Production and excretion of Nod metabolites by Rhizobium leguminosarum bv. trifolii are disrupted by the same environmental factors that reduce nodulation in the field

• Published in: Applied and Environmental Microbiology 1993-10, Vol.59 (10), p.3385-3392
• Main Authors: McKay, I.A, Djordjevic, M.A
• Format: Article
• Language: English
• Subjects: Cellular biology; DISPONIBILIDAD DE NUTRIENTES; DISPONIBILITE D'ELEMENT NUTRITIF; FORMATION DE NODOSITES; FOSFORO; Legumes; LIPOPOLISACARIDOS; LIPOPOLYSACCHARIDE; Metabolism; METABOLISME DES GLUCIDES; METABOLISMO DE CARBOHIDRATOS; METABOLITE; METABOLITOS; Microorganism-Plant Interactions; NODULACION; OLIGOSACARIDOS; OLIGOSACCHARIDE; PHOSPHORE; RHIZOBIUM LEGUMINOSARUM; Rhizobium leguminosarum trifolii; RHIZOBIUM TRIFOLII; SECRECION; SECRETION; TEMPERATURA; TEMPERATURE
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/aem.59.10.3385-3392.1993

Lipooligosaccharides (Nod metabolites) have been shown to be essential for the successful nodulation of legumes. In strains of Rhizobium leguminosarum bv. trifolii, Nod metabolites were detected predominantly within the cell and to a lesser extent in the periplasmic space and the growth medium. The production, and in particular the excretion, of Nod metabolites was restricted by a range of environmental conditions which are associated with poor nodulation in the field. Lowering the medium pH from 7.0 to 5.0, reducing the phosphate concentration from 1 micromolar to 5 micromolar KH2PO4, and lowering the incubation temperature from 28 to 18 degrees C affected the number and relative concentrations of the Nod metabolites made. The form and concentration of the nitrogen source affected the relative concentrations of the Nod metabolites produced and excreted. KNO3 concentrations of 10 mM did not affect cell growth rate but substantially reduced the number of Nod metabolites released. Environmental stresses differentially altered Nod metabolite production and excretion in the same strain carrying different introduced nod regions. Strain ANU845(pWLH1) produced and excreted comparatively fewer Nod metabolites at pH 5.0 and at 18 degrees C than strain ANU845(pRI4003). The excretion but not the production of Nod metabolites by strain ANU845(pRtO32) was dependent on the presence of both nodI and nodI. Tn5-induced nodI and nodJ mutants did not accumulate any metabolites either outside the cell or within the outer membrane or periplasmic space. Recognition that Nod metabolite accumulation is a complex system of production and excretion, with each component responding differently to changes in environmental conditions, has many consequences, both at the molecular level and in the field