At the Helm of Infection: Investigating Genetic Regulators of Burkholderia glumae Virulence

Almost two decades ago, Burkholderia glumae's quorum sensing (QS) mechanism was found to modulate its virulence factors for rice bacterial panicle blight (BPB).  However, prior research has challenged this paradigm, and we recently showed that the regulatory gene qsmR affects virulence in a hypervirulent B. glumae strain, independent of the QS.  Here, we investigate which of these regulatory systems is the master control of the virulence in B. glumae. Initial transcriptomic data showed upregulation of phage-related genes and downregulation of genes involved in non-ribosomal polyketide synthesis in the hypervirulent and avirulent strains, respectively. These pathways may be involved in the pathogenicity of the bacteria. However, succeeding transcriptomic analyses did not identify which of these regulators controls these pathways. Additional RNA-Seq and ChIp-Seq data are currently generated to determine the regulons directly regulated by the qsmR gene. Additionally, comparative genomics of five avirulent and four virulent strains found changes in the toxE gene, which disrupts toxoflavin synthesis, a key virulence component.  Pangenomic analysis is currently being conducted to seek more B. glumae virulence driver genes.  This research will illuminate the molecular mechanisms underpinning BPB virulence and provide the groundwork for developing effective BPB management measures.