Pathogenic and Molecular Relationships among Strains of Xylella fastidiosa from Grapevine and American Elder

Abstract

Strains of Xylella fastidiosa cause diseases that result in large losses in many economically important plants (1). While all strains of Xylella have been classified into a single species, there is enough strain variability in host range, nutritional fastidiousness, and DNA homology to indicate the need for separation at the pathovar, or subspecies, level (3). Confusing the issue even more is the probability that genetically distinct strains of the bacterium may produce similar symptoms in a common host.