In Vitro sterilization protocol for callus induction of Baccaurea courtallensis (Wight) Müll.Arg. - An endemic tree of Southern Western Ghats, India

Abstract

Experiments were carried out to establish in vitro culture using terminal and lateral buds of the endemic tree Baccaurea courtallensis of Phyllanthaceae which presented formidable difficulties. Besides the profuse phenol exudation, cultures were infected with intense fungal contamination. Efforts directed to control the schedule by adjusting the concentration of disinfectants NaOCl and HgCl2 with additional rinsing of explants with 70% ethanol and pre-soaking of shoots in various concentrations of the fungicide Bavistin never fetched any success. The intricately connected fungus seems to have found a niche amidst the leaf primordia in shoot apices and the axillary crevices of the nodal regions completely establishing itself in cultures. Perplexed with no remedy in sight, an interesting attempt of quick surface washing with 70% acetone was introduced in the surface sterilization schedule. Fresh explants were quickly rinsed with 70% acetone, followed by 0.1% mercuric chloride, 1% bavistin along with 4% PVP in succession and later wash with sterile distilled water enabling effective establishment of culture. Callus formation was observed on MS and WPM supplemented with auxin and cytokinin. Callus induction from the nodal region was observed at all concentrations and combinations of PGRs supplemented. Maximum induction of callus was obtained from MS medium augmented with BAP 4μM alone and in combination with IBA 1 μM +TDZ 4 μM.