The first stage in the establishment of the Rhizobium-legume symbiosis is the infection of the root of the host legume by the appropriate Rhizobium species. A recent and complete review of the infection process has been given by Dart (1). In the clover symbiosis, infective strains of Rhizobium trifolii enter the host through root hairs. A characteristic deformation is curling at the root hair t...
