Figure 4.

Two evolved isolates from transfer 30 outcompete the ancestor on the root but suffer a fitness disadvantage under shaking conditions in LB + xylan

(A and B) Pairwise competitions between ancestor (magenta) and evolved isolates (green) during root colonization (A) and in LB xylan (0.5%) under shaking conditions (B) for 48 h. In A and B, the bar plots show the starting ratio of the evolved isolate and ancestor in the mix, and the observed ratios after 48 h. Bars represent the mean (N = 3-4), the error bars represent the SD and the points show the replicates for the evolved (below) and ancestor (above). For statistical analysis, the relative fitness (r) of the evolved isolates was calculated by comparing the frequency of the evolved isolate at the beginning and end of the competition experiment. The log2-transformed relative fitness values were subjected to a One-sample t-test to test whether the mean was significantly different from 0. ∗p < 0.05.

(C) A. thaliana roots colonized by a 1:1 mix of ancestor and evolved isolates imaged by CLSM. Both fluorescence combinations are shown. The top row shows the overlay of the fluorescence channels and the bright field image. Images are representative of three independent A. thaliana seedlings. Color codes are shown at the top. Scale bar is 50 μm. See also Figure S1.