Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 24, 2012
Publication Date: November 1, 2012
Citation: Nadler, J.D., Pooler, M.R., Olsen, R.T., Coleman, G. 2012. In vitro induction of polyploidy in Cercis glabra Pamp. Scientia Horticulturae. 148:126-130. Interpretive Summary: Redbuds (genus Cercis) are valued in the landscape for their showy pink to magenta pea-like flowers that emerge in early spring before leaf flush. The U.S. National Arboretum has an ongoing breeding program aimed at developing redbud cultivars that are disease and pest resistant, tolerant of environmental stresses, and have superior ornamental attributes. In addition, research is underway to develop techniques to create seedless forms of woody ornamental plants. This paper describes efforts to create tetraploid forms of Chinese redbud (Cercis glabra) using in-vitro methods. These tetraploid plants can then be hybridized with diploid plants to create superior varieties of seedless triploids.
Technical Abstract: Methods for in vitro induction of polyploid Cercis glabra Pamp. using oryzalin were developed and evaluated. Methods included treating shoot or callus cultures for different exposure durations with either an aqueous solution of 150 µM oryzalin or by inclusion of oryzalin into solidified culture media. Polyploidy induction by the various oryzalin treatments was assayed by measuring nuclei DNA content using flow cytometry. Results indicate that treating either apical or lateral buds from in vitro shoot cultures with an aqueous solution of oryzalin for 12 to 96 hours produced tetraploid plants irrespective of the type of bud treated. In contrast, shoots cultured on the solidified media containing oryzalin failed to produce polyploid nuclei. Using aqueous treatments of oryzalin and shoot cultures polyploid Cercis glabra plants were successfully rooted and produced. Although an increase in the frequency of polyploidy nuclei was detected in callus cultures grown on media containing orzyalin, these treatments significantly reduced callus growth and viability. Results from this study indicate that aqueous treatment of in vitro grown shoot cultures may provide an efficient and simple method for the generation of polyploidy plants.