Tissue Culture And Plant Regeneration Of Fraxinus Rhynchophylla Hance

Fraxinus rhynchophylla Hance is a deciduous hardwood species in the genus Fraxinus in Family Oleaceae, with wood hard and fine materials, that have important economic value and, medicinal value, but also and landscape trees and shrubs ornamental values. This study was designed to establish the plant regeneration system for F. rhynchophylla via organ and somatic embryogenesis by tissue culture in vitro. This research for laidying a theoretical foundation for vitro rapid propagation, development and utilization of germplasm resources conservation and species subsequent use development of this species. The results are as follows:(1) April was superior to other periods for collecting dormant buds. The modified B5medium is the optimal medium suitable for the growth and proliferation of F. rhynchophylla stem segments. The proliferation of stem segments from in vitro culture seedling was better than from dormant buds; terminal bud proliferation was better than auxiliary bud multiplication; the first generation of proliferation in vitro culture was better than the subculture multiplication. The best proliferation effect was obtained on improved B5medium supplemented with4mg·L-1BA and0.10mg·L-1IBA for the stem segments both from dormant bud or in vitro cultured seedlings, and the proliferation coefficient was2.32and3.29respectively. The optimal medium for rooting was1/2MS medium supplemented with0.5mg·L-1NAA, and the rooting rate could reach95.0%. Survival rate of the established plantlets could reach93.3%after transferred to the transplanting growing medium with the composition of50%peat moss,40%vermiculite and10%polite. Regeneration plantlets were growing well, and the seedling height growth was40.2%. Shoot could root after quickly dipping in200g·L-1IBA and survival rate could reach60.0%in the same growing medium.(2) Immature zygotic embryos of F. rhynchophylla were used as explants for somatic embryogenesis. Immature ZEs were cultured on MS1/2medium containing400mg·L-1Casein hydrolysate (CH),70g·L-1sugar,6g·L-1sucrose. The highest induction rate (34.7%) occurred in the hormone combination treatment, which was supplemented with0.25mg·L-1BA and1.5mg·L-1NAA.(3) Mature zygotic embryos of F. rhynchophylla were used as explants, which were cultured on the media that was the same to the Immature ZEs cultured. Similarly, somatic embryos were induced. The highest (10.0%) induction rate occurred in the hormone combination treatment, which was supplemented with0.25mg·L-1BA and2mg·L-1NAA. Somatic embryogenesis development of F. rhynchophylla had gone through four typical stages of angiosperm somatic embryogenesis:globular, heart-shaped and torpedo-shaped and cotyledonary stage.(4) As for the study on cotyledonary embryo germination and plant regeneration of F. rhynchophylla, CEs were cultured on MS1/2with no hormones under the light. The germination rate was87.6%. Afterwards, germinated somatic embryos were transferred to the medium supplemented with0.01mg·L-1NAA, the plant regeneration rate was45.5%. The regenerated plants were transplanted into the growing medium with the composition of50%peat moss,40%vermiculite and10%polite. After30days, survival rate was75.5%.