Research Notes: The glnA Gene of Rhizobium leguminosarum bv. phaseoli and Its Role In Symbiosis. Soledad Moreno. Centro de Investigacion sobre Ingenieria Genetica Biotecnologia, Apartado Postal 510-3, Cuernavaca, Mor. 62271 Mexico. Roberto Meza(1), Josefina Guzman(1), Alfonso Carabez(2), and Guadalupe Espin(1). (1)Centro de Investigacion sobre Ingenieria Genetica Biotecnologia and (2)Instituto de Fisiologia Celular Universidad Nacional Autonoma de Mexico, Apartado Postal 510-3, Cuernavaca, Mor. 62271 Mexico.. MPMI 4:619-622. Accepted 9 July 1991. Copyright 1991 The American Phytopathological Society.

We have determined glutamine synthetase (GS) activity in bacteroids isolated from nodules of Phaseolus vulgaris induced by Rhizobium leguminosarum biovar phaseoli CE3 wild type strain. GSI but not GSII activity was detected. No GS activity was detected in bacteroids of strain SM58, which carries a glnA::Km insertion mutation. Acetylene reduction activity of nodules induced by strain SM58 was about 50% of that found in nodules induced by the wild type. Microscopic analysis of nodules induced by strain SM58 showed that the number of bacteroids within the infected cells was reduced as compared to the number of bacteroids present in the wild type-induced nodules. In addition, SM58 bacteroids contained high amounts of poly-Β-hydroxybutyrate granules.