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United States Department of Agriculture

Agricultural Research Service


Location: Southern Horticultural Research

2012 Annual Report

1a. Objectives (from AD-416):
Develop improved germplasm for ornamental plants and small fruit crops adapted to the Gulf Coast Region. Research will also determine genetic factors that regulate plant disease, growth characteristics, and tolerance to environmental stress, as well as accelerate the development and release of improved cultivars for production. Develop molecular tools, such as TILLING (Targeting Induced Local Lesions IN Genomes)and/or microarray methods to identify and/or map Quantitative Trait Loci (QTLs), candidate genes, and/or “functional genetic markers” for cold tolerance, drought tolerance, and/or pest and pathogen resistance in priority ornamental genera for the Gulf States, including Cercis (redbud), Cornus (dogwood), and Hydrangea in collaboration with university and U. S. National Arboretum cooperators, to enhance breeding programs of woody landscape plants.

1b. Approach (from AD-416):
Identify desirable traits in small fruit and ornamental plants, develop improved varieties using traditional and modern genetic methods, and release superior germplasm in order to increase profitability of small acreage farms in the Gulf Coast Region. Germplasm from established cultivars, wild clones, and their hybrids will be cooperatively evaluated at USDA-ARS and University Experiment Stations throughout the southeastern United States. Small fruit cultivars that are released will have improved vigor and fruit quality, expanded ripening seasons including earlier harvests, enhanced adaptation, greater productivity with larger yields, improved fresh or processing berry qualities, and enhanced suitability for mechanical harvesting. This research project, combined with cooperative testing and technology transfer efforts with land grant universities, will develop superior cultivars for rabbiteye and southern highbush blueberry, muscadine grapes and other small fruit. Because the ornamental commodity comprises hundreds of plant species, target genera will be selected for improvement from both herbaceous perennials and woody landscape crops. Superior ornamental cultivars that are released will have increased disease resistance and enhanced ornamental qualities including greater aesthetic appeal. In addition to traditional breeding to develop superior ornamental cultivars, this project plan also includes molecular genetic research to accelerate breeding of woody landscape plants by shortening the evaluation, selection, and release cycle. In total, ornamental research described in this plan will impact new cultivar development for crapemyrtle, hibiscus, begonia, butterfly ginger, Dichroa, redbud, fringe tree, and dogwood.

3. Progress Report:
Genetics research on small fruits and ornamental plants is focused on the development of new germplasm and cultivars with adaption to the Gulf Coast region of the U.S. Small fruit research is focused on conventional breeding to enhance commercial production of blueberries and muscadine grapes. Early ripening, high productivity, and superior fruit quality are the top breeding goals for rabbiteye and southern highbush blueberries. Blueberry breeding also includes improved berry storage and handling, taste and nutritional value. More than 100 crosses were completed among rabbiteye and southern highbush blueberry parents. New selections were planted in field conditions to evaluate performance. Approximately 8,000 blueberry seedlings from the previous season’s breeding efforts were established as progeny for initial selection for fruit quality. Muscadine grape selections, including new seedlings from last year’s breeding efforts, were established in field plantings for evaluation. Research on ornamental plants includes modern genetic methods, conventional breeding, and tissue culture. Because of the immense diversity within the nursery and greenhouse industry, research is underway on a wide variety of ornamental crops including crapemyrtle, hibiscus, begonia, hydrangea, redbud, fringe tree, and dogwood. Elite crapemyrtle selections with improved disease resistance in combination with dark purple, dark red, pink or white flowers have been evaluated and selections have been made for release. Cold-hardy begonia germplasm that was improved to include more desirable horticultural traits has been selected for release. A new variegated ornamental ginger cultivar ‘Ramata’ has also been released. Linkage mapping is underway in Hydrangea macrophylla. Further analysis will link the expression of newly discovered genes with important traits. Molecular markers were also developed for two native ornamental trees, fringe tree and redbud. These markers were used to show relatedness between cultivars and species to better understand the resources available for breeding. Markers are also being used to better understand population differences among stands of native trees such as dogwood, redbud and fringe tree.

4. Accomplishments

Review Publications
Stringer, S.J., Draper, A., Spiers, J.M. 2012. 'Pearl' Southern Highbush Blueberry. International Journal of Fruit Science. 12:1-3,246-248.

Hadziabdic, D., Wang, X., Wadl, P., Rinehart, T.A., Ownley, B., Trigiano, R. 2012. Genetic diversity of flowering dogwood in the Great Smokey Mountains National Park. Tree Genetics and Genomes. 8(4):855-871. DOI 10.1007/s11295-012-0471-1.

Akond, G., Pounders Jr, C.T., Blythe, E., Wang, X. 2012. Longevity of crapemyrtle pollen stored at different temperatures. Scientia Horticulturae. 139:53-57.

Stringer, S.J., Draper, A., Marshall, D.A., Spiers, J. 2012. 'Gupton' southern highbush blueberry. HortScience. 47(2):293-295.

Sakhanokho, H.F., Witcher, A.L., Pounders Jr, C.T., Spiers, J. 2012. 'Ramata': a new dwarf and variegated Hedychium J. Koenig cultivar. HortScience. 47(6):803-805.

Cheng, Q., Windham, A.S., Klingeman, W.E., Sakhanokho, H.F., Saxton, A.M., Li, Y., Windham, M. 2011. Histological investigation of infection processes of Discula destructiva on leaves of Cornus florida. Canadian Journal of Plant Pathology. 33:525-531.

Wadl, P.A., Saxton, A.N., Wang, X., Pantalone, V.R., Rinehart, T.A., Trigiano, R.N. 2011. Quantitative trait loci associated with red foliage in Cornus florida L. Molecular Breeding. 27:409-416.

Wadl, P.A., Dattilo, A.J., Scheffler, B.E., Trigiano, R.N. 2011. Development of microsatellite loci for the endangered species Pityopsis ruthii (Asteraceae)1. American Journal of Botany. 0:e1-e4.

Dean, D., Wadl, P.A., Trigiano, R., Wang, X., Klingeman, W., Ownley, B.H., Rinehart, T.A., Scheffler, B.E. 2011. Screening and characterization of eleven novel microsatellite markers from Viburnum dilatatum. HortScience. 46(11):1456-1459.

Rajasekaran, K., Sakhanokho, H.F., Tabanca, N. 2012. Antifungal activities of Hedychium essential oils and plant extracts against mycotoxigenic fungi. Journal of Crop Improvement. 26:389-396.

Hadziabdic, D., Wadl, P.A., Boggess, S.L., Scheffler, B.E., Windham, M.T., Trigiano, R.N. 2011. Development and characterization of sixteen microsatellite loci for Geosmithia morbida, the causal agent of thousand canker disease in black walnut (Juglans nigra). Conservation Genetics. 4(2):287-289.

Wadl, P.A., Trigiano, R.N., Werner, D.J., Pooler, M.R., Rinehart, T.A. 2012. Simple sequence repeat markers from Cercis canadensis show wide cross-species transfer and use in genetic studies. Journal of the American Society for Horticultural Science. 137:189-201.

Last Modified: 10/17/2017
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