Somatic embryogenesis and plant regeneration from zygotic embryo explants of onion

Resumo

We investigated the effect of two synthetic auxins on somatic embryogenesis and plant regeneration from mature embryo explants of 16 onion cultivars. Cotyledons were removed from the embryos and remaining portions were cultured on MS medium supplemented with 1.0 mg L^-1 2,4-D, 5.0 mg L^-1 picloram or 1.0 mg L^-1 2,4-D and 2.5 mg L^-1 picloram. Among the media studied, MS medium supplemented with 5.0 mg L^-1 picloram was found to be best for both embryogenic callus induction (85%) and callus growth (3.8 mm). Of the 16 cultivars studied, ‘Yeoeuijuhwang’ exhibited the lowest frequency of embryogenic callus induction (50.5%), whereas all the other 15 cultivars showed more than 60% embryogenic callus induction in all studied media. SEM analysis of embryogenic callus showed all stages of somatic embryos such as globular, scuetellar and coleoptilar. Plant regeneration was significantly affected by the embryogenic callus induction media. The greatest frequency of somatic embryo conversion was obtained from embryogenic callus develop in MS medium with 2,4-D (70.1%) followed by picloram (38.9%) and 2,4-D + picloram (34.5%). The germinated plantlets further developed on the half-strength MS medium containing 3% sucrose and were acclimatized in the culture room with 98% survival rate.