Somatic Hybridization Of Ramie

Ramie, one of the special plants native to China, is a very important fibre crop for the national textile industry, and it's products have been exported to many countries over the world. Ramie has been used and cultivated in china for more than 5000 years. Many varieties released hundreds years ago are still being used for commercial cultivation. The selecting method, include asexual clone selection and seedlings selection, has acted the major role in the process of ramie variety improvement. The somatic hybridization has been used as a new way to improve crops variety since 1970's, and obtained successful results or progress in crops such as rice, potato, wheat, corn, tobacco, tomato, cabbage, citrus, apple and Kiwifruit. But there are still no successful reports in ramie. Five genotypes of two species, Boehmeria nivea Baud. and B. tricuspis Makino, are used as materials in this thesis to study on somatic hybridization of ranue. 1. Large amount of protoplasts can be isolated from both stem callus and young leaves by using enzyme solution which contained 6% cellulose RS and 0.2% Pectolynase Y23. Mannitol(0.7molL is commended to keep a higher viability of protoplasts after isolation. 2. Both PEG-mediated fusion and electrofusion can be applied for ramie protoplasts fusion to obtain somatic hybrids. Compare to PEG- mediated fusion, electrofusion achieved a higher fusion frequency at 200v/m with pulse of 1 .Omsecs duration. The optimum density of protoplasts is 5 X 104ml and 0.5mM CaCl, and 11% mannitol are added to the electrolyte free solution. 3. Medium KPR and medium B5 are used in sequence protoplasts culture after fusion .The fused protoplasts are cultured in semi- solidified KPR using nurse culture. Protocalli are formed after 40- 7odays of culture .Then microcalli are transferred to medium B5 supplemented with 2mgLAA + lmgJA2,4-D + lmgLT + 2%CM + 200mgJJ casein hydrolysate + 2%glucose + 1% sucrose + 0.8%agar to promote callus development. 4. By culturing of macrocalli in differentiation medium (MS + 2.OmgL BAP + 0.5mgL A3 + 0.O2mgt BA+ 3%glucose) and rooting medium (1/2MS + 0.3mgL IBA + 0.O5mgU払AP + 0.05% activated charcoal + 2% sucrose), respectively. 66 plantlets have been regenerated. 5. Finally,16 regenerated plantlets of 9 hybrid combines are identified as somatic hybrids by using chromosome and RAPD analysis. Postgraduate: Xiong XingYao Supervisor: Li ZongDao...