In vitro Cultures and Colchicine-Induced Tetraploidy of Sundew (Drosera spatulata Labill.)

抄録

Sundew (Drosera spatulata Labill.) has become a favorite ornamental plant because of their carnivorous nature, the beauty of their glistening traps and their value as medicinal herb. It is also because of their low propagation rate in their natural environment that in vitro propagation of carnivorous plants is pursued. The objective of this research was to cultivate sundew in vitro to increase its propagation rate. The tetraploid of D. spatulata was induced by the colchicine treatment, providing valuable plant material for further breeding programs. Plantlets of D. spatulata were cultured on MS agar medium (pH 5.4-5.8), and growth and survival rates were observed. The results showed the highest survival of 100 percent in an MS (pH 5.6) medium. Results observed after nine weeks showed that a 1/3MS (pH 5.6) medium promotes the highest growth with an average plant diameter of 25.95 mm. For tetraploids induction, plantlets were immersed in aqueous solutions of colchicine (6 and 12 mg l^-1) for the duration of one week. The effects of different concentrations on survival and growth were recorded. Putative polyploids were identified by stomata density and stomata size. The ploidy level was determined by chromosome counting. The survival rate of treated plantlets decreased in all treatments. The most efficient colchicine concentrations were in the range from 6 to 12 mg l^-1. The chromosome number of the tetraploid plants was 2n = 4x = 40, while that of the control diploid plants was 2n = 2x = 20. The diameter of the tetraploid plants increased, and the length of the leaves and number of inflorescences were more than those of the diploid. The tetraploid plants derived from exposure to colchicine exhibited variations, such as larger stomata and lower density of stomata.