Journal of Taiwan Agricultural Research

Author:Wha-Shin Hsu, Li-Chun Huang, Pan-Chi Liou, Yin-Huay Cheng, You-Ming Chang and Chi-Hsiung Hsiao

Abstract:

Lycoris aurea is an important native tuberous flowering plant in Taiwan. People are favorably impressed with its noble and attractive flowers. Unfortunately, owing to less genetic variability, L. aurea has only little color diversities and almost only one unique flower type can be seen in the market. We are trying to solve this problem through artificial mutagenesis. In December 1997, we treated bud primordia of in vitro shoot with chemical mutagens, including 5-azacytidine (5-Ac), ethyl methane sulfonate (EMS), and colchicine. The various concentrations and exposure duration were used including one day immersion separately in 0.05, 0.5, 5, and 50mM 5-azacytidine; one hour treatment in 0.1, 0.2, or 0.5% EMS suspension; and 0.1 and 0.2% colchicine separately for one and four days exposure. Besides we repeated the cochicine treatments (0.05, 0.1, 0.2% colchicine for 1, 2, 4 days immersion) in May 2000. In this study we found an increase of the concentrations of various chemical mutagens along with a greater toxicity and lethality in the mutagen-treated explants. The highest regeneration ratio (52%) was found in 0.5 mM azaC for 1-day treatment and the lowest ratio (2.5%) was found in 0.2% colchicine for 1-day treatment in the former experiment one month after treatments. The major phenotypic variations appeared in cultured mutant including etiolated leaves base, curve and thicken leaves. The variation ratio of cultured mutant were over 50% for all treatments, even the CK (without any chemical treatment) also has 5% somaclonal variation. Mutants with variegated and etiolated leaves were found in 0.5mM azaC for 1-day treatment after transplanting to field. No differences in chromosome number (2n = 2x = 14) in the former experiment were found however a ploidy chimeras were found in the later experiment (such as 2n = l0x - 2 = 68 in 0.2% colchicine for 4 days treatment). According to the cytological data, it revealed that something changed in genomic DNA level. The morphological changes on flower color and types have not yet collected since it took 4 - 5 years for growing the flowering bulbs. We hope that using this approach the efficiency of variety improvement on L. aurea could significantly enhance, therefore benefiting the development of the L. aurea industry.

Key words:Lycoris aurea Herb., Chemical mutagen, 5-Azacytidine (azaC), Ethyl methane sulfonate (EMS), Colchicine, Chromosome analysis

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