Studies On The Establishment Of In Vitro Regeneration System Of Paeonia Suffruticosa Andr.

Micropropagation of tree peony (Paeonia suffruticosa) was studied and in vitro regeneration system was established on single form cultivar 'Feng Dan Bai'.The content of total phenols and activity of PPO was analysed among cultivars with different flower form and 5 different explants of 'Feng Dan Bai'. The relationship was analyzed between total phenols content, activity of PPO and browning of explants. We investigated the effects of sterilization, pre-treatment, medium composition and culture condition on the browning during culture of young leaves used as explants. With young leaves, petioles and cotyledon as explants, the influence of medium composition, the kind and concentration of hormones, carbon source and culture condition were studied to establish regeneration system of tree peony. The influences of medium composition on the vitrification of cluster-buds regeneration by direct induction from mature embryos as explants were studied. With dormant axillary buds as explants, the reproductive capabilities were compared among 60 cultivars of tree peony.The results are as follows.(1) The aptitude explants for incipient micropropagation of tree peony were selected. Odds were significant in the content of total phenols, activity of PPO and browned degree among cultivars or kinds of explants. With lower content of total phenols and lower activity of PPO, cotyledons and young stems were seclected as explants for in vitro incipient culture.(2) Effective technique to reduce browning of explants was experimented. Following operation were : sterilizing with 10%NaOCl for 10 min, pre-treatment with antioxidant solution (MS + citric acid 150mg/L+ Vc100mg/L) for 30min, use of WPM as the basic medium, adding PVP500mg/L or Vc15mg/L to the medium, and culture explants at low temperatures(18~20℃) and dim light.(3) The aptitude mediums for in vitro culture of tree peony were selected. WPM medium with 2, 4-D 0.5mg/L+TDZ 0.5mg/L or 2,4-D 1mg/L+TDZ 1mg/L, was suitable for the induction of callus. WPM medium with TDZ 0.5mg/L was better for the bud redifferentiation of callus originated from cotyledon. With mature embryos as the explants, WPM medium with 6-BA2.5mg/L + 2,4-D 0.1mg/L is the aptitude medium for the direct-induce of cluster-buds. As for rooting, 1/2WPM medium with 2mg/L IBA showed a better result. Pre-treatment at low temperatures and dark conditions for 10 days and 5 weeks culture in WPM medium without hormones could improve a rooting rate. In the process of seedlings acclimatization, removing container cap for 3 to 5 days before transplanting, controlling temperature strictly at 25℃ ± 1 ℃ and humidity at 80% could improve a surviving rate of seedlings to 80% after transplanted.(4) Vitrification on cluster buds was controlled effectively by modified WPM medium with addition of NAA0.1mg/L + 6-BA1mg/L and agar 7g/L.(5) Genotype plays a important role in the micropropagation of tree peony. With dormantaxillary buds as explant, an obvious odd is showed in reproductive capabilities of 60 cultivars of tree peony with its coefficient ranging from 2 to 5. Reproductive capability of axillary buds was relative to genotype significantly. In addition, reproductive rates decreased for most cultivars after 48 weeks subculture except for three cultivars — 'Da Hu Hong', 'Zi Jin Ling' and 'Cong Zhong Xiao'.