First Report from Syria of Citrus tristeza virus in Citrus spp.

During the spring of 2006, the main Syrian citrus-growing areas of Lattakia (Jableh, Aledyye, Eseelya, Siano, and Hresoon provinces) and Tartous (Almintar, Aljammase, Karto, Majdaloonelbahr, Yahmour, Amreet, Althawra, and Safita provinces) were surveyed to assess the presence of Citrus tristeza virus (CTV). Eight nurseries (approximately 130 plants per nursery), two budwood source fields (approximately 230 trees per field), and 19 groves (approximately 60 trees per grove) containing the main citrus varieties were visually inspected and sampled for serological assays. The hierarchical sampling method was carried out in each selected grove (2). Infected samples were collected from two nurseries, two budwood source fields, and six groves. Stems and leaf petioles from nursery trees and flower explants from the groves were collected and analyzed for CTV by direct tissue blot immunoassay (DTBIA) with the commercial kit from Plantprint (Valencia, Spain). Of 2,653 samples tested, 89 (4%) CTV-infected plants were detected. Five citrus varieties were found to be infected and Meyer lemon (Citrus limon ‘Meyer’) had the highest incidence at 16%. Numerous sweet orange varieties (Citrus sinensis L.) were found to be highly infected in the field, but only the Washington navel sweet orange was found to be infected in the nurseries. No clear CTV symptoms were observed during the survey. Samples that were positive for CTV by DTBIA were also positive by biological indexing on Mexican lime (C. aurantifolia) and immunocapture-reverse transcription-PCR as described by Nolasco et al. (3). Coat protein gene sequences obtained from five selected clones of a Syrian CTV isolate (GenBank Accession No. EU626555) showed more than 99 and 98% nucleotide sequence identity to a Jordanian CTV isolate (GenBank Accession No. AY550252) and the VT isolate (GenBank Accession No. U56902), respectively. Almost all infected samples induced moderate vein clearing symptoms when grafted to Mexican lime. Symptoms of vein clearing, leaf cupping, stunting, and stem pitting on Mexican lime were induced by graft transmission of CTV from one Valencia sample from the Tartous area. The viral inoculum is widely and randomly distributed in commercial groves, especially in the southern Tartous area and in some nurseries. To our knowledge, this is the first report of CTV in Syria. However, CTV was reported from the neighboring citrus-growing countries of Lebanon, Turkey, and Jordan (1), and the severe seedling yellows strain is present in this area, which poses a potential threat to Syrian citriculture. References: (1) G. H. Anfoka et al. Phytopathol. Mediterr. 44:17, 2005. (2) G. Hughes and T. R. Gottwald, Phytopathology 88:715, 1998. (3) G. Nolasco et al. Eur. J. Plant Pathol. 108:293, 2002.

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First Report of Citrus tristeza virus in Greece

Plant Disease ◽

10.1094/pdis.2002.86.3.329b ◽

2002 ◽

Vol 86 (3) ◽

pp. 329-329 ◽

Cited By ~ 4

Author(s):

D. Dimou ◽

J. Drossopoulou ◽

E. Moschos ◽

C. Varveri ◽

F. Bem

Keyword(s):

Citrus Tristeza Virus ◽

Sweet Orange ◽

Enzyme Linked Immunosorbent Assay ◽

First Report ◽

Vein Clearing ◽

Carrizo Citrange ◽

Sweet Lime ◽

Tristeza Virus ◽

Propagation Material ◽

Citrus Tristeza

Large-scale surveys of Citrus spp. for the presence of Citrus tristeza virus (CTV) by the Ministry of Agriculture in Greece began in 1995. Over 26,000 trees have been tested by enzyme-linked immunosorbent assay and immunoprinting (2). In summer 2000, the first CTV-infected sweet orange cv. Lane Late tree grafted on CTV-tolerant Carrizo citrange was found in Argolis County, Peloponnese. This tree belonged to a batch of CAC propagation material (20 trees) illegally introduced from Spain in 1994, which was subsequently traced and found to be infected (45%). A follow-up search of trees grafted with the above material was undertaken in the two concerned regions (Argolis and Chania-Crete), and more than 3,500 trees have been removed. Extensive surveys continue to identify and destroy new infections. Few cases (15 of 16,800) of natural transmission to cultivars other than cv. Lane Late have been found. All of these have been close to the initially infected trees in the Argolis area. Surveys in spring 2001 were extended to certified propagation material of Clemenpons mandarin on Carrizo citrange imported from Spain, and 7 of 1,038 plants were infected (0.64%). The virus was successfully graft-transmitted to sweet orange cv. Madame Vinous and sweet lime seedlings, where it was identified by immunoprinting and reverse transcription-polymerase chain reaction (1). Mild vein clearing symptoms appeared on both indicators. Vein clearing on sweet lime was also accompanied by leaf cupping. To our knowledge, this is the first report of CTV in Greece. References: (1) A. Sambade et al. J. Virol. Methods 87:25, 2000. (2) C. Vela et al. J. Gen. Virol. 67:91, 1986.

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Severity of Citrus tristeza virus Isolates from Texas

Plant Disease ◽

10.1094/pd-89-0575 ◽

2005 ◽

Vol 89 (6) ◽

pp. 575-580 ◽

Cited By ~ 8

Author(s):

C.M. Herron ◽

T.E. Mirkov ◽

N. N. Solís-Gracia ◽

C.J. Kahlke ◽

M. Skaria ◽

...

Keyword(s):

Citrus Tristeza Virus ◽

Sweet Orange ◽

South Texas ◽

Sour Orange ◽

Lower Rio Grande Valley ◽

Mexican Lime ◽

Single Stranded Conformational Polymorphism ◽

Or Gene ◽

Tristeza Virus ◽

Citrus Tristeza

Citrus tristeza virus (CTV) isolates collected from the Lower Rio Grande Valley in south Texas and east Texas were characterized using citrus indicators and molecular methods. The citrus indicators were Mexican lime (Citrus aurantifolia), sour orange (C. aurantium), sweet orange (C. sinensis) grafted to sour orange, Duncan grapefruit (C. × paradisi), and Madam Vinous sweet orange, with some CTV isolates additionally indexed using the Texas commercial grapefruit cvs. Rio Red and Star Ruby, and Marrs and N-33 sweet orange. Severity ratings used 11 biotype groups or cumulative mean relative indices. Molecular characterization was carried out using poly- and monoclonal antibodies, seven strain-specific probes and single-stranded conformational polymorphism, and all were based on the CTV major coat protein or gene. All Texas CTV isolates produced vein clearing symptoms on inoculated Mexican lime plants. Over half of the CTV isolates tested were placed in biotype groups IX and X (causing decline of sweet orange on sour orange, seedling yellows on sour orange and grapefruit seedlings, and stem pitting of grapefruit or sweet orange), and one isolate was in biotype I (mild).

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