Plant Disease (2020) 104, 1584-1588

Fang Ding, Shu-ang Peng and John S. Hartung (2020)
Enhanced serologically based detection of Liberibacters associated with citrus huanglongbing
Plant Disease 104 (6), 1584-1588
Abstract: ' Candidatus Liberibacter spp.' are associated with the most devastating disease of citrus Huanglongbing (HLB). In previous work, we established an in situ tissue print method for the detection of ' Ca. L. asiaticus' (CLas) in sweet orange. We optimized the protocol by preincubation of the anti-Omp antibody with 5% (w/v) extract of healthy rough lemon. This simple process eliminated cross reactions between citrus and the antibody. The optimized protocol enhanced the application of the polyclonal antibody, and we demonstrate detection of CLas from all parts of the world, including isolates from Japan, Thailand, Vietnam, Pakistan, Saudi Arabia, Brazil, the United States, and a selection of strains from China representative of the diversity extant there. The assay also was used to detect four isolates of ' Ca. L. africanus' (CLaf) representative of the diversity present in South Africa. The corresponding outer membrane genes of representative isolates were cloned and sequenced. The coding sequences were highly conserved, and isolates of CLas and CLaf shared 53.8 to 55.9% identity between species at the amino acid level. The optimized protocol is efficient for recognition of both CLas and CLaf in phloem cells of different citrus tissues regardless of geographic origin of the HLB samples. The method is simple and scales well to match the urgent need for accurate, sensitive, and high-throughput screening of HLB bacteria, and may play an important role especially for plant inspection and quarantine programs.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): John S. Hartung

Research topic(s) for pests/diseases/weeds:
identification/taxonomy
surveys/sampling/distribution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Liberibacter asiaticus	Citrus (genus)	Japan
	Liberibacter asiaticus	Citrus (genus)	Thailand
	Liberibacter asiaticus	Citrus (genus)	Vietnam
	Liberibacter asiaticus	Citrus (genus)	Pakistan
	Liberibacter asiaticus	Citrus (genus)	Saudi Arabia
	Liberibacter africanus	Citrus (genus)	South Africa