Induction and identification of polyploidy by colchicine treatment in Lilium regale

Abstract

In order to produce an autotetraploid population of Lilium regale, different concentration of colchicine was used as chemical mutagen treatment to induce in vitro polyploidy. Bulb scales were soaked in various filter sterilized colchicine solutions (0.01, 0.05 and 0.1%) for 6, 12 and 24h separately, then bulb scales were shifted to colchicine free MS medium for regeneration and normal growth. The ploidy level of the regenerated plantlets from treated bulb scales was estimated by chromosome counting in root tips. However, the length of stomatal guard cell, density and chloroplast number guard cell used as cytological parameters to compare between diploid and polyploid plantlets. The results of the experiment showed that high tetraploid plantlets (27.3%) were produced by 0.01%+ 24h colchicine treatment. However, the highest survival rate (72%) was observed in 0.01%+ 6h colchicine treatment. The stomatal number was reduced significantly (p≤0.01) in tetraploid compared to diploid. The result of the evaluation revealed that an increase in the length of stomatal and chloroplast number guard cell was found in polyploid plantlets as well as a reduction in stomatal number per unit area. It is found that colchicine at rate 0.01% for 24h was the most effective treatment in inducing polyploidy in L. regale plantlets.