The nodule conductance to O-2 diffusion increases with high phosphorus content in the Phaseolus vulgaris-rhizobia symbiosis

Abstract

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699International audienceAlthough recent studies have addressed the effects of phosphorus (P) deficiency on nodule O-2 permeability, little attention has been given to the relationship between nodule P status and nodule permeability. To study these traits, four recombinant inbred lines, namely RILs 34, 83, 115, 147 and one local variety (Concesa) of common bean (Phaseolus vulgaris) were inoculated with RhM11 (a native rhizobial strain from Haouz area of Marrakesh), and grown in hydroaeroponic culture under P-sufficiency (250 mu mol P plant(-1) week(-1)) versus P-deficiency (75 mu mol P plant(-1) week(-1)) conditions. At the flowering stage, the biomass of plants and nodules and their P contents was determined after measuring O-2 uptake by nodulated roots (Conr) and nodule conductance to O-2 diffusion (g(n)). The results showed that P-deficiency significantly decreased plant growth and nodulation, though there were differences between bean genotypes. P-deficiency also induced a decrease in nodule P content (31%) in both sensitive (83, 147) and tolerant lines (34, 115), a 42 and 27% reduction in shoots of sensitive and tolerant lines, respectively. These decreases were associated with significant variations in nodule surface and O-2 permeability among bean genotypes and P-nutrition. Under P-deficiency, gn increased more for the sensitive (39%) than for the tolerant lines (27%). This increase was linked with a rise both in the P levels in nodules and shoots, as well as in the efficiency of symbiotic nitrogen fixation as determined by nodule-dependent biomass production for the sensitive lines. Furthermore, positive correlations were found between O-2 permeability, gn and P content both in nodules and shoots (r(2)=0.94** and r(2)=0.96**). We conclude that nodule variations in Conr and gn are related to nodule P content, and may contribute to the adaptation of energy metabolism in N-2-fixing bean nodules to P-deficiency