Fig. 5

Effects of different synthetic communities on Cd phytoremediation by S. nigrum. a Results of one-strain knockout experiment. b Cd accumulation results of one-strain knockout experiment. Biomass (c), Cd concentration (d), Cd accumulation (e), and soil nitrate reductase (f) performance in simplified synthetic community experiments (n = 9). g Colonization abundance of each SynCom3 member in rhizosphere soil (n = 9). h Expression of soil nitrate reductase encoding genes in rhizosphere soil (n = 9). i OLS linear regression between the strain NCT- 2 colonization abundance and the Sn319 or Sn486 colonization abundance in the rhizosphere soil (n = 18). The fitted lines are regression lines from OLS regression, and the shaded areas indicate 95% confidence interval of the fit. The statistical test used is F-test. In b-d and f, the two-sided unpaired t-test was used for statistical significance testing (**P < 0.01, ***P < 0.001). In g, different letters above bars indicate significant differences (P < 0.05) according to Duncan’s multiple comparison. In e and h, Mann–Whitney U test was used for statistical significance testing (***P < 0.001). Error bars represent standard deviations