Effect of the phenylurea cytokinins CPPU and TDZ on the regeneration and the growth of adventitious shoots of Mesembryanthemum crystallinum
2006
Sunagawa, H.(Saga Univ. (Japan). Faculty of Agriculture) | Agarie, S. | Makishi, Y. | Umemoto, M. | Nose, A.
Mesembryanthemum crystallinum L. (the common ice plant) has been used as a model plant to study on the regulatory properties in Crassulacean acid metabolism (CAM) and tolerance to abiotic stresses. However the transgenic procedure has not been established in this species due to recalcitrancy for in vitro regeneration. Here we have assessed the effects of synthetic cytokinins N -(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) and N-phenyl-N'-1, 2, 3, -thidiazol-5-ylurea (TDZ) on the induction and the growth of adventitious shoot from hypocotyl and cotyledonary node in M. crystallinum. Although callus formation occurred on hypocotyl explants, no adventitious shoots were regenerated. The adventitious shoots were obtained only from the cotyledonary node. The TDZ were more effective for in vitro shoot regeneration and morphogenesis of the adventitious shoots than CPPU and benzyladenine. Exogenous application of cytokinin alone to the medium has resulted in the increase of the fresh weight and the higher regeneration rate than the other treatments. We have found that the 2.5 mg/L of TDZ induced the highest number of multiple shoots from single explant. The regenerated shoots were rooted on the MS medium within one month, and it produced more roots by the replacement of the agar medium with vermiculite or Florialite. This simple, reproducible and rapid regeneration system may prove useful for producing transgenic plants of M. crystallinum.
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