Genomic Insights into Xylella fastidiosa Interactions with Plant and Insect Hosts

The utilization of genomic data and widespread availability of genomics tools is still incipient in plant pathology. The first genome of a plant pathogen, that of the bacterium Xylella fastidiosa, was only completed in 2000 (Simpson et al. 2000). Since then, many bacterial plant pathogens have been sequenced, but much of the scientific knowledge extracted from these data is still limited, especially when compared to human pathogens. Nevertheless, significant advances have been made during the last decade, when genomics became widely available to the plant pathology community. Our understanding of the functional role of genes and pathogen taxonomy and evolution has improved significantly. The availability of genome sequences has served as the backbone for much of this work. 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. Although X. fastidiosa is widely thought of as a plant pathogen, its biology is more complex and focus on its pathogenicity to crops clouds our broader understanding of its biology, ecology, and evolution. We predict that genomic data and further research on isolates that do not cause crop diseases will permit a more complete view of X. fastidiosa. This is especially important in the context of emerging diseases, as data suggest that novel X. fastidiosa isolates are particularly prone to emerge as crop pathogens of economic importance.