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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Crop Diseases, Pests and Genetics Research » Research » Publications at this Location » Publication #334857

Title: A unique nrdB gene can be used to improve the current HLB pathogen detection system

item Chen, Jianchi
item ZHENG, ZHENG - South China Agricultural University
item WU, FENIGAN - South China Agricultural University
item DENG, XIAOLING - South China Agricultural University

Submitted to: Citrograph
Publication Type: Trade Journal
Publication Acceptance Date: 10/25/2016
Publication Date: 1/20/2017
Citation: Chen, J., Zheng, Z., Wu, F., Deng, X. 2017. A unique nrdB gene can be used to improve the current HLB pathogen detection system. Citrograph. 8:64-68.

Interpretive Summary:

Technical Abstract: Citrus Huanglongbing (HLB), also referred to as yellow shoot disease and citrus greening disease, seriously threatens citrus production worldwide. Currently, the impact of HLB is grave, as there is no cure. A bacterium, “Candidatus Liberibacter asiaticus” (CLas), has been considered as the pathogen due to strong association with HLB. Detection of CLas is a critical step for proper HLB diagnosis. To detect CLas, the current standard procedure uses PCR based on the 16S rRNA gene. 16S rRNA gene can be found in all bacteria and is commonly used for bacterial classification. However, due to similarity of 16S rRNA genes among different bacterial species, the 16S rRNA gene-based system for CLas detection runs the pertinent risk of producing false positive results, particularly due to CLas-related but non-HLB causing bacteria. In this study, another target gene, nrdB, was identified in the CLas genome. Like the 16S rRNA gene, nrdB also can be found in all bacteria but is less conserved in sequence among different bacterial species. Therefore, the nrdB gene-based PCR is less likely to produce false positive results. Furthermore, while CLas has three copies of the 16S rRNA gene, it has five copies of nrdB. This makes the nrdB-based PCR system more sensitive (>3-fold) than the 16S rRNA-based PCR system.