Symbiotic plant-microbe interaction

Symbiotic nitrogen fixation is profoundly important for the environment and sustainable agriculture. Most crop plants assimilate nitrogen only from soil via added fertilizers. An alternative source is the rhizobia-legume symbiosis that provides a major source of fixed nitrogen. Rhizobia are capable of inducing the formation of nodules on the roots of their leguminous host plants. These specialized plant organs are invaded by the bacteria which fix nitrogen in an endosymbiotic bacteroid state within the plant cell. This process involves specific recognition and coordinated differentiation of both bacterial and host cells.

Establishment of the Sinorhizobium meliloti-Medicago sativa symbiosis (Figure: D. Kapp, Bielefeld University)

Images of the Sinorhizobium meliloti-Medicago sativa symbiosis (Stanford University, Long lab)

Nodule and root
3 days old nodule
Invading bacteria
Nodule section


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University of Freiburg
Department of Biology

Prof. Dr. Anke Becker
79104 Freiburg


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