Effective in vitro culture using dormant bud of nodal sections from a mature Acacia tree

The micropropagation system described is a commercially viable method for asexual propagation of a mature 'elite' tree of Acacia confusa. The main stem of a mature tree was hardly pruned to induce new shoots for the explants. This study showed that PPM (TM) (Plant Preservative Mixture) was an effective agent for controlling the contamination of nodal explants and was added to the initial culture medium. This medium consisted of Murashige and Skoog (MS) basal salts and vitamins, supplemented with 4.0 mg L-1 BA, 0.1 mg L-1 IBA, 10 mg L-1 GA, 12 mg L-1 AS, 3.2 g L-1 PVP, and 2.0 mL L-1 PPM (TM), and was adequate for the establishment of in vitro mother stock for proliferation. The excellent growth response of nodal explants, obtained from May to July in 2019 to 2020, had shoot formation rate ranging from 15.8 to 18.5%. The optimal shoot multiplication was derived on MS medium supplemented with 1.0 mg L-1 BA, 0.5 mg L-1 TDZ, 12 mg L-1 AS, and 500 mg L-1 glutamine which could support feasible 23.7 +/- 3.4 shoot proliferation per explant. Shoots generated in vitro with a length of 3 to 5 cm were excised and cultured on MS with 1.0 mg L-1 IBA for rooting. The rooting frequency could be increased to 72.2% within 6 wk. Rooted plantlets in vitro were acclimatized for 4 wk before transplanting to the pots in a greenhouse.

Automated summary

The micropropagation system for Acacia confusa is a viable method for asexual propagation of mature 'elite' trees, using effective plant growth regulators and control of contamination. With optimal conditions and media, successful establishment of in vitro mother stock and efficient plant growth and root development were achieved.