Twenty-two sweetpotato varieties of different origin were tested for their potential to produce plants from somatic embryos. Callus induction media containing different levels of 2,4-dichlorophenoxiacetic acid (1.4, 2.3, 4.5 and 9.0 μM) were tested. Bud meristems of 16 clones were observed to form globular and heart-shaped structures either directly or indirectly on calli after a culture period of 10 to 40 days, and varying according to the genotype. The formation of embryogenic callus was dependent on the genotype and on the induction medium composition. Each genotype formed embryos at a specific concentration of 2,4-dichlorophenoxiacetic acid. Further development of somatic embryos from the globular to the heart-shaped stage and to plantlets was obtained in 14 genotypes, by placing the embryogenic calli onto a medium free of 2,4-dichlorophenoxiacetic acid and cytokinins. If transferred to a medium containing only cytokinin, the embryogenic calli reverted to green, compact, solid calli. The frequency of embryogenic calli from meristems (60%) was ten times higher than that from intact buds (6%). When subcultured on 2,4-D containing medium, small pieces of embryogenic callus and of isolated embryos (early and late torpedo, or cotyledonary stage), reverted to whitish and/or brownish, watery, dispersed calli, which subsequently produced several secondary embryos.

Cited By (since 1996): 2Export Date: 26 August 2010Source: Scopus