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[Protoplast culture and plant regeneration of the methionine resistant variant of Astragalus cicer L].

A protoplast-to-plant system for the methionine resistant variant of Astragalus cicer L. has been developed. The friable calli induced from stem segments of variant plants were used as materials for protoplast isolation through enzyme digestion. The effects of different media and plating densities on protoplast divisions and plant regeneration were studied. Sustained cell divisions and colony formation from the protoplasts of the methionine resistant cell line of Astragalus cicer L. were obtained by a DPD medium containing 2.0 mg/L 2,4- dichlorophenoxyacetic acid (2,4-D), 0.2 mg/L 6 -benzylaminopurine(6-BA), 0.3 mol/L mannitol, 200 mg/L casein hydrolysate and 2% (W/V) sucrose at a plating density of 2x10(5) /ml. The division frequency was 38.3%. At the same time, different dividing types of protoplasts were found. Organogenesis and shoot formation from the protoplast-derived calli were induced on MS medium supplemented with 0.5 mg/L NAA, 10 mg/L KT and 2% (W/V) sucrose. The protoplast-derived calli still expressed resistance to methionine. The protoplast to plant regeneration protocol developed in this study might provide the foundation for the resistant cell line as a parent for somatic hybridization.