Infection of cowpea mesophyll protoplasts by tobacco mosaic virus and tobacco necrosis virus

Samenvatting Protoplasten werden geïsoleerd uit cowpeabladeren en konden worden geïnfecteerd met tabaksmozaïekvirus en tabaksnecrosevirus serotype A. De virusvermeerdering in de protoplasten werd tot twee dagen na de inoculatie onderzocht.     

Tobacco mosaic virus in Pythium spec

Cultures of the soil inhabiting fungusPythium spec. were inoculated in vitro with tobacco mosaic virus. Virus could be demonstrated in the mycelia from 4 days on after inoculation. In 15 days old cultures the virus concentration in the mycelium was higher than in the liquid culture medium. It is not yet clear whether the virus only accumulates, or also multiplies in the mycelium. After growth on solid medium infected mycelia still contained virus indicating that the virus is able to persist and possibly also to multiply in the hyphae.Samenvatting Cultures van de bodemschimmelPythium spec. werden in vitro geïnoculeerd met tabaksmozaïekvirus. In enkele gevallen kon al 4 dagen na inoculatie virus in mycelium worden aangetoond. In 15 dagen oude cultures bevatte het mycelium meer virus dan de cultuurvloeistof. Het is nog niet bekend of het virus zich slechts ophoopt of zich ook vermeerdert in het mycelium. Na groei op een agarmedium gedurende 7 dagen bevatte het mycelium nog virus, wat er op zou wijzen dat het virus in staat is zich te handhaven in de hyfen en zich daarin wellicht ook te vermeerderen.     

Infection and necrosis of cowpea mesophyll cells by tobacco necrosis virus and two strains of tobacco mosaic virus

When cowpea mesophyll tissue with or without any epidermal layer was inoculated with tobacco necrosis virus (TNV), local necrotic lesions were produced. In epidermal strips isolated after inoculation of intact leaves local lesions were never observed. Homogenates of epidermal strips removed within 30 min after inoculation of the leaf with the cowpea strain of tobacco mosaic virus (Cp-TMV) or with TNV and incubated on agar for 2 or 4 days were not infectious. However, when clusters of mesophyll cells or vein pieces were still attached to the epidermal strips after stripping, the homogenates showed virus activity. When cowpea leaves were inoculated with Cp-TMV or a common strain of TMV (TMV-U) infective virus material was present in the mesophyll tissue as measured in the homogenates, at the moment of stripping, i.e. within 10 min after inculation.It may be concluded that cowpea mesophyll cells can act as primary sites of viral ingress into the leaf and that the epidermis is not required for necrosis production after virus inoculation.Samenvatting De mogelijkheid werd onderzocht om cowpea-mesofylcellen zonder de aanwezigheid van epidermiscellen met TNV te infecteren. Kleine lokale necrotische lesies werden 40–72 uur na inoculatie zichtbaar waaruit blijkt, dat bij cowpea de epidermis niet noodzakelijk is voor de vorming van TNV-lesies. Geïsoleerd epidermisweefsel vertoonde nooit lokale lesies. Homogenaten van met TNV geïnoculeerde en daarna geïsoleerde cowpea-epidermisstukjes werden getoetst op virusactivitiet. Als de stukjes volledig vrij waren van mesofylcellen of nerfweefsel, dan vond daarin geen virusvermeerdering plaats tijdens een incubatie van 2 of 4 dagen op agar. Als na het strippen nog enkele mesofylcellen of nerfstukjes aanwezig waren, kon wel enige virusactiviteit in de homogenaten worden aangetoond.In cowpeabladeren die geïnoculeerd werden met de cowpea-stam van TMV of de normale stam van TMV had infectieus virusmateriaal al binnen 10 min na inoculatie het mesofyl bereikt. Blijkbaar is in cowpeabladeren de epidermis niet noodzakelijk voor de binnenkomst van virus of voor de necroseproduktie na virusinoculatie.     

Selection of Drug-Tolerant Strains of Pythium sylvaticum Using Sublethal Enrichment

ABSTRACT Sublethal enrichment was used to generate mutants of Pythium sylvaticum tolerant to kanamycin and tetracycline. Kanamycin tolerance was readily generated, and mutants had growth rates similar to wild-type isolates at antibiotic concentrations lethal to wild-type isolates. Based on crosses between wild-type and mutant isolates, two types of inheritance of tolerance were identified. A high level of kanamycin tolerance was inherited in progeny only when the maternal parent was drug tolerant and was correlated with the inheritance of maternal mitochondrial DNA. A lower level of tolerance was observed in some progeny when the paternal parent was tolerant to the antibiotic and, based on the lack of inheritance of paternal mitochondrial DNA, was presumably nuclear-encoded. Selection of mutants tolerant to tetracycline took longer to generate than kanamycin-tolerant mutants. Based on crosses between tolerant and wild-type parents, tolerance to tetracycline was nuclear-encoded. Tolerance to both antibiotics was stable, with cultures retaining tolerance following repeated transfers on nonamended medium and after storage for 7 years.     

烟草品种对烟草花叶病毒病和黄瓜花叶病毒病的抗性鉴定

由烟草普通花叶病毒(TMV)和烟草黄瓜花叶病毒(CMV)引致的烟草病毒病是世界烟草主产区普遍发生且危害严重的侵染性病害,每年给烟叶生产造成了重大的经济损失。本文采用温室苗期接种鉴定的方法,对16份烟草种质进行了TMV和CMV的抗病性鉴定。结果表明:不同的烟草品种对TMV和CMV的抗病性存在较大差异。在供试种质中,对TMV表现免疫的有‘牛耳烟’、‘8301’、‘台烟7号’、‘三生-NN’共4份材料;表现抗病的有‘吉烟5号’、‘双抗70’、‘大护脖香’、‘秦烟95’共4份材料;表现中抗的有‘铁把子’、‘中烟15’、‘秦烟98’、‘中烟98’共4份材料;表现中感的有‘NC89’、‘翠碧1号’、‘云烟97’共3份材料;表现感病的只有‘秦烟97’。对CMV表现中抗的材料有1份,是‘铁把子’;表现中感的有‘秦烟95’、‘三生-NN’、‘8301’、‘牛耳烟’、‘翠碧1号’共5份材料;表现感病的有‘秦烟98’、‘云烟97’、‘中烟98’、‘NC89’、‘大护脖香’、‘双抗70’、‘秦烟97’、‘中烟15’、‘台烟7号’、‘吉烟5号’共10份材料。研究发现,‘铁把子’是兼抗这两种病毒病的材料。本研究明确了我国16个烟草品种资源的抗病性水平,为抗耐病品种的利用与品种合理布局提供科学依据,同时为烟草抗病毒病育种的亲本选择提供抗源信息。     

Effect of 6-azauracil on infection with tobacco mosaic virus

6-Azauracil caused a marked reduction in the number and size of local lesions on excisedNicotiana glutinosa leaves or leaf discs inoculated with tobacco mosaic virus or its nucleic acid. The amount of infectivity recovered from tobacco (N. tabacum White Burley) leaf discs floated on the pyrimidine analogue solution and subsequently ground and assayed 24, 48, 72, and 96 h after inoculation with intact virus was reduced in the 24, 48, and 72 h series but reached the same level as that of the water-treated control discs in the 96 h series.By contrast, the amount of infectivity in stripped epidermal tissue ofN. glutinosa leaves inoculated with nucleic acid was not reduced in strips floated on the analogue for 24, 50, and 70 h as compared with water-floated controls. The analogue had no effect on infectivity of the virus in vitro and did not act as an inhibitor of infection.Part of this paper was presented at the International Symposium on Plant Pathology, held in New Delhi from December 27, 1966 till January 1, 1967. A summary will be published in the symposium volume entitled Plant disease problems.     

电化学酶联免疫分析检测烟草花叶病毒和烟草环斑病毒

以邻苯二胺 (OPD)底物为例 ,用抗原直接包被法 (DAC -ELISA)同线性扫描极谱法 (LSV)相结合 ,检测烟草花叶病毒 (TMV)的提纯液 ,检出限可达 0 2 5ng/ml,TMV粗提液的最高稀释比为 1 :1 0 2 4 0 0 ;检测烟草环斑病毒 (TRSV)提纯液 ,检出限为 1 0ng/ml,粗提液的最高稀释比为 1 :1 0 0 0 0 ,该方法的灵敏度比DAC -ELISA光度法提高了 5倍以上     

三环己基氯化锡对烟草花叶病毒的抑制作用

以心叶烟为试材,采用活体钝化法测定了三环己基氯化锡对烟草花叶病毒(TMV)的抑制作用,并通过电镜、琼脂糖凝胶电泳及紫外光谱法分别测定了三环己基氯化锡对TMV、TMV-RNA及TMV-外壳蛋白(TMV-CP)的体外作用。活体钝化结果显示:500 μ g/mL的三环己基氯化锡对TMV的抑制率达到75.77%±0.11% (P<0.01);三环己基氯化锡与TMV体外作用30 min,电镜下观察,显示病毒粒体出现断裂现象,粒体结构遭到破坏;琼脂糖凝胶电泳显示,三环己基氯化锡对TMV-RNA具有体外降解作用;紫外光谱法测定结果表明,三环己基氯化锡对TMV-CP的体外聚合过程具有抑制作用。     

Genetic aspects of polyacrylic-acid-induced resistance to tobacco mosaic virus and tobacco necrosis virus in Nicotiana plants

Among the Nicotiana tabacum cultivars and hybrids tested, polyacrylic acid (PAA) only induced resistance to tobacco mosaic virus (TMV) and tobacco necrosis virus (TNV) in the cultivars Xanthi-nc (NN) and Xanthi (nn) respectively. This varietal response to the PAA treatment could be sexually transmitted. The complete genetic analysis of the inheritance of the PAA response is reported for the first time, demonstrating that the response is a dominant character with a Mendelian segregation which occurs independently of either the N gene responsible for resistance to TMV or the PRb-protein genes. Possible relationships between the N gene, the gene for the PAA response and the PRb genes are discussed.     

Infection of tomato seed by different strains of tobacco mosaic virus with particular reference to the symptomless mutant MII-16

Eight different strains of TMV were used to inoculate tomato plants when the first truss was in flower. The proportion of the seeds infected by TMV was highest with the enation strain followed by tomato and winter necrosis strains. The other strains, viz. yellow ringspot, yellow mosaic, crusty fruit and tobacco strains and the symptomless mutant MII-16, either resulted in a low proportion of seeds with TMV or none at all. MII-16-inoculated plants consistently gave the lowest proportion of TMV-infected seeds. The possibility of using this strain to produce virus-free seeds is discussed.     

激活蛋白PeaT1诱导烟草对TMV的系统抗性

枯斑三生烟草(Samsun-NN)经激活蛋白PeaT1诱导后接种烟草花叶病毒(Tobacco mosaic virus,TMV),对TMV产生了明显的系统获得抗性,枯斑抑制率达54.15%,枯斑大小也受到一定程度的限制。研究结果表明,PeaT1处理烟草植株下位三片叶不同时间后,其上部叶片中PPO、POD和PAL 3种抗病防御酶活性均比对照提高,第4 d酶活性达到最高值。实时荧光定量PCR检测结果显示,经PeaT1诱导4 d后烟草叶片中抗病相关基因PR1a、PR1b、NPR1在转录表达水平上较未诱导对照都有不同程度的上调。由以上结果我们推测PeaT1诱导烟草产生了系统获得抗性,本研究为进一步阐明PeaT1诱导植物抗病的信号传导途径奠定了基础。     

Does tobacco mosaic virus occur in apple in the Netherlands?

Tobacco mosaic virus was detected twice in herbaceous test plants inoculated with sap from leaves and petals of apple. However owing to the high infectivity of the virus and the low infection rate of the test plants it could not be concluded whether the infection of the test plants was due to contamination or to its actual presence in apple. Using the latex-agglutination test, the virus could not be detected in fruit tree material.Samenvatting Gedurende 1965 en 1966 werd herhaaldelijk tabaksmozaïekvirus (TMV) aangetroffen in kruidachtige toetsplanten die met sap van appel waren geïnoculeerd. Dit feit en gegevens uit latere publikaties van Amerikaanse onderzoekers over het algemeen voor-komen van TMV in appel, peer en kers in de VS en Canada, leidden in 1967 en 1968 tot een meer gericht onderzoek naar het voorkomen van TMV in appels in Nederland. Bij dit onderzoek werd wederom tweemaal een TMV-reactie op de toetsplanten verkregen. Deze resultaten waren echter niet reproduceerbaar en daarom is met dit onderzoek niet bewezen dat het virus in Nederland in appels voorkomt. Gezien de zeer hoge infectiositeit van TMV kan niet uitgesloten geacht worden dat de infectie van de toetsplanten veroorzaakt werd door verontreiniging.Ook op een meer directe wijze, door verschillende sapmonsters van appel serologisch met behulp van de latex-agglutinatietoets te onderzoeken, kon het virus niet worden aangetoond. Bladsap gaf dikwijls een niet-specifieke uitvlokking. Dit hoeft echter nog geen aanwezigheid van TMV uit te sluiten want door toevoeging van gezuiverd virus aan sap, waarin geen spontane uitvlokking optrad, werd toch geen positieve serologische reactie verkregen. Dit was wel het geval met gezuiverd virus zonder saptoevoegingen.