Phenazine-1-carboxylic acid-producing Pseudomonas fluorescens LBUM223 represses the growth and alters the transcriptome of Phytophthora infestans
R. ROQUIGNY (1), D. Joly (1), M. Filion (1) (1) Université de Moncton, Canada

Phytophthora infestans is responsible for late blight, one of the most important potato diseases. Phenazine-1-carboxylic acid (PCA)-producing Pseudomonas fluorescens LBUM223 isolated in our laboratory shows strong potential to control late blight. An in vitro confrontational assay was performed using P. infestans inoculated alone (control) or in the presence of wild-type LBUM223, its phzC- isogenic mutant not producing PCA, or synthetic PCA. Destructive sampling was performed at 6, 9 and 12 days and the transcriptome of P. infestans was analysed using RNA-sequencing. Both LBUM223 and synthetic PCA significantly repressed P. infestans’ growth at all times, while the mutant barely altered the growth of the pathogen. Transcriptomic analysis showed that the non-producing PCA mutant did not significantly alter the transcriptome of P. infestans and yielded results similar to the control treatment. However, LBUM223 and synthetic PCA significantly altered P. infestans gene expression. Although time had a slight effect on the number of differentially expressed genes, LBUM223 and synthetic PCA yielded similar responses. The number of overexpressed P. infestans genes varied between 4% and 6% (LBUM223) and between 1% and 6% (synthetic PCA), while both treatments repressed the expression from 1% to 2% of genes. Gene ontology analyses revealed that PCA production by LBUM223 is altering the expression of key functional genes involved in various functions of interest.

Abstract Number: P5-126
Session Type: Poster