Abstract the application of compounds that inhibit the formation of biofilm increases control of citrus canker the citrus canker caused by the bacterium Xanthomonas citri subsp. Citri (XAC) is an economically important disease of Citrus in the world. The formation of biofilm plays an important role in early infection of XAC in host leaves.In this study, we evaluated the hypothesis that small molecules capable of inhibiting the formation of biofilm and reduce the infection XAC improve disease control of citrus canker.Were not found (leucine and 3 - indolilacetonitrila (IAN), to avoid the formation of biofilm on abiotic surfaces in different XAC and let the host at a concentration lower than the minimum inhibitory concentration (MIC).Quantitative analysis on real time polymerase chain reaction (QRT reverse transcription - PCR) indicated that Ian suppressed gene expression of chemotaxis \/ related to motility in XAC.In laboratory experiments, the planktonic and biofilm cells of XAC treated with D - leucine and Ian, either alone or in combination, were more susceptible to copper (CuSO4) than those without treatment.In greenhouse tests, D - leucine and Ian applied alone, or in combination with copper reduced both the number of ulcer lesions and bacterial populations of XAC hosts in the leaves of citrus. This study provides the basis for the use of inhibitors of biofilm of foliar application to the control of the alone or in combination with copper citrus canker - bactericides.resumo aplicação de compostos que inibem a formação de biofilme aumenta o controle do cancro cítrico o cancro cítrico causado pela bactéria xanthomonas citri o subsp. citri (xac) é uma doença economicamente importante dos citros no mundo. a formação de biofilme desempenha um papel importante na infecção precoce de xac nas folhas hospedeiras. neste estudo, avaliou-se a hipótese de que pequenas moléculas capazes de inibir a formação de biofilme reduzir a infecção xac e melhorar o controle da doença ca
