UC Berkeley

The genome of Xylella fastidiosa encodes the properties that enable it to alternately colonize its plant and insect hosts. In this chapter, we take a holistic approach and explore X. fastidiosa evolution, biology, and management based on information and insights that would not have been possible, or would have been technically challenging, during the pre-genomics period of plant pathology. Analysis of genome sequences illustrates the major physiological differences between X. fastidiosa and plant pathogens in the sibling genus Xanthomonas, which possess substantially larger genomes and a variety of genes that are essential for pathogenicity, yet absent from the X. fastidiosa genome. Genome sequence data have enabled reverse-genetic approaches to transfer knowledge from more genetically tractable organisms, along with examination of gene regulatory effects that are involved in colonization of the various hosts. The availability of reference genome sequences has also facilitated the examination of genetic diversity among X. fastidiosa found in different geographic regions and different host plants. Existing data demonstrates the importance of mobile genetic elements in producing genetic diversity among X. fastidiosa isolates. Genome-wide descriptions of diversity will be a powerful tool to identify the genetic changes that underlie the emergence of new agricultural diseases.