Dual RNA-Seq of Lysobacter capsici AZ78 – Phytophthora infestans interaction shows the implementation of attack strategies by the bacterium and unsuccessful oomycete defense responses

Biological interactions in the microbial communities of the rhizosphere continuously shape the gene expression patterns of each individual microorganism. A dual RNA-Seq approach was applied to obtain a comprehensive overview of the molecular mechanisms activated during the interaction between the biocontrol rhizobacterium Lysobacter capsici AZ78 and the soilborne phytopathogenic oomycete Phytophthora infestans. The RNA-Seq transcriptional profile of L. capsici AZ78 was characterized by up-regulation of genes concerned in the biogenesis of type 4 pilus and lytic enzymes, involved in host colonization and subsequent attack of the P. infestans cell wall, respectively. The activation of detoxification processes allowed L. capsici AZ78 to overcome the attempted defense processes of P. infestans. Moreover, the genes involved in antibiotic biosynthesis were up-regulated in L. capsici AZ78 and caused cell death in P. infestans, with the activation of putative apoptotic processes. The consequences of P. infestans cell death resulted in overall down-regulation of primary metabolic pathways, such as carbohydrate, nucleic acids and protein metabolisms. Overall, the mechanism of action of L. capsici AZ78 was related to parasitism and predatory activities that cause the death of P. infestans.