Normalized and pairwise-compared expression data from the L. japonicus Affymetrix GeneChip were kindly provided by S. Radutoiu (Department of Molecular Biology, Aarhus University; M, FDR, where M is the log2ratio of average signal intensity values from any two conditions [three biological replicates each] and FDR is the false discovery rate-corrected P value;Høgslund et al., 2009). Nodule expression values as compared with those from uninoculated root samples of the same genotype were analyzed. A significance criterion of FDR-corrected P # 0.05 was applied (Høgslund et al., 2009).Fold change values were calculated as |M|2.