Abstract: In the present study, hairy roots of Stevia rebaudiana were induced by Agrobacterium rhizogenes ACCC10060, and then cultured to produce chlorogenic acids. Furthermore, the effect of methyl jasmonate on the synthesis of chlorogenic acids was also investigated. Leaf explants of Stevia rebaudiana were infected with Agrobacterium rhizogenes ACCC10060, and then co-cultured for inducing hairy roots. After 14 days, hairy roots grew out. The PCR analysis results indicated that the rolB and rolC genes of Ri plasmid in Agrobacterium rhizogenes were successfully transferred into the hairy root genome, which confirmed that the tested induced roots were hairy roots. Compared with B5 and WPM liquid medium, MS was more suitable for hairy root growth and the accumulation of chlorogenic acids. After 35-day culture, the dry weight of hairy roots increased about 30 times, and the maximum contents of chlorogenic acid, 3,5-dicaffeylquinic acid, and 4,5-dicaffeylquinic acid were 3.47, 11.47 and 3.04 mg/g, respectively. Methyl jasmonate solutions at 15, 45 and 100 μmol/L were added into the medium, respectively as an inducer for higher production of chlorogenic acids after three weeks of culture. Both biomass and chlorogenic acid content were increased when the hairy roots were treated with methyl jasmonate for 1, 2, 4 and 8 days respectively. The optimal concentration of methyl jasmonate was 45 μmol/L for chlorogenic acid production. The total yield of chlorogenic acids was increased to 2.68 folds as compared to that of the control group (P < 0.01). These results suggested that Stevia rebaudiana hairy roots could be used to produce chlorogenic acids and that methyl jasmonate treatment could significantly increase chlorogenic acid production.

Key words: Stevia rebaudiana, Agrobacterium rhizogenes, hairy root, methyl jasmonate, chlorogenic acids