Abstract
Melia azedarach L. is a valuable source of antioxidants and secondary metabolites. This study is a first extensive report about the effect of different serialization protocols and plant growth regulators (PGRs) on explant disinfection efficiency, callus induction and secondary metabolites production and accumulation in callus cultures of M. azedarach L. In this regard, the effect of plant growth regulators on callus induction and secondary metabolites production were examined. In addition, different sterilization agents were evaluated for disinfection of chinaberry leaf explants. The results showed that the lowest percentage of explant contamination and browning with the highest percentage of callus induction and callus growth obtained with explants pretreated with benomyl (2 g/L) for 2 h and sterilized with 7% H2O2 for 10 min and NaOCl 2% (without pH adjustment) for 12 min. Although adjusting the pH of NaOCl to pH = 7 and 10 significantly reduced the microbial contamination and increased the percentage of contamination-free cultures of M. azedarach L., adversely influenced the explant viability and callus induction and growth. The highest percentage of callus induction obtained on the MS medium containing 3 mg/L NAA/2,4-D and 1 or 3 mg/L Kin/BAP, and the highest callus yield (1804.833 mg/explant) belonged to the MS medium supplemented with 5 mg/L 2,4-D and 5 mg/L Kin. The callus cultures grown on the MS medium supplemented with 3 mg/L NAA and 1 mg/L Kin produced the highest amount of Quercetin (2.06 mg/g fresh weight), Rutin (5.56 mg/g fresh weight) and Kaempferol (1.84 mg/g fresh weight).