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United States Department of Agriculture

Agricultural Research Service

Research Project: CHARACTERIZATION & EPIDEMIOLOGY OF CITRUS TRISTEZA VIRUS & OTHER INVASIVE & EMERGING GRAFT-TRANSMISSIBLE DISEASES OF CITRUS IN CALIFORNIA Title: Molecular Detection of Spiroplasma Citri Associated with Stubborn Disease in Citrus Orchards in Syria

item Kubaa, Raied Abou -
item Saponari, Maria -
item Djelouah, Khaled -
item Yokomi, Raymond
item El-Khateeb, Ali -
item Jamal, Majd -

Submitted to: Arabian Journal of Plant Protection
Publication Type: Abstract Only
Publication Acceptance Date: August 24, 2009
Publication Date: October 26, 2009
Citation: Kubaa, R., Saponari, M., Djelouah, K., Yokomi, R.K., El-Khateeb, A., Jamal, M. 2009. Molecular Detection of Spiroplasma Citri Associated with Stubborn Disease in Citrus Orchards in Syria. Arabian Journal of Plant Protection. 27(V57):93. Available:

Technical Abstract: Spiroplasma citri, a phloem-limited pathogen, causes citrus stubborn disease (CSD) and can be transmitted from plant to plant by several species of phloem-feeding leafhoppers. CSD is an important disorder in certain warm and arid citrus-growing areas, and its agent has been recorded from several Mediterranean and Middle Eastern countries, including Syria. In September 2008, columella were collected from fruits of 130 symptomatic and symptomless trees, 102 of which were from 10 commercial stands in Lattakia and 28 were from 2 groves in Tartous. Silica gel-dessicated columella samples were brought to the University of Bari for S. citri detection. DNA extraction and polymerase chain reaction (PCR) were performed according to Yokomi et al. (Plant Dis. 92: 253-260, 2008), using the primer pairs P58-6f/4r and P58 3f/4r in conventional and real-time PCR, respectively. Twelve sweet orange trees (9.2%) from two different groves (11 in Lattakia and 1 in Tartous) were S. citri-positive in both assays. Nucleotide sequences of the P58-6f/4r amplicon of four selected spiroplasma isolates showed 98% identity with the putative adhesin gene of S. citri strain T9 (accession No. EU602314) from California and strain BR3-3X (DQ344812). The presence of S. citri in Syrian citrus orchards was therefore confirmed by molecular tools. Because PCR-based techniques are more apt than traditional S. citri culturing for large scale analysis, their use will allow more rapid and systematic surveys in commercial citrus plots as well as in mother plant repositories and nurseries. The leafhopper Neoaliturus haematoceps has been shown to be a vector of S. citri in Syria. Thus, the use of these tools for the early detection of the pathogen in infected plants and leafhopper vectors will be critical for improving the management and containment of the disease.

Last Modified: 11/27/2015
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