Uptake of auxotrophic cells of a heterocyst-forming cyanobacterium by tobacco protoplasts, and the fate of their associations.

Auxotrophic cells of the filamentous cyanobacterium Anabaena variabilis Kütz. were introduced into protoplasts of Nicotiana tabacum L. in an attempt to engineer a nitrogen-fixing endosymbiosis. Conditions were established to maximize uptake of the cyanobacteria by use of polyethylene glycol. Culture of the novel association was not successful: tobacco protoplasts with Anabaena inside did not appear to divide. Most of the protoplasts expelled the cyanobacteria and simultaneously disintegrated. The reasons for the incompatibility are not known.