Optimisation of the tissue culture protocol for the endangered Aloe polyphylla

Abstract

An optimised, rapid tissue culture protocol was established for the highly endangered Aloe polyphylla (Schonland ex Pillans). Shoot cultures of Aloe polyphylla were initiated from young shoot explants of in vitro grown plants. The basal medium was MS medium (Murashige and Skoog 1962), supplemented with 100mgl - 1 myo-inositol, and 30gl - 1 sucrose. Different cytokinins (kinetin, zeatin and BA) singly or in combination with auxins (IBA and NAA), were tested for shoot proliferation activity. All the cytokinins gave good shoot proliferation. The optimal concentrations for shoot proliferation of each of the cytokinins tested were: zeatin (0.5mgl - 1 ), kinetin (1.5mgl - 1 ) and BA (1.5mgl - 1 ). In combination with auxins, the optimal combinations were kinetin/NAA (2.0/0.1mgl - 1 ), kinetin/IBA (1.5/1.0mgl - 1 ), zeatin/IBA (1.0/0.5mgl - 1 ), zeatin/NAA (1.0/1.0mgl - 1 ), BA/IBA (1.0/1.0mgl - 1 ) and BA/NAA (1.5/0.1 mgl - 1 ). Although it gave the highest number of shoots per explant, BA (1.0–3.0mgl - 1 ) induced hyperhydricity. Temperature and sucrose also influenced shoot proliferation. The optimal temperature was 25 °C, while 30gl - 1 was the optimal concentration of sucrose. Plants rooted well in plant growth regulator-free MS medium. Amongst the potting mixtures tested, soil:sand:vermiculite (1:1:1 v/v/v) was the best, with a 98% plantlet survival.