The reaction of two lettuce cultivars to mixed infection by beet western yellows virus, lettuce mosaic virus and cucumber mosaic virus     

D. G. A. WALKEY  C. J. PAYNE 《Plant pathology》1990,39(1):156-160

The interaction of beet western yellows virus (BWYV), lettuce mosaic virus (LMV) and cucumber mosaic virus (CMV) has been studied in lettuce cultivars Little Gem and Saladin. LMV infection alone or in combination with BWYV and or CMV caused the most severe symptoms and yield losses in both cultivars. BWYV caused more severe reactions in Little Gem than in Saladin; the reactions caused by CMV were mild in both cultivars. The interaction between BWYV and CMV infection resulted in a significantly greater yield loss in both cultivars than that caused by BWYV or CMV infection alone.  相似文献   

Differentiation of pathotypes of lettuce mosaic virus   总被引：2，自引：0，他引：2  

D. A. C. PINK  D. KOSTOVA  D. G. A. WALKEY 《Plant pathology》1992,41(1):5-12

Differential interactions between six crisphead cultivars of lettuce and five isolates of lettuce mosaic virus (LMV) have identified a novel resistance factor in the cultivar Ithaca. The LMV isolates could be grouped into three pathotypes, two of which have not been identified previously. One of these, pathotype III represented by an isolate from Spain, was virulent on all of the cultivars. There were differences in aggressiveness between isolates of the same pathotype.  相似文献   

Further observations on variation of lettuce mosaic virus in relation to lettuce (Lactuca sativa), and a discussion of resistance terminology     

L. Bos  N. Huijberts  C. Cuperus 《European journal of plant pathology / European Foundation for Plant Pathology》1994,100(5):293-314

Two potyvirus isolates from endive, originating from southern France (Ls252) and from the Netherlands (Ls265), that were highly and poorly pathogenic on lettuce, respectively, were compared with a common isolate (Ls1) of lettuce mosaic virus (LMV) and with two highly deviant Greek isolates fromHelminthia (Picris) echioides (Gr4) and endive (Gr5), earlier recognized as LMV. The isolates could not be distinguished by particle morphology and serology, and were all identified as LMV. Leaf curling, plant stunting and necrosis were more characteristic of the virus than mosaic. The isolates studied varied considerably on differential host species and a range of lettce cultivars including pathotype differentials of Pink et al. [1992b]. Ls1 and Ls265 reacte largely as pathotype II, including the common strain of the virus, but Ls265 was least pathogenic on lettuce. Ls252 fitted pathotype IV and was very similar to LMV-E (the Spanish strain). The Greek isolates were very similar to each other in causing very severe symptoms on some non-lettuce hosts and a number of lettuce cultuvars. In lettuce variectal reaction Gr4 resembled pathotype I, but Gr5 severely affected Salinas 88, resistant to pathotypes I, II and III, and it appears to be a novel pathotype. Genetic interaction between lettuce and LMV is not following a simple yes-or-no pattern, and it is not a mere matter of resistance versus susceptibility. Adoption of a more realistic resistance terminology is proposed. None of the lettuce cultivars tested was resistant to the most pathogenic isolate Ls252, but resistance to it was found in 2 out of 12 wildLactuca species tested (Lactuca perennis andL. tatarica) while the symptomless plants ofL. perennis clearly reacted in ELISA.  相似文献   

Lettuce mosaic virus   总被引：10，自引：1，他引：10  

S. DINANT  H. LOT 《Plant pathology》1992,41(5):528-542

Lettuce mosaic virus (LMV) is an economically significant virus of lettuce and endive. The virus has spread world-wide due to the exchange of seed of lettuce varieties. A very high proportion of infected plants may result from a low level of infected seed, because of very efficient transmission by a number of aphid species. The symptoms are characteristic but the diagnosis can be difficult, particularly on lettuce, because numerous viruses may coinfect this species. A very reliable and sensitive method by ELISA has been established for diagnosis and detection, which gives a good estimation ofthe contamination level in a seed batch. The use of virus-free seed, preventive cultural practices and the use of tolerant varieties were shown to be good methods for control if rigorously applied. Up to now, strains able to overcome the genes g and mo, considered to be identical, were shown to be non-seed-transmissible. Studies carried out with several virulent isolates have shown that genes mo and g are different and probably allelic, and that one strain infects seed at a very high level on susceptible and tolerant genotypes. These features have necessitated the production of virus-free seed, including systematic checks on all cultivars, and have stimulated research on new sources of resistance. Recent molecular studies have provided clones for detection and strain differentiation. Assays to introduce different LMV genes into lettuce seem promising.  相似文献   

豌豆病毒病病原研究   总被引：2，自引：0，他引：2  

周雪平  濮祖芹 《植物病理学报》1994,24(3):207-212

 1986年至1990年,从豌豆田中采集了150余份病毒病样本,鉴定出蚕豆萎蔫病毒(BB-WV)、芜菁花叶病毒(TuMV)、马铃薯Y病毒组分离物、黄瓜花叶病毒(CMV)、莴苣花叶病毒(LMV)、大豆花叶病毒(SMV)、豌豆花叶病毒(PMV)、菜豆黄花叶病毒(BYMV)和苜蓿花叶病毒(AMV)等9种病毒。样本中,BBWV所占的比例最高,达59.2%,其次为CMV,占15.5%。BBWV常与CMV复合侵染豌豆,LMV发生也较普遍。田间调查表明,豌豆病毒病发病率因种植地区及品种不同而有差异,平均发病率为12.4%。  相似文献   

Molecular and biological characterization of two potyviruses infecting lettuce in southeastern France          下载免费PDF全文

C. Desbiez  A. Schoeny  B. Maisonneuve  K. Berthier  I. Bornard  C. Chandeysson  F. Fabre  G. Girardot  P. Gognalons  H. Lecoq  H. Lot  P. Millot  K. Nozeran  V. Simon  M. Tepfer  E. Verdin  C. Wipf‐Scheibel  B. Moury 《Plant pathology》2017,66(6):970-979

Several potyviruses affect lettuce (Lactuca sativa) and chicory (Cichorium spp.) crops worldwide and are important constraints for production because of the direct losses that they induce and/or because of their seed transmission. Here, the molecular and biological properties are described of two potyviruses that were recently isolated from lettuce plants showing mosaic or strong necrotic symptoms in an experimental field in southeastern France. The first potyvirus belongs to the species Endive necrotic mosaic virus and is present in a large number of wild plant species, especially Tragopogon pratensis. It is unable to infect lettuce cultivars with a resistance to Turnip mosaic virus that is present in many European cultivars and probably conferred by the Tu gene. The second potyvirus belongs to the tentative species lettuce Italian necrotic virus and was not observed in wild plants. It infected all tested lettuce cultivars. Wild accessions of Lactuca serriola, Lactuca saligna, Lactuca virosa and Lactuca perennis were identified as resistant to one or the other potyvirus and could be used for resistance breeding in lettuce. No resistance against these two potyviruses was observed in the tested Cichorium endivia cultivars. In contrast, all tested Cichorium intybus cultivars or accessions were resistant.  相似文献   

Biological and molecular variability of lettuce mosaic virus isolates     

Revers F  Lot H  Souche S  Le Gall O  Candresse T  Dunez J 《Phytopathology》1997,87(4):397-403

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The Use of Green Fluorescent Protein-Tagged Recombinant Viruses to Test Lettuce mosaic virus Resistance in Lettuce     

Candresse T  Le Gall O  Maisonneuve B  German-Retana S  Redondo E 《Phytopathology》2002,92(2):169-176

ABSTRACT Seed certification and the use of cultivars containing one of two, probably allelic, recessive genes, mo1(1) and mo1(2), are the principal control methods for Lettuce mosaic virus (LMV) in lettuce. Although for a few LMV isolates, mo1(2) confers resistance with most isolates, the genes mo1(1) or mo1(2) confer a tolerance, and virus accumulation is readily detected in mo1-carrying plants. This phenotype complicates evaluation of the resistance status, in particular for mo1(1), for which there are no viral strains against which a true resistance is expressed. Two green fluorescent protein (GFP)-tagged viruses were constructed, derived from a non-resistance breaking isolate (LMV-0) and from a resistance-breaking isolate (LMV-E). An evaluation of 101 cultivars of known status was carried out with these recombinant viruses. Using the LMV-0-derived recombinant, identification of mo1-carrying cultivars was simple because, contrary to its wild-type parent, systemic movement of LMV-0-GFP was abolished in resistant plants. This assay detected four cases of misidentification of resistance status. In all these cases, further tests confirmed that the prior resistance status information was incorrect, so that a 100% correlation was observed between LMV-0-GFP behavior and the mo1 resistance status. Similarly, the LMV-E-derived recombinant allowed the identification of mo1(2) lettuce lines because its systemic movement was restricted in mo1(2) lines but not in susceptible or in mo1(1) lines. The tagged viruses were able to systemically invade another host, pea, irrespective of its resistance status against another member of the genus Potyvirus, Pea seed-borne mosaic virus. The use of these recombinant viruses could therefore greatly facilitate LMV resistance evaluation and speed up lettuce breeding programs.  相似文献   

Field resistance against potato virus Y infection using natural and genetically engineered resistance genes     

S. Dinant  C. Kusiak  B. Cailleteau  J.L. Verrier  M.C. Chupeau  Y. Chupeau  Thi Anh Hong Le  R. Delon  J. Albouy 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(4):377-382

Commercial tobacco cultivars BB16 (burley) and PBD6 (dark air cured) were transformed with the coat protein gene of lettuce mosaic potyvirus (LMV). Transgenic BB16 plants showed resistance to potato virus Y (PVY) infection, against the necrotic strain PVY-N Versailles, as well as the resistance breaking necrotic strain PVY-N 107. Transgenic PBD6, which carries the recessive va gene conferring resistance to PVY, was also protected against PVY-N 107. In the progenies of most BB16 and PBD6 transformants, 45% to 100% of the inoculated plants were immune to PVY infection. The rest of the plants were tolerant, with atypical attenuated non necrotic symptoms and reduced virus accumulation. No recovery was observed in the tolerant plants, which stably expressed detectable level of LMV coat protein. This suggested a protein-mediated mechanism of heterologous protection.  相似文献   

Genetics of resistance to beet western yellows virus in lettuce   总被引：1，自引：0，他引：1  

D. A. C. PINK  D. G. A. WALKEY  S. J. McCLEMENT 《Plant pathology》1991,40(4):542-545

Resistance to beet western yellows virus (BWYV) in the lettuce cultivars Burse 17 and Crystal Heart was controlled by a single recessive gene designated bwy. ELISA tests showed that resistant plants were not immune to infection by BWYV, and may develop some mild symptoms. However, the concentration of virus found in resistant plants was less than in susceptible ones. The cultivar Crystal Heart is being used as a source of resistance for breeding BWYV-resistant crisp lettuce (iceberg) cultivars.  相似文献   

Lettuce mosaic poty virus is the causal agent of a new disease inBupleurum spp.     

J. Cohen  A. Rosner  L. Maslenin  N. Mor  M. Lampel  M. Zeidan  A. Gera 《Phytoparasitica》2002,30(1):88-95

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Properties of viruses of the potyvirus group. 2. Buoyant density,S value,particle morphology,and molecular weight of the coat protein subunit of bean yellow mosaic virus,pea mosaic virus,lettuce mosaic virus,and potato virus YN     

H. Huttinga  W. H. M. Mosch 《European journal of plant pathology / European Foundation for Plant Pathology》1974,80(1):19-27

The buoyant densities of bean yellow mosaic virus (BYMV) B25, pea mosaic virus (PMV) E198, lettuce mosaic virus (LMV), and potato virus Y^N (PVY^N) were 1.318, 1.321, 1.330, and 1.326 g/ml, respectively. Their S values were 143, 140, 143, and 145 S. The particle morphology of BYMV B25, PMV E198, and LMV could reversibly be changed by magnesium ions. PVY^N particles were broken in the presence of magnesium ions. The molecular weight of the coat protein subunit of the four viruses was 34,000 daltons. In many preparations also a 28,000 daltons component was present. This must be considered to be a breakdown product, derived from the 34,000 daltons component by proteolytic activity.Samenvatting De zweefdichtheden van het bonescherpmozaiekvirus (BYMV) B25, het erwtemozaiekvirus (PMV) E198, het slamozaïekvirus (LMV) en het aardappelvirus Y^N (PVY^N) bedroegen respectievelijk 1,318, 1,321, 1,330 en 1,326 g/ml. Hun sedimentatiecoëfficiënten waren 143, 140, 143 en 145 S. De deeltjesvorm van BYMV B25, PMV E198 en LMV kon reversibel worden veranderd door toevoeging en verwijdering van magnesium-ionen. Deze induceerden het optreden van breuken in de deeltjes van PVY^N. Het molecuulgewicht van de manteleiwiteenheid van de vier virussen bedroeg 34.000 daltons. In veel preparaten was bovendien een component van 28.000 daltons aanwezig. Deze moet worden beschouwd, als een proteolytisch afbraakprodukt dat ontstaat uit de component van 34.000 daltons.  相似文献   

Molecular and Biological Characterization of Lettuce mosaic virus (LMV) Isolates Reveals a Distinct and Widespread Type of Resistance-Breaking Isolate: LMV-Most   总被引：1，自引：0，他引：1  

Krause-Sakate R  Le Gall O  Fakhfakh H  Peypelut M  Marrakchi M  Varveri C  Pavan MA  Souche S  Lot H  Zerbini FM  Candresse T 《Phytopathology》2002,92(5):563-572

ABSTRACT Lettuce mosaic virus (LMV) causes an economically important seedborne and aphid-transmitted disease of lettuce and ornamental crops worldwide. The genetic diversity among 73 LMV isolates was examined based on a 216-nucleotide sequence at the variable region encoding the NIb-coat protein junction. Three clusters of LMV isolates were distinguished: LMV-Yar, LMV-Greek, and LMV-RoW. In the latter cluster, two subgroups of isolates, LMV-Common and LMV-Most, accounted for a large proportion of the LMV isolates analyzed. These two subgroups included the seedborne isolates, consistent with this property contributing a selective advantage and resulting in widespread distribution. In addition to being seedborne, LMV-Most isolates overcome the two resistance genes commonly used in lettuce, mo1(1) and mo1(2), and thus represent a potential threat to lettuce cultivation. The complete sequence of an LMV-Most isolate (LMV-AF199) was determined, allowing a better definition of the genetic relationships among LMV-Most, LMV-Common, and an additional isolate of the LMV-RoW cluster.  相似文献   

Further characterization of dandelion yellow mosaic virus from lettuce and dandelion     

L. Bos  N. Huijberts  H. Huttinga  D. Z. Maat 《European journal of plant pathology / European Foundation for Plant Pathology》1983,89(5):207-222

A damaging virus isolated in the Netherlands from lettuce was studied and compared with a virus isolated from dandelion orginating from Czechoslovakia. It was found to biologically resemble dandelion yellow mosaic virus incompletely described from dandelion and lettuce in Great Britain (Kassanis, 1944, 1947) and from dandelion in Germany (Hein, 1963). Mechanical transmission was greatly improved by buffer solution and transmission byMyzus persicae seemed to be in the non-persistent manner. Longevity in vitro of the virus hardly exceeded one day. Thermal inactivation was between 60 and 65 °C and the dilution end-point was between 10 000 and 100 000. It was still infectious in leaf material dried and stored over CaCl₂ at 4 °C for 6 1/2 years. The virus was isolated and purified with difficulty and was found to consist of one type of spherical particle of ca 30 nm diameter, with a sedimentation coefficient of 159 S, a buoyant density of 1.42 g.cm^?3 and an A₂₆₀/A₂₈₀ ratio of 1.67. An antiserum was prepared with a titre of 256 in the agar double-diffusion test. The virus could be identified in crude extracts from lettuce andChenopodium amaranticolor by enzyme-linked immunosorbent assay (ELISA), but not by agar double diffusion. It could only be visualized in crude sap in the electron microscope after trapping of virus particles on antiserum-coated grids. The virus cannot yet be assigned to any known virus group. It is of potential economic importance to lettuce because of its occurrence in widely differing regions in Europe, its aggressiveness and virulence on 22 out of 23 lettuce cultivars tested (and on endive) and its pathogenicity toLactuca genotypes which are resistant to lettuce mosaic virus and other important pathogens of lettuce. ‘Laibacher Eis’ was the only cultivar showing some tolerance.  相似文献   

Two diseases of dimorphotheca caused by lettuce mosaic potyvirus and tomato spotted wilt tospovirus     

I. N. Manoussopoulos  E. K. Chatzivassiliou  I. N. Smyrnioudis  N. I. Katis 《Phytoparasitica》1999,27(3):227-232

In 1997, virus-like symptoms were observed in dimorphotheca plants(Dimorphotheca sinuata) at two different locations in Greece. In a greenhouse near Heraklion (Crete), plants showed chlorotic patches mainly in the older leaves, and a mild stunting; near Katerini (Macedonia), garden plants showed chlorotic rings. Sap inoculation of healthy dimorphotheca plants with extracts from diseased plants from the two regions, reproduced each of the two diseases. Examination by electron microscopy (EM) of samples from diseased plants from the first region revealed filamentous particles, whereas samples from the second region showed quasi-spherical particles. The filamentous particles were decorated in EM with antibodies specific to lettuce mosaic potyvirus (LMV). Samples from the second location reacted with antibodies specific to tomato spotted wilt tospovirus (TSWV) in EL1SA tests. It is concluded that LMV and TSWV are the causal agents of the disease noticed in Heraklion and in Katerini, respectively. http://www.phytoparasitica.org posting May 31, 1999.  相似文献   

Studies on resistance to beet western yellows virus in lettuce (Lactuca sativa) and the occurrence of field sources of the virus   总被引：1，自引：3，他引：1  

D. G. A. WALKEY  D. A. C. PINK 《Plant pathology》1990,39(1):141-155

An effective method based on glasshouse and field procedures was developed for screening commercial cultivars and other lettuce types for resistance to beet western yellows virus (BWYV). Field experiments in 1985, 1986 and 1987 showed that lettuce cultivars varied in their reaction to BWYV, but no high levels of resistance were identified in the main commercial types. Crisp types generally showed milder symptoms than butterhead or cos types, but individual butterhead cultivars were identified with resistance equal to the best crisp types. The highest levels of resistance were identified in Batavian type cultivars and extreme resistance or possible immunity was found in Lactuca perennis and L. muralis . BWYV caused yield reductions in some cultivars as high as 63% and reduced maturation by up to 38%, in others. There was no correlation between chlorotic leaf symptom severity and yield reduction.
BWYV was isolated from a range of weed and non-lettuce host species growing near affected lettuce crops. Isolates of BWYV obtained from infected lettuce and brassicas appeared to be similar. They infected sugar beet with difficulty but caused no symptoms, and could only be detected by ELISA serology.  相似文献   

Further evidence of Mirafiori lettuce big-vein virus but not of Lettuce big-vein associated virus with big-vein disease in lettuce     

Sasaya T  Fujii H  Ishikawa K  Koganezawa H 《Phytopathology》2008,98(4):464-468

Mirafiori lettuce big-vein virus (MLBVV) and Lettuce big-vein associated virus (LBVaV) are found in association with big-vein disease of lettuce. Discrimination between the two viruses is critical for elucidating the etiology of big-vein disease. Using specific antibodies to MLBVV and LBVaV for western blotting and exploiting differences between MLBVV and LBVaV in host reaction of cucumber and temperature dependence in lettuce, we separated the two viruses by transfering each virus from doubly infected lettuce plants to cucumber or lettuce plants. A virus-free fungal isolate was allowed to acquire the two viruses individually or together. To confirm the separation, zoospores from MLBVV-, LBVaV-, and dually infected lettuce plants were used for serial inoculations of lettuce seedlings 12 successive times. Lettuce seedlings were infected at each transfer either with MLBVV alone, LBVaV alone, or both viruses together, depending on the virus carried by the vector. Lettuce seedlings infected with MLBVV alone developed the big-vein symptoms, while those infected with LBVaV alone developed no symptoms. In field surveys, MLBVV was consistently detected in lettuce plants from big-vein-affected fields, whereas LBVaV was detected in lettuce plants not only from big-vein-affected fields but also from big-vein-free fields. LBVaV occurred widely at high rates in winter-spring lettuce-growing regions irrespective of the presence of MLBVV and, hence, of the presence of the big-vein disease.  相似文献   

Enzyme-linked immunosorbent assay (ELISA) and dispersedye immuno assay (DIA): Comparison of simultaneous and separate incubation of sample and conjugate for the routine detection of lettuce mosaic virus and pea early-browning virus in seeds     

J. W. L. Van Vuurde  D. Z. Maat 《European journal of plant pathology / European Foundation for Plant Pathology》1985,91(1):3-13

Two modifications of ELISA and DIA were compared in relation to sensitivity of detection of two plant viruses and suitability for large-scale routine testing. DIA is a solid phase immuno assay like ELISA, in which the enzyme conjugate is replaced by a dye sol conjugate and substrate incubation is replaced by immediate dissolving of the dye molecules from the conjugate with an organic solvent. Sample and conjugate were incubated separately (ELISA 1, DIA 1) or simultaneously (ELISA 2, DIA 2). The seed-borne viruses viz. lettuce mosaic virus (LMV) and pea early-browning virus (PEBV) were subjected to the assays. DIA detected LMV in a purified extract ofNicotiana benthamiana. However, compounds present in crude virus-free and virus-containing plant extracts strongly interfered with DIA, necessitating adaptation of DIA to plant viruses in crude extracts.With the extracts of lettuce and pea seeds ELISA 2, in comparison with ELISA 1, resulted in equal (LMV) or slightly higher (PEBV) extinction values and in a higher ratio between extinction values of virus-containing and virus-free samples. The higher sensitivity of ELISA 2 in combination with its higher efficiency as a result of simultaneous sample and conjugate incubation, indicates the potential of this method for large-scale indexing.Samenvatting Twee modificaties van ELISA en DIA werden vergeleken met betrekking tot hun gevoeligheid voor het aantonen van twee plantevirussen en hun geschiktheid voor routinematige toepassing. DIA is een serologische toetsmethode die veel overeenkomst vertoont met ELISA, maar waarin het enzymconjugaat is vervangen door een conjugaat met gedispergeerde kleurstofdeeltjes en de incubatie met enzym-substraat door het direct oplossen van de kleurstofmoleculen van het conjugaat met een organisch oplosmiddel. Incubatie van monster en conjugaat vond zowel gescheiden (ELISA 1, DIA 1) als gelijktijdig (ELISA 2, DIA 2) plaats. Twee met zaad overgaande virussen, te weten slamozaïekvirus (LMV) en vroege-verbruiningsvirus van erwt (PEBV) werden bij het onderzoek betrokken. Met DIA kon LMV worden aangetoond in een gezuiverd extract vanNicotiana benthamiana. In ruwe planteëxtracten bleken echter stoffen voor te komen die in DIA sterke niet-specifieke reacties tot gevolg hadden. Verder onderzoek is dan ook noodzakelijk om DIA geschikt te maken voor het aantonen van plantevirussen in ruwe extracten van planten. Betere resultaten werden verkregen met de beide ELISA-modificaties. Met de extracten uit slazaad en erwtezaad gaf ELISA 2 vergelijkbare (LMV) of iets hogere (PEBV) extinctiewaarden dan ELISA 1. Bovendien was de verhouding tussen de extinctiewaarden van virusziek materiaal en die van virusvrij materiaal, bij ELISA 2 hoger dan bij ELISA 1. De grotere gevoeligheid van ELISA 2 en de grotere doelmatigheid ten gevolge van de gelijktijdige incubatie van monster en conjugaat duiden op de bijzondere geschiktheid van deze methode voor routinematige toepassing op grote schaal.  相似文献   

Control of lettuce big-vein disease by application of fungicides and crop covers     

I. Opatovsky  M. Elbaz  I. Dori  L. Avraham  S. Mordechai-Lebiush  A. Dombrovsky  L. Tsror 《Plant pathology》2019,68(4):790-795

One of the economically important diseases of lettuce is lettuce big-vein disease (LBVD), which leads to severe yield losses. LBVD is associated with a complex of two viruses, Lettuce big-vein associated virus (LBVaV) and Mirafiori lettuce big-vein virus (MLBVV). These viruses are transmitted by motile zoospores of Olpidium spp. fungi, which persist in the soil for decades through resting spores. In greenhouse and field experiments, this study tested whether changing plant and soil temperatures together with fungicide application would have a significant effect on controlling LBVD in lettuce. Soil fumigation with metam sodium was not effective at controlling the disease, as opposed to treatment with chloropicrin and methyl bromide. Moreover, the fungicides carbendazim and fluazinam were effective in reducing the incidence of Olpidium virulentus. Nevertheless, control of the fungal vector did not seem to be sufficient to control the disease due to the transition ability of the virus under low vector abundance. Crop covers, which affect the favourable environmental conditions for the viruses by lowering soil temperature and raising air temperature, reduced the disease symptoms. Combining fungicides with crop cover had a synergistic effect on reducing disease symptoms, thus providing a sustainable solution for LBVD.  相似文献   

Transmission by Olpidium brassicae of Mirafiori lettuce virus and Lettuce big-vein virus, and Their Roles in Lettuce Big-Vein Etiology     

Lot H  Campbell RN  Souche S  Milne RG  Roggero P 《Phytopathology》2002,92(3):288-293

ABSTRACT Big-vein disease occurs on lettuce worldwide in temperate conditions; the causal agent has been presumed to be Lettuce big-vein virus (LBVV), genus Varicosavirus, vectored by the soilborne fungus Olpidium brassicae. Recently, the role of LBVV in the etiology of big-vein disease has been questioned because a second soilborne virus, Mirafiori lettuce virus (MiLV), genus Ophiovirus, has been found frequently in big-vein-affected lettuce. LBVV and MiLV, detectable and distinguishable by enzyme-linked immunosorbent assay using specific antisera, were tested for their ability to be transmitted from lettuce to lettuce by mechanical inoculation of sap extracts, or by zoospores of O. brassicae, and to cause big-vein disease. Both viruses were mechanically transmissible from lettuce to herbaceous hosts and to lettuce, but very erratically. LBVV was transmitted by O. brassicae but lettuce infected with only this virus never showed symptoms. MiLV was transmitted in the same manner, and lettuce infected with this virus alone consistently developed big-vein symptoms regardless of the presence or absence of LBVV. With repeated mechanical transmission, isolates of both viruses appeared to lose the ability to be vectored, and MiLV appeared to lose the ability to cause big-vein symptoms. The recovery of MiLV (Mendocino isolate, from Cali-fornia) from stored O. brassicae resting spores puts the earliest directly demonstrable existence of MiLV at 1990.  相似文献