Objective: To study effects of the cycle of light and exogenous plant growth regulators on growth of normal root and hairy root of Lycium barbarum and establish a long-term system of in vitro culture of L. barbarum roots.
Method: Using normal roots from aseptic seedlings and hairy roots originated from Agrobacterium rhizogenes A4-mediated genetic transformation of L. barbarum, the growth of root segments was examined after 20 days of culture under different culture conditions.
Result and conclusion: When cultured on the MS medium with different plant growth regulators (IAA, IBA, NAA), normal root segments of L. barbarum could elongate and branch, and the addition of 1 mg x L(-1) IBA into the medium was the most suitable for long-term in vitro culture of L. barbarum root. When cultured on MS medium without hormone, light promoted the elongation and lateral root formation of type II hairy root, but not of type I hairy root. Among three tested hormones, IAA at low concentration was the best for growth of type I hairy root, while 1 mg x L(-1) IBA was the most suitable for growth of type II hairy root. With the increase of hormone level added into MS medium, callusing frequencies of type I, II hairy roots were increased, at the same time, the formation of lateral root from hairy root or callus was inhibited.