A Brazilian consortium has published the genome sequence of a major citrus pathogen, a step growers hope will foster the development of resistant plants.
The pest, a bacterium called Xylella fastidiosa, causes variegated chlorosis— chlorophyll loss and yellowing—and premature, small, tough fruit. Some strains also infect coffee, nuts, and other fruits.
X. fastidiosa feed inside the plants’ xylem, or water transport structure, into which they are injec-ted by sharpshooter leafhoppers.
The sequence, published in the journal Nature, reveals some unique characteristics of the bacterium that may be exploited.
Lacking any genes coding for enzymes that convert amino acids to sugars, the pest must rely solely on carbohydrates. And at least 67 genes, the authors report, are involved in sucking iron and other valuable transition metals from the victim’s sap, depleting the plant of important nutrients. The consortium has also identified gum genes, which allow the X. fastidiosa to attach itself to both its insect vector and plant host.
The X. fastidiosa genome is available on the author’s website, http://onsona.lbi.dcc.unicamp.br/xf/.