title: A nonRD receptor-like kinase prevents nodule early senescence and defense-like reactions during symbiosis.
abstract: Rhizobia and legumes establish symbiotic interactions leading to the production of root nodules, in which bacteria fix atmospheric nitrogen for the plant's benefit. This symbiosis is efficient because of the high rhizobia population within nodules. Here, we investigated how legumes accommodate such bacterial colonization. We used a reverse genetic approach to identify a Medicago truncatula gene, SymCRK, which encodes a cysteine-rich receptor-like kinase that is required for rhizobia maintenance within the plant cells, and performed detailed phenotypic analyses of the corresponding mutant. The Medicago truncatula symCRK mutant developed nonfunctional and necrotic nodules. A nonarginine asparate (nonRD) motif, typical of receptors involved in innate immunity, is present in the SymCRK kinase domain. Similar to the dnf2 mutant, bacteroid differentiation defect, defense-like reactions and early senescence were observed in the symCRK nodules. However, the dnf2 and symCRK nodules differ by their degree of colonization, which is higher in symCRK. Furthermore, in contrast to dnf2, symCRK is not a conditional mutant. These results suggest that in M. truncatula at least two genes are involved in the symbiotic control of immunity. Furthermore, phenotype differences between the two mutants suggest that two distinct molecular mechanisms control suppression of plant immunity during nodulation.
authors.affiliation: Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France.
authors.forename: Fathi
authors.initials: F
authors.lastname: Berrabah
authors.affiliation: Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Bourcy
authors.affiliation: Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France.
authors.forename: Alexis
authors.initials: A
authors.lastname: Eschstruth
authors.affiliation: Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Cayrel
authors.affiliation: Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France.
authors.forename: Ibtissem
authors.initials: I
authors.lastname: Guefrachi
authors.affiliation: Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France.
authors.forename: Peter
authors.initials: P
authors.lastname: Mergaert
authors.affiliation: Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA.
authors.forename: Jiangqi
authors.initials: J
authors.lastname: Wen
authors.affiliation: Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France.
authors.forename: Viviane
authors.initials: V
authors.lastname: Jean
authors.affiliation: Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA.
authors.forename: Kirankumar S
authors.initials: KS
authors.lastname: Mysore
authors.affiliation: Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Gourion
authors.affiliation: Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Ratet
mesh_terms: D000595:Amino Acid Sequence; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D046913:Medicago truncatula / Q000201:enzymology* / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation / Q000235:genetics; D057865:Plant Immunity / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D053204:Root Nodules, Plant / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D016962:Sinorhizobium meliloti; D013559:Symbiosis / Q000276:immunology*
chemical_list: D010940:Plant Proteins; D011494:Protein Kinases
keywords: chronic infection; defense reactions; endosymbiosis; intracellular infection; nitrogen fixation; nodulation; rhizobium