Pierce’s disease (PD) of grapevine is caused by the plant pathogen Xylella fastidiosa and deleteriously affects the grape production in the southern United States. Epidemic losses of vines in California have dramatically increased by the recent introduction of Glassy-winged Sharpshooter (GWSS), Homalodisca coagulata (Hemiptera: Cicadellidae) that transmits the bacterium from plant to plant through xylem feeding activities. The use of bacteria associated with insects to disrupt disease transmission is a new approach to disease control. Alcaligenes xylosoxidans denitrificans ( Axd) was isolated frequently from the mouthpart of wild captured GWSS. Axd was chosen to be the first candidate for transformation with products that inhibit or kill X. fastidiosa. To find an appropriate agent for control of PD, 150 antimicrobial peptides (AMPs) were tested for activity on Axd and 11 X. fastidiosa strains. 72 peptides showed potent antimicrobial activity against all strains studied. 10 AMPs were found with toxicity forwards to X. fastidiosa but not against the GWSS symbiotic bacterium Axd. Artificial genes to code these peptides are being designed and constructed with appropriate regulatory elements and signal peptides for expression and secretion by Axd.

Species 1: Hemiptera Cicadellidae Homalodisca coagulata Keywords: bacterial symbionts, Xylella fastidiosa, antimicrobial peptides, biological control