Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/1998
Publication Date: N/A
Interpretive Summary: Pierce's Disease, caused by a fastidious plant pathogenic bacterium, has devastated the bunch grape industry in the southeastern U. S. This bacterium also infects muscadine grapes and a number of important tree species. The difficulties of isolating and identifying this bacterium has slowed progress on determining the epidemiology and control of diseases caused by this bacterium. A RAPD fingerprinting method was developed to identify the bacterium and to separate strains of it pathogenic on grapes from strains pathogenic on other hosts. Furthermore, allele frequencies revealed significant variations between isolates from bunch grapes compared to those from muscadine grapes. The use of this RAPD fingerprint method and allele frequencies will be used by plant pathologists in the development of disease control strategies including documenting possible alternate hosts of the bacterium in native plant species and by plant geneticist of developing Pierce's Disease resistant bunch and muscadine cultivars. When this disease is controlled, the grape industry in the southeastern U. S. should flourish.
Technical Abstract: A fingerprinting method based on random amplified polymorphic DNAs (RAPDS) was developed to verify Pierce's disease (PD) strains of Xylella fastidiosa isolated from different Vitis species and hybrids showing PD symptoms from a vineyard in North Florida. One hundred and twenty-nine of 130 strains were confirmed to be PD strains by RAPD profile matching using five selected primers (OPA-02, OPA-03, OPA-09, OPA-11, and OPA-18). In contrast, strains of X. fastidiosa periwinkle wilt, plum leaf scald, and phony peach were readily separated from the PD strain due to the differences in RAPD fingerprints. To insure the accuracy of RAPD fingerprinting, the RAPD experiment were repeated at least once. Alternatively, a minimum of two primers were used. To understand the population structure, RAPD variations within PD strains were first analyzed by cluster analysis using Dice's index by UPGMA (unweighted pair group methods with arithmetic average) algorithm. Cluster analysis produced no significant difference between PD strains isolated from bunch grapes and muscadines. However, further analysis using paired t-test of allele frequencies revealed significant variations between strains isolated from bunch grapes and muscadines (P = 0.06).