Sugar Beet Yellows Virus Research Articles

Beet luteovirus coat protein sequence variation

SummaryThe sequences of cDNA clones covering the coat protein genes of 29 isolates of beet mild yellowing virus from sugar beet and beet western yellows virus mainly from oilseed rape were compared. The sequences could be partitioned into seven distinct clusters falling into three main groups. Group 1 isolates were found both in oilseed rape and sugar beet mainly from north Europe; group 2 isolates were from hosts other than sugar beet in England and France; group 3 isolates were beet‐specific and found from northern Italy and Iran. The factors affecting this variation and its significance in relation to coat protein‐mediated protection are discussed.

Candidate high spectral resolution infrared indices for crop cover

The sensitivity of near-infrared/red ratio vegetation indices to soil reflectance and plant color result in ambiguous interpretation of plant condition and productivity. Measurements of the reflectance of crop canopies were made at high spectral resolution to investigate candidate vegetation indices, in the near- and middle-infrared (800–2500 nm), for their ability to umambiguously estimate foliage cover independently of the extraneous effects of variations in canopy color and soil background brightness. Reflectances were measured with an IRIS spectroradiometer over plots of sugar beet ( Beta vulgaris L.) sown on different denss and at different densities to produce a wide range in canopy cover. Vegetation color was varied by infecting selected plots with sugar beet yellows virus. Soil brightness was varied by placing trays of peat between the plant rows. Selected narrow-band near- and middle-infrared reflectances were tested for their relationship with canopy cover and their sensitivity to variations in canopy color and soil brightness. The relationship between canopy cover and traditional near-infrared/red ratio indices was f to be sensitive to both canopy color and soil brightness. Most infrared indices were insensitive to the effects of canopy color, but those showing the highest correlations with cover tended to be significantly influenced by soil brightness. The most promising NIR reflectances were those beyond the range (760–900 nm) of near-infrared reflectance detected by current space-borne systems, such as Landsat TM and SPOT HRV.

Effects of the pyrethroid deltamethrin on the acquisition and inoculation of viruses by Myzus persicae

SUMMARYThe pyrethroid, deltamethrin, alone or as an emulsifiable formulation, hindered infection of healthy plants with the persistent beet mild yellowing virus (BMYV) and both acquisition of, and infection with, the non‐persistent potato virus Y (PVY) and the semi‐persistent sugar beet yellows virus (BYV) by Myzus persicae in glasshouse tests.Another pyrethroid, RU‐15525, also protected against infection with PVY. Even sub‐lethal amounts of deltamethrin decreased virus transmission by rapidly incapacitating the aphids, the effect being least with aphids most resistant to organophosphorous insecticides and to certain pyrethroids including deltamethrin. Demeton‐S‐methyl hindered infection only with BMYV. This work shows that deltamethrin restricts transmission of persistent, semi‐persistent and perhaps more importantly of non‐persistent viruses in the glasshouse, and has potential for doing the same in the field.

Observations of Linked Plant Virus Particles

SUMMARY Two types of plant virus particles, sugar beet yellows virus and pea early-browning virus, show nucleocapsids joined by cross bridges when viewed in the electron microscope. Sugar beet yellows virus particles preferentially aggregate in pairs which are joined by up to ten cross bridges originating from a morphologically different end of the virus particle. The long virus particles of pea early-browning infections were found to possess crystalline aggregates in the plant cytoplasm and many of the virus particles were linked by cross bridges extending the whole length of the virus particle.

Biochemical and serological comparisons between carnation yellow fleck virus and sugar beet yellows virus protein subunits

Carnation yellow fleck virus is serologically related to sugar beet yellow virus. Amino acid analyses and tryptic peptide maps indicate about 50 amino acid differences between the proteins from the two viruses.

Purification and partial characterization of sugar beet yellows virus

A technique was devised for obtaining purified infectious preparations of sugar beet yellows virus (SBYV) particles. As the use of mechanical blending resulted in shearing of particles, infected leaves were hand ground in a mortar; the extracts were clarified with bentonite, concentrated using polyethylene glycol, and further purified by rate zonal and isopycnic gradient centrifugation. The purified particles had a modal length of 1270 nm, sedimented at 110 S, had an unusual ultraviolet absorption spectrum and contained about 5% RNA. The molecular weight of the infectious RNA, estimated by sedimentation and by gel electrophoresis was about 4.3 × 10 6; that of the coat protein subunit was about 23,500. These properties are discussed in relation to the structure of the virus particles and also are compared with the properties of viruses allied to SBYV.

The changes in the titre of the sugar beet yellows virus in sugar beet leaves in the course of the vegetation period

Using the quantitative serological method of double diffusion in agar, the amount of sugar beet yellows virus in the leaves of sugar beet was investigated and the possibility of an accurate serological analysis was examined at certain time periods in the course of vegetation. In sugar beets infected artificially at the beginning of the vegetation period the increase of the titre has a fluctuating course at first. In August, after the intensive growth of plants is over, the virus content maintains on a relatively high degree, increasing further toward the end of vegetation. For a reliable virus analysis the sap can be diluted approximately in the ratio 1/128. The table presented enables one to determine the probable accuracy of the serological analysis at the individual time periods during the vegetation of sugar beet.

Differentiation of strains of sugar beet yellows virus onTetragonia expansa Murr. and other indicator plants

Five different isolates of beet yellows virus were maintained without any changes in their properties onTetragonia expansa Murr. syn.T. tetragonoides Pall. for a long period of time. According to their characteristics and different properties especially in a diploid inbred line of sugar beet the isolates are considered to be strains of BYV and are classified into three groups: group of mild strains (the mild masked and mild strains), normal strains (the common strain) and necrotic strains (the severe necrotic and necrotic strains). The necrotic strains of BYV were relatively easily transmissible manually to sugar beet plants and other indicator species. The common strain can be transmitted to sugar beet,Chenopodium quinoa Willd. but not toC. capitatum L. Asch. Mild strains are transmissible with difficulty andC. quinoa is the only species which develops a larger number of local lesions after inoculation. In contrast to the mild masked and common strains it is manually transmissible toC. capitatum. The mild masked strain can not be transmitted to sugar beet.Nicotiana quadrivalvis Pursh. is not susceptible to mechanical inoculation with BYV. Aphid transmission withMyzus persicae (Sulz.) was positive in experiments with necrotic strains only. Mechanical transmission of BYV was successful also toC. foliosum (Moench) Asch.,C. murale L. andClaytonia perfoliata Donn. The last two species were susceptible to inoculation by aphids as well. Attempts to transmit the virus manually toT. expansa Murr. andC. giganteum Donn. failed.

Electron microscopical proof of the presence of sugar beet yellows virus particles in the roots of sugar beet

The presence of beet yellows virus (BYV) particles was electron microscopically proved in the roots of sugar beet. Specimens for the electron microscopical examination of root sap were prepared by differential centrifugation. It was proved that, contrary to expectations, examinations in spring showed most virus particles in the basal part of the root. At the same time it was found by experiment that the diagnostical BYV antiserum, for which the antigen was prepared from sugar beet leaves, did not react with a purificate of BYV containing virus particles.

Relation of beet yellows virus to the phloem and to movement in the sieve tube.

In minor veins of leaves of Beta vulgaris L. (sugar beet) yellows virus particles were found both in parenchyma cells and in mature sieve elements. In parenchyma cells the particles were usually confined to the cytoplasm, that is, they were absent from the vacuoles. In the sieve elements, which at maturity have no vacuoles, the particles were scattered throughout the cell. In dense aggregations the particles tended to assume an orderly arrangement in both parenchyma cells and sieve elements. Most of the sieve elements containing virus particles had mitochondria, plastids, endoplasmic reticulum, and plasma membrane normal for mature sieve elements. Some sieve elements, however, showed evidence of degeneration. Virus particles were present also in the pores of the sieve plates, the plasmodesmata connecting the sieve elements with parenchyma cells, and the plasmodesmata between parenchyma cells. The distribution of the virus particles in the phloem of Beta is compatible with the concept that plant viruses move through the phloem in the sieve tubes and that this movement is a passive transport by mass flow. The observations also indicate that the beet yellows virus moves from cell to cell and in the sieve tube in the form of complete particles, and that this movement may occur through sieve-plate pores in the sieve tube and through plasmodesmata elsewhere.

Spread of Yellows Virus by Myzus persicae in Sugar Beet Crops

WINGLESS Myzus persicae were reared on sugar beet plants (provided by Dr. G. E. Russell, Plant Breeding Institute, Cambridge) infected with sugar beet yellows virus (SBYV), sugar beet mild yellows virus (SBMYV)1, or both viruses. Eight widely separated plants in a 7¼-acre field of sugar beet each received three adult and six young aphids from these cultures on May 31, 1962, and nearby plants were examined for aphids and virus symptoms at weekly intervals thereafter.

Do aphids carry transmissible sugar beet yellows virus via their stylets?—Evidence from ultraviolet irradiation

To celebrate the sixtieth anniversary of Virology a survey is made of the plant viruses, virologists and their institutions, and tools and technology described in the first decade of plant virus publications in Virology. This was a period when plant viruses increasingly became tools of discovery as epistemic objects and plant virology became a discipline discrete from plant pathology and other life sciences.

Effect of keeping viruliferous aphids on plants or glass on their transmission of sugar beet yellows virus

A rapid and simple protocol for preparing viral RNA from aphids (Myzus persicae) and potato (Solanum tuberosum L.) tissue (leaves, sprouts, and tubers) for reverse transcription–polymerase chain reaction (RT–PCR) was developed. The four-step method involves: (1) preparing plant crude sap or aphid macerates in a buffered detergent (Triton XL-80N) solution; (2) immobilizing clarified sap on a nitrocellulose membrane; (3) performing reverse transcription using eluted water extract from cut-out spot from membrane; and (4) amplifying cDNA through PCR. The entire procedure from tissue grinding to RT–PCR can be completed within 6 h. The protocol was applied successfully for the detection of individual potato viruses: carlavirus Potato virus S (PVS), potexvirus Potato virus X (PVX), potyvirus Potato virus Y (PVY), and polerovirus Potato leafroll virus (PLRV). PLRV was also detected from individual viruliferous aphids or composites of viruliferous and healthy aphids. PVY and PLRV were detected from extracts immobilized on nitrocellulose membranes, stored for more than 65–273 days at room temperature (25 °C). The protocol was companed with the ‘long protocols’ involving enzyme and phenol extraction for aphids or sodium sulfite and phenol extraction for tubers. The simplified protocol was found comparable in sensitivity to these long procedures, and is especially suitable for those regions where specialized PCR laboratories are only available in centralized locations. Viral RNA immobilized membranes can be mailed out for detection by RT–PCR to these centralized laboratories from remote areas of the country.

Effect of treating stylets of aphids with formalin on the transmission of sugar beet yellows virus

Formalin treatment of exposed stylets of anesthetized Myzus persicae (Sulzer) apterae or nymphs, which had fed on Swiss chard plants infected with sugar beet yellows virus, resulted in a depression in virus transmission; but it also depressed frequency and depth of stylet penetration during the first few hours of inoculation access time to test plants. Because of the treatment-feeding interaction, it was not possible to determine whether or not this semipersistent aphid-borne virus is stylet-borne or internally translocated prior to transmission.

Influence of Caging and Transferring Techniques on Aphid Mortality and Virus Transmission

Various methods of caging and transferring aphids used in the investigation of plant virus transmission were compared as to their effect on transmission efficiency and vector mortality. The methods of caging compared had no significantly measurable effect on the ability of the green peach aphid, Myzus persicae (Sulz.), to transmit sugar beet yellow-net virus. Darkening leaf cages by wrapping with aluminum foil did not reduce aphid mortality, nor did it increase sugar beet yellows virus transmission. None of the four methods used to transfer insects seemed to increase mortality, Survival of test aphids was found to be differentially affected by the host plant species used in the feeding sequences. Plants used were sugar beet, Beta vulgaris L., and smooth leaf mustard, Brassica juncea (Coss.).

Een geval van noodrijpheid bij blauwmaanzaad

Premature dying of seed poppies, of unknown cause, was observed in The Netherlands, in 1959, at the end of the vegetative growth period. In a spraying experiment with systox the untreated plants died prematurely and showed a 50% decrease in yield based mainly on the weight of harvested seed. This disorder may be due to sugar beet yellows virus or to aphid damage alone. One spray before flowering reduced the disease and increased the yield. The fungusPyrenophora calvescens (Fr.) Sacc., which also is supposed to cause a premature ripeness of seed poppies, was present to the same degree in both the untreated and the sprayed plots.

SUGAR BEET YELLOWS: A PRELIMINARY STUDY OF THE DISTRIBUTION AND INTERRELATIONSHIPS OF VIRUSES AND VIRUS STRAINS FOUND IN EAST ANGLIA, 1955‐57

Aphid transmissions to sugar beet seedlings from yellowed sugar beet leaves collected from commercial fields in East Anglia during the summers of 1955, 1956 and 1957, showed the occurrence of two yellowing viruses. One was sugar beet yellows virus (SBYV) and produced vein‐etch and yellowing symptoms on beet seedlings in the glasshouse; the other produced yellowing but no etch. These two viruses were apparently unrelated, so that sugar beet tolerant to one of them would not necessarily be tolerant to the other. The second virus, called ‘sugar beet mild yellowing virus’ (SBMYV), decreased the root yield of sugar beet plants grown under glass, by as much as did the milder SBYV strains, but less than did the severe SBYV strains. The proportions of the two viruses in the samples differed from year to year and from place to place.

Über die Korrelation zwischen Partikellänge und Infektiosität beim Vergilbungsvirus der Rüben

Crude leaf sap of plants suffering from sugar beet yellows was partially purified by density gradient centrifugation in the cold at different values of pʜ (6,2-9,0). After standing over night at 2° C the material was dialysed against buffer of pʜ 6,8 at room temperature. - As estimated by electron microscopy the most frequent length of the threadlike particles (Fig. 2) which were believed to be the infectious agent of sugar beet yellows shows a gradual shift from longer to shorter ones with rising pʜ (Fig. 1 a-e). The infectivity of the suspensions depends upon the pʜ of the preparation too. From the distribution curve of the particle lengths the relative concentrations of particles with different given minimal lengths were estimated. The dependence from the pʜ of the preparation of these relative concentrations was compared with that of the infectivity. Best agreement was observed with particles of 12 700 - 12 800 A minimal length (Fig. 3). This length seems to be identical with the “normal length” of the particles found in exsudates (12 400 -12 500 A). From these results it was concluded that a) particles which possess the normal length as found in exsudates are the infective entities of this disease, b) shorter particles are non-infectious, c) the infectious entities of the sugar beet yellows virus are of the threadlike type. There is no evidence that spherical particles are necessary for starting an infection with the sugar beet yellows virus.

Effects of Changing Temperature on Plant Virus Diseases

Publisher Summary This chapter summarizes various observations that have been made on the ways in which changing temperature affects the interactions between viruses and their host plants. The chapter emphasizes the need for controlling temperature to obtain consistent results. It is reported that the effects of heat and darkness in increasing susceptibility to infection are additive; plants kept in the dark at 36° reach their maximal susceptibility much sooner than similar plants kept in the dark at 20° and sooner than at 36° in the light. It is demonstrated that the severity of symptoms caused by sugar beet yellows virus in sugar beet by altering the temperature. Physalis floridana plants infected with potato leaf roll Virus lose their symptoms after 20 days at 35°, and the symptoms return in 6 days when the infected plants are returned to 24°. Temperature also greatly influences the movement of the virus in the plant, and sampling the entire plant can often give quite different results from sampling only the inoculated leaves.

Zentrifugation fadenförmiger Partikel in einem Dichtegradienten: Die Abtrennung des Vergilbungsvirus der Rüben aus Blatthomogenisaten

Density gradient centrifugation in sucrose solutions has been proved useful in experiments to separate the sugar beet yellows virus from normal constituents of leaf homogenates. After dialysis at pH 6,8 in a combined veronal-phosphate-buffer following centrifugation the virus has lost practically nothing of its serological activity and only little of its infectivity. Density gradient centrifugation as a mean to prevent compact sediments is supposed to be especially useful in all attempts to isolate threadlike particles.