Nodules and oxygen

摘要

In root nodule symbioses, bacterial microsymbionts are hosted inside plant cells and supply the host plant with the products of biological nitrogen fixation, rendering it independent of soil nitrogen sources. Two types of such interactions are known, legume/rhizobia symbioses involving several alpha- and beta-proteobacterial genera, collectively called rhizobia, and members of the Leguminosae (Fabaceae) family, and actinorhizal symbioses involving members of the Gram-positive actinomycetous genus Frankia and a diverse group of plants from 25 genera from eight different families, collectively called actinorhizal plants, with one exception trees or woody shrubs.