No abstract

Salvia castanea Diels f. tomentosa Stib. is an endemic medicinal plant distributed in China, and the notably high content of tanshinone IIA in the root is proven effective for the therapy of heart diseases. Hairy root induction of this Salvia species was inoculated with Agrobacterium rhizogenes strain ATCC 15834. Transformed hairy root was cultured in 6,7-V liquid medium for growth kinetics assessment and elicitation. An S curve was present in the hairy root cultures based on the fresh and dry weights with an interval of 3 days. An optimum concentration of the applied elicitors (15 μM Ag(+), 200 μM methyl jasmonate, and 200 mg l(-1) yeast extract elicitor) benefitted both the growth status and tanshinone accumulation in the hairy root cultures. Tanshinone IIA contents were mostly stimulated 1.8-fold and 1.99-fold compared with the control by Ag(+) and methyl jasmonate elicitation, respectively. Yeast extract dramatically enhanced dry mass accumulation, while it promoted cryptotanshinone content of 2.84 ± 0.33 mg g(-1) dry weight at most in the hairy root cultures. Selected elicitors diversely influenced tanshinone accumulation in the time courses of hairy root cultures within 7 days. Furthermore, transcripts of selected genes in the tanshinone biosynthetic pathway were remarkably upregulated with elicitation. Yeast extract elicitor heightened 13.9-fold of isopentenyl diphosphate isomerase expression level at 12 h, while it increased 16.7-fold of geranylgeranyl diphosphate synthase transcript at 24 h compared with that of the control, which was more effective than Ag(+) and methyl jasmonate. This study provided a convenient hairy root culture system of S. castanea Diels f. tomentosa Stib. for tanshinone production for the first time.

Prunella vulgaris L. hairy roots: Culture, growth, and elicitation by ethephon and salicylic acidHairy roots have gained popularity as an alternative source for secondary metabolites not only because of their biosynthetic and bioactive potentials, but also because of studies of experimental systems aiming to understand secondary metabolic pathways. While many secondary metabolites have been identified in Prunella vulgaris, a comprehensive understanding of the metabolic pathways has remained elusive. Here, Agrobacterium rhizogenes (ATCC15834)-mediated hairy root induction of P. vulgaris resulted in 15-30 times more rosmarinic acid (RA) than in the intact plant. After the growth and RA biosynthesis of P. vulgaris, hairy roots were investigated over a 1-month period, we studied elicitation by ethephon (Eth) and salicylic acid (SA) and found 200 μg L −1 Eth and 6.9 mg L −1 SA exhibited the optimum induction efficiency. These concentrations were further selected for a time-course assay of hairy root cultures to assess exposure to these compounds over 8 days. During that period, RA reached maximum accumulations of 1.66-fold 8 days after Eth elicitation and 1.48-fold 2 days post-SA addition. We also examined the transcripts of genes involved in the RA biosynthesis pathway, and found the expression of tyrosine aminotransferase (TAT) and phenylalanine ammonia-lyase (PAL) were increased by Eth, and SA heightened the expression of TAT, 4-hydroxyphenylpyruvate reductase (HPPR), PAL, 4-coumaric acid CoA-ligase 1 (4CL1), and cytochrome P450-dependent monooxygenase (CYP). Altogether, our results indicate that the convenient hairy root culture system of P. vulgaris can provide an alternate source for RA production and would be conducive for the engineering of secondary metabolic pathways in P. vulgaris.