The differentiation and development of somatic embryos were observed in 15 genotypes of sweet potato using shoot tip explants with one or two leaf primordia. Somatic embryogenesis was induced using MS media and vitamins, 3% sucrose, 0,2% phytagel, supplemented with 2,4-D (0,0; 0,5; 1,0 and 2,0 mg/L). The cultures were maintained in the dark at 27ºC. The addition of 2,4-D was necessary for embryogenic callus induction in the genotypes '92', '94', '184', '188', '319', '370', '374', '442', '449', '549', '594', '645', 'PI3138463', 'White Star' and 'Jewel'. Clones '169', '202', '605', '633' and '643' did not respond to embryogenic callus induction. Embryogenic callus showed a yellow and opaque color, compact and granular texture. Nonembryogenic callus was translucent in color and friable. Calluses were originated at the periphery of explants. In the established conditions better formation of embryogenic calluses was obtained with 2,0 mg/L of 2,4-D. The transfer of embryogenic callus to 2,4-D free medium allowed embryo development to heart, torpedo and cotiledonary stages.
Ipomoea batatas; adventive embryogenesis; micropropagation; tissue culture
