Fig. 4: Sucrose promotes competitive root colonization by B. subtilis.

A LSCM images of root colonization by WT (3610) and the mutants (ΔsacA and ΔsacB) treated without or with sucrose (+S). B The difference on the tomato root colonization between the WT and the two mutants was determined by counting colony forming unit (CFU) per mm root length. Error bars represent standard deviations. ** indicates p value < 0.01; * indicates p value < 0.05. C The colonization competition between 905 and 3610 (including its derivates) on tomato roots was determined by counting CFU per mm root length. * indicates p value < 0.05; ** indicates p value < 0.01; NS, no statistical difference. D The pictures of seedlings of wild-type A. thaliana (Col-0) and its derivatives impaired in sucrose transport [ΔAtSUC2 (At1g22710, SALK_0038124), ΔAtSTP1 (At1g11260, SALK_048848c), and ΔAtSUC3 (At2g02860, SALK_077723)]. Weakened developmental effects were observed in some of the mutants. Pictures are representative of at least 20 independent plants (Scale bars: 1.4 cm). E LSCM pictures of 15-day-old roots of wild-type A. thaliana and the mutants. The roots were observed 72 h after inoculation with strain 3610 constitutively expressing mKate2. Pictures are representative of at least 20 independent roots (Scale bars: 50 μm). F The influence of different sugar transporters on the colonization of 3610 on the A. thaliana roots was determined using colony forming unit (CFU) per mm root length by plate recovery counting. The letters above the columns indicate statistically significant differences of different groups based on Student’s t test (p < 0.01).