Symbiotic diversity in the cosmopolitan genus Acacia

Abstract

Acacia is the second largest genus within the Leguminosae, with 1352 species identified. This genus is now known to be polyphyletic and the international scientific community will presumably split Acacia into five new genera. This review examines the diversity of biological nitrogen fixation symbiosis within Acacia as a single genus. Due to its global importance, an extensive body of scientific literature is available on Acacia, particularly in the area of symbiotic nitrogen fixation. Most significantly, Acacia can be separated into nodulating and non-nodulating species. The nodulating Acacia species are symbiotically compatible with a wide range of soil rhizobia. Four different genera of rhizobia are known to nodulate with species of Acacia, while most other legumes nodulate with only a single species of rhizobia. The diversity of symbiotic interactions in Acacia also corresponds to a wide range of flavonoid inducers produced by the different species. Corresponding to the chemical inducers produced by the host Acacia, the nodulating rhizobia also produce a wide range of lipo-chito-oligosaccharide inducers, called Nod factors. The symbiotic diversity we describe for Acacia helps to explain the adaptability of different species within this genus to a wide range of extreme environments.

Citation

Leary, James K.; Singleton, Paul W.; Scowcroft, Paul G.; Borthakur, Dulal. 2006. Symbiotic diversity in the cosmopolitan genus Acacia. Symbiosis 4: 107-117