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1.
Candidatus Phytoplasma prunorum was detected for the first time in almond (Prunus dulcis Mill.) cv. ‘Abiod’ in Tunisia. Infected trees showed emergence of new growth during dormancy and leafed out before flowers opened in addition to early defoliation in summer. Phytoplasma was detected by nested polymerase chain reaction (PCR) using universal phytoplasma primer pairs P1/P7 and F2n/R2. A band with expected size was observed in samples collected from five symptomatic, but not symptomless almond trees. PCR products (1.2 kbp) were used for restriction fragment length polymorphism (RFLP) analysis after digestion with endonucleases RsaI and SspI. RFLP patterns obtained were similar to those reported previously for the European stone fruit yellows (ESFY, 16SrX-B). Identification has been further confirmed by PCR using ESFY specific primer pairs (ECA1/ECA2). This is the first report of Ca. Phytoplasma prunorum infecting almonds in Tunisia.  相似文献   

2.
Candidatus Phytoplasma prunorum’ is the causal agent of the European stone fruit yellows (ESFY) disease. This phytoplasma affects wild and cultivated species of Prunus to different degrees, depending on their susceptibility. ‘Candidatus Phytoplasma prunorum’ is present in the four regions of Spain surveyed in this study (Aragon, Catalonia, Extremadura and Valencia) with a variable incidence. Results showed that ‘Ca. Phytoplasma prunorum’ was detected in all of the cultivated Prunus species studied, except P. avium and P. dulcis, and was widespread in Spain. The most affected species was P. salicina, with symptoms including early bud break and blooming, leaf curling and yellowing, collapse, and a major decrease in production. In some plots in the Baix Llobregat area of Barcelona province (Catalonia), the incidence of ESFY on P. salicina was as high as 80%. The insect vector, Cacopsylla pruni, was present in all four of the regions studied, with the highest captures in yellow sticky traps in Catalonia on P. mahaleb and in Extremadura in peach orchards. In Baix Llobregat, large populations of C. pruni were present on infected P. mahaleb bushes, and with high infection rates. This was a key factor in the local pathogenic cycle that caused a major ESFY outbreak in the nearby P. salicina orchards. In the Ebro valley (Lleida and Aragon) and Valencia, the surveys showed very low incidences of the disease and low C. pruni populations.  相似文献   

3.
From 2003 to 2007 surveys have been conducted in different stone fruit growing regions in southwest Germany to detect European stone fruit yellows (ESFY) disease in Germany. Samplings have been done regularly in selected reference orchards in the regions Neuwieder Becken, Rheinhessen, Vorderpfalz and Südpfalz in summer on trees showing ESFY typical symptoms as well as on branches of trees with unspecific symptoms. All samples have been analysed by PCR for infection with Candidatus Phytoplasma prunorum. The phytoplasma could be detected in all investigated regions on the cultivated Prunus species P. armeniaca, P. persica and P. domestica. No infection was found in wild Prunus species. The main spread of the disease appeared on apricot while peach and European plum were less affected. A good correlation between symptoms and molecular detection of the pathogen could be shown for the typical symptoms in summer and winter for apricot as well as for peach. During regular psyllid captures in the reference orchards the population dynamics of Cacopsylla pruni could be described in southwest Germany for several years. By PCR-testing all collected insects individually a yearly natural infection rate of about 1–2% of all individuals of C. pruni could be calculated.  相似文献   

4.
《EPPO Bulletin》2017,47(2):146-163

Specific scope

This Standard describes a diagnostic protocol for ‘Candidatus Phytoplasma mali’, ‘Ca. P. pyri’ and ‘Ca. P. prunorum’. This Standard should be used in conjunction with PM 7/76 Use of EPPO diagnostic protocols

Specific approval and amendment

Approved as PM 7/62 Candidatus Phytoplasma mali and PM 7/63 Ca. P. pyri in 2006. Revised in 2017‐02 as a single Standard as PM 7/62 (2) with the addition of ‘Ca. P. prunorum’.  相似文献   

5.
ABSTRACT European stone fruit yellows (ESFY) is becoming a major economic problem for Prunus growers in Europe. The causal agent ("Candidatus Phytoplasma prunorum") and its vector (Cacopsylla pruni) have been identified, but the present knowledge of the risk factors for this disease relies, at best, on specific experiments. To assess the relative significance of several factors correlated with ESFY incidence in the field, an exhaustive survey was performed on apricot and Japanese plum orchards in the Crau plain (France). After a preliminary multivariate exploration of the data, we used a logistic regression model to analyze and predict the cumulative number of diseased trees on the basis of a set of quantitative (age, planting density, and area of the orchard) and categorical variables (species, cultivar, and rootstock). Because of the nature of the data, we used an overdispersed binomial model and we developed a parametric bootstrap procedure based on the beta-binomial distribution to obtain confidence intervals. Our results indicated that the age, species, and cultivar of the scion were the major factors explaining the observed number of diseased trees. The planting density and the rootstocks used in the zone under study were less significant, and the area of the orchard had no effect. The residuals of the model showed that some explanatory variables had not been taken into account, because part of the remaining variability could be explained by a grower effect. The spatial distribution of the residuals suggested that one of the reasons for this grower effect was the correlation between orchards closer than 100 m, possibly caused by the flight behavior of infectious vectors.  相似文献   

6.
Between 1994 and 1998 a field study was conducted to identify plant hosts of the European stone fruit yellows (ESFY) phytoplasma in two apricot growing regions in southern and southwestern France where the incidence of apricot chlorotic leaf roll was high. A total of 431 samples from 51 different plant species were tested for the presence of phytoplasmas by PCR using universal and ESFY-specific primers. ESFY phytoplasma was detected in six different wild growing Prunus species exhibiting typical ESFY symptoms as well as in symptomless dog rose bushes (Rosa canina), ash trees (Fraxinus excelsior) and a declining hackberry (Celtis australis). The possible role of these plant species in the spread of ESFY phytoplasma is discussed. PCR-RFLP analysis of ribosomal DNA amplified with the universal primers was carried out to characterize the other phytoplasmas found. Thus, elm yellows phytoplasma, alder yellows phytoplasma and rubus stunt phytoplasma were detected in declining European field elm trees (Ulmus carpinifolia Gled), in declining European alder trees (Alnus glutinosa) and in proliferating Rubus spp. respectively. The presence of rubus stunt phytoplasma in great mallow (Malva sylvestris) and dog rose was demonstrated for the first time. Furthermore, the stolbur phytoplasma was detected in proliferating field bindweed (Convolvulus arvensis) and a previously undescribed phytoplasma type was detected in red dogwood (Cornus sanguinea). According to the 16S rDNA-RFLP pattern this new phytoplasma belongs to the stolbur phytoplasmas group.  相似文献   

7.
Two genetically distinct evolutionary lineages of the oomycete pathogen Phytophthora ramorum are responsible for the major epidemic on larch (Larix spp.) in the UK: EU1 (historically widespread) and the recently identified EU2 (reported only from Northern Ireland and a small area in southwest Scotland). Methods for lineage discrimination have required pure cultures of P. ramorum but, as the pathogen is challenging to isolate from infected larch tissue, only limited data have been available on the distribution of EU2. In this study a protocol was developed to determine the lineage of P. ramorum in infected larch tissue without the need for isolation. The protocol was applied to 134 UK samples collected during 2013–14. In addition, lineage testing was applied to over 300 P. ramorum isolates cultured from a wide range of hosts between 2002 and 2012. Combined data confirmed that EU2 is restricted to Northern Ireland and a small area of southwest Scotland where it is the dominant lineage. There was no evidence of EU2 spread into England and Wales where only EU1 was found. However, EU2 was more widely distributed in southern and eastern parts of Scotland than previously reported. Furthermore, EU1 and EU2 were detected <10 km apart in larch plantations. This study provides the first reports of natural EU2 infection on European larch (Larix decidua), hybrid larch (Larix × eurolepis), beech (Fagus sylvatica), noble fir (Abies procera) and western hemlock (Tsuga heterophylla).  相似文献   

8.
Several uncultivated trees of the species Prunus spinosa , P. cerasifera and P. domestica , sampled both adjacent to European stone fruit yellows (ESFY)-infected orchards and in isolation from cultivated stone fruit plants, were found to be infected by ESFY phytoplasma. These species were also colonized by Cacopsylla pruni , vector of the ESFY agent. In contrast, uncultivated species of Prunus avium , P. cerasus and P. mahaleb hosted neither the pathogen nor the vector. Insect- and graft-transmission trials of ESFY phytoplasma conducted under controlled conditions confirmed the data obtained in the field. The role played by the wild Prunus species is discussed and appears to be fundamental in the epidemic cycle of the disease.  相似文献   

9.
During the late summer-early autumn of 2002, surveys were carried out in Turkey to determine the presence of phytoplasma diseases in fruit trees. Phytoplasmas were detected and characterized by PCR-RFLP analysis and TEM technique in stone fruit and pear trees in the eastern Mediterranean region of the country. Six out of 24 samples, including almond, apricot, peach, pear and plum, gave positive results in PCR assays. RFLP analysis usingSspI andBsaAI enzymes of PCR products obtained with primer pair f01/r01 enabled identification of the phytoplasmas involved in the diseases. Stone fruit trees, including a local apricot variety (‘Sakıt’) and a pear sample, were found to be infected with European stone fruit yellows (ESFY, 16SrX-B) and pear decline (PD, 16SrX-C) phytoplasmas, respectively. This is the first report in Turkey of PD phytoplasma infecting pear and of ESFY phytoplasma infecting almond, apricot, myrobalan plum and peach; ESFY phytoplasma infecting Japanese plum was previously reported. http://www.phytoparasitica.org posting July 21, 2005.  相似文献   

10.
Peach orchards in the northeast of Spain were severely affected in 2012 by a previously unreported disease in this area. The symptoms included early reddening, leaf curling, decline, abnormal fruits, and in some cases death of the peach trees. All the infected peach samples were positive for ‘Candidatus Phytoplasma pyri’, but none were infected by the ‘Ca. Phytoplasma prunorum’. In this work, potential vectors able to transmit ‘Ca. Phytoplasma pyri’ from pear to peach and between peach trees were studied and their infective potential was analysed at different times of the year. Transmission trials of the phytoplasma with potential vectors to an artificial feeding medium for insects and to healthy peach trees were conducted. Additionally, isolated phytoplasmas were genetically characterized to determine which isolates were able to infect peach trees. Results showed that the only insect species captured inside peach plots that was a carrier of the ‘Ca. Phytoplasma pyri’ phytoplasma was Cacopsylla pyri. Other insect species captured and known to be phytoplasma transmitters were present in very low numbers, and were not infected with ‘Ca. Phytoplasma pyri’ phytoplasma. A total of 1928 individuals of C. pyri were captured in the peach orchards, of which around 49% were phytoplasma carriers. All the peach trees exposed to C. pyri in 2014, and 65% in 2015, were infected by ‘Ca. Phytoplasma pyri’ 1 year after exposure, showing that this species is able to transmit the phytoplasma to peach. Molecular characterization showed that some genotypes are preferentially determined in peach.  相似文献   

11.
Bark‐ and wood‐boring beetles in the genus Agrilus (Coleoptera: Buprestidae) can survive wood‐chipping, and Agrilus planipennis has established in North America and European Russia with devastating impacts on forest ecosystems. The work presented in this paper combined import statistics of deciduous wood chips, Maximum entropy modelling (MaxEnt) of climatic similarities, and the distribution of potential tree hosts to predict the likelihood of four selected North American Agrilus species to become introduced and established in Europe. In agreement with the EU's energy‐policy target of increased use of wood chips, there was a linear or exponential increase in European imports of deciduous wood chips during the past 10 years from countries harbouring potentially harmful Agrilus species. MaxEnt showed high environmental suitability in Europe for the four selected Agrilus species, particularly in Eastern Europe and European Russia for Aanxius, A. bilineatus and A. planipennis and in southern Europe for A. politus. Documented susceptible host trees are widely distributed in the predicted areas of Agrilus distribution in Europe, and these areas receive large quantities of deciduous wood chips from countries where these and other Agrilus species are present. Thus, it was concluded that the fundamental conditions for introduction and establishment of Agrilus species in Europe are in place.  相似文献   

12.
Epidemiological aspects and transmission routes of bois noir (BN), a grapevine yellows disease induced by ‘Candidatus Phytoplasma solani’, have been exhaustively studied in the affected vineyards of continental Europe but not in the Mediterranean coastal zone. Because ‘Ca. Phytoplasma solani’ and its principal vector Hyalesthes obsoletus presumably originate from the Mediterranean, gaining knowledge of the epidemiological peculiarities of the disease in this area is essential for understanding its global spread and diversification, as well as for designing local management strategies. In this study, molecular epidemiology was applied to trace transmission pathways of ‘Ca. Phytoplasma solani’ in the Mediterranean vineyards of Montenegro, using multilocus sequence typing of tuf, vmp1 and stamp genes of the isolates associated with various hosts. Thus, ‘Ca. Phytoplasma solani’ was tracked from a tentative reservoir plant (inoculum source) through an associated vector population to the infected grapevine. Three pathways of transmission were documented, originating from Urtica dioica, Convolvulus arvensis and Vitex agnus‐castus; however, only the route originating from U. dioica was direct, whereas the latter two were overlapping and could be intermixed. Vitex agnus‐castus is a natural source of ‘Ca. Phytoplasma solani’, representing an important link in disease epidemiology in the Mediterranean and a possible origin of several genotypes occurring in central Europe. Experimental confirmation of the role of Vitex‐associated H. obsoletus in BN transmission in Montenegrin vineyards indicates its tentative role as a vector in the wide area of the Mediterranean, where some of the major wine‐producing regions are located.  相似文献   

13.
The phloem‐sucking psyllid Cacopsylla picta plays an important role in transmitting the bacterium ‘Candidatus Phytoplasma mali’, the agent associated with apple proliferation disease. The psyllid can ingest ‘Ca. Phytoplasma mali’ from infected apple trees and spread the bacterium by subsequently feeding on uninfected trees. Until now, this has been the most important method of ‘Ca. Phytoplasma mali’ transmission. The aim of this study was to investigate whether infected C. picta are able to transmit ‘Ca. Phytoplasma mali’ directly to their progeny. This method of transmission would allow the bacteria to bypass a time‐consuming reproductive cycle in the host plant. Furthermore, this would cause a high number of infected F1 individuals in the vector population. To address this question, eggs, nymphs and adults derived from infected overwintering adults of C. picta were reared on non‐infected apple saplings and subsequently tested for the presence of ‘Ca. Phytoplasma mali’. In this study it was shown for the first time that infected C. picta individuals transmit ‘Ca. Phytoplasma mali’ to their eggs, nymphs and F1 adults, thus providing the basis for a more detailed understanding of ‘Ca. Phytoplasma mali’ transmission by C. picta.  相似文献   

14.
Jarausch  Lansac  Bliot  & Dosba 《Plant pathology》1999,48(2):283-287
In vitro grafting was tested as a technique for inoculating Prunus rootstock Prunus marianna GF 8-1 with European stone fruit yellows (ESFY) phytoplasmas and apple rootstock Malus pumila MM106 with apple proliferation (AP) phytoplasmas. In vitro shoot cultures of ESFY-infected Prunus marianna GF 8-1 and AP-infected Malus pumila MM106 were used as graft inoculum to transmit the phytoplasmas to the respective healthy rootstock. Phytoplasma transmission was assessed after a graft contact of 1, 2 or 3 months. Healthy autografts were used as controls to monitor parameters of in vitro grafting. Successful graft union formation ranged from 58 to 79% irrespective of the plant species and the sanitary state of the graft. Pathogen-specific polymerase chain reaction (PCR) was used to test the inoculated rootstocks for the presence of ESFY and AP phytoplasmas, respectively. The rate of ESFY phytoplasma transmission in successful Prunus -grafts increased from 69 to 94% with the time of contact. AP phytoplasma transmission to Malus occurred in 80 to 97% of successful grafts. To our knowledge this is the first report of phytoplasma transmission by grafting in vitro . The results provide a good basis for the establishment of a preliminary in vitro screening method for phytoplasma resistance in Prunus and Malus .  相似文献   

15.
Invasive oomycete pathogens have been causing significant damage to native ecosystems worldwide for over a century. A recent well‐known example is Phytophthora ramorum, the causal agent of sudden oak death, which emerged in the 1990s in Europe and North America. In Europe, this pathogen is mainly restricted to woody ornamentals in nurseries and public greens, while severe outbreaks in the wild have only been reported in the UK. This study presents the results of the P. ramorum survey conducted in Swiss nurseries between 2003 and 2011. In all 120 nurseries subjected to the plant passport system, the main P. ramorum hosts were visually checked for above ground infections. Phytophthora species were isolated from tissue showing symptoms and identified on the basis of the morphological features of the cultures and sequencing of the ribosomal ITS region. Phytophthora was detected on 125 plants (66 Viburnum, 58 Rhododendron and one Pieris). Phytophthora ramorum was the most frequent species (59·2% of the plants), followed by P. plurivora, P. cactorum, P. citrophthora, P. cinnamomi, P. cactorum/P. hedraiandra, P. multivora and P. taxon PgChlamydo. The highest incidence of P. ramorum was observed on Viburnum × bodnantense. Microsatellite genotyping showed that the Swiss P. ramorum population is highly clonal and consists of seven genotypes (five previously reported in Europe, two new), all belonging to the European EU1 clonal lineage. It can therefore be assumed that P. ramorum entered Switzerland through nursery trade. Despite sanitation measures, repeated P. ramorum infections have been recorded in seven nurseries, suggesting either reintroduction or unsuccessful eradication efforts.  相似文献   

16.
Monilinia fructicola is a quarantine fungal pathogen in Europe, but many major stone fruit growing countries in Europe have reported its presence recently. In Switzerland, the fungus was first found in a single apricot orchard in 2008. This study confirms the presence of M. fructicola in nine out of 22 commercial orchards in Canton Valais, Switzerland. Five simple sequence repeat markers (SSRs) were developed for M. fructicola and samples from Switzerland, Spain, Italy, France and the United States were analysed and compared in order to assess the genetic diversity of the pathogen, identify the origin of the disease, and verify if the fungus reproduces sexually in Europe. In the 119 European samples analysed, 12 different haplotypes were found, indicating a relatively high genetic diversity of the pathogen considering that the first report in Europe was 10 years ago. Three haplotypes found in Europe were identical to those found in the American samples (two from the east coast and one from the west coast). Population structure analysis suggests that the European population is derived from at least two ‘invasion’ events probably originating from the US (one from the east coast, the other from the west coast). Preliminary evidence of sexual reproduction of M. fructicola in Europe is reported.  相似文献   

17.
The objective of this study was to determine whether genetically differentiated groups of Puccinia triticina are present in Europe. In total, 133 isolates of P. triticina collected from western Europe, central Europe and Turkey were tested for virulence on 20 lines of wheat with single leaf rust resistance genes, and for molecular genotypes with 23 simple sequence repeat (SSR) markers. After removal of isolates with identical virulence and SSR genotype within countries, 121 isolates were retained for further analysis. Isolates were grouped based on SSR genotypes using a Bayesian approach and a genetic distance method. Both methods optimally placed the isolates into eight European (EU) groups of P. triticina SSR genotypes. Seven of the groups had virulence characteristics of isolates collected from common hexaploid wheat, and one of the groups had virulence characteristics of isolates from tetraploid durum wheat. There was a significant correlation between the SSR genotypes and virulence phenotypes of the isolates. All EU groups had observed values of heterozygosity greater than expected and significant fixation values, which indicated the clonal reproduction of urediniospores in the overall population. Linkage disequilibria for SSR genotypes were high across the entire population and within countries. The overall values of RST and FST were lower when isolates were grouped by country, which indicated the migration of isolates within Europe. The European population of P. triticina had higher levels of genetic differentiation compared to other continental populations.  相似文献   

18.
Brown rot is a devastating disease of stone fruits caused by Monilinia spp. This study was conducted to investigate the disease aetiology on blossoms and fruit in peach, apricot, sweet cherry and plum orchards, in Greece. In total, 1433 isolates obtained from orchards located in the main stone fruit production regions of Greece were identified to species based on the presence/size of a cyt b intron. Monilinia laxa and M. fructicola were detected at frequencies of 59 and 41%, respectively, while M. fructigena was absent. Monilinia fructicola was more common on fruit whereas M. laxa occurred in similar frequency on blossoms and fruit. Monilinia laxa was replaced by M. fructicola in fruit infections of peach in both regions investigated and in fruit infections of plum in the Imathia region. Assessments of aggressiveness of 30 isolates of both species on the petals and fruits of the hosts showed that M. fructicola isolates were more aggressive. This suggests that the predominance of M. laxa on the blossoms cannot be explained by higher aggressiveness. Measurements of the effect of temperature on mycelial growth showed that M. laxa isolates had a higher growth rate than M. fructicola at the lowest temperature tested of 5°C, whereas M. fructicola isolates showed higher growth rates at higher temperatures. The observed high frequency of M. fructicola in Greece represents a major threat for stone fruit production. Furthermore, the information obtained about delineation of species and plant organ preference could be useful for the implementation of disease management strategies.  相似文献   

19.
The presence of phytoplasmas in seven coniferous plant species (Abies procera, Pinus banksiana, P. mugo, P. nigra, P. sylvestris, P. tabuliformis and Tsuga canadensis) was demonstrated using nested PCR with the primer pairs P1/P7 followed by R16F2n/R16R2. The phytoplasmas were detected in pine trees with witches’ broom symptoms growing in natural forest ecosystems and also in plants propagated from witches’ brooms. Identification of phytoplasmas was done using restriction fragment length polymorphism analysis (RFLP) of the 16S rDNA gene fragment with AluI, MseI and RsaI endonucleases. All samples showed RFLP patterns similar to the theoretical pattern of ‘Candidatus Phytoplasma pini’, based on the sequence of the reference isolate Pin127S. Nested PCR‐amplified products, obtained with primers R16F2n/R16R2, were sequenced. Comparison of the 16S rDNAs obtained revealed high (99·8–100%) nucleotide sequence identity between the phytoplasma isolates. The isolates were also closely related to four other phytoplasma isolates found in pine trees previously. Based on the results of RFLP and sequence analyses, the phytoplasma isolates tested were classified as members of the ‘Candidatus Phytoplasma pini’, group 16SrXXI.  相似文献   

20.
In late 2009, a European Food Safety Authority (EFSA)‐funded project (Prima phacie) began work to review and test methodologies for conducting pest risk assessment by means of case studies on three phytoplasmas (Candidatus Phytoplasma mali, Ca. P. prunorum, Ca. P. pyri); two bacteria (Acidovorax avenae subsp. citrulli, Xanthomonas citri [=X. axonopodis] pv. citri); two fungi (Guignardia citricarpa, Mycosphaerella dearnessii); two nematodes (Meloidogyne chitwoodi, M. fallax); and an insect (Anoplophora glabripennis). Multiple risk assessment schemes and methods will be applied to each of the case study pests, allowing for a comparative assessment of methods. Methods to assess the effectiveness of possible risk management options for each pest will also be evaluated. The project will further develop the scientific basis for pest risk assessment within the European Community and identify methodologies most suitable for conducting risk assessments and for evaluating the effectiveness of possible risk management options by the EFSA Panel on Plant Health in order to support European decision making. The project lasts 29 months, and is being conducted by an international consortium of 11 partners consisting of phytosanitary organizations, research institutes and a university. Results will be disseminated via conventional publications and at a workshop in March 2012.  相似文献   

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