Location: Floral and Nursery Plants Research2012 Annual Report
1a. Objectives (from AD-416):
Objective 1: Accurately identify and characterize existing genetic resources, and elucidate their genetic relationships and genetic variation within species, in understudied groups of specialty crops (primarily woody landscape plants). • Sub-objective 1.A. Elucidate relationships among selected species of elms (Ulmus). • Sub-objective 1.B. Determine whether apomixis occurs in selected species of hackberry (Celtis). • Sub-objective 1.C. Determine whether pollen competition affects the occurrence and frequency of interspecific hybridization in oaks (Quercus). • Sub-objective 1.D. Characterize the evolutionary and systematic relationships for the approximately 11 species of the economically important landscape plant genus Catalpa, culminating in a biosystematic monograph for the genus. • Sub-objective 1.E. Construct an initial systematic and phylogenetic analysis of the evolutionary relationships between the relatively few temperate species of the landscape plant Chionanthus and their many tropical congeners. • Sub-objective 1.F. Carry out research projects relating to other families and genera to reach a broad audience in the form of regional floras and botanical manuals in collaboration with other scientists and horticulturists. Objective 2: Maintain and enhance the National Arboretum herbarium as a scientific resource and a collection documenting important agricultural research and germplasm. Objective 3: Investigate the identity and basic biological characteristics of selected invasive woody plants in the U.S.
1b. Approach (from AD-416):
Investigations will utilize a variety of different data types, primarily morphological data, DNA sequence variation, and variation in single-locus DNA markers within variable sites in the genome, analyzed using phylogenetic analyses and other multivariate statistical methods. Organisms will be studied in the field, herbarium, laboratory, and garden.
3. Progress Report:
Elm research (objective 1A) has concentrated on the Ulmus americana polyploid complex. Flow cytometry has been carried out on elm seeds from stands of mixed ploidy. Additional Ulmus americana have been characterized for different SSR markers, and a set of SSR markers giving maximum information about genetic structure in the group has been identified. DNA sequencing for representative species of elm is being carried out via a cooperative agreement with Morton Arboretum (see the report for 1230-21000-050-04S for more information). Additional morphological and flow cytometry work has also been carried out on Celtis (objective 1B), and a nomenclatural problem was addressed in a publication. The Quercus pollination project (objective 1C) was abandoned due to reductions in manpower and budget and retirement of support scientist with expertise in pollination of wind-pollinated trees. Morphological characterization of Catalpa species (objective 1D) continues, using data from living and dried specimens throughout their life cycles, and this information is being databased to allow further analysis. Accessions of native American fringetree (objective 1E) are being characterized for selected DNA markers; preliminary results indicate that there are no discernable genetic differences between the pygmy and common fringe trees in central and northern Florida. Work in the herbarium (objective 2) has been limited since the main building at the National Arboretum has been closed all year for thorough renovation, and most of the herbarium is inaccessible. Sites where specimens are stored have been monitored for insect infestation and humidity. Having a renovated building with adequate climate control will benefit the herbarium greatly, however. Most of the collection is inaccessible during the renovation, but specimens of interest have been kept out, and work continues with these. Staff and volunteers have added more than 8000 records to the herbarium database. Herbarium collecting has mainly been carried out through contracts and cooperative agreements with collaborators across the country, which will result in the addition of approximately 3000 specimens of North American cultivated plants of interest to the herbarium. The invasive risk assessment project (objective 3) has been delayed due to the retirement of the collaborator on the project. Staff is seeking a new collaborator to complete this; the project is not expected to be finished until the following project cycle.
1. The book, The Jepson Manual: Higher Plants of California ed. 2 (University of California Press, containing several chapters prepared by an ARS scientist at the U.S. National Arboretum, was published. This book is an important and widely-used source of information on the native and invasive plants of California, the state with the largest group of flora in the U.S., and it will be used by professional land managers, educators, conservationists, and sophisticated amateur botanists and horticulturalists throughout the western United States, insuring that work on land management and conservation will be based on full, accurate and up-to-date information about the basic biology and relationships of these organisms.