title: What Does It Take to Evolve A Nitrogen-Fixing Endosymbiosis?
abstract: Plant rhizo- and phyllospheres are exposed to a plethora of nitrogen-fixing bacteria, providing opportunities for the establishment of symbiotic associations. Nitrogen-fixing endosymbioses are most profitable and have evolved more than ten times in the angiosperms. This suggests that the evolutionary trajectory towards endosymbiosis is not complex. Here, we argue that microbe-induced cell divisions are a prerequisite for the entrance of diazotrophic prokaryotes into living plant cells. For rhizobia and Frankia bacteria, this is achieved by adapting the readout of the common symbiosis signalling pathway, such that cell divisions are induced. The common symbiosis signalling pathway is conserved in the plant kingdom and is required to establish an endosymbiosis with mycorrhizal fungi. We also discuss the adaptations that may have occurred that allowed nitrogen-fixing root nodule endosymbiosis.
authors: Wageningen University, Department of Plant Science, Laboratory of Molecular Biology, Droevendaalsesteeg 1, 6708PB, The Netherlands. Electronic address: rene.geurts@wur.nl.
authors: Rene
authors: R
authors: Geurts
authors: Wageningen University, Department of Plant Science, Laboratory of Molecular Biology, Droevendaalsesteeg 1, 6708PB, The Netherlands.
authors: Ting Ting
authors: TT
authors: Xiao
authors: Department of Microbe-Plant Interaction, Faculty 2, University of Bremen, PO Box 33 04 40, 28334 Bremen, Germany. Electronic address: breinhold@uni-bremen.de.
authors: Barbara
authors: B
authors: Reinhold-Hurek
mesh_terms: D005075:Biological Evolution; D002455:Cell Division; D009586:Nitrogen Fixation; D015398:Signal Transduction; D013559:Symbiosis
keywords: common symbiosis signalling pathway; evolution; lipochitooligosaccharides; nitrogen-fixing endosymbiosis