Effect of explant source and auxins on somatic embryogenesis of selected cassava (Manihot esculenta Crantz) cultivars

Competence for somatic embryogenesis of eight cassava cultivars T200, AR9-18, MTAI16, CR25-4, CM523-7, BRA1183, MCOL2261 and SM707-17 was compared to model cultivar TMS60444 in induction media containing 12 mg/l picloram or 8 mg/l 2,4-dichloro phenoxyacetic acid (2,4-D), using axillary buds (AB) and immature leaf lobes (ILL) as explants. There were significant differences (p < 0.01) among the cassava genotypes for ability to form somatic embryos (SE). In general, AB as the explant and picloram-containing medium had the highest frequency of SE for TMS60444, T200, MTAI16, CR25-4 and CM523-7 while AR9-18 had greater efficiency using ILL on picloram. Cultivars BRA1183, MCOL2261 and SM707-17 produced insignificant amounts of SE; however, loose callus and friable embryogenic callus (FEC) appeared to be the predominant tissue type observed. Five out of the eight cultivars studied showed capability of producing SE although their efficiency for somatic embryogenesis was not as high as the model cultivar TMS60444.