Fanleaf Virus Research Articles

Gathered from the vine: a survey of seven grapevine viruses within New England vineyards.

Vineyards in the Southeastern New England American Viticultural Area were surveyed for the incidence of seven major viruses: grapevine leafroll-associated viruses (GLRaV-1, GLRaV-2, GLRaV-3, and GLRaV-4), grapevine fanleaf virus (GFLV), tomato ringspot virus (ToRSV), and tobacco ringspot virus (TRSV). Viruses were detected by ELISA and confirmed by RT-PCR and Sanger sequencing. Multiple viruses were present in 19 out of the 25 vineyards surveyed between 2018 to 2020. GLRaV-3 (27.59%) was the most prevalent virus followed by GLRaV-4 (14.90%), GLRaV-1 (13.52%), GLRaV-2 (11.03%), ToRSV (6.34%), GFLV (5.24%), and TRSV (2.62%). Furthermore, phylogenetic analyses of the viral partial genome sequences acquired in this study revealed that the grapevine viruses present in this area are diverse, indicating that they may have been introduced from different sources. Our findings stress the need for improving the sanitary status of planting materials to avoid the introduction and dissemination of viruses to vineyards in this important wine-producing region of New England.

Potential Implications and Management of Grapevine Viruses in Mexico: A Review

Worldwide, virus infections in grapevines are of concern due to the potential for economic loss. Although the grape industry in Mexico is relatively small and focused mainly on the local market, production dates back to the time of the Spanish colonization. This manuscript discusses the findings on grapevine viruses in Mexico. Nine viruses have been identified in the last fifty years, including grapevine red blotch virus (GRBV), grapevine leafroll-associated virus 3 (GLRaV-3), grapevine fanleaf virus (GFLV), and grapevine virus A (GVA). Important information is provided about these viruses and viral pathogens that have not yet been reported in Mexico, but represent an ongoing threat to plant health and grapevine production in other viticultural regions of the world. Strategies for virus control in vineyards are described. The information discussed here should be shared with growers and stakeholders to prevent future negative impacts on the Mexican grapevine industry and to save ancient grapevine accessions.

Identification of grapevine virus G and grapevine virus H in Sardinia, Italy

Grapevine virus G (GVG) and grapevine virus H (GVH) (genus Vitivirus) are recently discovered viruses. Analysis of 38 samples from Sardinian grapevine cultivars for the presence of GVG and GVH was carried out using RT-PCR. All samples were also tested for grapevine Pinot gris virus (GPGV) using RT-PCR, and for grapevine leafroll virus -1, -2 and -3, grapevine virus A (GVA) and B (GVB), arabis mosaic virus (ArMV), grapevine fanleaf virus (GFLV) and grapevine fleck virus (GFkV) using multiplex RT-PCR. GVG was confirmed in four vines, and GVH was detected in only one sample. In phylogenetic analyses of the coat protein (CP) region, the Sardinian GVG isolates clustered separately from isolates from Croatia and New Zealand. The Sardinian GVH isolate clustered with most sequences from other countries, but with greater affinity to isolates from California (USA) for the CP region, whereas it clustered with isolates from Croatia in the RNA-dependent RNA polymerase (RdRp) region. In addition to GVG and GVH, many samples were coinfected with GVA, viruses from the leafroll complex, and GPGV. This is the first record of GVG and GVH occurring in Italy.

Occurrence of Nine Grapevine Viruses in Commercial Vineyards of Mendoza, Argentina

Grapevine is a widely grown fruit crop that is seriously affected by different viruses, reducing grape yield and quality, as well as threatening profitability. Vineyard disease management requires accurate identification of viral infections. This study aimed to survey the presence of ten grapevine viruses in four geographic sites in the Mendoza province of Argentina. Two hundred twenty-three composite cane samples from 1060 plants of six cultivars were collected from 26 blocks distributed across 11 vineyards. The cane samples were screened by RT-PCR for the following viruses: grapevine leafroll-associated viruses 1-4 (GLRaV 1, 2, 3, and 4), grapevine fanleaf virus (GFLV), grapevine fleck virus (GFkV), grapevine virus A (GVA) and B (GVB), grapevine rupestris stem pitting associated virus (GRSPaV), and arabis mosaic virus (ArMV). The results showed an uneven occurrence of viruses through the sampled regions, with GRSPaV being prevalent (71.1%), followed by GFLV (28.9%), GFkV (20.6%), and GLRaV-2 (14.7%). GVB was not detected. This study revealed a moderate prevalence of viruses associated with economically impactful diseases in the vineyards surveyed.

Real-time RT-PCR high-resolution melting curve analysis to detect and differentiate Brazilian variants of grapevine viruses

Detecting and identifying viral infections in perennial plants, such as grapevines, can be challenging. Therefore, the aim of this study was to perform a real-time RT-PCR (RT-qPCR) high-resolution melting (HRM) curve analysis to detect and differentiate Brazilian variants of grapevine leafroll-associated virus 3 (GLRaV-3) and grapevine fanleaf virus (GFLV) in 74 and 10 infected plants, respectively, maintained in a collection block of grapevines. A single amplification curve was generated for each sample by RT-qPCR. Considering the amplified region of genomes of these two viruses, it was possible to identify and distinguish different variants of GLRaV-3 and of GFLV, which showed significantly different melting temperature (Tm) values between themselves, reflecting differences in the nucleotide sequences of the respective amplicons, and allowing discriminating variants and assess the viral diversity in grapevine accessions. The HRM analysis was validated by sequencing and nucleotide comparisons among Brazilian isolates of GLRaV-3 and GFLV.

Viral diseases of fruit and berry crops in the South of the Russian Far East

Aim. To systematise data on pathogens of viral diseases of garden and berry crops in the south of the Russian Far East.Discussion. The peculiar climatic features of the Far East limit the range of garden and berry crops. However, there are a significant number of species of wild fruits and berry plants in the region, which have increased (often – record breaking) frost resistance and are therefore actively used for breeding new cultural forms. At the same time, for the last century and a half new varieties of garden crops have been actively introduced to the Far East, which has lead to an increase in the risk of penetration of entire phytovirus complexes together with vegetatively propagated (cuttings, vaccinations) plants. The greatest damage to garden crops in the Far East is caused by a number of representatives of the genus Nepovirus (Picornavirales: Secoviridae): Tomato ringspot virus, Arabis mosaic virus, Raspberry ringspot virus, Grapevine fanleaf virus, Grapevine linear pattern virus as well as several still unidentified viruses. Among other taxonomic groups of phytoviruses dangerous for fruit and berry crops one could point out Potato virus Y (Patatavirales: Potyviridae, Potyvirus), Carnation ringspot virus (Tolivirales: Tombusviridae, Dianthovirus), Clover yellow mosaic virus (Tymovirales: Alphaflexiviridae, Potexvirus), Cucumber mosaic virus (Martellivirales: Bromoviridae, Cucumovirus), Alfalfa mosaic virus (Martellivirales: Bromoviridae, Alfamovirus). The paper considers the species composition of aphids‐carriers of phytoviruses affecting garden crops of the region.Conclusions. In connection with the further prospects for the development of horticulture in the Russian Far East, it is necessary to intensify ecological and virological studies of this section of phytovirology as well as to increase access to agricultural producers with available test systems.

<i>Xiphinema index</i>-resistant grapevine materials derived from muscadine are also resistant to a population of <i>X. diversicaudatum</i>

Grapevine is severely affected by two major nepoviruses that cause grapevine degeneration: the grapevine fanleaf virus (GFLV) and the arabis mosaic virus (ArMV), specifically transmitted by the dagger nematodes Xiphinema index and X. diversicaudatum, respectively. While natural resistance to X. index has been shown to be a promising alternative for controlling X. index and GFLV transmission, the resistance interaction between X. diversicaudatum and grapevine has not yet been documented. In the present study, we evaluated the host suitability to X. diversicaudatum in materials previously characterised for their resistance to X. index. Two X. index-resistant accessions VRH8771 (F1 hybrid) and Nemadex Alain Bouquet (BC1 hybrid) derived from muscadine, together with the X. index-susceptible reference accession V. vinifera cv. Cabernet-Sauvignon and the X. index-resistant reference accession V. riparia ‘10128’, were challenged with a X. diversicaudatum population obtained from woody host plants and a reference isolate of X. index. The reproduction factors of X. diversicaudatum and its numbers per gram of roots paralleled those of X. index, showing a resistance interaction to the population of the former species and suggesting that resistance determinants to both nematode vectors might be the same or linked. Nevertheless, these two criteria illustrated a poorer host suitability of grapevine materials to this X. diversicaudatum population than to X. index.

Characterization of Grapevine Fanleaf Virus Isolates in 'Chardonnay' Vines Exhibiting Severe and Mild Symptoms in Two Vineyards.

Fanleaf degeneration is a complex viral disease of Vitis spp. that detrimentally impacts fruit yield and reduces the productive lifespan of most vineyards worldwide. In France, its main causal agent is grapevine fanleaf virus (GFLV). In the past, field experiments were conducted to explore cross-protection as a management strategy of fanleaf degeneration, but results were unsatisfactory because the mild virus strain negatively impacted fruit yield. In order to select new mild GFLV isolates, we examined two old ‘Chardonnay’ parcels harbouring vines with distinct phenotypes. Symptoms and agronomic performances were monitored over the four-year study on 21 individual vines that were classified into three categories: asymptomatic GFLV-free vines, GFLV-infected vines severely diseased and GFLV-infected vines displaying mild symptoms. The complete coding genomic sequences of GFLV isolates in infected vines was determined by high-throughput sequencing. Most grapevines were infected with multiple genetically divergent variants. While no specific molecular features were apparent for GFLV isolates from vines displaying mild symptoms, a genetic differentiation of GFLV populations depending on the vineyard parcel was observed. The mild symptomatic grapevines identified during this study were established in a greenhouse to recover GFLV variants of potential interest for cross-protection studies.

Transmission and translocation of Grapvine fanleaf virus (GFLV) from Vitis vinifera L. pollen to seeds and grape

To better understand the distribution and genetic variety of Grapevine fanleaf virus (GFLV) in two organs of the grapevine, the presence of this virus was tested in leaf and pollen samples by ELISA and RT-PCR methods. On average, the GFLV is present in the pollen and the leaves with percentages 93 and 36% respectively. Capsid protein sequences were aligned and showed 85–92,1% identity at the nucleotide level for isolates obtained from leaves and 96–99% identity for isolates obtained from pollen. GFLV isolates from pollen are less divergent and phylogenetically closer to each other than those detected in leaves based on the analysis of the 2 CP sequences. GFLV was detected in seeds, berries, peduncles and grape bunches. Pollen appeared to have potential contribution in GFLV transmission by cross-pollination flowers on healthy plants, which leads to the formation of infected seeds and racemes.

Recovering Ancient Grapevine Cultivars in the Balearic Islands: Sanitary Status Evaluation and Virus Elimination.

Recuperation and genetic diversity preservation of local cultivars have acquired a huge interest in viticulture areas worldwide. In the Balearic Islands, most of the old cultivars are only preserved in grapevine germplasm banks, and so far, the sanitary status of these local cultivars has remained unexplored. The aim of this study was to survey and detect the virus incidence of all conserved cultivars in the government Grapevine Germplasm Bank of the Balearic Islands and to promote the sanitary recovery of two important minor cultivars, Argamussa and Gorgollassa. Enzyme-linked immunosorbent assay (ELISA) screenings were performed on 315 vines of 33 local cultivars. It was shown that the local cultivars were highly infected with simple (39.7%) and mixed infections (52.1%) and only 8.25% of them were free from the viruses tested. Grapevine leafroll-associated virus 3 (GLRaV-3) infection was the most common (82%). Moreover, Grapevine fanleaf virus (GFLV) and Grapevine fleck virus (GFkV) were also present with considerable incidence (25.4% and 43.5%, respectively). In addition, two sanitation protocols were used: shoot tip culture (ST) and thermotherapy in combination with shoot tip culture (CT). Virus elimination using only ST was effective to obtain “healthy” vines of cvs. Argamussa and Gorgollassa. It is important to emphasize that the methods described in the current study were rapid and effective in eliminating both GLRaV-3 and GFLV, also in combination.

Survey for Major Grapevine Viruses in Commercial Vineyards of Northwestern Argentina.

This study aimed to survey the occurrence of eight grapevine viruses in commercial vineyards located in the Calchaquíes Valleys in the northwest region of Argentina. A total of 103 samples of mature canes of vines showing either none or some viral-like symptoms were randomly collected. The samples were tested by RT-PCR/PCR-based assays for the screening of the following viruses: Grapevine fanleaf virus (GFLV), Grapevine leafroll-associated viruses (GLRaV-1, -2, -3, -4), Grapevine virus A (GVA), Grapevine rupestris stem pitting-associated viruses (GRSPaV), and Grapevine red blotch virus (GRBV). Sixty percent of the analyzed samples showed infection with some of the analyzed viruses, except GRBV. GLRaV-3 and GFLV were the most frequent viruses, present in 34% and 21% of the positive samples, respectively. This study represents the first survey report of the presence of grapevine viruses in the region of the Calchaquíes Valleys and contributes to the knowledge to maintain the sanitary status of commercial vineyards in Argentina.

Raman Spectroscopy Applications in Grapevine: Metabolic Analysis of Plants Infected by Two Different Viruses.

Grapevine is one of the most cultivated fruit plant among economically relevant species in the world. It is vegetatively propagated and can be attacked by more than 80 viruses with possible detrimental effects on crop yield and wine quality. Preventive measures relying on extensive and robust diagnosis are fundamental to guarantee the use of virus-free grapevine plants and to manage its diseases. New phenotyping techniques for non-invasive identification of biochemical changes occurring during virus infection can be used for rapid diagnostic purposes. Here, we have investigated the potential of Raman spectroscopy (RS) to identify the presence of two different viruses, grapevine fan leaf virus (GFLV) and grapevine rupestris stem pitting-associated virus (GRSPaV) in Vitis vinifera cv. Chardonnay. We showed that RS can discriminate healthy plants from those infected by each of the two viruses, even in the absence of visible symptoms, with accuracy up to 100% and 80% for GFLV and GRSPaV, respectively. Chemometric analyses of the Raman spectra followed by chemical measurements showed that RS could probe a decrease in the carotenoid content in infected leaves, more profoundly altered by GFLV infection. Transcriptional analysis of genes involved in the carotenoid pathway confirmed that this biosynthetic process is altered during infection. These results indicate that RS is a cutting-edge alternative for a real-time dynamic monitoring of pathogens in grapevine plants and can be useful for studying the metabolic changes ensuing from plant stresses.

Incidence of Grapevine Fanleaf Virus (GFLV) and Grapevine Leafroll-Associated Viruses (GLRaV 1−3) in Vojvodina Province

Summary During May and June of 2021, a total of 123 grapevine leaf samples were collected and analyzed for infection by grapevine fanleaf virus (GFLV) and three viruses from the grapevine leafroll-associated virus complex -1, -2 and -3 (GRLaV-1, GRLaV-2 and GRLaV-3, respectively). The samples were collected from commercial vineyards, small backyard vineyards and grapevine nurseries located across the entire Vojvodina Province (Bačka, Banat and Srem). OEPP/EPPO sampling protocols were followed during the sampling of leaf tissues showing possible virus infection symptoms. Among the 123 samples, 47 were collected from Bačka region (Bačko Gradište − 11, Bečej − 10, Temerin − 15, Vrbas − 1, Hajdukovo − 10), 50 from Banat region (Srpska Crnja − 10, Vojvode Stepe − 10, Čoka − 10, Uljma −20) and 26 from Srem region (Šid − 6, Banoštor − 10, Sremski Karlovci − 10) and serological ELISA tests were performed for virus detection. GFLV was detected in five samples (4.06%), GLRaV-1 was detected in six samples (4.87%), while GLRaV-2 was not detected in any of the analyzed grapevine samples. GLRaV-3 was present in five samples (4.06%). When infection rates were examined in relation to cultivars, GFLV was detected in Cardinal, Zalagyöngye, Black Muscat, Italian Riesling and Dornfelder. GRLaV-1 was detected in cultivars Cardinal, Black Muscat, Italian Riesling and Merlot, and GRLaV-3 in cultivars Othello and Italian Riesling. Based on these results, it can be concluded that GFLV and GRLaV-1 and GRLaV-3 are present in vineyards across Vojvodina Province and affect different grapevine cultivars. To effectively control virus infections and their spreading, continuous monitoring of these viruses and their vectors is required along with the planting of healthy propagation material.

Virus and Virus-like Pathogens in the Grapevine Virus Collection of Croatian Autochthonous Grapevine Cultivars.

Grapevine collections play an important role, especially in the study of viruses and virus-like pathogens. In 2009, after an initial ELISA screening for eight viruses (arabis mosaic virus, grapevine fanleaf virus, grapevine fleck virus, grapevine leafroll-associated viruses 1, 2, and 3, and grapevine viruses A and B), a collection of 368 grapevine accessions representing 14 different Croatian autochthonous cultivars and containing single or mixed infection of viruses was established to further characterize the viral pathogens. Subsequently, Western blot, RT-PCR, cloning, and sequencing revealed that grapevine rupestris stem pitting-associated virus was frequently found in accessions of the collection, with isolates showing substantial genetic diversity in the helicase and coat protein regions. High-throughput sequencing of 22 grapevine accessions provides additional insight into the viruses and viroids present in the collection and confirms the fact that Croatian autochthonous grapevine cultivars have high infection rates and high virome diversity. The recent spread of “flavescence dorée” phytoplasma in Europe has not spared the collection. After the first symptoms observed in 2020 and 2021, the presence of phytoplasma was confirmed by LAMP in six grapevine accessions and some of them were lost. Single or multiple viruses and viroids, as well as own rooted grapevines in the collection, make the plants susceptible to various abiotic factors, which, together with the recent occurrence of “flavescence dorée”, makes the maintenance of the collection a challenge. Future efforts will be directed towards renewing the collection, as 56% of the original collection has been lost in the last 13 years.

Comparative Metabolomic Analysis of Four Fabaceae and Relationship to In Vitro Nematicidal Activity against Xiphinema index.

The grapevine fanleaf virus (GFLV), responsible for fanleaf degeneration, is spread in vineyards by the soil nematode Xiphinema index. Nematicide molecules were used to limit the spread of the disease until they were banned due to negative environmental impacts. Therefore, there is a growing interest in alternative methods, including plant-derived products with antagonistic effects to X. index. In this work, we evaluated the nematicidal potential of the aerial parts and roots of four Fabaceae: sainfoin (Onobrychis viciifolia), birdsfoot trefoil (Lotus corniculatus), sweet clover (Melilotus albus), and red clover (Trifolium pratense), as well as that of sainfoin-based commercial pellets. For all tested plants, either aerial or root parts, or both of them, exhibited a nematicidal effect on X. index in vitro, pellets being as effective as freshly harvested plants. Comparative metabolomic analyses did not reveal molecules or molecule families specifically associated with antagonistic properties toward X. index, suggesting that the nematicidal effect is the result of a combination of different molecules rather than associated with a single compound. Finally, scanning electron microscope observations did not reveal the visible impact of O. viciifolia extract on X. index cuticle, suggesting that alteration of the cuticle may not be the primary cause of their nematicidal effect.

Small RNA Sequencing and Multiplex RT-PCR for Diagnostics of Grapevine Viruses and Virus-like Organisms

Metagenomic approaches used for virus diagnostics allow for rapid and accurate detection of all viral pathogens in the plants. In order to investigate the occurrence of viruses and virus-like organisms infecting grapevine from the Ampelographic collection Kromberk in Slovenia, we used Ion Torrent small RNA sequencing (sRNA-seq) and the VirusDetect pipeline to analyze the sRNA-seq data. The used method revealed the presence of: Grapevine leafroll-associated virus 1 (GLRaV-1), Grapevine leafroll-associated virus 2 (GLRaV-2), Grapevine leafroll-associated virus 3 (GLRaV-3), Grapevine rupestris stem pitting-associated virus (GRSPaV), Grapevine fanleaf virus (GFLV) and its satellite RNA (satGFLV), Grapevine fleck virus (GFkV), Grapevine rupestris vein feathering virus (GRVFV), Grapevine Pinot gris virus (GPGV), Grapevine satellite virus (GV-Sat), Hop stunt viroid (HSVd), and Grapevine yellow speckle viroid 1 (GYSVd-1). Multiplex reverse transcription-polymerase chain reaction (mRT-PCR) was developed for validation of sRNA-seq predicted infections, including various combinations of viruses or viroids and satellite RNA. mRT-PCR could further be used for rapid and cost-effective routine molecular diagnosis, including widespread, emerging, and seemingly rare viruses, as well as viroids which testing is usually overlooked.

Elimination of Eight Viruses and Two Viroids from Preclonal Candidates of Six Grapevine Varieties (Vitis vinifera L.) through In Vivo Thermotherapy and In Vitro Meristem Tip Micrografting.

Viruses and virus-like organisms are a major problem in viticulture worldwide. They cannot be controlled by standard plant protection measures, and once infected, plants remain infected throughout their life; therefore, the propagation of healthy vegetative material is crucial. In vivo thermotherapy at 36–38 °C for at least six weeks, followed by meristem tip micrografting (0.1–0.2 mm) onto in vitro-growing seedling rootstocks of Vialla (Vitis labrusca × Vitis riparia), was successfully used to eliminate eight viruses (grapevine rupestris stem pitting-associated virus (GRSPaV), grapevine Pinot gris virus (GPGV), grapevine fanleaf virus (GFLV), grapevine leafroll-associated virus 3 (GLRaV-3), grapevine fleck virus (GFkV), grapevine rupestris vein feathering virus (GRVFV), grapevine Syrah virus-1 (GSyV-1), and raspberry bushy dwarf virus (RBDV)), as well as two viroids (hop stunt viroid (HSVd) and grapevine yellow speckle viroid 1 (GYSVd-1)) from preclonal candidates of six grapevine varieties (Vitis vinifera L.). A half-strength MS medium including vitamins supplemented with 30 g/L of sucrose and solidified with 8 g/L of agar, without plant growth regulators, was used for the growth and root development of micrografts and the subsequently micropropagated plants; no callus formation, hyperhydricity, or necrosis of shoot tips was observed. Although the overall regeneration was low (higher in white than in red varieties), a 100% elimination was achieved for all eight viruses, whereas the elimination level for viroids was lower, reaching only 39.2% of HSVd-free and 42.6% GYSVd-1-free vines. To the best of our knowledge, this is the first report of GPGV, GRVFV, GSyV-1, HSVd, and GYSVd-1 elimination through combining in vivo thermotherapy and in vitro meristem tip micrografting, and the first report of RBDV elimination from grapevines. The virus-free vines were successfully acclimatized in rockwool plugs and then transferred to soil.

1-Phylogenetic status of Grapevine fanleaf virus isolate of Lorestan province of Iran

1-Phylogenetic status of Grapevine fanleaf virus isolate of Lorestan province of Iran

Detection of Ampelovirus and Nepovirus by Lab-on-a-Chip: A Promising Alternative to ELISA Test for Large Scale Health Screening of Grapevine.

The Ampelovirus Grapevine leafroll-associated virus 3 (GLRaV-3) and the Nepovirus Grapevine fanleaf virus (GFLV) are pathogens reported in many grapevine-growing areas all over the world, main causal agents of grapevine leafroll disease and grapevine fanleaf disease, respectively. Prevention of virus spread thanks to rapid diagnosis of infected plants is a key factor for control of both diseases. Although serological (e.g., enzyme-linked immunosorbent assay-ELISA test) and molecular methods are available to reveal the presence of the viruses, they turn out to be quite expensive, time-consuming and laborious, especially for large-scale health screening. Here we report the optimization of a lab-on-a-chip (LOC) for GLRaV-3 and GFLV detection, based on an electrochemical transduction and a microfluidic multichamber design for measurements in quadruplicate and simultaneous detection of both targets. The LOC detect GLRaV-3 and GFLV at dilution factors more than 15 times higher than ELISA, providing a higher sensitivity in the detection of both viruses. Furthermore, the platform offers several advantages as easy-to-use, rapid-test, portability and low costs, favoring its potential application for large-scale monitoring programs. Compared to other grapevine virus biosensors, our sensing platform is the first one to provide a dose-dependent calibration curve combined with a microfluidic module for sample analysis and a portable electronics providing an operator-independent read-out scheme.

Distribution and Phylogeny of Grapevine fanleaf virus in Vineyards of Khorasan Razavi Province Based on Coat Protein Region

ویروس برگ باد بزنی مو (Grapevine fanleaf virus, GFLV) در تاکستان‌های مناطق مختلف دنیا شیوع دارد. علائم ایجاد شده توسط این ویروس اغلب در سه گروه برگ بادبزنی، موزاییک زرد و رگبرگ نواری تقسیم‌بندی شده‌اند که علت تفاوت در ایجاد علائم، به تنوع ژنتیکی جدایه‌ها نسبت داده شده است. شدت علائم ایجاد شده به جدایه‌ی ویروس، حساسیت رقم مو و شرایط محیطی بستگی دارد. در این تحقیق پراکنش و تحلیل تبارزایی ناحیه کدکننده پروتئین پوششی ویروس بررسی شد. نمونه‌ها از تاکستان‌های‌ استان خراسان رضوی جمع‌آوری و ژن پروتئین پوششی از پنج جدایه تکثیر، همسانه‌سازی و تعیین ترادف شد. به این منظور، تعداد 109 نمونه برگ دارای علائم‌ از تاکستان‌ها جمع‌آوری و در آزمون الایزا با استفاده از آنتی‌بادی اختصاصی GFLV آلودگی به ویروس در 58 نمونه تأیید شد. بیشترین میزان آلودگی در بین نمونه‌های جمع‌آوری شده از منطقه محمدیه واقع در شهرستان کاشمر بود. با استفاده از آغازگرهای اختصاصی قطعه‌ای بطول 1760 جفت باز مربوط به طول کامل ناحیه کد‌کننده پروتئین پوششی ویروس و قسمتی از انتهای'3 ژنوم تکثیر شد. پروتئین پوششی جدایه‌های انتخاب شده در سطح نوکلئوتیدی و آمینواسیدی به ترتیب 94-90 و 97-91 درصد با جدایه‌های سایر نقاط دنیا شباهت داشت. تحلیل تبارزائی بر اساس ناحیه کد کننده پروتئین پوششی، جدایه‌های ایرانی GFLV را در شاخه‌ای مجزا از جدایه‌های سایر نقاط دنیا قرار داد. همچنین جدایه‌های شمال شرق کشور در گروهی مجزا از جدایه‌های شمال غرب کشور قرار گرفتند، که نشان‌دهنده اثر جدایی جغرافیایی در تکامل GFLV است. نتایج حاصل از این تحقیق بیانگر بومی بودن GFLV در ایران و گسترش احتمالی آن از این منطقه به سایر نقاط جهان است.