Sinorhizobium fredii HH103 invades lotus burttii by crack entry in a nod factor-and surface polysaccharide-dependent manner

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  • Sebastián Acosta-Jurado, Departamento de Microbiología, Universidad de Sevilla
  • ,
  • Dulce Nombre Rodríguez-Navarro, IFAPA, Centro Las Torres-Tomejil
  • ,
  • Yasuyuki Kawaharada
  • ,
  • Juan Fernández Perea, IFAPA
  • ,
  • Antonio Gil-Serrano, Departamento de Química Orgánica, Universidad de Sevilla
  • ,
  • Haojie Jin
  • ,
  • Qi An, Departamento de Microbiología, Universidad de Sevilla
  • ,
  • Miguel A. Rodríguez-Carvajal, Departamento de Química Orgánica, Universidad de Sevilla
  • ,
  • Stig U. Andersen
  • Niels Sandal
  • Jens Stougaard
  • José María Vinardell, Universidad de Sevilla
  • ,
  • José E. Ruiz-Sainz, Departamento de Microbiología, Universidad de Sevilla

Sinorhizobium fredii HH103-Rifr, a broad host range rhizobial strain, induces nitrogen-fixing nodules in Lotus burttii but ineffective nodules in L. japonicus. Confocal microscopy studies showed that Mesorhizobium loti MAFF303099 and S. fredii HH103-Rifr invade L. burttii roots through infection threads or epidermal cracks, respectively. Infection threads in root hairs were not observed in L. burttii plants inoculated with S. fredii HH103-Rifr. A S. fredii HH103-Rifr nodA mutant failed to nodulate L. burttii, demonstrating that Nod factors are strictly necessary for this crack-entry mode, and a noeL mutant was also severely impaired in L. burttii nodulation, indicating that the presence of fucosyl residues in the Nod factor is symbiotically relevant. However, significant symbiotic impacts due to the absence of methylation or to acetylation of the fucosyl residue were not detected. In contrast S. fredii HH103-Rifr mutants showing lipopolysaccharide alterations had reduced symbiotic capacity, while mutants affected in production of either exopolysaccharides, capsular polysaccharides, or both were not impaired in nodulation. Mutants unable to produce cyclic glucans and purine or pyrimidine auxotrophic mutants formed ineffective nodules with L. burttii. Flagellin-dependent bacterial mobility was not required for crack infection, since HH103-Rifr fla mutants nodulated L. burttii. None of the S. fredii HH103-Rif r surface-polysaccharide mutants gained effective nodulation with L. japonicus.

Original languageEnglish
JournalMolecular Plant - Microbe Interactions
Pages (from-to)925-937
Number of pages13
Publication statusPublished - 1 Dec 2016

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