Fig. 4: Symbiotic properties of the P. phymatum nodS mutant in soybean.

Soybean seedlings were inoculated with the P. phymatum STM815T wild-type (wild type), nodS mutant (nodS), complemented nodS mutant strains (nodS_C) and B. diazoefficiens USDA 110Tspc4 (110spc4). (a) The number of nodules per plant, (b) the dry weight per nodule and (c) the nitrogenase activity were characterized 21 days after inoculation. Three biological replicates per strain were tested, consisting of a total number of plants equal to or higher than eight plants. Error bars indicate the standard error of the mean (SEM). Significant difference between strains was analyzed with unpaired t test (p-value ≤ 0.05). n.s.: not significant; ****; p-value ≤ 0.0001.