biofilm formation by GR4 and its
derivative mutant. A) Confocal images of biofilms established on alfalfa root surfaces 3 dpi. Bars, 70 μm. B) Colony forming unit (CFU) counts recovered from alfalfa roots. Data are expressed per gram of root fresh weight (RFW). Error bars indicate the standard error from the mean of three independent experiments. According to the Games-Howell test (P ≤ 0.05) values followed by the same letter do not differ significantly.