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Medicago – Sinorhizobium symbiotic specificity evolution and the geographic expansion of Medicago
Author(s) -
BÉNA G.,
LYET A.,
HUGUET T.,
OLIVIERI I.
Publication year - 2005
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/j.1420-9101.2005.00952.x
Subject(s) - biology , rhizobia , medicago , genus , phylogenetic tree , symbiosis , sinorhizobium , nitrogen fixation , phylogenetic diversity , botany , root nodule , mesorhizobium , phylogenetics , evolutionary biology , ecology , bacteria , genetics , gene
The legume genus Medicago interacts with soil bacteria commonly referred to as rhizobia, in a nitrogen fixing symbiosis. We analysed the diversity of symbiotic association specificity among the two organisms, and its evolution in the plant genus. Nitrogen fixation tests and molecular phylogenetic reconstructions revealed that the genus Medicago includes more symbiotic specificity groups than previously suggested and that plant specificity is highly unstable and has repeatedly switched along the diversification of this genus. A phylogenetic analysis including geographical data shows that bacterial geographical diversity distribution has a strong influence on the geographic distribution of plant species and their ability to colonize new areas. Multiple other modifications of specificity occurred along the diversification of the genus, presumably due to selection for specialization to a single bacterial biovar. Codivergence between plants and bacteria may also have taken place.