INDIRECT SHOOT ORGANOGENESIS AND SELECTION OF SOMACLONAL VARIATION IN Dieffenbachia

of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy INDIRECT SHOOT ORGANOGENESIS AND SELECTION OF SOMACLONAL VARIATION IN Dieffenbachia 11 By Xiuli Shen May 2007 Chair: Michael E Kane Cochair: Jianjun Chen Major: Horticultural Science 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 μM TDZ and 1 μM 2,4-D. The maximum shoots regenerated per callus (7.9) was obtained on a basal medium supplemented with 40 μM 2ip and 2 μM 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