Calli Culturation And In Vitro Selection Of Salt-tolerant Mutants In Potato (Solanum Tuberosum.L)

In this research, the callus culture, regeneration and salt-tolerant mutants screening were studied by use of four potato varieties, Favorite, Dongnong 303, Sharpdi and E No.1, with stem and leaf as the explants and MS+sucrose 3%+arg 0.8% as the basic medium. The high efficient regeneration system was established, and the effect of different treatments, different explant type, the subculture times and the salt concentration on screen of salt-tolerant mutant were investigated. Some salt-tolerant mutants were abtained and the salt-tolerant characters were identified. The results showed:The optimal medium for callus induction from leaf discs was found to be MS+6-BA 2.5 mg/L+NAA 0.2 mg/L for "Dongnong 303" and "E No.l", MS+6-BA 2.0 mg/L+NAA 0.1 mg/L for "Favorite" and MS+6-BA 2.0 mg/L+NAA 0.2 mg/L for "Sharpdi", and for callus induction from stem explants was found to be MS+6-BA 3.0 mg/L+NAA 0.01 mg/L for "Dongnong 303", "Sharpdi" and "E No.1", MS+6-BA 3.0 mg/L+NAA 0.1 mg/L for "Favorite".The optimal medium for adventitious bud differentiation from leaf callus was found to be MS+6-BA 2.5 mg/l+GA3 5.0 mg/L for "Favorite", MS+6-BA 1.0 mg/L+IAA 0.1 mg/L+GA3 2.5 mg/L for "Dongnong 303", MS+6-BA 2.5 mg/L+IAA 0.5 mg/L+GA3 2.5 mg/L for "Sharodi" and MS+6-BA 2.5mg/L+IAA 0.1 mg/L+GA3 1.0 mg/L for "E No.1", and for adventitious bud differentiation from stem callus was found to be MS+6-BA 2.0 mg/L+NAA 0.2 mg/L for "Favorite" and "E No.l", MS+6-BA 2.0mg/L+NAA 0.1 mg/L for "Dongnong 303" and MS+6-BA 2.0 mg/L+NAA 0.3 mg/L for "Sharpdi".Two methods were tried to select salt tolerant callus. One was screen of salt tolerant callus by directly inducing from explants of leaf discs and stem segments on medium with salt (NaCl). The second was by culture of callus firstly from explants on medium with no salt (NaCl), and then inducing salt tolerant callus from normal callus on medium with different level of salt step by step (progressively). There were differences insalt-tolerant charaters among callus of different vareities. "Dongnong 303" and "E No.1" were tolerant to 2.0 % NaCl, "Favorite" were tolerant to 1.5% NaCl but "Sharpdi" was inferior in salt tolerane and only tolerant to 1.0% NaCl. The salt tolerance of mutants derived by progressive method was found to be unstable. Only the plantlets regenerated from high level NaCl directly induced salt-tolerant calli showed high tolerance under NaCl stress.Adventitious buds could not be induced from salt-tolerant leaf discs callus on differentiation medium without salt if the calli were subcultured more than 10 times on medium with salt, or on differentiation medium with salt if the calli were subcultured more than 8 times. However, the adventitious buds could be induced from stem segment calli even the calli were subcultured more than 8 or 12 times on medium with or without salt. Therefore, the optimal mehord to got salt-tolerant mutants were to reduce subculture times and enhance directly salt stress.There were differences in salt-tolerant characters between the regenerated plantlets and the salt tolerant callus. The salt-tolerant ability of regenerated plantlets was on the same level as the salt tolerant callus only in varieties of "Dongnong 303" and "E No. 1". The salt-tolerant ability of regenerated plantlet was found lower than that of the salt tolerant callus.