Mesorhizobium australicum sp. nov. and Mesorhizobium opportunistum sp. nov., isolated from Biserrula pelecinus L. in Australia.

Biserrula pelecinus L. is a pasture legume that was introduced to Australia from the Mediterranean basin in 1993. Although the native rhizobial population could not nodulate B.

In situ lateral transfer of symbiosis islands results in rapid evolution of diverse competitive strains of mesorhizobia suboptimal in symbiotic nitrogen fixation on the pasture legume Biserrula pelecinus L.

The multi-billion dollar asset attributed to symbiotic nitrogen fixation is often threatened by the nodulation of legumes by rhizobia that are ineffective or poorly effective in N(2) fixation. This study investigated the development of rhizobial diversity for the pasture legume Biserrula pelecinus L., 6 years after its introduction, and inoculation with Mesorhizobium ciceri bv.

Mesorhizobium ciceri biovar biserrulae, a novel biovar nodulating the pasture legume Biserrula pelecinus L.

Biserrula pelecinus L. is a pasture legume species that forms a highly specific nitrogen-fixing symbiotic interaction with a group of bacteria that belong to Mesorhizobium. These mesorhizobia have >98.

Rapid in situ evolution of nodulating strains for Biserrula pelecinus L. through lateral transfer of a symbiosis island from the original mesorhizobial inoculant.

Diverse rhizobia able to nodulate Biserrula pelecinus evolved following in situ transfer of nodA and nifH from an inoculant to soil bacteria. Transfer of these chromosomal genes and the presence of an identical integrase gene adjacent to a Phe tRNA gene in both the inoculant and recipients indicate that there was lateral transfer of a symbiosis island.