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.

Legume receptors perceive the rhizobial lipochitin oligosaccharide signal molecules by direct binding

“…In this two-way exchange, Nod factors synthesized by rhizobia function as central signal molecules, which induce early physiological responses, gene expression, and cell division in susceptible legumes (1)(2)(3). In root cells of the legume hosts, perception is mediated by Nod factor receptors (NFRs) containing ectodomains with three lysin motif (LysM) modules and cytoplasmic serine/threonine kinase domains (4)(5)(6)(7)(8)(9). Mutant studies in the model legumes Lotus japonicus (Lotus) and Medicago truncatula (Medicago) as well as the crop legumes soybean (10,11) and pea (5,6) have shown that NFRs are required for nodulation.…”

“…In root cells of the legume hosts, perception is mediated by Nod factor receptors (NFRs) containing ectodomains with three lysin motif (LysM) modules and cytoplasmic serine/threonine kinase domains (4)(5)(6)(7)(8)(9). Mutant studies in the model legumes Lotus japonicus (Lotus) and Medicago truncatula (Medicago) as well as the crop legumes soybean (10,11) and pea (5,6) have shown that NFRs are required for nodulation. Mutant analysis in Lotus identified two NFRs, NFR1 and NFR5, and phenotypic analysis showed that both nfr1 and nfr5 mutants are equally impaired in nodule initiation (4,5).…”

Studying the biochemical function of the pea receptor-like kinases sym10, sym37 and k1, required for the legume-rhizobia symbiosis development

“…У гороха P. sativum L. анализ мутантов позволил выявить три наиболее вероятных кандидата на роль рецепторов к Nod-факторам: LysM-РПК, кодируемые генами Sym10, Sym37 и K1 [1,8]. Наличие LysM-мо-тивов в LysM-РПК Sym10, Sym37 и K1 позволяет от-нести их к классу рецепторов, потенциально способных связывать Nod-факторы, поскольку эти мотивы при-сутствуют в белках, узнающих соединения, состоящие из остатков N-ацетилглюкозамина [9].…”

“…Вместе с тем анализ мутантов по генам, кодирую-щим рецепторы Sym10, Sym37 и K1, свидетельствует о необходимости этих рецепторных киназ для инициа-ции развития симбиоза [1,8]. Возможным объяснением этих данных может быть способность рецепторов свя-зывать Nod-факторы с высокой аффинностью только при формировании гомо-или гетероолигомерных ком-плексов.…”

Fine localization of the sym31 locus in pea linkage group III

“…В результате за прошедшее десятилетие с использованием анализа геномной синтении были выявлены серии ортологичных симбиотических генов у ряда бобовых культур (Kouchi et al, 2010). У гороха посевного были определены нуклеотидные последовательности симбиотических ге-нов sym7 (Dolgikh et al, 2011), sym8 (Edwards et al, 2007), sym9 (Lévy et al, 2004), sym10 (Zhukov et al, 2008), sym19 (Endre et al, 2002), sym28 (Krusell et al, 2011), sym29 (Krussel et al, 2002), sym33 (Ovchinnikova et al, 2011), sym35 (Borisov et al, 2003) и sym37 (Zhukov et al, 2008). Тем не менее, у гороха не всегда оказывается возможным клонировать ген по гомологии с модельными бобовыми, т.к.…”