The unbearable naivety of legumes in symbiosis

• Published in: Current opinion in plant biology Vol. 12; no. 4; pp. 491 - 499
• Main Authors: Den Herder, Griet, Parniske, Martin
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2009; [Oxford, UK]: Pergamon: Elsevier Science
• Subjects: bacterial proteins; bacteroids; effector proteins; evolution; Fabaceae; Fabaceae - genetics; Fabaceae - metabolism; Fabaceae - microbiology; ferredoxin hydrogenase; genetics; Genotype; host plants; Host-Pathogen Interactions; legumes; metabolism; microbiology; Models, Biological; Nitrogen Fixation; nitrogen-fixing bacteria; Nitrogenase; Nitrogenase - metabolism; physiology; Rhizobiaceae; Rhizobium; Rhizobium - physiology; Root Nodules, Plant; Root Nodules, Plant - genetics; Root Nodules, Plant - metabolism; Root Nodules, Plant - microbiology; roots; signal transduction; Symbiosis
• ISSN: 1369-5266; 1879-0356; 1879-0356
• DOI: 10.1016/j.pbi.2009.05.010

The mechanisms by which legumes choose their rhizobial partners operate independently from their ability to fix nitrogen. As a result of this naivety, symbiotic nitrogen fixation is often suboptimal. The initial recognition of the bacterial partner and the subsequent signal transduction in the host root utilises components that are functionally conserved between legumes and probably actinorhiza host plants. However, the later steps, which largely determine symbiotic performance, are subject to ongoing evolutionary diversification of molecular mechanisms. For example, the impact of bacterial effector proteins, the occurrence of terminal bacteroid differentiation and the expression of bacterial hydrogenase, all depend on the plant genotype. Strategies towards increased nitrogen fixation of legumes in agriculture need to encompass this diversification of mechanisms.