ARS | Publication request: Variation of prophage frequency in “Canidatus Liberibacter asiaticus” strains from two geographical distinct citrus growing Provinces in China

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 7, 2010
Publication Date: August 7, 2010
Citation: Liu, R., Zhang, P., Chen, J., Deng, X. 2010. Variation of prophage frequency in “Canidatus Liberibacter asiaticus” strains from two geographical distinct citrus growing Provinces in China. Phytopathology. 100:S73.

Technical Abstract: Prophages are genetic elements of bacterial genomes and are involved in lateral gene transfer, pathogenicity, environmental adaptations and interstrain genetic variability. In this study, the sequence of a phage terminase gene of “Candidatus Liberibacter asiaticus”, a bacterium associated with citrus Huanglongbing (HLB), was identified and used to represent the corresponding prophage. Based on the DNA sequence, a set of primers was designed and used for PCR detection of prophage in HLB citrus samples collected from two geographically distinct provinces, Guangdong with an average altitude of <500 m , and Yunnan with an average altitude of >2,000 m. The frequency of prophage detection was 15.8% (19/120) in Guangdong and 97.4% (38/39) in Yunnan. Chi-square analysis showed that the prophage frequencies between the two regions were significantly different (P<0.0001). However, the prophage gene sequences obtained from 10 Guangdong strains and 8 Yunnan strains shared 100% similarity, suggesting identity or high similarity of the corresponding prophage. The absence of the terminase gene sequence in some “Ca. L. asiaticus” strains suggests that the prophage or putative phage has both lytic and lysogenic cycles. To our knowledge, this is the first observation on phage lytic activity in “Ca. L. asiaticus”.