SOFIA, Bulgaria
Institute of Genetics, Bulgarian Academy of Sciences
In vitro colchicine - mediated doubling of corn maternal haploids --Nedev, T, Gadeva, P, Krapchev, B, Kruleva, M Experiments have been made with colchicine, dimethyl sulfoxide (DMSO), and Tween 80 (Fluka AG, Buchs SG) to optimize dose treatment combination for double halpoidization (DH) plants. Maternal haploids were derived from dry seeds. Corn genotype, Ig1IRL - 93 - 18/8 - 6 x A 654, was used in this investigation. Seeds were surface sterilized with 70% ethanol, followed by sodium hypochloride solution, washed a few times with autoclaved tap water and transferred onto three variants of artificial medium: colchicine; colchicine plus DMSO; colchicine plus DMSO plus Tween 80. Different concentrations and different durations for components of variants were examined. Regarding procedures for colchicine preparation, concentration, and treatment duration, please see our publication in Maize Genetics Cooperation Newsletter No 73. After treatment, seeds were rinsed with sterile water and transferred onto medium free of colchicine to promote germination. The ploidy status of the plants obtained was determined by chromosome counting of germinated root tip cells. Experiments performed have shown that variations of chromosome number, including aneuploidy, diploidy and polyploidy were observed. Depending on combination used, different percentages of DH plants were obtained. Considering the total number of cells counted, the colchicine (for the best concentration and treatment duration, please see our publication in Maize Genetics Cooperation Newsletter No 73), DMSO and Tween 80 medium was very effective. The greater frequency of DH plants on the colchicine plus DMSO plus Tween 80 medium is probably due to slow penetration of these substances, which maybe favors and allows more doubling. From our point of view, these results clearly demonstrate the high potential of such treatment in acting as a chromosome doubling agent.

In summary, the results of this study suggest that the combination of colchicine plus DMSO plus Tween 80 optimized chromosome doubling of corn dry seeds of genotype Ig1IRL - 93 - 18/8 - 6 x A 654.

This work was supported by grant B-602 from the National Fund of Scientific Investigations of the Bulgarian Ministry of Education and Science.

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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