2006 Annual Report
1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter?
The environmental horticulture industry, also known as the "Green Industry", is one of the fastest growing segments of the nation's agricultural economy and is comprised of a variety of businesses involved in production, distribution and services associated with ornamental plants, landscape and garden supplies and equipment. The National Gardening Association reported that 85 million U.S. households spent $39.6 billion at lawn and garden retail outlets in 2002. The USDA National Agricultural Statistics Service reported that in 2005 the wholesale value of floral crops was $15.22 billion with 12,258 growers employing 187,563 workers. Over one quarter of these growers (28%) had sales less than $100,000.
The introduction of new ornamental plants has long been a driving force behind the nursery and landscape industries in the U.S. Landscape shrubs are increasingly important resources in the enhancement of residential, recreational, public, and industrial plantings. As suburban areas continue to expand, so does the need for landscape plants that are tolerant to a wide range of environmental stresses and that resist diseases and pests without chemical spraying or treatment.
To resolve the issue of the continual need for improved landscape plants by the nursery and landscape industries, the objective of this project is to develop landscape trees and shrubs that are pest resistant, tolerant of environmental stresses, and are of superior ornamental value. Genera currently under investigation include Cercis, Gaylussacia, Halesia, Ilex, Hamamelis, Lagerstroemia, Malus, Prunus, Stewartia, and Viburnum. Specific germplasm enhancement methods include intra- and interspecific hybridizations followed by backcrossing or selfing; identification of hybrid progeny by molecular markers; evaluation of genetic relationships by molecular markers; and genetic engineering with genes for ornamental or disease resistance traits. This project also involves a cooperative evaluation and stock increase program with the nursery industry to ensure transfer of this research to the end users.
These problems and objectives are part of the current Project Plan titled "Genetics, genetic resource evaluation, and genetic improvement of landscape trees and shrubs". This research falls primarily under National Program 301(Plant, Microbial and Insect Germplasm, Conservation, and Development), Component 3 (Genetic improvement of crops). Aspects of this research serve to safeguard threatened genetic resources, conserve and document genetic resources, expand germplasm evaluations, and transfer this information and resulting germplasm releases to the end user.
2.List by year the currently approved milestones (indicators of research progress)
Year 1 (FY 2003)
Germinate Cercis chinensis x racemosa F2 hybrids.
Create more interspecific F1 hybrids using C. racemosa.
Perform interspecific crosses with Prunus maackii, P. campanulata, and other flowering cherry species.
Release new flowering cherry cultivar, Prunus 'First Lady'.
Optimize regeneration systems for Prunus incisa.
Make initial selections of crapemyrtle hybrids from 2001 pollinations.
Release red-flowering crapemyrtle cultivars 'Arapaho' and 'Cheyenne'.
Establish crapemyrtle selection(s) in vitro.
Create segregating F2 population by self-pollination of lilac 'Betsy Ross' or backcross 'Betsy Ross' to Syringa oblata var. dilatata.
Perform controlled hybridizations with Gaylussacia brachycera accessions.
Year 2 (FY2004)
Obtain genes for genetic transformation of Cercis yunnanensis with antifungal protein.
Perform interspecific crosses with Prunus maackii, P. campanulata, and other flowering cherry species.
Transform Prunus incisa with marker gene or other constructs as available.
Continue to make selections selections of crapemyrtle hybrids from 2001 pollinations.
Rogue mature crapemyrtles in back nursery to select for purple and unique (fluorescent or salmon) pink flower color.
If in-vitro crapemyrtle cultures are well-established, attempt regeneration using leaf pieces or other explant material.
Obtain evaluation feedback information from cooperators for two Syringa hybrids that are currently under evaluation.
Germinate Syringa seedlings from 2003 pollinations.
Conduct controlled experiments to optimize propagation of Gaylussacia brachycera.
Use AFLP markers to determine genetic distances among Gaylussacia brachycera accessions.
Use AFLP markers to determine genetic relationships among accessions of American elm.
Year 3 (FY2005)
Attempt to transform Cercis yunnanensis with antifungal protein.
Use SSR markers to determine genetic relationships among ornamental Prunus taxa.
Propagate promising selections of crapemyrtle for further evaluation by cooperators.
Evaluate Halesia seedlings from 2001 crosses and plant to field.
Attempt to transform crapemyrtle if in-vitro establishment and regeneration works.
Begin work on molecular diversity study of Lagerstroemia species (with an ARS cooperator at Poplarville, MS).
Notify cooperators to begin stock increase of two Syringa selections.
Use sequence analysis of ChsA gene to determine evolutionary relationships among Gaylussacia brachycera accessions.
Complete elm AFLP project from FY2004.
Year 4 (FY2006)
Send promising crapemyrtle selections to cooperators for evaluation.
Complete work on molecular diversity study of Lagerstroemia species (with an ARS cooperator at Poplarville, MS).
Propagate promising Halesia seedling selections, if any.
Evaluate Stewartia interspecific hybrid seedlings from 2000, 2001 crosses.
Evaluate Syringa seedlings from 2003 pollinations for mildew resistance.
Initiate stock increase of viburnum selection for release in 2008.
Initiate stock increase of Prunus selections sent out for evaluation in 1980s and 1990s.
Complete AFLP study to determine clonality of box huckleberry populations.
Year 5 (FY2007)
Evaluate Cercis F2 hybrids from 2003 and earlier for vigor, disease resistance, and possibly flower traits.
Begin evaluation and selection for vigor and flower characteristics of Prunus hybrids created in 2003 and 2004.
Send promising Halesia selections for cooperative evaluation.
Release two new Syringa selections, if not done in FY2006.
Evaluate Syringa seedlings from 2003 pollinations for flower traits.
4a.List the single most significant research accomplishment during FY 2006.
Release of new lilacs 'Old Glory' and 'Declaration'
Two new lilac cultivars, 'Old Glory' and 'Declaration', were released to the nursery and landscape industry in FY2006. These introductions address the need for new landscape plants that are disease and pest resistant and of superior ornamental value. Specifically, these lilacs, which have fragrant, blue-purple ('Old Glory') or red-purple ('Declaration') flowers and field tolerance to powdery mildew, will offer nurseries and the public, especially in traditional lilac-growing regions, a greater diversity of well-adapted landscape material from which to choose. The lilac cultivars are currently being propagated by several wholesale growers for expected retail availability in 2008.
4b.List other significant research accomplishment(s), if any.
Recombination in the clonally propagated rare native plant, Gaylussacia brachycera
In FY2006, over one hundred open-pollinated seed were harvested from multiple accessions of box huckleberry growing in cultivation. The resulting seedlings represent the most extensive recombination of genes in this species' natural history, and therefore serve to contribute to the preservation of germplasm diversity. The box huckleberry (Gaylussacia brachycera) is a rare native evergreen groundcover that is characterized by usually isolated clonal populations. Sexual reproduction in the wild is rare due to self-incompatability. Because our collection includes over 20 different accessions in close proximity, outcrossing among diverse populations was accomplished. This seed represents an entirely new recombination of genes in the species that could lead to selections and cultivars.
Sterile triploid invasive species
This report serves to document research conducted under a specific cooperative agreement 1230-21000-041-01S between ARS and North Carolina State University. In this agreement, we are creating sterile nursery plants through triploidy. Because triploid plants have three sets of chromosomes, they are sterile. Triploid plants can be created by crossing tetraploid plants, which contain four sets of chromosomes, with normal diploid plants, which contain two set of chromosomes. We have artificially created tetraploids of Acer tartaricum subsp. ginnala (amur maple), Acer platanoides (Norway maple), Albizia julibrissin (mimosa), Campsis x tagliabuana (trumpet vine), Cytissus scoparius (Scotch broom), Hypericum androsaemum (tutsan St. Johnswort), Koelreuteria paniculata (goldenraintree), Ligustrum species (privet), Pyrus calleryana (callery pear), and Ulmus parvifolia (lacebark elm). Through breeding, we have created triploids of Pyrus calleryana, Ligustrum species, and Hypericum androsaemum. We have initiated work on Hedera helix (English ivy) and Miscanthus sinensis (maiden grass). As triploids are developed and begin to flower, they will be evaluated for fertility, seed production, seed viability, and other characteristics of interest. If sterile, these triploid plants will be beneficial not only to prevent invasion, but also to eliminate nuisance fruit, reduce pollen-induced allergies, and to improve flowering and re-blooming characteristics.
This report serves to document research conducted under a specific cooperative agreement 1230-21000-041-02S between ARS and Oregon State University. In this agreement, we are creating transgenic sweetgum to induce sterility. In the past, transformed lines were created using five different constructs containing sterility genes. In FY2006, putative transformed lines were created with an additional five different constructs. These lines are currently being tested to confirm their stable transformation. Stably transformed plants will be propagated and evaluated for sterility. This technology and the gene constructs could be useful in producing sterile plants in a wide variety of woody and non-woody invasive or potentially invasive ornamental plants. Creation of these and other sterile plants will be beneficial not only to prevent invasion, but also to eliminate nuisance fruit, reduce pollen-induced allergies, and to improve flowering and re-blooming characteristics.
Evaluation of Viburnums
This report serves to document research conducted under a Specific Cooperative Agreement (58-1230-5-415) between ARS and the Morton Arboretum. The research was conducted as part of a germplasm evaluation proposal endorsed by the Woody Landscape Plant Crop Germplasm Committee. This study evaluates dates of flowering, fruiting and fall color; insect infestation; and disease susceptibility of seedlings from populations of Viburnum lentago, V. prunifolium, V. rufidulum, and V. cassinoides. Results for flowering and fruiting dates indicate V. prunifolium and V. lentago flower earliest, followed by V. nudum. The average date of the first ripe fruit was a week earlier for V. lentago accessions as a whole than for V. prunifolium and V. nudum accessions. All plants in the study that were planted before 2004 were infected by tip borers, while only two plants of the 21 younger plants in the study showed tip borer damage. Nearly all (97%) the V. lentago plants in the study were infected by powdery mildew, while fewer than half (49%) of the V. prunifolium plants showed powdery mildew symptoms. Softwood cuttings were taken from each of the V. lentago and V. prunifolium plants to assess ease of propagation. Overall, 70% of the cuttings rooted and produced leaves after winter dormancy. The rooting rates were similar for both species. In 2006, 281 rooted cuttings were sent to the Woody Landscape Plant Germplasm Repository at the U. S. National for distribution and long-term preservation.
5.Describe the major accomplishments to date and their predicted or actual impact.
Release of two new crapemyrtles
Two new crapemyrtles 'Arapaho' and 'Cheyenne' were introduced in 2003. The introduction of these cultivars address the need for new landscape plants that are disease and pest resistant and of superior ornamental value. Specifically, the crapemyrtles, which have bright red flowers, are easy to propagate, and show outstanding tolerance to powdery mildew, will offer nurseries and the public, especially in the Southeastern U.S., a greater diversity of well-adapted landscape material from which to choose. The crapemyrtle cultivars are now available at the retail level through garden centers and mass merchandisers. This accomplishment was a Milestone in the current Project Plan (for Year 1, 2003), and is part of National Program 301, Component 3 (Genetic improvement of crops), Problem Statement 3C.
Release of a new flowering cherry
A new flowering cherry 'First Lady' was introduced in 2003. The introduction of this cultivar addresses the need for new landscape plants that are disease and pest resistant and of superior ornamental value. 'First Lady'is characterized by exceptionally dark pink blooms and an upright, almost columnar growth habit. It is currently available through a limited number of wholesale and retail nurseries. This accomplishment was a Milestone in the current Project Plan (for Year 1, 2003), and is part of National Program 301, Component 3 (Genetic improvement of crops), Problem Statement 3C.
Genetic diversity of American elm
DNA molecular markers (AFLP) were used to determine the genetic relationships among 19 accessions of American elm and seven other species. This accomplishment addresses the problem of unknown genetic relationships among various American elm accessions, and establishing the identity of a popular elm clone. A total of 135 polymorphic ALFP markers were generated and used to construct a "tree" to help visualize the genetic relationships among various taxa. The information and technology generated here can be used for authenticating cultivars, clones, and hybrids of elms, which have been widely used as urban trees because they can withstand various environmental stresses, and have received renewed attention with the release of several disease-tolerant selections. This research was done in cooperation with the Tree Breeding Project within our Unit (1230-21000-043D). It is part of National Program 301, Component 1 (Plant and Microbial Genetic Resource Management), Problem Statement 1B.
Model system for studying anthocyanin regulatory gene expression
Anthocyanins pigments are responsible for red through blue flower, fruit and leaf colors. Anthocyanin pigmentation requires the coordinated expression of two classes of regulatory genes (Myb and Myc). A model system was developed to measure regulatory gene expression through biolistic bombardment of white petals from a mutant Phalaenopsis orchid that lacks Myb and Myb expression. A visible marker gene (green fluorescent protein) was used to standardize anthocyanin expression between treatments. This system was used to demonstrated that differences in the ratio of Myc and Myb expression had a significant influence on the amount of anthocyanin produced. This information will be important for creating plants with novel patterns of anthocyanin expression, such as plants with pigmented leaves. This research was done in cooperation with the Genetic Improvement of Floral Crops for Pest, Disease and Stress Tolerance and Ornamental Qualities Project within our Unit (1230-21000-040-00D). It is part of National Program 301, Component 3 (Genetic improvement of crops), Problem Statement 3A.
6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?
Two new lilac cultivars ('Old Glory' and 'Declaration') were introduced to the nursery industry in 2006. These plants are currently being propagated by wholesale growers and are expected to be available at the retail level in 2008.
Information on characterization of the MYC and MYB regulatory genes and their effect on anthocyanin expression in ornamental plants was presented at local and international meetings. This information is still theoretical and has not been commercialized or adopted by other scientists.
Information about the National Arboretum and its Breeding Programs was presented at a booth at the Mid-Atlantic Nursery Trade Show in Baltimore, MD, January 2006.
Information on winterhazel as a new plant was presented to an audience at the TEDCO Showcase in Beltsville, MD, February 23, 2006.
A Green Industry Open House was held at the U.S. National Arboretum, May 9, 2006.
7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below).
An invited talk about new ornamental plants was presented at the Pennsylvania Nursery and Landscape Association Trade Show in State College, PA, February 7, 2006.
Geracimos, Ann. Papery crape myrtle - Hardy varieties thrive in the region.
Washington Times, September 21, 2005 (This article discusses crapemyrtles in Washington, DC, including the breeding program at the National Arboretum).
New plants for gardeners. Washington Post, April 7, 2006 (This article mentions the new crapemyrtle introduction 'Arapaho').
Dardick, Karen. Make a floral splash - Crape myrtles come in all sizes and are easy to grow. San Diego Union-Tribune, June 15, 2006 (This article discusses advances in crapemyrtle breeding, including current work from the National Arboretum).
Pooler, M.R. 2006. Crapmyrtle - Lagerstroemia indica. In N.O. Anderson (ed). Flower breeding and genetics. Issues, challenges, and opportunities for the 21st century. 2:428-449. Springer, New York.
Pooler, M.R., Townsend, A.M. 2005. DNA fingerprinting of clones and hybrids of American elm and other elm species with AFLP markers. Journal of Environmental Horticulture. 23:113-117.
Pooler, M.R. 2006. 'Arapaho' and 'Cheyenne' Lagerstroemia. HortScience. 41:855-856.