摘要:

AbstractThe fungusEutypa latawas isolated from diseased walnut trees (Juglans regia) exhibiting small cankers. The morphological characteristics of the culture and the pathogenicity were compared with those of known isolates of the fungus from other hosts. Inoculation tests with walnut isolates on grape, walnut, almond and apricot yielded characteristic cankers. Furthermore, pathogenicity tests on walnut with isolates from other different hosts resulted in differences in virulence. Similar differences in virulence were observed between 13 single ascospore isolates of the fungus ex apricot inoculated on walnut.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01008.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractDetection of plant viruses by ELISA using horseradish peroxidase for antibody labelling (ELISA‐peroxidase) has been standardized by evaluating variants of the procedure, regarding composition and concentration of buffers and additives. Immunoglobulins (IgG) are isolated from antisera by precipitation with ammonium‐sulphate and by purification with DEAE‐52 (Whatman) cellulose. IgG are conjugated with horseradish peroxidase by a modified oxidation‐periodate method.In ELISA‐peroxidase 0.05 M carbonate‐bicarbonate coating buffer pH 9.6 has been substituted by 0.01 M carbonate buffer pH 9.2. Extraction buffer is used with 0.5% bovine serum albumin (BSA), without polyvinylpyrrolidone (PVP). Samples are diluted in, phosphate buffered saline (PBS) pH 7.2 with 0.05% Tween 20 and 0.5% BSA. IgG are conjugated with horseradish peroxidase, diluted in 0.1 M Tris‐HCl, pH 7.4 with 0.05% Tween 20 and 1% BSA. The substrate is incubated in the darkness for 20 min at room temperature. ELISA‐peroxidase proved to be equivalent in sensitivity and specificity with ELISA using alkaline phosphatase for antibody labelling. Its advantage is a lower cost of chemicals u

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01009.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractPhytophthora citrophthorawas inhibited to a greater extent thanP. nicotianacvar.parasiticaby chloramphenicol, hymexazol, PCNB and pimaricin at concentrations used in selective media for the isolation ofPhytophthoraspp. Reduced concentrations of the antimicrobial components of the selective media to tolerant levels forP. citrophthoramarkedly increased the recovery of the two brown rot pathogens from soil.Mycelium of bothPhytophthoraspp. survived in air‐dried soil for at least 5 months while mycelium of mostPhytophthoraspp. do not survive in dry soil. In moist soil,P. nicotianaevar.parasiticaproduced hyphal swellings, sporangia and chlamydospores.P. citrophthoraproduced hyphal swellings and sporangia, but no chlamydospores. No oospores were produced, even in pairing cultures on agar plates with isolates obtained from several locations of citrus groves andfruits by both species. Sporania were obtained in both species in citrus groves on mycelium mats, in the rhizosphere, in infected leaves and fruits buried at soil depths of 5–35 cm. Numbers of propagules declined during the incubation period, but conside, rable numbers survived throughout the experimental period (6 months). AlthoughP. nicotianaevar.parasiticaproduced chlamydospores whileP. citrophthoradid not, numbers of surviving propagules recovered from soil after 6 months were comparable with both species. The brown rot pathogens survived in soil both as colonizers of detached leaves and fruits and as parasites in living root tiss

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01010.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractGenomic RNA of plum pox virus (PPV) was used as a template for the synthesis of complementary DNA (cDNA). The generated cDNA molecules were subsequently cloned into pBR 322. A physical map covering 9700 bases of the PPV genome was constructed from 8, clones by hybridization and restriction endonuclease digestion. Clone pPPV‐NAT 309, starting at the 3′‐end, with an 866 bp insert was used in Northern‐ and Dot‐hybridizations for the detection of single‐stranded viral RNA in total nucleic acid as well as in sap preparations of PPV infectedNicotiana clevelandii.The nucleotide sequence of this clone was determined, the amino acid sequence of the coat protein C‐terminal part was deduced and compared with four other coat proteins o

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01011.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe development of infection structures by the directly infecting soybean rust fungus of different artificial membranes was followed by light and scanning electron microscopy. On water agar uredospores developed germ tubes without appressoria. On dialysis membranes more than 80% of the uredospores formed appressoria. With low frequencies (1–7%) also primary hyphae and/or penetration hyphae were present. When cellulose nitrate membrane filters with pore diameters ≤ 0.2 μm were used, uredospores germinated but showed a strongly reduced appressoria formation. Membranes with pores ≥ 0.1 μm allowed a development of infection structures similar to that on dialysis membranes. In experiments with paraffin oil incorporated into collodion membranes more than 90% of the uredospores formed appressoria, about 50% of the appressoria developed hyphae. Ungerminated spores and germ tubes always contained 2 nuclei. In fully developed appressoria 4 nuclei were present. Compared with stomata entering rust fungi appressoria formation byPhakopsora pachyrhizioccurred more frequently and seemed to be less dependent on specific stimuli. Moreover, in most cases only few of the appressoria formed penetration or primary hyphae. The induction of these structures seemed to be dependent on further unknown

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01012.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractPseudomonas fluorescensandErwinia herbicolawere isolated from Italian ryegrass surviving to infection byXanthomonas campestrispv.graminis.They reduced symptom expression and mortality of young ryegrass plants when inoculated simultaneously with or prior to the parasite. Protection from wilt was a quantitative effect, depending on the ratio pathogenic/non‐pathogenic bacteria: it was good with 1/99, less with 10/90 and moderate to low with 50/50.The effect of preinoculation by leaf‐clipping with scissors contaminated byP. fluorescensorE. herbicolacould be detected at least seven days after clipping and at a distance of 2 cm below the clipping level. Preinoculation of roots, or stem bases did not protect the plants from leaf infection by the paras

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01013.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractVarious chromogenic bacteria were isolated from the mowing site in natural and sown meadows and in pastures. Their ability to protect young ryegrass plants from wilt by simultaneous inoculation withXanthomonas campestrispv.graminiswas tested under low concentrations of the parasite inoculum. From about 200 isolates tested 35% had a very high protective effect, 45% a moderate one, and only 20% had no significant effect. Mixtures of different species of phylloplane bacteria usually gave very good protection. Most of these bacteria live between the leaf‐sheaths.In vitroantagonism of the phylloplane bacteria was not related to their protective effect. Avirulent mutant strains ofX. c.pv.graminisand pathovars, of other grass species, e.g. pv.poae, pv.phlei, and pv.arrhenatheri, have the same protecting effect. Heat killed bacteria were no longer effective.These observations suggest an unspecific reaction of the plant, such as the induction of a general defense mechanism which results in resistance also to the parasit

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01014.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA partial purification procedure is described for a flexuous filamentous virus from leaves of the ornamental crop tuberose (Polianthes tuberosaL.) exhibiting mottle symptoms. Particular problems associated with the purification included particle aggregation and the highly viscous nature of the plant sap. The former difficulty was partially alleviated by the addition of 1.0 M urea to the extraction buffer and the latter by treatment of the extract with cellulase. The mean virus particle length from negatively stained leaf dips was 742 nm (SD = 54) which is characteristic of viruses belonging to the potyvirus group. In addition, electron microscopy of thin sections of infected leaf tissue demonstrated the presence of several types of inclusion bodies similar in appearance to inclusions previously described in association with potyvirus infections in other plants.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01015.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractImmatureCapsicum annuumfruits treated at wound‐sites with glucans from the hyphal walls ofGlomerella cingulataand incubated for 24 h or longer accumulated levels of capsicannol phytoalexins sufficient to inhibit rot development byBotrytis cinerea.Elicitor application to intact fruits induced the accumulation of relatively low levels of capsicannol compounds but further phytoalexin accumulation in fruits after wound‐inoculation withB. cinereawas much more rapid than in untreated fruits and rot development was suppressed.Capsicannol phytoalexins were produced in the live cells of the epidermis and little or no necrosis was associated with quantities produced in intact tissues. Elicitor treatment of intact fruits to protect against rot development byB. cinereawas achieved without the fruits sustaining unsightly dam

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01016.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe levels ofB. cinereaconidia in the air of greenhouses with pepper or eggplant crops at El Morche (Málaga, Spain) were studied during the 1981–82 and 1982–83 growing seasons.The number of conidia collected, the temperatures and relative humidities recorded during different periods were analyzed and fitted to different regression models. Several types of transformation were made to straighten the curves.In both seasons, the regression analyses of the pepper crop data showed no statistical significance, but those for eggplant crops did. The levels of significance for the eggplants were good and those of the 1981–82 experiment were the best.During the 24 h period prior the conidia collection, there was a negative correlation between temperatures measured 6 and 8 h prior to conidia sampling and the number of conidia collected. When the 2nd pair of variables was used,B. cinereaconidia collections were less the longer the periods of temperatures between 20 and 30°C with relative humidities above 70%.This type of information would facilitate a more rational physical and chemical control of the disease in greenhouse vegetable crops to prevent or reduce crop

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01017.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY