology and Health.

Johnson T.,Georgia Institute of Technology | Cruse-Sanders J.M.,Atlanta Botanical Garden | Pullman G.S.,Georgia Institute of Technology | Pullman G.S.,Institute of Paper Science And Technology
In Vitro Cellular and Developmental Biology - Plant | Year: 2012

Xyris tennesseensis is a critically endangered species native to the southeastern USA. A micropropagation protocol was developed which may assist in the safeguarding and augmentation of dwindling natural populations of this ecologically and medically valuable plant. Four different batches of seeds were sterilized using hydrogen peroxide and germinated in vitro on modified one third-strength Murashige and Skoog medium. Shoot multiplication from seedling tissue was obtained using modified one third-strength Murashige and Skoog medium containing 1 mg/l kinetin and 0. 1-0. 5 mg/l α-naphthaleneacetic acid. Optimal shoot size and sustainable multiplication rates of three to five per 2-mo subculture occurred on medium containing 0. 3-0. 4 mg/l α-naphthaleneacetic acid. Shoots rooted successfully when placed on growth regulator-free medium for 10 d followed by transfer to greenhouse soil under high humidity. Use of seed cryopreservation resulted in significant increases in germination compared to control treatments with average germination rates of 97%. Shoot tip cultures from soil-grown plants of X. tennesseensis and Xyris spathifolia were also developed using the above protocols. Plant tissue culture tools will assist in the multiplication, long-term storage, and conservation of these rare and valuable plants as well as provide a template for the micropropagation of other Xyris species. © 2012 The Society for In Vitro Biology.

Perullo N.,Georgia Institute of Technology | Determann R.O.,Atlanta Botanical Garden | Cruse-Sanders J.M.,Atlanta Botanical Garden | Pullman G.S.,Georgia Institute of Technology | Pullman G.S.,Institute of Paper Science And Technology
In Vitro Cellular and Developmental Biology - Plant | Year: 2015

Helonias bullata, commonly known as swamp pink, is a perennial rhizomatous herb native to the eastern coast of the United States that is found mainly in forested wetlands, swamps, and mountain bogs. Habitat destruction has caused H. bullata to become rare, and it is federally listed as threatened. Protocols were developed for in vitro germination, shoot micropropagation, shoot establishment in soil, and seed cryopreservation that will assist in the safeguarding and conservation of dwindling natural populations. Seeds were germinated in vitro on plant growth regulator (PGR)-free 1/3-strength Murashige and Skoog (MS) medium after seed sterilization in H2O2 and used for establishment of shoot cultures. Shoot multiplication and elongation occurred on 1/3-strength MS medium containing 0.25–1 mg/l kinetin or 1–2 mg/l trans-zeatin followed by growth on PGR-free medium. All shoots (100%) rooted when planted directly into potting media. Rapid-immersion seed cryopreservation resulted in statistically significant increases in germination in vitro or in potting mix compared to control treatments. H. bullata seeds share characteristics of both orthodox and recalcitrant seeds including rapid loss of viability over time, survival at 5°C, and survival after cryopreservation. Therefore, they are most accurately classified as intermediate-type seed. © 2015, The Society for In Vitro Biology.

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