Poster: Molecular & Cellular Plant-Microbe Interactions: Proteomics/Metabolomics/Genomics
773-P
The virulence function and regulation of the metalloprotease gene prtA in the bacterial plant pathogen, Burkholderia glumae
T. DE PAULA LELIS (1), J. Peng (1), S. Osti (1), J. Hyun Ham (1) (1) Louisiana State University, U.S.A.
Bacterial panicle blight caused by Burkholderia glumae is a major bacterial disease of rice in the United States. Our preliminary RNA-seq study showed that a serine metalloprotease gene, named prtA, is positively regulated by the TofI/TofR-mediated quorum sensing system like other genes for producing important virulence factors of B. glumae, such as toxoflavin. To study the function of prtA in B. glumae 336rg-1, a null mutant of prtA was generated through an insertional mutagenesis approach. Extracellular protease activity was not detected when the prtA mutant was grown on LB-agar plates amended with 1% skim milk, indicating that prtA is solely responsible for the extracellular protease activity of B. glumae 336gr-1. In addition, inoculation of rice panicles with the prtA mutant resulted in reduction of disease severity compared to the wild type strain, showing the requirement of ptrA for full virulence. This study also revealed that the regulation pattern of extracellular protease activity is similar to that of toxoflavin production. Particularly, it was newly found that qsmR, known as the quorum-sensing master regulator gene, is essential for both extracellular protease activity and toxoflavin production by B. glumae 336gr-1. Furthermore, additional genetic elements that control extracellular protease activity were newly identified through screening of random mini-Tn5 mutants, which provide useful information to understand the mechanism of prtA regulation.