Plant regeneration and ploidy variation in culture derived plants of Asclepias curassavica L.

Clonal propagation of medicinal milkweed, Asclepias curassavica L. (Asclepiadaceae) was achieved by culturing excised nodes on MS medium (Murashige and Skoog, 1962) supplemented with different hormone combinations. Both BAP and Kn were found equally effective for shoot initiation. IAA and NAA were found suitable for root induction. Combinations of Kn and NAA induced both roots and shoots after 30 days of culture. Chromosomal variation was observed in the roots of in vitro regenerated plants. Regenerants with higher chromosome number (33; 2n=22) obtained on MS medium in response to 9.2 μM Kn+10.7 μM NAA showed vigorous growth and higher propagation rates in culture than the plants possessing less than the diploid chromosome number (2n-2=20, 2n-4=18). Such variations are more likely due to genetic fitness of different aneuploids grown on a particular nutrient medium.