|Nyochembeng, Leopold -|
|Islam-Fardi, Nurul -|
Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: August 23, 2010
Publication Date: June 1, 2012
Citation: Sakhanokho, H.F., Rajasekaran, K., Sampson, B.J., Nyochembeng, L., Pounders Jr, C.T., Wedge, D.E., Islam-Fardi, N., Spiers, J.M. 2012. Induced polyploidy and mutagenesis of embryogenic cultures of ornamental giner (Hedychium J. Koenig). Acta Horticulturae. 935:121-128. Interpretive Summary: Hedychium (ornamental gingers or ginger lilies) are popular because of their showy and scented flowers, but they are mainly planted in the landscape because they are generally too tall to be grown as potted plants. Also, although Hedychium plants are much heralded for the diversity of their showy flowers, other desirable ornamental traits such as variegated foliage are lacking. Treatment of plants with the chemicals colchicine and oryzalin can lead to polyploidy or increased chromosome number, which is sometimes associated with reduced plant height. Treatment of plants with the mutagens sodium azide (NaN3) and ethylmethanesulphonate (EMS) can produce plants with variegated foliage. Therefore, a study was conducted to develop short and compact plants on the one hand and variegated plants on the other. In vitro cultures of Hedychium bousigonianum were subjected to various concentrations of colchicine or oryzalin, which led to increased chromosome numbers and the creation of dwarf forms for this species. Also, application of sodium azide to the hybrid Hedychium muluense x ‘White Starburst’ produced plants with variegated leaves. Hedychium muluense x ‘White Starburst’ is a dwarf plant, so the newly created plant is both dwarf and variegated.
Technical Abstract: Hedychium J. Koenig is among the largest genera of Zingiberaceae. These plants are increasingly being used as ornamentals worldwide because of their diverse and showy, scented flowers. Hedychium plants are mainly planted in the landscape because they are generally too tall to be grown as potted plants. In 2004, a Hedychium breeding program was initiated at the USDA-ARS research station in Poplarville, Mississippi, where new and efficient tissue culture protocols were developed for micropropagation and other in vitro manipulations, including the induction of polyploidy and mutagenesis in selected cultivars and species. For example, polyploidy was successfully induced in several Hedychium hybrids and species, including H. bousigonianum, leading to the creation of dwarf forms of this species. Embryogenic calli from selected Hedychium species and hybrids were subjected to various concentrations of sodium azide (NaN3) and ethylmethane-sulphonate (EMS) to induce mutations. H. muluense × ‘White Starburst’ calli treated with 20 mM NaN3 for 6 hours produced variegated plants. However, no variegation was obtained with EMS treatments. These in vitro assisted breeding techniques are accelerating the development of new and improved Hedychium cultivars.