SRA

Pantoea stewartii subsp. stewartii (Pss) causes Stewarts wilt disease in corn, which is the primary bacterial disease of corn in the USA. Pss is introduced into corn via the corn flea beetle vector, Chaetocnema pulicaria, when beetle feces enter wounds created during feeding. The infection begins in the apoplast of the leaf where Pss causes leaf blight. Subsequently, the bacteria move to the xylem and form a biofilm, preventing water transport. This causes wilting and leads to necrosis, consequently affecting both crop yield and survival. A previous RNA-Seq analysis provided a snapshot of the wild type Pss transcriptome during growth in planta and evidence of differential Pss gene expression when it resides in the xylem. Tn-Seq experimentation subsequently identified specific genes essential to survival in planta including lrp, which encodes the global transcription factor, Leucine-responsive Regulatory Protein (Lrp). The Lrp protein family is found across many bacterial and archaeal species where it regulates multiple critical physiological functions. In Pss, Lrp is known to positively control motility and biofilm production, which are important for the in planta lifestyle of Pss. Bioinformatic analyses using RNA-Seq data comparing wild-type Pss to a Lrp mutant strain was completed to define the Lrp regulon in planta through differential gene expression. Results provide support for Lrp involvement in regulating capsule biosynthesis, and nitrogen-associated assimilation and metabolism. This work has provided insights into how Pss recognizes and exploits the corn xylem environment.