Direct primary somatic embryogenesis and shoot formation from immature leaves of Manihot esculenta

Primary somatic embryogenesis and shoot organogenesis in vitro could be directly induced from immature leaves of cassava (Manihot esculenta Crantz) with higher concentration (10 to 80 mg/L) of NAA. Compared with 4 mg/L 2,4-D on the induction and regeneration system, NAA showed some advantageous characteristics, that is, NAA could directly induce both primary somatic embryogenesis and shoot organogenesis, whereas 2,4-D could only induce somatic embryogenesis. NAA induced somatic embryogenesis much quicker, producing visible somatic embryos within 9 to 13 days and shoot (tips) within 10 to 14 days, than 2,4-D, which would induce visible somatic embryos after 15 days. Plant regeneration from the NAA-induced somatic embryos was as high as 48%, but was only 4. 1% from that of 2,4-D. The test also showed that primary somatic embryogenesis or shoot organogenesis could be induced directly from immature leaves in 12 out of 16 cassava varieties.