Efficient plant regeneration and callus induction from nodal and hypocotyl explants of goji berry (Lycium barbarum L.) and comparison of phenolic profiles in calli formed under different combinations of plant growth regulators

Goji berry (Lycium barbarum L.) is a fruit that has many beneficial effects (such as antidiabetic, antioxidant, anticancer, antidepressant, and immunomodulatory) on human health because of several dietary constituents such as phenolics, vitamins, carotenoids, and polysaccharides. In order to develop in vitro culture protocols for callus induction and plant regeneration from different explants of Goji plants and to compare the phenolic composition in calli of different origin, various combinations of plant growth regulators (PGRs) were applied. Various types of explants (leaf, petiole, root, hypocotyl, and node) were cultured on MS medium containing 28 different concentrations and combinations of PGRs [thidiazuron (TDZ) and naphthalene acetic acid (NAA), TDZ and indole-3-acetic acid (IAA), benzyl adenine (BA) and NAA, alone TDZ, and alone BA]. The highest mean number of shoots (23.33 +/- 1.86) and percentage of shoot formation (100%) were obtained from nodal explants on medium containing 0.5 mg/l BA alone. The highest mean callus diameter was obtained from hypocotyl explants on medium containing 0.25 mg/l TDZ and 0.1 mg/l IAA (21.40 +/- 0.71 mm). The amounts of selected phenolic substances were significantly different in the callus obtained from different PGRs or combinations, individually. The combination of BA/NAA significantly increased the production and accumulation of chlorogenic acid and caffeic acid. The TDZ/IAA combination, TDZ alone, and TDZ/NAA combination significantly increased vanillic acid and rutin, gallic acid, and quercetin synthesis, respectively. These outcomes indicate that different PGRs lead to the production of different kinds of secondary metabolites and affect/accelerate accumulation in the callus of goji berry. The culture protocol described in this paper could be employed for the development of novel methods for the commercial production of goji secondary metabolites.