Characterization of Elm Germplasm of Horticultural Interest
Floral and Nursery Plants Research Unit
2011 Annual Report
1a.Objectives (from AD-416)
Characterize germplasm of elms with potential importance to the American nursery industry, concentrating on recently introduced species and on newly discovered genetic races of native species. Analyze genetic diversity among elm accessions and the phylogenetic relationships among them. Provide genetic markers and taxonomically well-identified and characterized germplasm that will be useful for elm research and breeding in the future.
1b.Approach (from AD-416)
Accessions will be identified according to the latest understanding of elm taxonomy, collecting herbarium specimens at different times of the year to allow coding of characters of the flowers, fruit, and leaves, and winter buds. Genetic diversity and phylogenetic relationships will be analyzed by DNA analysis of appropriate nuclear and chloroplast regions, evaluating new markers as necessary. Genome size and ploidy of representative accessions will be investigated using flow cytometry and (if necessary) chromosome counts.
Herbarium specimens have been prepared at different times of the year to preserve flowering, fruiting, and leaf material of elm taxa of interest in the living collections of the National Arboretum (DC and Maryland) and Morton Arboretum (Illinois). This material will allow morphological characterization of the germplasm, and accurate identification of material used for research and (potentially) for future breeding and commercial release.
Two single-copy nuclear genes, nitrate reductase (NIA) and chloroplast expressed glutamine synthetase (ncpGS) have been amplified successfully for 14 target taxa. Sequences were successfully obtained from some taxa using direct sequencing of gel-purified DNA products, and genes are currently being cloned to obtain sequences from the remaining individuals.
Research activities conducted under this agreement were monitored by regular email communication and by submission of reports by the cooperator.