Abstract

Do Hai Lan,Do Xuan Dong, Le Van Son, Le Tran Binh, and Chu Hoang Ha

In this study, we developed a method for the induction of somatic embryogenesis in two cassava genotypes from Vietnam is described. The explants used were immature leaves and apical shoots isolated from in vitro 2- 3-week plants. Somatic embryogenesis was achieved at high frequencies by the addition in the induction medium of the auxin picloram over a wide range of concentrations. Our results show that the highest rate of somatic embryos formation for both cultivars was obtained by using 12 mg/l picloram supplemented to Murashigh - Skoog (MS) media. For immature leaves: the number of embryos per explant was similar between two cultivars for 4 weeks, the KM94 cultivar gave a higher rate (81,4 ±1,7%) than the KM140 cultivar (70,4 ± 2,9%). For apical shoots: the number of embryos per explant was similar between two cultivars for 4 weeks, the KM94 cultivar gave a higher rate (82 ±1.7%) than the KM140 cultivar (59.6 ± 2.9%). Somatic embryos were subsequently transferred onto media (MS supplemented with 0.3 mg/l BAP) for the highest frequency of plantlet regeneration (KM140 - 82,1 ± 3,1% and KM94 - 79,2 ± 2,3%), for immature leaves and (KM140 - 81 ±3.2% and KM94 - 79 ± 2.3%) for apical shoots. Shoots with the length of about 1.0-1.5 cm were transferred onto free - hormone MS media for 100% of rooting for 2 weeks. Complete plantlets were cultivated on a mixture of rice husk and sand-soil under ratio 4:6 in a greenhouse. This protocol required 16 to 18 weeks and is entirely appropriate for mass production of various cassava genotypes and further genetic transformation experiments.