Varietal differences in plant regeneration from solid and suspension cultures in onion (Allium cepa L.)

Seeds of 22 onion (Allium cepa L.) cultivars were cultured on solid Murashige and Skoog (MS) medium containing 50 mu M 4-fluorophenoxyacetic acid (4-FPA) and 1 mu M N-6 (2-isopentenyl) adenine (2iP). Callus formation was observed in all cultivars. Some of the calli in solid culture were transferred into liquid MS medium containing 50 mu M 4-FPA and 1 mu M 2iP and were cultured in suspension. After subculturing in a liquid medium of 0.2M of sucrose, light yellow and large (LL) type cell clumps were obtained. To investigate the varietal differences in plant regeneration from solid and suspension cultures, the calli in solid culture and LL type clumps in suspension culture were transferred onto solid MS medium containing 1 mu M 2iP. Plantlets were regenerated directly from the calli and the LL type clumps. The frequency of plantlet regeneration from suspension cultures tended to be higher than that from solid cultures. Significant differences were observed among the cultivars in the frequencies of plantlet regeneration from solid cultures and from suspension cultures. After suspension culture, 'Kurenai' showed the highest regeneration frequency (98%).