Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Abstract only
Publication Acceptance Date: 12/15/2010
Publication Date: 12/15/2010
Citation: Lewis, B., Chen, J., Farrar, J. 2010. Genomic characterization of a lysogenic phage from Xylella fastidiosa. In: Proceedings of the Pierce's Disease Research Symposium, Dec 15-17, 2010, San Diego, CA. p. 107-111. Interpretive Summary:
Technical Abstract: Xylella fastidiosa is an important pathogen causing disease of several economically important crops such as grape and almond in Central California. Despite intensive efforts to study this nutritionally fastidious pathogen, many biological traits of the bacterium such as bacteriophages remains poorly characterized. Phage particles have been consistently recovered from supernatants of X. fastidiosa culture. Further study on phage requires genome characterization. In this study, an experiment was conducted to induce release of lysogenic phage particles from bacterial hosts in PD3 broth. Phage particles were enriched from culture supernatant. Examination by electron microscopy showed particles with morphology similar to those in the family Podovirideae. Strain Dixon showed a relatively higher phage titer and therefore was used for phage genome characterization. Bacterial chromosomal DNA in the phage preparation was removed by DNAse digestion. Phage DNA was amplified by PCR using random primers, cloned, and sequenced. BLAST search identified a cloned sequence matching a prophage region in the whole genome sequence of several X. fastidiosa strains. This sequence also shares similarity (but is not identical) with a phage sequence from a Texas strain of X. fastidiosa. Using the published whole genome sequences as a guide, an effort to identify the phage genome is in progress. Several challenges need to be overcome: 1) Phage titer is still not sufficiently high to generate large quantity of phage DNA for analysis; 2) DNAse inhibitors are presence in phage preps; and 3) The draft genome sequence of strain Dixon is not enclosed and sequence quality remains to be evaluated.