S05 - Session P4 - Phenotypic and ploidy level Evaluation of Echeveria Viyant species using colchicine

Authors: Khanh Ha *, Raisa Aone M. Cabahug, Ki-Byung Lim, Yoon-Jung Hwang

Mutation breeding, by exposing planting materials to mutagens, is known as one of the effective tools that can produce mutants with desirable characteristics, increased pest and disease resistance, and visual quality. Breeders and growers have employed mutagenesis to improve the quality of ornamental plants and other crop varieties because this method has overcome the limitations of conventional methods (i.e. long production time and low mutation rates). Chemical mutations are more widely used than physical ones as it is inexpensive, and has high indices of mutation induction. Echeveria genus, known as succulents, has a high potential demand in horticulture communities due to its attractive color, and variation in leaf formation. Colchicine was employed to test its application on E . 'Viyant' ( E. cuspidata var. Zaragozae × E. lauii ) at four durations (3, 6, 9, and 12h) and five concentrations (0.2, 0.4, 0.6, 0.8, and 1%; v/w%). The results revealed that leaf cuttings treated at higher concentrations (0.4% - 1%) produced more mutants, whereas those treated at 6h had higher survival rates than those treated at 3h and 12h. To confirm plant mutants, leaf phenotypic evaluation and ploidy analysis of colchicine-treated leaf cuttings were done. Results suggest that there was a decrease in plant height (2-87%), diameter (1-100%), number of leaves (30-200%), and increased leaf width (6-30%) and thickness (6~83%). These differences were significantly different compared to the control. Mutants produced from the application of colchicine on the leaf cuttings of E. 'Viyant' exhibited plant compactness and widened leaf apex which was found visually distinct from control plants. Mutant plants were also found to have darker hues changing from greyed-green to grey-brown color group. Flow cytometry peaks were displayed at 2x for the control, while MV 1 plants exhibited a 2x-4x complex. The results of this study highly provide technical guidance for the production of new cultivars for other succulent ornamental plants or related species.