Numerical taxonomy of photosynthetic rhizobia nodulating Aeschynomene species

Abstract

Fifty-two strains of photosynthetic rhizobia isolated from stem and root nodules of Aeschynomene afraspera, Aeschynomene denticulata, Aeschynomene evenia, Aeschynomene indica, Aeschynomene nilotica, Aeschynomene pratensis, Aeschynomene rudis, Aeschynomene schemperi, and Aeschynomene sensitiva were compared with reference rhizobial strains representing Rhizobium, Bradyrhizobium, and Azorhizobium species by performing a multivariate statistical analysis of 150 phenotypic characteristics. Eight phena, some of which contained subphena, were identified. Aeschynomene rhizobia which synthesize bacteriochlorophyll were grouped in phenon 6, which contained three subphena, while nonphotosynthetic Aeschynomene rhizobia were grouped in phena 1 and 2. Our results indicate that the photosynthetic rhizobia nodulating Aeschynomene species belong to a phenon (phenon 6) that is separate from the genera Bradyrhizobium (phena 1 to 5), Azorhizobium (phenon 7), and Rhizobium (phenon 8).