Effects of 6-benziladenine, thidiazuron, and 1-naphthaleneacetic acid on the in vitro callus formation and shoot multiplication from leaves of Mai vang (Ochna integerrima) HD01 line

Mai vang (Ochna integerrima (Lour.) Merr.) not only is a popular ornamental plant but also possesses numerous valuable herbal properties. An exceptional line, the HD01, was bred by adept florists at the Binh Loi Mai village, Ho Chi Minh City. The objective of this research was to determine the optimal 6-benziladenine (BA), thidiazuron (TDZ) and 1-naphthaleneacetic acid (NAA) concentrations appropriate for callus formation from leaf samples and regeneration of shoots from callus of the HD01 cultivar in in vitro condition. The study including two experiments was arranged in a completely randomized design with one factor and two factors, respectively. For callus induction, the culture medium supplemented with concentrations of TDZ combined with concentrations of NAA was used, while to induce shoots, concentrations of BA combined with concentrations of NAA were added to the medium. The results indicated that 0.2 mg/L TDZ combined with 0.25 mg/L NAA on the base of MS (Murashige and Skoog) medium supplemented with 7 g/L agar and 30 g/L sugar gave 100% callus formation rate after 17.6 days, with the largest callus diameter (2.7 cm) and highest callus mass (2.4 g) after 60 days of culture. The leaf-derived callus produced the best results when cultured on MS medium supplemented with 7 g/L agar, 30 g/L sugar, and a combination of 1 mg/L BA and 0.25 mg/L NAA, forming shoot clusters with the height of 2.2 cm, an average of 8.5 shoots per cluster and 9.7 leaves per cluster after 60 days of culture. Based on these results, a preliminary protocol for Mai vang HD01 micropropagation was established.