Patterns of direct and indirect embryogenesis from mesophyll protoplasts of Medicago sativa

摘要: Clones of three cultivars Medicago sativa (‘Rambler’, ‘Regen S’ and ‘Rangelander’) were used as sources mesophyll protoplasts. Although all clones readily produced protoplasts, the subsequent development patterns in culture varied greatly among genotypes, with protoplasts from ‘Rambler’ forming calli which could be induced to form embryos, ‘Rangelander’ undergoing direct embryogenesis. Protoplasts exhibited high rates division while those tended aggregate only a few cells per surviving. The surviving gave rise proembryos within aggregates; these developed into differentiated embryos after 5–7 weeks culture. Based on initial protoplast population, efficiency embryo formation averaged 0.13% ranged 0.001–0.4%. Observations during early stages indicated that cell aggregation was prerequisite for