Involvement of Beet western yellows virus, Cauliflower mosaic virus, and Turnip mosaic virus in Internal Disorders of Stored White Cabbage

ABSTRACT Experiments over two growing seasons clearly showed that Turnip mosaic virus (TuMV) infection was associated with internal necrosis (sunken necrotic spots 5 to 10 mm in diameter) and Beet western yellows virus (BWYV) infection was associated with collapse of leaf tissue at the margins (tipburn) in heads of stored white cabbage (Brassica oleracea var. capitata). Virtually no tipburn was seen in cv. Polinius, whereas cv. Impala was affected severely. Internal necrotic spots were seen in both cultivars. BWYV appeared to interact with TuMV. Plants infected with both viruses showed a lower incidence of external symptoms and had less internal necrosis than plants infected with TuMV alone. Cauliflower mosaic virus (CaMV) did not induce significant amounts of internal necrosis or tipburn, but did, in most cases, exacerbate symptoms caused by TuMV and BWYV. BWYV-induced tipburn worsened significantly during storage. Post-transplanting inoculation with TuMV induced more internal necrosis than pre-transplant inoculation. There was a significant association between detection of TuMV just prior to harvest and subsequent development of internal necrotic spots. Individually, all three viruses significantly reduced the yield of cv. Polinius, whereas only BWYV and CaMV treatments reduced the yield of cv. Impala.     

复合RT-PCR方法同步检测百合X病毒、百合无症病毒及百合斑驳病毒

建立了特异性检测百合X病毒(LVX)、百合无症病毒(LSV)及百合斑驳病毒(LMoV)的单一、双重及三重PCR体系并对各体系的灵敏度进行了研究。结果表明,单一PCR体系可检测的LVX最低浓度在1×10^-7μg/mL,LSV最低浓度在1×10^-8μg/mL,LMoV最低浓度在1pg/mL;双重PCR体系可明显检测的LVX、LSV最低浓度在1pg/mL,LSV、LMoV最低浓度在1ng/mL,LVX、LMoV最低浓度在1pg/mL;三重PCR体系可明显检测的LVX、LSV和LMoV的最低浓度为1ng/mL。     

Soilborne viruses: advances in virus movement,virus induced gene silencing,and engineered resistance

Until recently soilborne plant viruses were considered important only because they are causative agents for agricultural diseases. In recent years, soilborne plant viruses have played a significant role in advancing research into mechanisms of plasmodesmata transport, gene silencing, and engineered resistance to plant pathogens. Three different mechanisms by which viruses move through plasmodesmata have been identified using dianthoviruses, nepoviruses, and benyviruses. The infectious clone of the tobravirus Tobacco rattle virus (TRV) has become an important tool for studying virus induced gene silencing and may be a tool to silence meristematic gene expression. Investigations of soilborne viruses may enable the development of new strategies for control of soilborne diseases. The potential use of pathogen-derived resistance to control soilborne viruses is currently being explored in several laboratories.     

Parsley latent virus,a new and prevalent seed-transmitted,but possibly harmless virus of Petroselinum crispum

Parsley latent virus, a hitherto undescribed virus, was isolated from 38 out of 54 samples of seed of parsley (Petroselinum crispum) of 17 out of 24 cultivars and from all five European countries tested, but not from some samples from the USA. It could easily be detected in seedlings and also in seeds germinated on moist filter paper, but not in dry seeds or in seeds soaked in water. Strawberry latent ringspot virus was detected in five samples. The parsley virus is symptomless in parsley and caused latent systemic infection inGomphrena globosa, three cultivars ofSpinacia oleracea and weak and often transient systemic symptoms inChenopodium amaranticolor, C. giganteum, C. glaucum andC. quinoa, but did not infect any other species out of all 32 species of seven plant families tested in total.The virus could easily be transmitted mechanically but not by seven aphid species in the non-persistent manner. Dilution end-point was between 100 and 1000, thermal inactivation between 55 and 60°C and ageing in vitro between 7 and 10 days.Purification yielded a single infectious component. The particles were spherical, ca. 27 nm in diameter, with a sedimentation coefficient of 127.5 S, a buoyant density of 1.449 g/ml, an RNA content of 36% and one type of protein with a relative molecular mass of 22×10³. Purificition without Triton and urea resulted in preparations with aggregates each consisting of 12 particles in icosahedral array.The virus differs from all viruses described so far and did not show clear serological affinity with antisera to any of 34 widely differing viruses tested. It does not seem of direct practical importance and may be easily overlooked.Samenvatting In zaailingen van peterselie (Petroselinum crispum) werd een nog niet eerder beschreven virus aangetroffen. Het virus kon niet worden aangetoond door toetsing van droge of in water geweekte zaden opChenopodium quinoa maar wel in op filtreerpapier gekiemde zaden en vooral in zaailingen. Het werd aangetroffen in 38 van de 54 getoetste herkomsten, in 17 van de 24 getoetste rassen en in zaad vermeerderd in alle zes hierop onderzochte Europese landen maar niet in enkele zaadmonsters uit de USA. In sommige monsters bevatten nagenoeg alle zaden het virus. In vijf herkomsten werd eveneens het nog niet eerder in peterselie gerapporteerde latente aardbeikringvlekkenvirus geconstateerd. Dit virus kan bij toetsing gemakkelijk worden herkend door systemische symptomen inC. amaranticolor en komkommer.In geïnfecteerde peterselieplanten zijn geen afwijkingen waargenomen. Het virus kon niet op non-persistente wijze worden overgebracht met zeven bladluissoorten maar wel gemakkelijk met sap. Van 32 getoetste plantesoorten van zeven families, waaronder vier schermbloemigen, kon het virus slechts worden overgebracht op vierChenopodium-soorten,Gomphrena globosa en alle drie getoetste spinazierassen. AllenC. quinoa (Fig. 1),C. giganteum, C. glaucum en soms ookC. amaranticolor (Fig. 2) reageerden met vaak voorbijgaande systemische symptomen. Een lokalelesietoetsplant werd niet gevonden. Zaadovergang bijC. quinoa kon niet worden aangetoond.Voor de houdbaarheid van het infectievermogen werden de volgende waarden gevonden: verdunningseindpunt 100–1000, thermaal inactiveringspunt 55–60°C en houdbaarheid in vitro 7–10 dagen.Zuivering door homogenisatie in fosfaatcitroenzuurbuffer, behandeling met Triton X-100 en ureum en differentiële en daarna dichtheidsgradiëntultracentrifugering leverde preparaten op met uniforme deeltjes van ca. 27 nm diameter (Fig. 3B), een sedimentatiecoëfficiënt van 127,5 S, een zweefdichtheid van 1,449 g/ml, een RNA-gehalte van 36% en een relatieve moleculaire massa van de eiwitondereenheid van 22×10³. Bij zuivering zonder toepassing van Triton en ureum werd een extra zone verkregen met aggregaten van 12 deeltjes in icosaëdrische rangschikking (Fig. 4). In ruw plantesap waren slechts met grote moeite enkele deeltjes met behulp van de elektronenmicroscoop te vinden.Het virus reageerde niet met antisera tegen 33 bolvormige virussen en luzernemozaïekvirus (Tabel 1). Of de zwakke reactie verkregen met één antiserum tegen het tomate-aspermievirus een verre serologische verwantschap inhoudt, dan wel het gevolg is van een verontreiniging, werd niet vastgesteld.Het virus wordt beschouwd als een geheel nieuw virus waarvoor de naamlatent peterselievirus wordt voorgesteld. Het lijkt door zijn beperkte waardplantenreeks en symptoomloosheid in de vatbaar bevonden soorten, behalve in enkele als toetsplant te gebruikenChenopodium-soorten, nauwelijks van praktische betekenis.     

马铃薯Y病毒HC-Pro、CI、NIb和CP基因介导的病毒抗性比较研究

 根据已克隆的马铃薯Y病毒坏死株系(PVY^N)的基因组序列设计引物,利用PCR扩增HC-Pro、CI、NIb和CP4个基因的3'端400bp cDNA区段,分别反向插入含有査尔酮合成酶基因(Chalcone synthase,CHS)内含子的双元载体pRCHS中,构建了含内含子的发夹结构RNA (intron splicing hpRNA,ihpRNA)表达载体pRCHS-HC-Pro、pRCHS-CI、pRCHS-NIb和pRCHS-CP。利用农杆菌介导法转化烟草品种NC89,获得了多种转基因植株。病毒抗性检测的结果显示:转pRCHS-HC-Pro、pRCHS-CI、pRCHS-NIb和pRCHS-CP的烟草中,抗性植株的比例分别为55.34%、73.69%、61.54%和84.21%。大分子RNA和siRNA的Northern blot分析表明,目的片段转录产物的积累量与转基因植株的抗病性呈负相关,转基因植株中可检测到siRNA,说明所获得的抗病性是RNA沉默介导的。     

Economic impact of Turnip mosaic virus, Cauliflower mosaic virus and Beet mosaic virus in three Kenyan vegetables

Screenhouse experiments conducted in Kenya showed that inoculation of cabbage seedlings with Turnip mosaic virus (TuMV), either alone, or in combination with Cauliflower mosaic virus (CaMV), reduced the number and weight of marketable harvested heads. When viruses were inoculated simultaneously, 25% of cabbage heads were non-marketable, representing 20-fold loss compared with control. By contrast, inoculation with CaMV alone had insignificant effects on cabbage yield. This suggests that TuMV is the more detrimental of these pathogens, and its management should be a priority. Early exposure to TuMV produced cabbages that were 50% lighter than non-infected plants, but later infection was less damaging suggesting that controlling virus infection at the seedling stage is more important. TuMV was far less damaging to kale than it was to cabbage; although high proportions of TuMV-inoculated kale plants showed symptoms (>90%), the marketability and quality of leaves were not significantly reduced, and no clear relationship existed between timing of infection and subsequent crop losses. Early inoculation of Swiss chard with Beet mosaic virus (BtMV) significantly impaired leaf quality (∼50% reduction in marketable leaf production), but the impact of disease was greatest in plants that had been inoculated at maturity, where average leaf losses were two and a half times those recorded in virus-free plants. Disease-management of BtMV in Swiss chard is important, therefore, not only at the seedling stage, but particularly when plants are transplanted from nursery to field.     

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

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.     

地高辛标记的cDNA探针检测烟草花叶病毒、黄瓜花叶病毒及马铃薯Y病毒

 根据已发表的烟草花叶病毒(Tobacco mosaic virus,TMV)、黄瓜花叶病毒(Cucumber mosaic virus,CMV)和马铃薯Y病毒(Potato virus Y,PVY)的外壳蛋白基因序列,设计特异引物,分别以提取的TMV、CMV和PVY侵染的病叶总RNA为模板,反转录PCR进行体外扩增,分别得到长度为0.44、0.77、0.80 kb的目的片段,并克隆到pGEM-T easy质粒载体上,以构建的重组质粒为模板,用PCR方法合成了相应的地高辛标记的双链DNA探针。以合成的探针通过斑点杂交技术检测烟草病叶总RNA和烟草病叶汁液。TMV、CMV和PVY的3种地高辛探针检测各自感染的烟草病叶总RNA的稀释低限分别为1:1000、1:10000、1:320,检测各自侵染烟草病汁液的最大稀释倍数分别为1:100、1:100、1:10,而每种探针与健康烟草和其它2种病毒的反应均为阴性。     

Pea symptomless virus,a newly recognized strain of red clover mottle virus

A virus contaminating a culture of pea enation mosaic virus was isolated and studied. The virus, tentatively named pea symptomless virus (PSV), was not aphid-borne but was readily transmitted by sap inoculation of Amaranthaceae, Chenopodiaceae and Leguminosae. Purified preparations of PSV contained isometric particles 26 nm in diameter, which sedimented as three components with sedimentation coefficients of 55, 94 and 118S, respectively, and contained ribonucleic acid with a molar base content of G 22%, A 26%, C 17%, U 34%.PSV is a member of the cowpea mosaic group of plant viruses, is closely related to red clover mottle broad bean stain, and pea green mottle viruses, and protects plants against infection with red clover mottle virus. PSV, the viruses of broad bean stain, red clover mottle and pea green mottle, and possibly MF-virus, probably constitute a subgroup of the cowpea mosaic virus group and may even considered to be members of a single virus species.Samenvatting Een virus dat als verontreiniging voorkwam in een cultuur van het erwte-enatiemozaïekvirus werd geïsoleerd en bestudeerd. Het virus dat voorlopig met de naam pea symptomless virus (PSV) wordt aangeduid, gaat met sap over en wordt niet door de bladluizenMyzus persicae enAcyrthosiphon pisum overgedragen.Plantesoorten uit de families der Amaranthaceae, Chenopodiaceae en Leguminosae (Tabel 1) zijn vatbaar voor dit virus. Gezuiverde preparaten van PSV bevatten isometrische deeltjes met een diameter van 26 nm (Fig. 1) en bestonden uit drie fracties (met sedimentatieconstanten van 118,94 en 55S (Fig. 2). Voor de basenverhouding in het RNZ werd 22% guanine, 26% adenine, 17% cytosine en 34% uracil (Tabel 2) gevonden.Het beschreven virus is serologisch zeer nauw verwant met het rode-klavervlekkenvirus (RCMV) en wat minder verwant met andere leden van de cowpea mosaic virus (CPMV) groep, zoals het broad bean stain virus (BBSV), en pea green mottle virus (PGMV). De symptomen die PSV en RCMV veroorzaakten werden vergeleken (Tabel 1); RCMV veroorzaakte in alle gevallen heviger symptomen.PSV is in staat om erwteplanten volledig tegen RCMV te beschermen indien de planten 9 dagen van te voren met eerstgenoemd virus geïnoculeerd waren. De auteurs concluderen uit hun werk dat PSV met BBSV, PGMV en RCMV een sub-groep binnen de CPMV-groep vormen, waartoe ook het MF-virus dat in Frankrijk is gevonden, zou kunnen worden gerekend.     

Aubian wheat mosaic virus, a new soil-borne wheat virus emerging in France

The properties of Aubian wheat mosaic virus (AWMV), a new soil-borne wheat virus in France, were investigated. Symptoms include foliar mosaic and severe stunting of winter wheat. The vector of the disease is unknown but the plants infected carry Polymyxa graminis in the roots. AWMV was transmitted mechanically to wheat and to two dicotyledoneous species: Lactuca sativa and Vicia faba. This virus was transmitted by seed to three winter wheat cultivars tested. Purified preparations contained rod-shaped particles with a variable length of 150–700 nm. Certain particles are very long and appear flexible. Antiserum raised against AWMV reacted specifically with AWMV in both indirect and direct enzyme-linked immunosorbent assays (ELISA). The incidence of AWMV in 26 winter wheat cultivars was investigated in the field during the growing season of 1999–2000. AWMV was detected in roots and shoots of all cultivars regardless of the symptoms. Twelve virus species belonging to the genera Benyvirus, Bymovirus, Furovirus, Pecluvirus and Pomovirus did not react with the AWMV antisera. A new tubular virus described in winter wheat in Bedfordshire in England reacted strongly with AWMV in ELISA. It is concluded that AWMV and probably the Bedford-virus constitute a previously undescribed tubular virus biologically and serologically distinct from other soil-borne viruses of wheat.     

New insights into virus yellows distribution in Europe and effects of beet yellows virus,beet mild yellowing virus,and beet chlorosis virus on sugar beet yield following field inoculation

Beet yellows virus (BYV), beet mild yellowing virus (BMYV), beet chlorosis virus (BChV), and beet mosaic virus (BtMV) cause virus yellows (VY) disease in sugar beet. The main virus vector is the aphid Myzus persicae. Due to efficient vector control by neonicotinoid seed treatment over the last decades, there is no current knowledge regarding virus species distribution. Therefore, Europe-wide virus monitoring was carried out from 2017 to 2019, where neonicotinoids were banned in 2019. The monitoring showed that closterovirus BYV is currently widely spread in northern Europe. The poleroviruses BMYV and BChV were most frequently detected in the northern and western regions. The potyvirus BtMV was only sporadically detected. To study virus infestation and influence on yield, viruses were transmitted to sugar beet plants using viruliferous M. persicae in quadruplicate field plots with 10% inoculation density simulating natural infection. A plant-to-plant virus spread was observed within 4 weeks. A nearly complete infection of all plants was observed in all treatments at harvest. In accordance with these findings, a significant yield reduction was caused by BMYV and BChV (−23% and −24%) and only a moderate reduction in yield was observed for BYV (−10%). This study showed that inoculation at low densities mimics natural infection, and quick spreading induced representative yield effects. Within the background of a post-neonicotinoid era, this provides the basis to screen sugar beet genotypes for the selection of virus tolerance/resistance and to test the effectiveness of insecticides for the control of M. persicae with a manageable workload.     

Shallot latent virus,a new carlavirus

A new carlavirus, apparently omnipresent in shallot (Allium ascalonicum) without causing symptoms, is described as shallot latent virus. It has also been detected in naturally infected onion (A. cepa) and leek (A. porrum). The virus was easily transmissible in sap and could be transferred withMyzus ascalonicus. Infection after inoculation was symptomless in onion, leek,A. fistulosum andA. jailae. Chenopodium album, C. amaranticolor andC. quinoa reacted with local lesions.A. neapolitanum andA. schoenoprasum and 20 other plant species were immune. Dilution end-point was 10⁴–10⁵, thermal inactivation at ca. 80°C and ageing in vitro 8–11 days. Purification by molecular sieving on Sephadex G-200 followed by equilibrium density-gradient centrifuging in CsCl was successful. Sedimentation coefficient was 147.5 S, bouyant density 1.313 g/cm³ and molecular mass of protein subunits 23 200 dalton. With the antiserum (titre 1024) distant serological relationships to some carlaviruses were determined. No inclusion bodies were observed with the light microscope. With the electron microscope a high concentration of straight or slightly curved particles with a normal length of 650 to 652 nm could easily be detected in crude sap and in purified preparations.     

Properties of viruses of the potyvirus group. 1. A simple method to purify bean yellow mosaic virus,pea mosaic virus,lettuce mosaic virus and potato virus YN

Bean yellow mosaic virus, pea mosaic virus, lettuce mosaic virus, and potato virus Y^N were purified by homogenizing and clarifying infected leaves in a mixture of 0.1 M tris-thioglycollic acid buffer pH 9, carbon tetrachloride and chloroform, followed by differential centrifuging applying moderate centrifugal forces.Samenvatting Het bonescherpmozaïekvirus B25, het erwtemozaïekvirus E198, het slamozaïekvirus en het aardappelvirus Y^N konden worden gezuiverd door geïnfecteerde bladeren te vermalen in een mengsel van 0,1 M tris-thioglycolzuur pH 9, tetrachloorkoolstof en chloroform, en de geklaarde suspensie vervolgens differentiëel te centrifugeren bij matige centrifugaalkrachten.     

Host range and some properties of Physalis mosaic virus,a new virus of the turnip yellow mosaic virus group

An apparently undescribed virus was isolated fromPhysalis subglabrata in Illinois, USA, and its properties were studied. The virus was namedPhysalis mosaic virus (PMV). It was readily transmitted by sap inoculation to 23 out of 34 Solanaceae tested, toChenopodium foetidum andSonchus oleraceus but not to 28 other non-solanaceous species inoculated. Purified preparations of PMV contained isometric particles of 27 nm in diameter, which sedimented as two components with sedimentation coefficients of 50 and 112 S. The 112 S component was infectious, the 52 S component was not. The virus contained 38% ribonucleic acid with a molar base content of G 14.4%, A 22.9%, C 37,2% and U 25.5%.Purified preparations were highly infectious; a concentration of about 6000 particles per ml was infectious on plants.PMV is a member of the Andean potato latent virus subgroup of the turnip yellow mosaic virus group. The virus was closely related to the viruses: Andean potato latent, belladonna mottle, dulcamara mottle and egg-plant mosaic.Samenvatting Een nog niet eerder beschreven virus, dat in de staat Illinois (V.S. van Amerika) opPhysalis subglabrata was gevonden, werd in Wageningen bestudeerd. Het virus dat Physalis mosaic virus (PMV) (in het Nederlands:Physalis-mozaïekvirus) werd genoemd, kon met sap worden overgebracht.BehalveChenopodium foetidum enSonchus oleraceus bleken ook 23 van de 34 getoetste soorten uit de familie Solanaceae vatbaar voor dit virus te zijn. Gezuiverde virus preparaten bevatten isometrische deeltjes met een diameter van 27 nm (Fig. 2) Het virus bestaat uit twee deeltjes met sedimentatie-coëfficiënten van 112 en 50 S. Het 112 S deeltje bleek infectieus te zijn, het andere niet. Op grond van de sedimentatiecoëfficiënten kan worden berekend dat het 112 S deeltje 38% nucleïnezuur bevat. Voor de basenverhouding in het nucleïnezuur werd 22,9% adenine, 14,4% guanine, 37,2% cytosine en 25,5% uracil gevonden (Tabel 1). Het hoge gehalte van cytosine kwam ook tot uiting in de U.V. absorptiekromme van het virus en het nucleïnezuur (Fig. 1). Het gezuiverde virus bleek zeer infectieus te zijn; 6000 deeltjes/ml waren in staat een plant van de soortNicotiana clevelandii ziek te maken.Op grond van serologisch onderzoek kon het virus tot de turnip yellow mosaic virus groep worden gerekend. Het vertoonde serologische verwantschap met de Andean potato latent virus (APLV) subgroep (Tabel 2). In premunitieproeven bood het slechts een geringe bescherming tegen APLV en dulcamara mottle virus. Het omgekeerde werd eveneens geconstateerd. De leden van de APLV-subgroep kunnen op grond van hun waardplantenreeks van elkaar onderscheiden worden (Tabel 3).