Genome sequencing and functional characterization of Xanthomonas cucurbitae , the causal agent of bacterial spot disease of cucurbits

Bacterial leaf spot disease caused by has severely affected the pumpkin industries in the Midwestern region of United States, with the bacteria mainly infecting pumpkin leaves and fruits, and leading to significant yield losses. In this study, we utilized genomics and genetics approaches to elucidate molecular mechanisms of pathogenesis during interaction with its host. We generated the first reference-quality whole-genome sequence of the type isolate and compared to other species, has a smaller genome size with fewer virulence-related genes. RNA-seq analysis of under plant-mimicking media conditions showed altered transcriptional responses, with upregulation of virulence genes and downregulation of cellular homeostasis genes. Additionally, characterization of key virulence genes using gene deletion methods revealed that both type II enzymes and type III effectors are necessary for to cause infection in the pumpkin host.