Anatomical, morphological, and physiological changes in colchicine-treated protocorm-like bodies of Catasetum pileatum Rchb.f. in vitro

Abstract

Abstract Catasetum pileatum Rchb.f. is an important potting and cutting plant. This is the first report trying the polyploid induction in C. pileatum Rchb.f. Protocorm-like bodies (PLBs) explants of this orchid species were treated in vitro with different colchicine concentrations (0.00, 1.00, 2.00, 3.00, 4.00 and 5.00 mg l–1) and exposure time (24, 48 and 72 h) to induce polyploidy. Flow cytometry, chromosome counting (karyotype), and some anatomical, morphological, and physiological parameters were used to detect polyploidy induction. Treatment of 4.00 mg l–1 colchicine for 72 h resulted in a mixoploid plantlet. Results showed that none of the treatments induced tetraploidy or other levels of polyploidy, but changes in anatomical, morphological, and physiological parameters were observed. Differences in anatomical, morphological, and physiological parameters between treated plantlets were significant. The chromosome number detected by chromosome counting was 2 n = 2x = 54 in diploids. The largest size of stoma guard cells and maximum number of these cells was obtained in leaves of plantlets treated with 4.00 and 3.00 mg l–1 colchicine both for 72 h, respectively. The highest fresh and dry weights of plantlets and chlorophyll index in leaves was obtained in plantlets treated with 4.00 mg l–1 colchicine for 48 h. Average survival rates from treatments were greater than 90%.