Optimizing the micropropagation protocol for the endangered Aloe polyphylla:: can meta-topolin and its derivatives serve as replacement for benzyladenine and zeatin?

Benzyladenine (BA) is the most widely used cytokinin in the micropropagation industry due to its effectiveness and affordability. It, however, has disadvantages such as genetic alteration and abnormal growth in some plants. Naturally occurring zeatin on the other hand is not as widely used as BA and is far more expensive. The use of meta-topolin and its derivatives as alternatives to BA and zeatin, both of which frequently have negative effects in tissue culture was investigated. In vitro grown Aloe polyphylla (an endangered medicinal and ornamental aloe) were cultured on full strength Murashige and Skoog basal medium with different concentrations of cytokinins and solidified with 1% Bacteriological Agar (Oxoid No. 1). mT was the preferred cytokinin both in terms of multiplication rate and rooting. The optimum concentration that induced regeneration and rooting is 5.0 mu M. The problem of hyperhydricity was totally controlled. Plants rooted spontaneously in multiplication medium, thus avoiding the extra rooting step of the protocol. More than 91% of the plants transferred to ex vitro conditions were successfully acclimatized.