Molecular Plant-Microbe Interactions (2011) 24, 458-468

Shujian Zhang, Zomary Flores-Cruz, Lijuan Zhou, Byung-Ho Kang, Laura A. Fleites, Mark D. Gooch, Nelson A. Wulff, Michael J. Davis, Yong-Ping Duan and Dean W. Gabriel (2011)
´Ca. Liberibacter asiaticus' carries an excision plasmid prophage and a chromosomally integrated prophage that becomes lytic in plant infections
Molecular Plant-Microbe Interactions 24 (4), 458-468
Abstract: Huanglongbing (HLB), also known as citrus greening, is a lethal disease of citrus caused by several species of `Candidatus Liberibacter', a psyllid-transmitted, phloem-limited, alpha proteobacteria. `Ca. Liberibacter asiaticus' is widespread in Florida citrus. The recently published `Ca. L. asiaticus' psy62 genome, derived from a psyllid, revealed a prophage-like region of DNA in the genome, but phage have not been associated with `Ca. L. asiaticus' to date. In the present study, shotgun sequencing and a fosmid DNA library of curated `Ca. L. asiaticus' UF506, originally derived from citrus symptomatic for HLB, revealed two largely homologous, circular phage genomes, SC1 and SC2. SC2 encoded putative adhesin and peroxidase genes that had not previously been identified in `Ca. L. asiaticus' and which may be involved in lysogenic conversion. SC2 also appeared to lack lytic cycle genes and replicated as a prophage excision plasmid, in addition to being found integrated in tandem with SC1 in the UF506 chromosome. By contrast, SC1 carried suspected lytic cycle genes and was found in nonintegrated, lytic cycle forms only in planta. Phage particles associated with `Ca. L. asiaticus' were found in the phloem of infected periwinkles by transmission electron microscopy. In psyllids, both SC1 and SC2 were found only as prophage.
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Link to article at publishers website
Database assignments for author(s): Dean W. Gabriel, Nelson Arno Wulff, Michael J. Davis

Research topic(s) for pests/diseases/weeds:
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Liberibacter asiaticus	Citrus (genus)	U.S.A. (SE)