Reduced Root Secretion of Valine in -Microbe Interaction Contributes to the Decreased Colonization of Pathogenic .

Root exudates play a critical role in root-microbe interactions. causes crown gall disease in multiple plant species, but rose root exudate-mediated inhibition of in the rhizosphere is poorly understood. In this study, the influence of preinoculation with beneficial bacteria or pathogens on root exudates and subsequent colonization by was investigated in a split-root system. We found that preinoculation of rose plants in a split-root system with CLA178 or C58 inhibited subsequent colonization by C58. Root secretion of valine had positive effects on the chemotaxis, biofilm formation, colonization of C58, and crown gall disease severity, but valine secretion decreased significantly when plants were preinoculated with CLA178 or C58. These results indicated that rose plants reduced root secretion of valine in response to microbial colonization, thereby reducing the colonization of colonization and disease severity. This study provides new insights into the root exudate-mediated interactions of rose plants, , and and proposes a potential way to control crown gall disease.