Somatic Embryo Induction And Plant Regeneration In Vitro In Onion (Allium Cepa L.)

Tissue culture techniqeues of flower bud and mature embryo on onion propagationin vitro and the morphological and cytological analysis were showed as following:Flower bud was optimal material for callus induction. Callus occurred on both MS medium and BDS medium. Callus induction frequency was higher on MS medium than on BDS medium with the same hormone combination. The former is 67.81% and the later is 40.11%. The order of action among plant growth regulation 2,4-D, NAA, BA and KT was similar on both medium. It was 2,4-D>BA>KT>NAA on MS medium and 2,4-D>BA>NAA>KT on BDS medium. The best hormone combination was 2,4-D2 mgl-1+ BA2 mgl-1 +KT0.5 mgl-1+NAA0.5 mgl-1 on MS medium and 2,4-D2 mgT-1+ BA2 mgl-1 + KT1.0 mgl-1 + NAA 0.5 mgl-1 on BDS medium. Callus grew 6 days after flower bud inoculation and was strumae and coarseness on surface with yellow, green or kelly. The period of growth was significant for callus induction. It is difficult for callus occurring if the diameter of bud larger than 3 mm and the induction frequency only was 13.20% while it was 52.80% if the diameter smaller than 3 mm. At the same time, the genotype was a vital factor for callus induction. 3% sucrose concentration was suitable and dark culture , weak light culture and cold storage were unsuitable for callus induction.Calli could be maintained and turn to embryoid on condition that 2,4-D was halved and BA was doubled. We gained somatic embryo after getting rid of 2,4-D and instead with low concentration NAA. There were global, scutellate, and cordiform somatic embryo. The optimal medium for somatic embryo germination was MS0 without any hormone. Somatic embryo germination frequency was affected by culture time greatly and it was hardly regeneration after having cultured for 270 days.The mature embryo produced callus if inoculated on MS medium with 2,4-D (0-2.0 mgr-1),NAA(0-2.0mgr-1) and BA(0-2.0mgl-1). The most optimal hormone combination for callus induction is 2,4-D 1.0 mgl-1 + BA2.0 mgl-1 . Adventitious shoots gained after inoculated on cell differentiation medium and MS +NAA 0.1 mgl" +BA2.0 mgl" was very excellent. It was impossible for adventitious shoots to occur without cytokinin.The regenerated plants grew well on MS medium without any hormone. Chromosome analysis of 16 bud plantlets shows that they are deploids (2n=16) which maintain the genetic stability.