Effect of Different Concentration of Colchicine on Some Morphological and Phytochemical Characteristics of Dracocephalum Kotschyi Boiss

Background and ObjectivesDracocephalum kotschyi Boiss. (Labiateae) is an endemic perennial herbaceous plant known in Iran as Zarrin-Giah. Recent pharmacological studies have confirmed some of the methoxylated flavonoids in plant’s parts having anti-cancer properties. Excessive harvesting of wild plants and limited distribution areas are the main reasons why D. kotschyi is now listed as an endangered plant. Polyploidy induction is an effective tool in medicinal plant breeding. Chromosome duplication and polyploidization may affect plant morphology and breeding systems, ultimately enabling the release of improved genotypes.
Materials and Methods In this study, an efficient procedure was established for successful induction of tetraploid D. kotschyi by treating diploid explants with colchicine in horticulture laboratory of Urmia University during 2014-2015 years. Seedlings apical meristem treatment was carried out in two growth phases including, the two and four-leaf plants through presoaking manner. Colchicine at a concentration of 0, 0.05, 0.1, 0.2 and 0.5 % (w/v) was applied in each of these stages. Cytological and morphological evidence confirmed the results of flow cytometry analysis.
Results Cytological analyses showed the increase of chromosome numbers from 2n=2x=20 to 2n=4x=40. The results of this study demonstrated for the first time that chromosome counting in D. kotschyi of a total of 165 surviving seedlings, 7.27% was found to be tetraploids, 13.3% was chimers while the remainder were diploids. Tetraploid plants demonstrated significantly longer stomata and a higher stomatal index compared with diploid control plants. Negative correlation between stomata size, plants height, leaf number and lateral shoot number was obtained in treated plants. The total content of flavonoids increased from 1583.28 in diploids to 1890.07 (μg/g DW) in stable tetraploids.
Discussion It seems that 0.5% of colchicine can be used as an effective treatment for polyploidy induction in D. kotschyi.