Separate auxin- and cation-dependent mechanisms for glutamate utilization by normal and crown-gall teratoma cells of tobacco in culture

摘要

Crown-gall teratoma tissues of tobacco, when grown in culture, require exogeneous auxin (α-naphthaleneacetic acid) or high concentrations of K+in the medium to utilize ammonium glutamate as a nitrogen source. These factors are not required to utilize NO3-or glutamine. The effects of K+and auxin on glutamate utilization differ in that NH4+is required for the action of K+, but not for the action of auxin. The tissues grew optimally when the ratio of NH4+to glutamate was approximately one or greater. These results indicate that glutamate utilization involves at least two different mechanisms: one mechanism requires K+and stoichiometric amounts of NH4+, the other mechanism requires auxin. Experiments using explants of tobacco pith show that both mechanisms function in normal as well as crown-gall tissues of tobacco