Screening for strongly regenerative genotypes of spinach in tissue cultureusing subcultured root explants

A system for subculture of spinach (Spinacia oleracea L.) roots was establi shed, and differences in regeneration; namely, embryogenic competence, amon g individuals of the 'Nippon' cultivar were examined. Root tissues, excised from seedlings, were grown on medium without growth regulators and subcult ured on the same medium and then on medium that contained 10 muM naphthalen eacetic acid and 0.1 muM gibberellic acid to induce callus formation. Calli were transferred to medium without growth regulators. All explants formed calli. However, the frequency of embryo formation varied among lines. Highe r concentrations of gibberellic acid in the callus-induction medium had lim ited effects on somatic embryogenesis from poorly embryogenic lines. These results indicate that inherent factors are important for somatic embryogene sis in spinach and that the root subculture system is useful for identifyin g strongly regenerative genotypes among individuals of a single cultivar.