CHARACTERIZATION AND DIFFERENTIATION OF INDIGENOUS RHIZOBIA ISOLATED FROM CANARIAN SHRUB LEGUMES OF AGRICULTURAL AND ECOLOGICAL INTEREST

In the course of a study on rhizobia nodulating six indigenous legume shrubs from the Canary Islands, one Rhizobium and 27 Bradyrhizobium Ca narian isolates were characterised. It was found that those ascribed t o Bradyrhizobium were promiscuous and formed effective nodules not onl y in their original host but on Chamecytisus proliferus subsp. prolife rus (Tagasaste) as well. However, Rhizobium isolate RES-1 was more spe cific and only nodulated on its host (Teline canariensis). The serotyp ing of these isolates required a broad antisera panel due to the great antigenic diversity of these rhizobia, that appeared to be due to dif ferences in their lipopolysaccharides, the main antigenic determinants , that showed great structural diversity. The 28 isolates studied prod uced 22 easily distinguishable electrophoretic profiles of lipopolysac charides. Protein or plasmid electrophoretic profiles were equally or less discriminating than the lipopolysaccharides profiles and were mor e difficult to compare. The comparison of the lipopolysaccharide elect rophoretic patterns is a more reliable and discriminating method than serotyping or electrophoretic protein and plasmid profile analysis for the identification of Bradyrhizobium strains. No correlation between the lipopolysaccharide profiles of the isolates and the plant from whi ch they were obtained or their geographical origin was observed.