Somatic embryogenesis and plant regeneration in diploid Allium fistulosum × A. cepa F1 hybrid onions

Procedures were developed for disinfestation of non-dormant basal plate tissue excised from field grown basal plate tissue of diploid Allium fistulosum × A. cepa F1 hybrid onions. Contamination levels varied with the season and vegetative development of plant material. Callus initiated from basal plate tissue and immature inflorescences of the F1 hybrids was maintained on a BDS-based medium containing 0.75 mg/l picloram and 2.0 mg/l BA. When this medium was supplemented with vitamins and glycine, and with proline at 2.5 gm/1, somatic embryos began to form. Their development continued on a BDS-based shoot promotion medium containing 0.03 mg/l picloram and 0.32 mg/l 2iP supplemented with vitamins, glycine and proline. Genotypes differed significantly in the numbers of structures regenerated. Plantlets from somatic embryos were rooted into BDS or half-strength BDS medium without growth substances and were successfully transferred to sterilized potting mix in plastic commercial corsage boxes.