Integrated functional anlaysis of quorum-sensing in the rice pathogenic bacterium Burkholderia glumae

Quorum sensing (QS) is a cell-to-cell communication mechanism that allows bacterial cells to collectively behave like a multicellular organism. It regulates the expression of toxoflavin, one of the major virulence factors of the rice pathogen, Burkholderia glumae. The QS system of B. glumae is mediated by the core genes, tofI and tofR. N-octanoyl-L-homoserine lactone, the primary QS signal molecule of B. glumae, is synthesized by tofI and binds to the cognate receptor tofR at the quorum point. However, tofI and tofR null mutants produce toxoflavin in certain growth conditions, indicating the presence of tofI- and tofR-independent pathways for toxoflavin production. The present study identified regulators required for the tofI- and tofR-independent pathways, including flagella transcriptional activator, diguanylate cyclase, O-antigen polymerase family protein, QsmR QS-dependent master regulator and one hypothetical protein with its encoding gene located upstream of toxJ (encoding toxoflavin production activator). A novel QS regulatory element, tofM, was identified as a positive regulator of pathogenicity and a putative modulator of tofR in B. glumae. RNA-sequencing was also performed to investigate the QS regulon and medium condition-dependent gene expression in B. glumae. A large collection of target genes and noncoding RNAs was detected by comparative transcriptome analysis. From a comparison of the transcriptional profile of the wild type (336gr-1) and quorum sensing mutants grown on solid and liquid media, it is postulated that an alternative global regulator is activated to compensate for the dysfunction of AHL QS on solid medium.

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Plant Sciences

Grantor

Plant Pathology and Crop Physiology

Year dc:date.available

2013

Author dc:creator

• Chen, Ruoxi

• RNA-seq
• mutation
• quorum sensing
• Burkholderia glumae

Statement dc:rights

• unrestricted
• Release the entire work immediately for access worldwide.

Identifier

etd-11132013-230025
https://repository.lsu.edu/gradschool_dissertations/1287

OAI identifier oai:identifier

oai:repository.lsu.edu:gradschool_dissertations-2286