| A series of experiments were conducted to investigate the feasibility of selecting of somaclonal variants for new cultivar development in Dieffenbachia. In the first set of experiments, a protocol for indirect shoot organogenesis was established for Dieffenbachia cv. Camouflage. Maximum 96% callus formation frequency was observed on a basal medium supplemented with 5 microM TDZ and 1 microM 2,4-D. The maximum shoots regenerated per callus (7.9) was obtained on a basal medium supplemented with 40 microM 2ip and 2 microM IAA. In the second set of experiments, 4 Dieffenbachia cultivars were examined for the capacity for indirect shoot organogenesis and effects of genotypes, explant sources and plant growth regulators were investigated. There were significant genotypic effects on both callus formation and shoot regeneration. Cultivar Camouflage exhibited the greatest ability for indirect shoot organogenesis, while cv. Octopus had no capacity for shoot regeneration from calli. Only leaf explants taken from in vitro shoot cultures were capable of callus formation. Root explants failed to undergo indirect shoot organogenesis, regardless of cultivar. In the third set of experiments, somaclonal variation at the phenotypic level among Dieffenbachia plants regenerated via indirect shoot organogenesis was evaluated. Three types of somaclonal variations with different leaf variegation and color were observed in cv. Camouflage with a total somaclonal variation rate of 40.4%. Somaclonal variation in leaf shape was observed in cv. Camille with a somaclonal variation rate of 2.6%. No somaclonal variation was observed in regenerated plants of cv. Star Bright. The duration of callus culture of cv. Camouflage had no effect on somaclonal variation as variation rates between plants regenerated from 8 months and 16 months callus culture were similar. Our results indicated that selection of somaclonal variation has great potential for new cultivar development in Dieffenbachia.. |
