Host-controlled nitrogen fixation in the legime-rhizobium symbiosis: Incompatibility of pisumsativum l. ecotypes elatius bieb. and abyssinicum braun with european rhizobiumleguminosarum strains

European Rhizobium leguminosarum strains, effective on the cultivated pea, induced ineffective nodules on pea ecotypes elatius and abyssinicum, indigenous plants from Israel and Ethiopia, respectively. Effective nodules were formed on elatius plants by Rhizobium strains from soils of the Middle East, i.e. from regions where the elatius pea occurs naturally. No Ethiopian Rhizobium strains were available, but the Middle East Rhizobium ones were able to form an effective symbiosis with the abyssinicum peas. We conclude that there is a co-evolution between the local leguminous plants and the indigenous Rhizobium population within an isolated region.