Description:
Evaluation of cassava germplasms for in vitro regeneration ability is crucial for stable
genetic improvement of this crop via genetic transformation systems. Methods for reliable and
efficient transformation including somatic embryo regeneration and recovery of transgenic plants still
need to be developed and customized for each cassava genotype. Twenty one Tanzanian farmer- preferred cassava (Manihot esculenta Crantz) landraces widely grown in major cassava growing
zones were evaluated for somatic embryo induction, recovery, sustainability and plantlets
regeneration to whole plants. Somatic embryogenesis was induced from cassava leaf lobes on
Murashige and Skoog media supplemented with different concentrations of sucrose, Copper
sulphate and 2, 4-Dichlorophenoxyacetic acid and further developed to plantlets. Frequency of
somatic embryo production and subsequently regeneration stages were evaluated starting from 28
days post-inoculation. All cassava genotypes tested in this study were able to induce callus where by
62 % were able to induce somatic embryo cotyledons. Cassava landraces: Sagalato, Rangimbili, Mnazi and Kibandameno were highly responsive to somatic embryo production. The conversion rate
of embryos into plantlets was variable depending on the cassava landrace, Sagalato being the most
responsive and Kiroba the least. Somatic embryos from 8 cassava landraces reached plantlet stage, 5 of them being acclimatized and successfully developed to plants with normal phenotype and they
rooted on soil. The regeneration potentials of farmer-preferred cassava landraces observed in this
study is hoped to pave a way towards genetic improvement for both biotic and abiotic stresses via
genetic engineering approaches.