Overproduction of valuable methoxylated flavones in induced tetraploid plants of Dracocephalum kotschyi Boiss

Ploidy manipulation is considered an efficient method to increase production potential of medicinally important compounds. Dracocephalum kotschyi Boiss. is an endangered medicinal plant of Iran. Various concentrations of colchicine (0.05, 0.10, 0.20, and 0.50% w/v) were applied to shoot apical meristems of D. kotschyi seedlings in two and four-leaf stages to induce tetraploidy. According to the results, 0.5% (w/v) of colchicine can be effective for polyploidy induction in D. kotschyi. Putative tetraploids were selected by morphological and microscopic characteristics and their ploidy level was confirmed by flow cytometry analysis and chromosome counting. The chromosome number of original diploid plant was confirmed to be 2n = 2x = 20 whereas that of the tetraploid plant was 2n = 4x = 40. Tetraploid and mixoploid plants showed different morphological, physiological and microscopic characteristics from those of diploid counterparts. The total content of flavonoids was increased from 1583.28 in diploids to 1890.07 (mu g/g DW) in stable tetraploids. High-Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD) confirmed over accumulation of methoxylated hydroxyflavones in solid tetraploid plants of D. kotschyi.