Our Scientists

For more information on research projects, progress, and results, please visit the ARS website here.

Dr. Lisa Alexander

Research Geneticist
{McMinnville, TN}

Conducts research to develop, evaluate, and release improved germplasm of selected nursery crop species, including, but not limited to, Hydrangea, Osmanthus, and Callicarpa, and utilize genetic markers to accelerate the breeding process.

Dr. Jinyoung Barnaby

Research Geneticist
{Beltsville, MD}

Conducts research on the molecular mechanisms of dormancy (triggered by heat, drought, or cold stress) and pest resistance in cool and warm season turfgrasses, with the goal of identifying genes of value in breeding superior, sustainable turfgrass for different climatic zones. Methods employed include multi-omics approaches; determining the functions of key regulatory genes affecting desirable turfgrass qualities; and using gene-editing techniques for improvement of existing horticulturally well-adapted turf varieties.

Dr. Hui Duan

Research Geneticist
{Beltsville, MD}

Conducts research on genetic improvement of ornamental woody plants through plant biotechnology. The research uses new breeding technologies including transgenic approaches and gene editing. Current research interests: a) develop highly-efficient genetic transformation and gene editing platforms for selected ornamental woody plants, especially transformation recalcitrant species; b) introduce valuable consumer traits (flower/foliage color, plant architecture etc.) and sustainability traits (biotic and abiotic stress resistance, water/nutrient use efficiency) into select ornamental woody plants using developed biotechnology platforms.

Dr. John Hammond

Research Plant Pathologist
{Beltsville, MD}

Conducts research on virus diseases of ornamental crops, including identification and characterization of newly occurring viruses, resistance to virus infection and replication in transgenic plants, and virus detection and strain differentiation by serology and nucleic acid hybridization. Development of a Universal Plant Virus Microarray for detection and identification of plant viruses.

Dr. Qi Huang

Research Plant Pathologist
{Beltsville, MD}

Identifies, detects, and gains a better understanding of genetic relationships and molecular basis of pathogenicity of selected bacterial pathogens to facilitate effective control of bacterial diseases of major significance to ornamental and agronomic crops. Current research interests include: conducting research on Xylella fastidiosa including genome characterization and specific detection and identification of ornamental strains, as well as genetic relationships among ornamental and non-ornamental strains of X. fastidiosa; and improving current detection and identification methods for the select agent pathogen Ralstonia solanacearum race 3 biovar 2.

Dr. Ramon Jordan

Research Plant Pathologist
{Beltsville, MD}

Conducts research on the biochemical and biological nature of plant viruses, their genomes, and their gene products. Develops and utilizes serological and nucleic acid-based reagents and technologies for improved detection, differentiation and identification of new and emerging viruses; determines the genome organization of selected important ornamental viruses; and, develops methods and new strategies to confer virus resistance in plants through expression of antibody proteins or replicase-binding peptides in transgenic plants.

Dr. Margaret Pooler

Research Leader
{Beltsville, MD}

Conducts basic and applied research on breeding and genetics of ornamental shrubs and small trees, including flowering cherries, redbuds, and crapemyrtles, in order to develop new cultivars that are disease and pest resistant, tolerant of environmental stresses, and have superior ornamental qualities. Breeding methodologies include traditional crosses, ploidy manipulation, in-vitro techniques, as well as using molecular markers to identify hybrids or assess genetic diversity.

Dr. Todd Rounsaville

{Beltsville, MD}

Leads the U.S. National Arboretum Germplasm Program to improve the genetic and taxonomic resource base of woody plants in cultivation. Conducts research on genetic diversity, seed biology, and germplasm management via regeneration, storage, and gap analysis. Leads and collaborates on expeditions for domestic and international plant collection, germplasm evaluation trials, and plant conservation efforts both in situ and ex situ.

Dr. Jake Shreckhise

Research Horticulturist
{McMinnville, TN}

Conducts long-term research evaluating germplasm of novel or underused tree and shrub species (with an emphasis on North American native species) to select phenotypes with superior ornamental qualities and improved tolerance to abiotic stress (e.g., temperature extremes, drought), arthropod pests, and disease. Develops propagation and finishing protocols for difficult-to-cultivate woody ornamentals and investigates sustainable nursery production practices that improve water- and fertilizer-use efficiency while mitigating agrochemical leaching and runoff.

Dr. Harlan Svoboda

{Washington, DC}

Responsible for the preservation, management, and curation of the National Arboretum Herbarium and National Seed Herbarium (over 900,000 specimens combined), and oversees the collections’ digitization efforts. Provides taxonomic identifications and contributes to the growth of the herbaria through collecting expeditions and partnerships with stakeholders, with a focus on documenting plants in cultivation. Conducts basic research in the fields of plant systematics, taxonomy, and nomenclature.

Dr. Scott Warnke

Research Geneticist
{Beltsville, MD}

Conducts research on the genetics of plants used as turfgrasses. Identifies and develops enhanced germplasm from wild species that express improved biotic and abiotic stress resistance. Develops improved turfgrasses through the use of new technologies such as molecular markers and genomics.