| Populus euphtatica is one of the most valuable arbors naturally distributed in desert, and it is a rarity germ plasm resources of stress tolerance because of providing with characterizes of great resistance to salinity, alkalinty, drought, as well as strong wind. The most centralized area of polar forest is distributed in the south of Xinjiang province, and it offers great values on zoology and economy researches in every walk of life. Using leaves and apical shoots of seedling, leaflets and axillary buds of mature trees as explant, regeneration of Populus euphtatica via organogenesis and embryogenesis was processed and the factors were discussed in the course of culture respectively; we obtained somatic embryos for the first time and regenerated via organogenesis; Through histological observation measurement, callus of various status, embryos with different development, adventious buds with leaf primordial and structures of plantlet organs were observed, that will supply key techniques on breeding engineering of Populus euphtatica. The main results are as follows:1. Using leaves of seedling collected in different periods as explant, we found that morphogenesis of Populus euphratica in vitro depended on growth regulators, excision period and culture condition. The callus induced from leaf-explant was optimized in the basal medium(MS medium with 20mg/L Adenine and 400mg/L Lactalbumin hydrolysate) containing 0.75mg/L 6-BA and 0.5mg/L NAA with 3-wk darkness culture and the initiation rate was 67% in October -November, 98% in March -April. The induced callus was soft, whitish or light yellowish, Comparatively transparent, easy-maintained as well as high efficiency of proliferation, which have well differentiation ability through appropriate treatments. While using mature-leaflet as explant, the initiation rate of was lower and the callus should transfer immediately as soon as it is appearing, otherwise it would be brownish quickly.2. using leaves of seedling collected in March-April as explant, the basal medium with 0.5 mg/L BA and 0.1 mg/L NAA induced buds a lot and the initiation rate was up to 89%; elongated shoots could be separated and maintained on the basal medium fortified with lower growth regulator (0. lmg/L BA together with 0.25mg/L NAA) and sucrose(15g/L) for hardening seedlings; shoots were bested rooted on half-strength micro-salt MS medium containing 0.05 mg/L IBA, 0.1mg/L NAA and 15g/L sucrose. The culture condition was 16-h photoperiod (45μmol m-2 s -1), 25±2℃by day and 14±2℃at night with 3-wk interval of subculture.3. When used leaves of seedling collected in October-November as explant, callus were adjusted to embryogenic callus after several subculture upon TDZ-inducing medium(alone or together with NAA) or BA-containing medium combined with NAA. Embryogenic callus was optimized on the basal mediu fortified with 0.5mg/L 6-BA and 0.5mg/LNAA, on which developed the most abundant embryos. The induction condition of embryos was 16-h photoperiod (15μmol m-2s-1 at 14℃. On this medium, somatic embryos at various stages could be observed in single cluster because of asynchronous development. After the process of maturation, most embryos developed to the cotyledonary stay and most cotyledonary embryos germinated into shoots. Shoots obtained through indirect embryogenesis was much more vigorous and easier separated into individually seedlings, which made the higher survival rate than that via organogenesis.4. Using callus derived from axillary buds as target material, the effects of different concentrations of 2,4-D, ABA, sucrose and PEG on embryogenic callus inducition and embryoid development have been investigated, and the comparably identical embryoid were obtained through early screening of embryogenic callus and pressure treatments such as partial desiccation and lower temperature cultivation.5. The paraffin slice is used to trace the somatic embryos development as well as adventitious bud formation. Dealing with histological observation, we also observed the anatomy structure of regenerated plantlet.
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