Differentiation of Xylella fastidiosa via high resolution melting temperature analysis

The xylem-limited plant pathogenic bacterium Xylella fastidiosa (Xf) is the causal agent of Pierce's Disease, which affects grapevines eventually leading to plant death in 1 to 5 years. Xf is transmitted to the plants by xylem-feeding insect vectors, most commonly the glassy winged sharpshooter (Homalodisca vitripeninis). The three most abundant subspecies of Xf in the southwestern United States, which are also the target subspecies of this experiment, are as follows: Xf. subsp. fastidiosa, Xf. subsp. multiplex, and Xf. subsp. sandyi. Quantitative Real-Time Polymerase Chain Reaction (QRT-PCR) followed by high resolution melt temperature (HRM) analysis was used to determine the temperature at which a sample's DNA denatures in order to differentiate between subspecies of Xf. Insects were collected from multiple locations in Texas, both inside and outside vineyards, which were then tested for the presence of Xf. Additionally, position samples were tested to determine the subspecies of Xf that was detected.