Importance of Xylella fastidiosa RNA metabolism for cold survival and plant virulence
Xylella fastidiosa (Xf) is a xylem-obligate plant pathogenic bacterium that causes diseases in diverse crop plants. In grapevines the infection known as Pierce’s disease, is limited to regions with warmer climates. In previous research, it was observed that grapevines infected with Xf can lose the infection during the winter season (“cold curing”), but this phenomenon is not completely understood. Compared with other bacterial pathogens, Xf lacks certain aspects of cold response, including expression of cold-inducible cold shock proteins. Due to the importance of cold shock proteins in RNA stabilization, this study investigates the role of RNA metabolism in Xf in response to cold temperatures, specifically a polynucleotide phosphorylase homolog (PNPase). PNPase has been characterized in other bacterial systems for RNA exonuclease and polymerization activity essential to survival at low temperatures. An Xf PNPase knockout mutant (Δpnp) is currently being evaluated for cold survival, in planta virulence, and cold-inducible gene expression. The results will provide important information regarding Xf cold response which is relevant to understanding the mechanism of cold curing of Xf in grapevine.