Callogenesis in leaves of Kalanchoe pinnata Lam. by 2,4-D and BA action

The Kalanchoe pinnata Lam. is a bush species of the Crassulaceae that is distinguished by its important medicinal properties. Its leaves are used as cataplasm to treat headaches and wounds. There is evidence for a hypotensive and anti-inflammatory effect. Techniques of plant tissue culture have been applied to plant species that produce substances likely to be explored in pharmacology, cell suspension being the main technique. At the industrial level, this method utilizes bioreactors in order to produce secondary metabolites on a large scale. The objective of this study was to evaluate the effects of in vitro combinations of 2,4-dichlorophenoxiacetic acid (2,4-D) and benzylaminopurine (BA) on callus induction in leaf explants of K. pinnata. Leaf fragments were inoculated in MS medium supplemented with 3.0% sucrose, 0.8% agar and factorial combinations of 2,4-D (0.00, 4.52, 9.06, 18.12 µM) and BA (0.00, 4.44, 8.88, 17.76 µM). The cultures were kept in the darkness at 24±2ºC for 50 days. The percentage of callus induction and the area of explants covered by callus cells were evaluated. In the absence of growth regulators, callus induction did not occur, with necrosis of all explants. The highest percentage of callus induction was 100%, obtained with the combination of 9.06 µM 2,4-D and 8.88 µM BA, but the calluses covered only 25% of the leaf area. The most efficient combination was 4.52 µM 2,4-D and 8.88 µM BA, resulting in 91% callus induction with 50 to 100% of the explants being covered by callus cells