Blockage of mitosis in maize root tips using colchicine-alternatives

Mitosis in plants can be blocked by colchicine which has the capacity to bind microtubule subunits. In maize (Zea mays L.) breeding, it is frequently being used for doubling chromosome numbers of haploids for producing homozygous doubled haploids. However, colchicine is highly toxic for mammals and impacts negatively on the environment. Therefore, it was interesting to find substitutes like chemical compounds and/or physical methods which would be capable of doubling chromosome numbers in maize. For this purpose, a screening system was set up using root tips of maize. Herbicides like amiprophos methyl, oryzalin, and pronamide were identified to be effective in doubling chromosome sets of maize. Additionally, the toxicity of these compounds was lower than that of colchicine and treated seedlings recovered and grew. Therefore, they could be applied in reduced concentrations showing results comparable to colchicine.