Application of an Antibiotic Resets the Maize Leaf Phyllosphere Community and Increases Resistance to Southern Leaf Blight

Southern leaf blight (SLB) caused by the foliar fungus Chochliobous heterostrophus is one of the most important pathogens affecting maize (Zea mays L.) in warm humid regions. Direct genetic resistance has been studied extensively; more recently attempts have been made to control disease by changing microbial community composition on leaves. The effect of streptomycin sulfate antibiotic treatment on SLB disease progression was measured in the resistant Mo17 inbred and the susceptible B73 inbred under field conditions. Antibiotic treatment slowed disease progression in B73 and had no significant effect on Mo17. Additional analyses of previous experiments indicated that plants treated with streptomycin hosted a different and more competitive bacterial community. These results suggest that the bacterial community on B73 confers susceptibility to fungal disease, and that perturbing that community can reset community structure to confer greater pathogen resistance.