CHARACTERIZE AND ASSESS THE BIOCONTROL POTENTIAL OF BACTERIAL ENDOPHYTES OF GRAPEVINES IN CALIFORNIA

• Author(s): Kirkpatrick, Bruce; Civerolo, Ed; Jones, Dawna-Darjean; Purcell, Alexander;
• Abstract: Over 1000 putative bacterial endophytes were isolated from healthy, PD-affected and escape (apparently healthy grapevines growing in a vineyard with high incidence of Pierces disease) grapevines growing in Napa and Davis, California from 2000 to 2002. There were no differences in total populations of endophytes isolated in Napa versus Davis, however higher populations of endophytes were recovered from PD-affected versus healthy vines. The endophytes were identified by RFLP and sequence analysis of a portion of the 16S rDNA. Sixty six RFLP groups were determined and sequence analysis showed a diversity of bacterial genera were recovered from grapevines; the most predominant genus was Bacillus. Nineteen of the isolates completely inhibited the growth of Xylella fastidiosa (Xf) in an in vitro plate assay. Approximately 80 of 138 isolates that were tested were classified as grapevine colonists because they could be recovered in high populations more that 6cm from the point where they were inoculated into grapevines. Thirteen of the endophytes were classified as both Xf-antagonists and grapevine colonizers. Five of these isolates were pin-prick inoculated into grapevines growing in the greenhouse. These vines were then challenged by Xf-infectious sharpshooters in the insectary at University of California, Berkeley. None of the endophyte-inoculated vines prevented infection by Xf or decreased the severity of PD that developed in these vines.
• Publication Date: Aug 2003
• Journal: 2003 Pierce's Disease Research Symposium