Analysis of thein plantatranscriptome expressed by the corn pathogenPantoea stewartiisubsp.stewartiivia RNA-Seq
Pantoea stewartiisubsp.stewartiiis a bacterial phytopathogen that causes Stewart’s wilt disease in corn. It uses quorum sensing to regulate expression of some genes involved in virulence in a cell density-dependent manner as the bacterial population grows from small numbers at the initial infection site in the leaf apoplast to high cell numbers in the xylem where it forms a biofilm. There are also other genes important for pathogenesis not under quorum-sensing control such as a Type III secretion system. The purpose of this study was to compare gene expression during anin plantainfection versus either a pre-inoculumin vitroliquid culture or anin vitroagar plate culture to identify genes specifically expressedin plantathat may also be important for colonization and/or virulence. RNA was purified from each sample type to determine the transcriptome via RNA-Seq using Illumina sequencing of cDNA. Fold gene expression changes in thein plantadata set in comparison to the twoin vitrogrown samples were determined and a list of the most differentially expressed genes was generated to elucidate genes important for plant association. Quantitative reverse transcription PCR (qRT-PCR) was used to validate expression patterns for a select subset of genes. Analysis of the transcriptome data via gene ontology revealed that bacterial transporters and systems important for oxidation reduction processes appear to play a critical role forP. stewartiias it colonizes and causes wilt disease in corn plants.