Figure 3.

Taxonomically Diverse Root Commensals Improve Iron-Limiting Plant Performance

(A) Phylogenetic tree of 115-strain SynCom derived from At-RSPHERE culture collection (Bai et al., 2015) used for microbiota reconstitution. Red arrows indicate strains used in (D).

(B) Representative images of plants grown for 2 weeks on media containing available (avFe) and unavailable (unavFe) forms of iron inoculated with live SynCom or heat-killed control.

(C) SFW and total chlorophyll quantification of Col-0 plants after 2 weeks of growth on indicated iron conditions. Data are pooled from three experiments with avFe and unavFe: n = 42–54 plants per condition, and chlorophyll measured in pooled samples, n = 13–15 per group. Insufficient iron data are from one experiment, n = 18 plants. Letters indicate significant pairwise differences between groups (p-adj ≤ 0.05 by Dunn’s pairwise comparison with Bonferroni correction for SFW, and Tukey’s HSD corrected for multiple comparisons for chlorophyll content).

(D) Iron-limiting growth rescue activity of SynCom strains in mono-association. SFW was measured and plotted as percent growth rescue of bacteria-inoculated plants on unavFe compared with the growth deficit between sterile plants on avFe versus unavFe. Black and red lines indicate 0% (axenic plants on unavFe) and 100% growth rescue (axenic plants on avFe), respectively. Data are pooled from 1–4 experiments per strain and normalized to respective sterile controls (n = 18 plants per experiment). Asterisks indicate significance from sterile plants by Wilcoxon ranked sum test with FDR adjustment (^∗, ^∗∗, and ^∗∗∗ indicate p-adj ≤ 0.05, 0.01, and 0.001, respectively). See also Figure S4.