Medicinal Plants In Xinjiang Shikonin Isolated Breeding Research

An efficient in vitro propagation system was developed for Arnebia euchroma (Royle) Johnst, an important traditional medicinal plant, by means of indirect and direct organogenesis.In the experiments of indirect organogenesis, according to explants—induction of calli—subculture of calli—differentiation of calli—adventitious buds strengthening and micropropagation—roots induction and transfer to soil, a series of experiments were conducted.In the course of calli induction, different basal media, combination of plant growth regulators and explants were compared. Results showed that the best conditions for calli induction were as following: the stem segments were induced on the modified LS medium supplemented with 1.0 mg/L 2,4-D and 1.0 mg/L KT.Through subculture, the calli developed into two different types: One type of callus was compact and differentiated easily. The other type of callus was loose and could not be induced to differentiate, but it was proved to be excellent material for culturing secondary metabolin.For calli differentiation, different cytokinins (KT, BA, TDZ), ABA, PEG4000 and mannitolum, ethene inhibitor AgNO₃, and subculture times were tested. Results showed that KT's induction effects was better than BA and TDZ, and 1.5mg/L KT had the best induction effect with an induction frequency of 87% and average 7.4 adventitious buds per callus. Low concentrations of ABA promoted calli differentiation. PEG4000 was more favorable for adventitious buds develppment than mannitolum. 2.0mg/L AgNO₃ could promote calli differentiation frequency to 87% with 9.2 adventitious buds per callus. The calli differentition ability decreased as subculture times increased.For adventitious buds strengthening, Browning of the basal portion could be significantly reduced when 100mg/L PVP was supplemented. KT was more favorable for adventitious buds micropropagation than BA, and 1 .0mg/L KT could induce 6.5new buds per adventitious buds. For root induction, different strength basal medium and auxins were tested. The best induction frequency was 65% when induced on 1/2 strength LS medium amended with 1 .Omg/L IB A.In the experiments of direct organogenesis, TDZ's induction effects were studied. 1. Omg/L TDZ had the best induction effects, and TDZ alone was better than combination with other plant growth regulators. Furthermore, cotyledon explants' induction ability was better than hypocotyl explants. Different duration of TDZ exposure influence induction frequency, and the highest induction frequency occurred after 12 d of exposure, with each cotyledon explant forming approximately 8.6 shoots.Through experiments, an efficient in vitro propagation system was developed for Arnebia euchroma (Royle) Johnst. The highest induction effects were carried out by optimizing different influence facts. This protocol will be useful in many ways. It can be used for germplasm conservation for this threatened plant species as many plants can be produced through shoot organogenesis. Shikonin and its derivatives can be extracted from in vitro-grown plants instead of harvesting plants from their natural environment. Furthermore, the tissue culture system may be used for improvement of this plant species through somaclonal variation or genetic engineering.