Location: Floral and Nursery Plants Research2011 Annual Report
1a. Objectives (from AD-416)
The primary objective of this work is to develop seedless cultivars of invasive or potentially invasive nursery crops. Secondary objectives are to develop new technologies and methods to facilitate theses efforts and to further enhance pest resistance, adaptability, and commercial potential of these crops.
1b. Approach (from AD-416)
These efforts will focus on traditional breeding methods to develop seedless cultivars. Tetraploid clones will be identified or developed and then hybridized with diploids to create triploids. Additional approaches will include mutation breeding, wide hybridization and breeding for double flowers lacking pistils. Resulting progeny will be assessed for fertility and commercial merit. Target crops will include: amur maple (Acer ginnala), barberry (Berberis spp.), catalpa (Catalpa spp.), elaeagnus (Elaeagnus spp.), flowering crabapple (Malus spp.), flowering pear (Pyrus spp.), lace-bark elm (Ulmus parvifolia), miscanthus (Miscanthus spp.), mimosa (Albizia julibrissin), Norway maple (Acer platanoides), privet (Ligustrum spp.), spirea (Spiraea spp.), St. Johnswort (Hypericum spp.), and winged euonymus (Euonymus alatus).
3. Progress Report
The objective of this agreement is to develop methodologies, approaches, and ultimately seedless cultivars of invasive, but commercially important, nursery crops. Ongoing efforts have been successful in building germplasm collections, methods development, and initiating tetraploid clones of the principal taxa of interest, and hybridizing to create triploid progeny. Additional efforts are focused on developing methods for inducing sterility through mutation treatments. Non-invasive cultivars of these species provide environmentally friendly and commercially desirable alternatives to older, invasive forms of these plants. Additional benefits from these seedless plants include elimination of nuisance fruits, reduced pollen-induced allergies, and improved flowering and re-blooming characteristics. These new technologies and products will be made available to the nursery industry and will ultimately benefit the environment and the general public. Ongoing progress has been made in the development of tetraploid and triploid plants in diverse genera of woody taxa. We have developed tetraploids of Acer tartaricum subsp. ginnala (amur maple), Albizia julibrissin (mimosa), Cytisus spp. (Scotch broom), and Ulmus parvifolia (lacebark elm). These plants will be used to develop triploid plants once they reach reproductive age. In addition, we have developed triploid forms of Campsis sp. (trumpet vine), Elaeagnus spp., Euonymus alatus (winged euonymus), Hypericum androsaemum (tutsan St. Johnswort), Koelreuteria paniculata (goldenraintree), Ligustrum spp. (privet), Miscanthus spp. (maiden grass), Pyrus spp. (flowering pear), and Spiraea japonica (Japanese spiraea). These plants are currently being evaluated for commercial merit and fertility. Procedures have been developed for inducing sterility through mutation treatments for Berberis thunbergii (Japanese barberry) and Miscanthus spp. Tissue culture and chromosome doubling procedures have been developed for Acer platanoides (Norway maple) and Miscanthus. Liriope sp. (lily turf) have been established in tissue culture as an initial step in ploidy manipulation. An extensive study was published documenting that triploid H. androsaemum had no detectable female fertility and established methods for evaluating fertility in nursery crops. Three seedless triploid Hypericum androsaemum with attractive leaf variegations have been released to the nursery industry: ‘Pollock’, ‘Matisse’, and ‘Picasso’. Additional studies include analysis of ploidy levels and genome sizes in Berberis and Mahonia; evaluation of the fertility in triploid Miscanthus sinensis clones and Campsis selections. Research activities conducted under this agreement were monitored by regular email communication, submission of reports by the cooperator, and by in-person communication at scientific and stakeholder meetings.