Figure 1. Roots of axenically grown Arabidopsis and tomato were incubated with E coli or yeast expressing green fluorescent protein (^GFP E. coli or ^GFPyeast).

^GFP E. coli was detected at the surface of roots and root hairs (A and C), and inside roots and root hairs (B and D). ^GFPYeast was present inside roots and root hairs (E and F). (A, D and F) and (B, C and E) correspond to tomato and Arabidopsis root, respectively. Fluorescent images were taken by confocal laser scanning microscopy (CLSM).