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The global regulatory network for the virulence of Burkholderia glumae, the major causal agent of bacterial panicle blight of rice.
J. HAM (1). (1) Louisiana State University Agricultural Center, Baton Rouge, LA, U.S.A.

<i>Burkholderia glumae</i> causes bacterial panicle blight of rice, which is an emerging rice disease problem in many rice-growing regions around the world including the southern United States. Production of the phytotoxin, toxoflavin, and lipase and biogenesis of flagella are crucial for the virulence of <i>B. glumae</i>. These virulence-related phenotypes are globally regulated by the <i>N-</i>acyl homoserine lactone (AHL) quorum-sensing system of <i>B. glumae</i>, which is conferred by <i>tofI</i> and <i>tofR</i> genes encoding an AHL synthase and an AHL receptor, respectively. According to our recent study, PidS/PidR two-component system controls a functional type III secretion system and toxoflavin production in <i>B. glumae</i>. In this study, additional new regulatory factors of <i>B. glumae</i> were identified through various mutational approaches and characterized in terms of their functions in virulence-related phenotypes. Among the new regulatory genes, <i>ntpR</i> encoding a LysR-family protein and <i>tepR</i> encoding an RpoN-dependent response regulator acted as negative regulators for toxoflavin biosynthesis and virulence. <i>tofM</i> encoding an RsaM homolog and located between <i>tofI</i> and <i>tofR</i> was also characterized as a new regulatory gene for toxoflavin production in this study. Further functional and genetic studies on these newly found regulatory components in conjunction with other known regulatory systems, such as the TofI/TofR AHL quorum-sensing system, would provide a better view on the global regulatory network of this pathogen for pathogenesis.<p><p>Keywords:

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