Short‐duration colchicine treatment for <i>in vitro</i> chromosome doubling during ovule culture of <i>Beta vulgaris</i> L.

Abstract

Abstract Colchicine uptake into ovules of sugar beet after 7 days of culture and its chromosome‐doubling effect on ovule‐derived plants were studied with high colchicine concentrations (0.4–6.0%) and short treatment duration (0–5 h). The best result of 4.2 diploid plants per 100 ovules was produced by treatment with 0.4% colchicine for 2.5 h. Both colchicine concentration and treatment time of ovules showed toxic effects on embryo formation, but it was stabilized at a low level with short exposure. The chromosome‐doubling effect, by contrast, was unchanged with the colchicine concentrations used, but highly affected by the duration of exposure studied. A maximum percentage of 60% diploid plants was obtained after 3–5 h of uptake, which corresponds to only 31–39% of the total capacity for colchicine uptake in the ovules. Further uptake of the drug produced mainly toxic effects. Flow‐cytometric measurements of the ploidy level in plantlets in vitro and of the same plants before flowering in soil were similar in about 80% of cases. Thus, flow‐cytometric selection of diploid plants in vitro may be an efficient tool.