The 2012 ASHS Annual Conference

Organogenesis is unstable in tomato plants in vitro. Determinations of concentrations and valances in growth regulators for explants from various plant parts and cultivars are complicated. As recently-developed complete decapitation method (CDM), in which main and all lateral stems were cut to eliminate shoot apex, regenerated lots of shoots without using growth regulators. And L-2-aminooxy-3-phenylpropionic acid (AOPP), a potent inhibitor of phenylalanine ammonia-lyase, promoted shoot regeneration. Therefore, we investigated the effects of CDM in vitro (CDMi), where hyocotyl was cut, and AOPP on shoot regeneration of tomato ‘Micro Tom’ plants grown with MS medium. Percentage of hypocotyls with adventitious buds was 73% in CDMi compared with 20% in control method, hypocotyl culture on a MS medium with BA at 1.0 mg/L. Number of adventitious buds on the hypocotyl was 3.9 in CDMi compared with 2.0 in control method. Efficiency of multiplication, calculated using the percentage and the number, was 2.9 fold in CDMi compared to 0.4 fold in control method. When AOPP was included in MS medium at 0 (control), 0.01, 0.1, 1.0 mM, percentage of hypocotyls with adventitious buds was highest 100% at 0.1 mM. Number of adventitious buds on the hypocotyl was largest 5.9 at 0.01 mM. Efficiency of the multiplication was highest 4.5 fold at 0.01 and 0.1 mM. When formed shoots were cut into MS medium, percentage of adventitious root formation was 93% and 87% at 0.01 and 0.1 mM AOPP, respectively, similarly to 87% at 0 mM 4 weeks after in vitro cutting. Number of adventitious roots on a cutting was 3.3 and 2.7 at 0.01 and 0.1 mM, respectively, similarly to 2.9 at 0 mM. It is concluded that CDMi promotes adventitious bud formation on hypocotyls compared with control tissue culture. AOPP at 0.01 mM in MS medium promotes shoot regeneration in tomato plants and does not retard root formation.Organogenesis is unstable in tomato plants in vitro, and it is difficult and complicated to determine the optimal concentrations and types of plant growth regulators to induce regeneration from various explant types and cultivars. The recently developed complete decapitation method (CDM), in which main and all lateral stems were cut to remove the shoot apices, regenerated many shoots from tomato without using plant growth regulators. In addition, L-2-aminooxy-3-phenylpropionic acid (AOPP), a potent inhibitor of phenylalanine ammonia-lyase, promoted shoot regeneration. Therefore, we investigated the effects of CDM in vitro (CDMi), where the hypocotyl was cut, and AOPP was applied to induce shoot regeneration in tomato ‘Micro Tom’ plants grown on Murashige and Skoog medium. Hypocotyls were cultured on MS medium containing 1 mg/L benzyladenine as the control. After CDMi, 73% of hypocotyls formed adventitious buds, compared with 20% in the control. The average number of adventitious buds on each hypocotyl was 3.9 in CDMi compared with 2.0 in the control. The efficiency of multiplication, calculated from the percentage of hypocotyls with adventitious buds and the number of buds per hypocotyl, was 2.9-fold in CDMi and 0.4-fold in the control. We included AOPP in the MS medium at 0 (control), 0.01, 0.1, 1.0 mM, and found that 100% of hypocotyls formed adventitious buds with 0.1 mM AOPP. The greatest number of adventitious buds per hypocotyl was 5.9 with 0.01 mM AOPP. The highest efficiency of multiplication was 4.5-fold at 0.01 and 0.1 mM AOPP. When the shoots were cut and transferred to fresh medium, the percentage of shoots that formed adventitious roots by 4 weeks after cutting was 93% with 0.01 mM AOPP, 87% with 0.1 mM AOPP, and 87% with 0 mM AOPP. The average number of adventitious roots per cutting was 3.3, 2.7, and 2.9 at 0.01, 0.1, and 0.0 mM AOPP, respectively. We conclude that CDMi promoted adventitious bud formation from hypocotyls compared with the conventional tissue culture method, and that addition of 0.01 mM AOPP to the MS medium promoted shoot regeneration in tomato plants without retarding root formation.