In planta Transcriptome Analysis of Pseudomonas syringae

Profiling bacterial transcriptome in planta is challenging due to the low abundance of bacterial RNA in infected plant tissues. Here, we describe a protocol to profile transcriptome of a foliar bacterial pathogen, Pseudomonas syringae pv. tomato DC3000, in the leaves of Arabidopsis thaliana at an early stage of infection using RNA sequencing (RNA-Seq). Bacterial cells are first physically isolated from infected leaves, followed by RNA extraction, plant rRNA depletion, cDNA library synthesis, and RNA-Seq. This protocol is likely applicable not only to the A. thaliana-P. syringae pathosystem but also to different plant-bacterial combinations.