Exposure to subinhibitory concentrations of phenazine-1-carboxylic acid controls common scab of potato through transcriptomic changes in Streptomyces scabies
M. FILION (1), R. Roquigny (1), T. Arseneault (2), C. Goyer (3), A. Novinscak (1) (1) Université de Moncton, Canada; (2) University of Reading, United Kingdom; (3) Agriculture and Agri-Food Canada, Canada

Biocontrol of common scab of potato, an important disease primarily caused by Streptomyces scabies, has previously been demonstrated under controlled and field conditions using Pseudomonas fluorescens LBUM223, a phenazine-1-carboxylic acid (PCA)-producer. Reduced virulence in S. scabies following exposure to PCA was suggested as the main biocontrol mechanism involved, as no reduction in pathogen populations in soil occurred. To better understand this interaction and the impact of PCA in this system, whole transcriptome analyses (RNA-seq analyses) of S. scabies confronted with wild type LBUM223, its isogenic PCA-deficient mutant (phzC-) and purified PCA were performed. Following exposure to wild type LBUM223 or purified PCA, reduced mycelium and spore formation in S. scabies was observed, and 12%-14% of all genes were differentially expressed, including a strong down-regulation of the cfa biosynthetic cluster, which produces a virulence factor resembling coronatine, and a strong up-regulation of a rar conservon homologue, a negative regulator of differentiation. Many genes involved in oxidation-reduction homeostasis in S. scabies were also up-regulated in response to these treatments. 0.13% of S. scabies genes were differentially expressed in the presence of LBUM223 phzC-, suggesting that the main transcriptional changes observed are due to exposure to subinhibitory concentrations of PCA, which causes important transcriptional and physiological changes in the pathogen.

Abstract Number: C16-4, P5-136
Session Type: Concurrent