Chlorotic Leaf Spot Virus Research Articles

SPREAD OF VIRUSES IN PEAR ORCHARDS IN SOME REGIONS OF UKRAINE

The diagnostics of pear viruses was carried out in three regions of Ukraine. The infection rates of Аpple chlorotic leaf spot virus, Apple stem pitting virus, Apple stem grooving virus and Apple mosaic virus in pear orchards were determined by means of ELISA. The tests revealed that the general infection level of these four viruses in pear orchards is 18.1%. Initial virus free clones of pear cultivars and rootstocks were selected.

Putative Recombination Events and Evolutionary History of Five Economically Important Viruses of Fruit Trees Based on Coat Protein-Encoding Gene Sequence Analysis

To enhance the knowledge of recombination as an evolutionary process, 267 accessions retrieved from GenBank were investigated, all belonging to five economically important viruses infecting fruit crops (Plum pox, Apple chlorotic leaf spot, Apple mosaic, Prune dwarf, and Prunus necrotic ringspot viruses). Putative recombinational events were detected in the coat protein (CP)-encoding gene using RECCO and RDP version 3.31beta algorithms. Based on RECCO results, all five viruses were shown to contain potential recombination signals in the CP gene. Reconstructed trees with modified topologies were proposed. Furthermore, RECCO performed better than the RDP package in detecting recombination events and exhibiting their evolution rate along the sequences of the five viruses. RDP, however, provided the possible major and minor parents of the recombinants. Thus, the two methods should be considered complementary.

An improved procedure for the purification of apple chlorotic leaf spot virus

A reproducible procedure is described for the purification of apple chlorotic leaf spot virus (CLSV) from Chenopodium quinoa. Two cycles of sucrose density-gradient centrifugation in a magnesium-containing buffer were used. A relatively high yield of virus particles was obtained with little degradation observed. The average yield was 2.3 mg 100 g−1 fresh leaf tissue. The modal lengths of purified virus particles and particles from leaf sap were 692 nm and 704 nm, respectively.Key words: Chenopodium quinoa, sucrose density gradient, magnesium-containing buffer, intact virus

Production and use of monoclonal antibodies for the detection of apple chlorotic leaf spot virus

Stable hybridoma cell lines secreting antibodies specific for the apple chlorotic leaf spot virus (CLSV) were produced by fusing spleen cells of a Biozzi mouse immunized with CLSV P863 strain, with the non-secretory P3 X63 Ag8.653 myeloma cell line. Two hybridoma clones producing monoclonal antibodies of the IgG1 subclass were obtained. These monoclonal antibodies were used for virus detection by enzyme-linked immunosorbent assay (ELISA). In contrast to polyclonal antisera to CLSV, which always contain some antibodies to host components, monoclonal antibodies are highly specific for the virus. It was thus possible to develop a detection assay which is more sensitive and specific than the assays using polyclonal antibodies. Using monoclonal antibodies, it was possible to detect less than 0.1 ng/ml of purified virus. In addition, these two monoclonal antibodies recognize 17 strains or isolates maintained in our laboratory and representing most of the known CLSV strains.

The Particle Length of an Isolate of Apple Chlorotic Leafspot Virus from Prunus domestica

AbstractThe modal length of an isolate of apple chlorotic leafspot virus (CLSV) from Prunus domestica was determined by serologically specific electron microscopy. Particles adsorbed from leaf sap extracts (modal length c. 825 nm) were longer than those adsorbed from purified virus preparations (modal length c. 795 nm). Particles of a CLSV isolate from apple, however, had a modal length of only c. 700 nm.

Immunosorbent Electron Microscopy for Detecting Apple Chlorotic Leaf Spot and Plum Pox Viruses

Plum pox virus (PPV) and apple chlorotic leaf spot virus (CLSV) were detected in extracts of leaves of infected trees by immunosorbent electron microscopy (ISEM). Attachment of virus particles to antiserum-coated electron microscope grids provided a test as sensitive as the enzyme-linked immunosorbent assay (ELISA). Confirmation of the identity of the bound particles was obtained by coating further with homologous antibody followed by sheep antirabbit immunoglobulins which increases the sensitivity and facilitates the interpretation of the test. These results confirm the usefulness of ISEM for detecting several viruses and indicate its potential as a rapid and reliable alternative to ELISA for the detection of PPV and CLSV.

Fruit tree virus infections of ornamental rosaceous trees and shrubs

SummaryPlants from 24 ornamental Rosaceae species were virus tested by double-budding or direct budding into apple, pear, plum and cherry virus indicators and by sap inoculation. Apple chlorotic leafspot virus (CLSV) was detected in some Amelanchier, Chaenomeles, Prunus and Sorbus spp. Symptom expression of some CLSV isolates was changed by passage through certain hosts and some CLSV isolates failed to cross graft unions. Prunus necrotic ringspot virus (PNRSV) was detected in some Rosa cvs and their pollen. Apple mosaic virus, PNRSV and prune dwarf virus were detected in several Prunus spp., and strawberry latent ringspot virus was detected in a symptomless P. lusitanica plant. Sorbus mitchelli grafts induced apple stem pitting virus symptoms in woody indicators.

Hedgerow hawthorn (Crataegus spp.) and blackthorn (Prunus spinosa) as hosts of fruit tree viruses in Britain

SUMMARYApple chlorotic leafspot virus (CLSV) was detected in 27 of 109 hawthorn and three of 67 blackthorn plants sampled in various parts of Britain. The CLSV isolates possessed similar properties to those isolated from other rosaceous species but differed in the severity of symptoms they induced in woody indicators. No seed or aphid transmission of CLSV was detected.Prunus necrotic ringspot (PNRV) and prune dwarf (PDV) viruses were detected in four and three respectively of 67 blackthorn plants. The PNRV and PDV isolates were serologically closely related to isolates from cherry. Arabis mosaic virus was detected in one blackthorn plant, but plum pox virus was not found in any of the tested plants.

The detection of apple chlorotic leafspot virus by a modified procedure of enzyme‐linked immunosorbent assay (ELISA)

SUMMARYThe technique of enzyme‐linked immunosorbent assay (ELISA) was modified to enable detection of apple chlorotic leafspot virus (CLSV) both in herbaceous hosts and in several naturally infected fruiting and ornamental woody host species. Some of the characteristics of the modified method as used with different virus‐host combinations are described.

Back transmission of apple chlorotic leafspot virus (type strain) to apple and production of apple topworking disease symptoms in Maruba Kaido (Malus prunifolia Borkh. var. ringo Asami.

Apple chlorotic leafspot virus (CLSV) type strain isolated from an apple tree was back-transmitted to 8-day-old apple seedlings by rub-inoculation with partially purified and highly purified inoculum. The back-transmitted isolates induced typical apple topworking disease symptoms on a clone of Maruba Kaido (Malus prunifolia Borkh. var. ringo Asami) infected with other latent viruses (including the Maruba CLSV strain) as well as on a virus-free clone. The back-transmitted isolates induced symptoms identical to the parent isolate on a range of CLSV-sensitive indicator plants.

Responses of Scab-resistant Derivatives of Malus Species to Infection with Common Viruses1

Abstract Of 31 preliminary selections from the Geneva scab-resistance apple breeding program inoculated with apple chlorotic leaf spot virus (CLSV), 18 clones exhibited sensitivity during the first 2 growing seasons. Six advanced selections, all derivatives of the virus-sensitive Malus floribunda 821, were inoculated with CLSV or with a combination of other graft-transmissible agents that occur commonly as latent infections in apple. None of the 6 exhibited visible symptoms associated with virus content during 3 growing seasons; growth of 1 selection was slightly depressed. In a 3rd test, 1 of 7 advanced selections derived from M. floribunda exhibited depressed growth in an orchard trial on virus-infected Mailing (M) 9 rootstocks, compared to growth on virus-free M 9.

Pome Fruit Virus Infections of Some Woody Ornamental and Indigenous Species of Rosaceae

SummaryPlants from 46 species of Rosaceae were indexed for apple and pear viruses by double-budding with sensitive indicators. Some plants of Crataegus oxyacantha, Cydonia oblonga, Mespilus germanica and Sorbus tianshanica induced symptoms of apple chlorotic leaf spot virus (CLSV) in apple and pear virus indicators, while Crataegus korolkowii induced symptoms not typical of any known pome fruit virus. A Chaenomeles lagenaria and a Queen Elizabeth rose plant, both showing mosaic symptoms, induced symptoms of apple mosaic virus (ApMV).An apple isolate of CLSV induced a stunt in Sorbus aucuparia seedlings but no obvious symptoms in Crataegus and Mespilus seedlings. ApMV inoculated into Chaenomeles lagenaria seedlings induced mosaic symptoms similar to those found occurring naturally.

Biophysical and biochemical characterization of apple chlorotic leafspot virus

The particles of apple chlorotic leafspot virus (CLSV) banded in isopycnic Cs 2SO 4 gradients at ϱ − 1.27 g/cc and contained 5.2% nucleic acid. A single nucleic acid species of MW 2.3 × 10 6 was isolated from the virus. The molecular weight and structure of CLSV particles are discussed.

Soluble antigens associated with infection with apple chlorotic leaf spot virus

Virus-related soluble antigens, probably various polymeric forms of viral coat protein, were detected in crude extracts from plants infected with apple chlorotic leaf spot virus (CLSV), using highly specific antisera to two CLSV strains from apple and peach, respectively. The two antisera appeared to detect the soluble antigens differently, though with about the same sensitivity. Soluble antigen preparations were clarified by ultracentrifugation of crude sap, by acidification, freezing and thawing, and by ammonium sulfate precipitation. The last treatment allowed some concentration. Detection of soluble antigen in gel diffusion tests provided a specific diagnostic test for CLSV infection in Chenopodium quinoa, but not in apple tissue.

The effect of some epple viruses on the susceptibility of two clonal rootstocks to collar Rot caused byPhytophthora cactorum

SummaryThe incidence of collar rot caused by Phytophthora cactorum was increased in a stoolbed of MM. 104 apple rootstocks when they were infected by some apple viruses.Greater numbers and weights of rootstocks were harvested from the healthy MM. 104 stools and fewer died, than in the virus-infected treatments. A combination of rubbery wood virus, stem pitting virus, epinasty and decline virus, chlorotic leaf spot virus and platycarpa scaly bark virus caused the greatest reduction in growth and were associated with the most severe collar rot infection. The same viruses without rubbery wood reduced productivity less severely and fewer stools died.The growth of MM. 106 was only slightly checked by the same virus treatments, and the stools were not affected by collar rot. Apart from the check to growth no virus-like symptoms were seen on either rootstock.

Comparison of some apple latent viruses

SUMMARYApple latent viruses were eliminated from, the tips of apple shoots by exposure to a temperature of 36 °C for various periods. The length of treatment needed to eliminate a particular virus differed from plant to plant, but viruses were always inactivated in the same order: first chlorotic leaf spot, followed by stem pitting and finally Spy decline. Quince plants developed sooty ring‐spot and bark necrosis when inoculated with buds from some heat‐treated apple clones infected with Spy decline virus. Only chlorotic leaf spot virus was transmitted to herbaceous hosts by sap extracts from apple leaves, petals and fruits, and returned from herbaceous plants to apple. This virus, isolated from either apple or cherry, caused a dark green mottle on peach leaves.