Fig. 1From: Plant transcriptome analysis reveals specific molecular interactions between alfalfa and its rhizobial symbionts below the species levelSymbiotic performance of E. meliloti strains selected for plant transcriptome analysis. Shoot dry weights (a) and nitrogenase activities (b) were measured for four M. sativa cultivars: G9, Gannong No. 9; G3, Gannong No. 3; Q, Qingshui; L, Longzhong. Data are means and standard errors of four biological replicates. Nitrogenase activities were expressed as μmol·g− 1·h− 1. Level of significance was indicated by either two stars (P < 0.01) or four stars (P < 0.0001) above the bar. The Student’s t-test was performed in comparison with the uninoculated controls (CK). Effective one- and two-cultivar specificity biotypes (E1 vs. E2) were distinguished by two different colorsBack to article page