Induction and identification of tetraploid Hedychium coronarium through thin cell layer culture

Abstract

To shorten breeding progress of Hedychium coronarium, application of colchicine to thin cell layer (TCL) was carried out to induce tetraploid plants. The shoots from rhizomes were cultured on induction medium: Murashige and Skoog (MS) medium, 0.2 mg/L indole-3 acetic acid (IAA), and 3 mg/L 6-benzyladenine (BA). The obtained adventitious buds were transferred to rooting medium containing 1/2 MS medium, and 1 g/L activated charcoal for plantlets development. TCLs excised from the stem base of the plantlets were cultured on induction medium; average 9.7 buds were obtained from one plantlet after 4 weeks culture and generated into plantlets on rooting medium. TCLs were treated with three concentrations of colchicine for 24 h and cultured with the above TCL culture system. Eight tetraploid plants and two ones were derived from 0.4% and 0.2% colchicine treatments, respectively. The chromosome number of tetraploids was 2n = 4x = 68 and that of diploids was 2n = 2x = 34. The width and length of leaf, plant height and net growth of rhizome of tetraploids were higher than those of diploids. Leaf angles of tetraploids and diploids exhibited significant difference at different positions. The stomata size of the tetraploids was significantly larger than that of diploids. The tetraploids developed larger flower and pollen grain. Prolonged flower longevity was observed with 56% increase compared with diploids. All this showed that the TCL culture system was suitable for induction of tetraploid Hedychium coronarium, and the tetraploids exhibited desirable field characters and longer flower longevity, all contributing to higher ornamental value of Hedychium coronarium.