title: The pea Sym37 receptor kinase gene controls infection-thread initiation and nodule development.
abstract: Phenotypic characterization of pea symbiotic mutants has provided a detailed description of the symbiosis with Rhizobium leguminosarum bv. viciae strains. We show here that two allelic non-nodulating pea mutants, RisNod4 and K24, are affected in the PsSym37 gene, encoding a LysM receptor kinase similar to Lotus japonicus NFR1 and Medicago truncatula LYK3. Phenotypic analysis of RisNod4 and K24 suggests a role for the SYM37 in regulation of infection-thread initiation and nodule development from cortical-cell division foci. We show that RisNod4 plants carrying an L to F substitution in the LysM1 domain display a restrictive symbiotic phenotype comparable to the PsSym2(A) lines that distinguish 'European' and 'Middle East' Rhizobium leguminosarum bv. viciae strains. RisNod4 mutants develop nodules only in the presence of a 'Middle East' Rhizobium strain producing O-acetylated Nod factors indicating the SYM37 involvement in Nod-factor recognition. Along with the PsSym37, a homologous LysM receptor kinase gene, PsK1, was isolated and characterized. We show that PsK1 and PsSym37 are genetically linked to each other and to the PsSym2 locus. Allelic complementation analyses and sequencing of the extracellular regions of PsSym37 and PsK1 in several 'European' and 'Afghan' pea cultivars point towards PsK1 as possible candidate for the elusive PsSym2 gene.
authors.affiliation: Laboratory of Genetics of Plant-Microbe Interactions, All-Russia Research Institute for Agricultural Microbiology, Podbelsky chausse 3, 196608 Saint-Petersburg-Pushkin, Russia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Zhukov
authors.forename: Simona
authors.initials: S
authors.lastname: Radutoiu
authors.forename: Lene H
authors.initials: LH
authors.lastname: Madsen
authors.forename: Tamara
authors.initials: T
authors.lastname: Rychagova
authors.forename: Evgenia
authors.initials: E
authors.lastname: Ovchinnikova
authors.forename: Alex
authors.initials: A
authors.lastname: Borisov
authors.forename: Igor
authors.initials: I
authors.lastname: Tikhonovich
authors.forename: Jens
authors.initials: J
authors.lastname: Stougaard
mesh_terms: D000483:Alleles; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D018532:Pisum sativum / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D010641:Phenotype; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D018749:RNA, Plant / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016961:Rhizobium leguminosarum / Q000254:growth & development; D053204:Root Nodules, Plant / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D013559:Symbiosis / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D010940:Plant Proteins; D018749:RNA, Plant; D011494:Protein Kinases