Figure 1. Gibberellins regulate M. truncatula nodulation depending on DELLA proteins.

(a,b) Relative nodule density (nodule number per mg of root dry weight) of M. truncatula plants treated with GA₃ (a) or PAC (b) at different concentrations. (c) Relative nodule density in M. truncatula roots expressing a dominant-active DELLA protein (pMtDELLA1:della1-Δ18) or the empty vector control. (d) Relative nodule density (nodule number per mg of root dry weight) of the three della mutants. Results are shown as percentages relatively to the untreated control (a,b,d) or to the empty vector control (c). Quantifications were performed 21 days post inoculation with S. meliloti (strain 1021). Dotted lines indicate a ratio of 100%. Error bars represent confidence intervals (α=0.05, n>15 plants per condition), and letters indicate significant differences based on a Kruskal and Wallis test (α<0.05) for (a,b,d), and a Mann–Whitney test (α<0.05) for c. One representative example out of three biological replicates is shown.