摘要:

SummaryPopulations of cereal aphids were sampled from 1985–1988 and assayed for transmission of barley yellow dwarf virus (BYDV),Rhopalosiphum padi, Rho‐palosiphum maidis, Sitobion avenae, Metopolophium dirhodum, Schizaphis graminumandMacrosiphum euphorbiaecollected from host plants transmitted BYDV in bioassays. Of the 1028Diuraphis noxiacollected from plants, one may have transmitted BYDV. The isolate involved resembled SGV in serological and biological characteristics, but since it was not recoverable by any of more than 800D. noxiasubsequently tested, we suspect it may have been a contaminant.Among those aphids collected during the autumn from a suction trap adapted for live collection,R. paditransmitted BYDV most frequently. Other trapped species which transmitted BYDV included:R. maidis, Rhopalosiphum insertum, Macrosiphum euphorbiae, Metopolophium dirhodumandCeruraphis eriophori.An adapted Infectivity Index indicated thatR. padiis by far the most important vector of BYDV during the autumn sowing season in southwestern Idaho. MaleR. padiconsistently transmitted BYDV more frequently than did females collected during the same per

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03991.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryPlants with symptoms of barley yellow dwarf virus (BYDV) obtained in infection feeding assays of aphids collected in the field in Idaho between 1986 and 1988 were tested for virus transmissibility by possible aphid vectors. Isolates obtained during 1987–1988 were also tested with a range of polyclonal antisera which distinguished PAV, MAV, SGV, RPV and RMV serotypes. In 1989 some Idaho (ID) BYDV isolates, maintained as standards for comparison, were serotyped and tested for aphid transmissibility, using 11 species of aphids.There was not always the expected correspondence between serotype and vector specificity for ID isolates. For isolates obtained from field‐collectedRhopalosiphum padi, vector transmissibility and serotype corresponded with previous reports; however, 44% of isolates which were serotyped as RMV were also transmissible by species other thanRhopalosiphum maidis.Similarly, the transmissibility of the ID laboratory standards did not always conform to the reported vector specificity of serotypes. The laboratory ID‐MAV culture was transmitted byMetopolophium dirhodumandMyzus persicaeas well as bySitobion avenae.The laboratory ID‐SGV culture was transmitted byR. padiand 5.avenaeas well as bySchizaphis graminum.The ID‐RPV culture was transmitted byS. graminumandRhopalosiphum insertumas well asR. padi.Both of two laboratory ID‐RMV cultures were transmissible byR. insertumandR. paditransmitted one of them. The results indicate that, for isolates collected in Idaho, vector specificity cannot be assumed from thei

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03992.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryArtichoke yellow ringspot nepovirus (AYRV) was isolated from stunted broad bean plants in Crete showing leaf mottling and deformation and wrinkling of seed testas. AYRV identification was based on host range, behaviour during purification, electron microscopy and serology.AYRV‐broad bean isolate was seed‐transmitted in broad bean, and embryo infection appeared to be a prerequisite for virus transmission to seedlings. Transmission through pollen was not detected in broad bean plants, although pollen grains were externally contaminated by the virus. Ovule infection occurred in a high proportion of seed and was independent of pollinat

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03993.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryFour monoclonal antibodies (MCA) were obtained to the ‘Ahlum’ serotype of beet soil‐borne virus (BSBV). On ELISA plates which had been precoated with polyclonal antibodies (PCA) all four MCA detected this serotype with a higher sensitivity than alkaline phosphatase‐labelled PCA. Three of the MCA were specific for the ‘Ahlum’ serotype, but a fourth one also detected the distantly related ‘Wierthe’ serotype. Cross‐reactions with wheat soil‐borne or oat golden stripe furoviruses were not observed. One of the MCA reacted with an epitope which is exposed along the entire length of the BSBV particles, whereas two others were specific for epitopes which are exposed on one particle extremity only. Although these latter two epitopes occur apparently on the same extremity of the particles, they seem to be different, because one is found only on the particles of the ‘Ahlum’ serotype, whereas the other one is present also on the particles of the ‘Wierthe’ serotype. The fourth MCA is specific for a cryptotope which is not exposed on the intact virus particles, but presumably on some degradation product or precursor of the viral coat protein present in crude sap preparations. All four epitopes are SDS‐labile; they are not detected on denatured viral

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03994.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryLight and electron microscopy was used to study the ultrastructural effects of June Yellows (JY) in leaves of strawberry. Four cultivars of strawberry, affected to different extents by JY, were compared with healthy (JY‐free) cv. Cambridge Favourite and with strawberry infected with strawberry crinkle rhabdovirus,Fragaria vescainfected with strawberry mottle virus (SMotV), raspberry and black currant showing virus‐induced yellowing and with strawberry and raspberry showing chaemeric yellow sectors in the leaves. Except for isometric virus‐like particles detected in SMotV‐infectedF. vesca, no virus‐like particles or structures of other pathogenic agents were found in any of the tissues examined. Leaf cells of JY‐affected strawberry showed severe disruption of chloroplasts and plasmalemma, whorls of membranous vesicles and decreased vacuole size. The extent and severity of these abnormalities increased with increased severity of JY symptoms but, even in leaves with mild JY symptoms, chloroplast abnormalities were obvious. In the most severely affected leaves, the cells lacked discrete vacuoles and extensive hypertrophy was seen in other organelles such as nuclei and mitochondria. Few, if any, ultrastructural abnormalities were observed in virus‐infected strawberry orF. vesca, or in chaemeric leaves of strawberry and raspberry. By contrast, in raspberry and black currant with yellowed leaves caused by virus infection, the cells showed enlarged chloroplasts, decreased vacuole size and vesicle formation. However, chloroplast enlargement and disruption in this material seemed due to increased size of starch grains which were largely absent from swollen chloroplasts of JY‐affected strawberry. The ultrastructural abnormalities observed in JY‐affected strawberry are, therefore, not inconsistent with the possibility that a pathogenic agent may be involved

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03995.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryThe susceptible potato cultivar Désirée and the resistant cv. Diamant were cultivated on untreated and nematicide‐treated plots on two fields in northern Spain infested withGlobodera rostochiensisRol. Initial and final infestations of cysts and viable eggs were assessed. Multiplication rates differentiated more accurately the effects of the different treatments than final number of cysts and eggs, due to the elimination of some of the errors associated with variability of the initial infestation. Many new cysts were observed on all plots where susceptible potatoes had been grown, whether they had been treated with nematicide or not, although significantly fewer cysts were actually found on the nematicide‐treated plots. With the resistant cultivar no significant effects of the nematicide were detected even though there was a noticeable reduction of viable cyst contents over and above the effect of the resistant cul

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03996.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummarySeven trials conducted over four years on sites naturally infested with the white potato cyst nematode established that potato clones bred for resistance toGlobodera pallidaallowed significantly less nematode multiplication than conventional cultivars under field conditions. Nematode multiplication was inversely related to initial infestation level. The nematicide, aldicarb, significantly reduced nematode multiplication. However, nematode multiplication on nematicide treated susceptible cultivars was greater than on untreated partially resistant clones, indicating that resistance may offer more effective control ofG. pallidathan chemical treatment. Integration of host plant resistance and nematicide treatment is discussed.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03997.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryThirty three species and varieties ofNarcissusplus seventeen cultivars with recent species parentage were screened for resistance toFusarium oxysporumf.sp.narcissi.Accessions were either wholly resistant (bulbs remaining uninfected), partially resistant (a variable portion of the bulbs infected) or susceptible (all of the bulbs infected). Although a pattern of resistance was found among the species tested the genetic basis of the resistance is not known.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03998.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummarySomatic chromosome doubling of potato dihaploids was achieved by culturing callus from leaf pieces derived from glasshouse andin vitrogrown plants. The glasshouse‐grown leaves produced better callus on average but there was no significant difference between the average number of plantlets per callus regenerated from the two types of material.Mixtures of 2x and 4x plants were obtained from callus culture and the proportions of each ploidy type varied with the dihaploid genotype. Leaflet length/breadth ratios were chiefly determined but ploidy but there was variation within ploidy groups. There were also differences in blight and cyst nematode resistance between tetraploids derived from the same dihaploi

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03999.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryFive Chaite and three main season ricesOryza sativagenotypes were examined to assess the effect of low temperature on the germination and growth of roots and shoots, root regeneration capacity, the extent of chlorophyll synthesis of etiolated seedlings, total chlorophyll content and photo‐chemical efficiency (Fv/Fm) of chilled plants. Cultivated differences in the ability to germinate and grow at low temperatures have been found. The poor ability of Chaite rices to tolerate photo‐oxidative tissue damage during January and February seemed to be the major factor resulting in poor seedling gro

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb04000.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY