Impact of tryptophan and glutamine on the tissue culture of upland rice

Abstract

In order to evaluate the effect of tryptophan and glutamine on the tissue culture of upland rice cultivars, serial experiments were conducted using four cultivars: Kusan, Lamsan, Selasi and Siam. Mature seeds from these cultivars were subjected to 4 levels of tryptophan and glutamine on the MSB5 (MS macro elements, B5 micro elements and B5 vitamins) medium. Callus induction results showed a positive effect of tryptophan on all cultivars except Selasi. The optimal tryptophan concentration for callus induction in cultivars Kusan and Siam was 100 µmol, while in Lamsan the optimum was 200 µmol. With the exception of the Lamsan cultivar, incorporation of glutamine generally did not result in the enhancement of callus induction response that incorporation of tryptophan did. Plantlet regeneration frequency was significantly increased when an appropriate level of tryptophan was added to culture media, the optimum being 100 µmol or Kusan, Selasi and Siam, compared to an optimum of 200 µmol for Lamsan. Glutamine did not affect regeneration frequency in any of the cultivars under the conditions tested. In summary, the results showed that tryptophan is a useful additive for upland rice tissue culture.