摘要:

AbstractEuphorbia mosaic virus was purified from infected plants ofNicotiana benthamiana.Highest concentrations of virus particles were found in infected plant tissue between 10–12 days after inoculation. The enzyme driselase assisted in purification of the virus particles from the infected tissue yielding about 600 μg/kg of plant material. Purified preparations showed a maximum absorption at 260–263 nm and the ratio of absorption at 260 and 280 nm was 1.4. The viral nucleic acid was digestedby DNase I and S1Nuclease but not RNase A. A single coat protein with a MW of 32,000 d and two DNA bands with a MW 0.96 × 106d (2870 nucleotides) and 0.90 × 106d (2700 nucleotides) were associated with the purified virus particles. Virus specific DNA was isolated from infected tissue between 7 and 15 days after inocul

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00877.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractOf the two antifungal antibiotics produced byBacillus subtilisF‐29‐3, the dipeptide compound bacilysin inhibits yeasts (and bacteria), whereas the formerly unknown fengymycin, a complex of closely related lipopeptide components, shows antibiotic activity against filamentous fungi.Bacilysin production, formerly known for a few strains only, could be demonstrated for all 12 wild‐type cultures ofBacillus subtilistested during this study. The antibiotic also occurs in some strains of three otherBacillusspecies considered as closely realted toB. subtilis.Members of the lipopeptide class of antifungalBacillusmetabolites were formed by 8 of 12Bacillus subtilis‐isolates and several otherBacillusstrains.The antibiotics of F‐29‐3 were compared with antifungal metabolites of otherBacillusisolates using TLC, agar‐diffusion techniques and tests demonstrating the capacity of six lipopeptide and peptide preparations to protect rice seedlings from phytomycosis due toRhizoctonia solani.Fengymycin proved to be different from the other compounds tested. It was less toxic to the test plants and protected them better fromRhizoctoniadisease than the other antibiotics of

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00878.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractAfter infection with spores of a virulent strain ofAscochyta rabieithe chickpea (Cicer arietinum) cultivars ILC 1929 (susceptible) and ILC 3279 (resistant) were compared with regard to pterocarpan phytoalexin and isoflavone accumulation. Quantitative HPLC analyses of total extracts of aerial parts were used to measure the induced formation of the phytoalexins medicarpin and maackiain and the accumulation of the constitutive isoflavones biochanin A and formononetin together with their, 7‐0‐glucosides and their 7‐0‐glucoside‐6″‐0‐malonates. The two cultivars showed no significant difference in the level of isoflavones and isoflavone conjugates. On the other hand, the resistant cultivar ILC 3279 rapidly accumulated large amounts of both, phytoalexins (20–26 nmole g−1fr.w.) whereas cultivar ILC 1929 only produced very small amounts (5 nmole g−1fr.w.) of medicarpin. The data are discussed with regard to isoflavonoid metabolism and the significance of induced and constitutive levels of phytoalexins and isoflavones in resistance of chic

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00879.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractQuantitative powdery mildew resistance in compatible host‐pathogen‐combinations was measured by the number of pastules/cm2leaf area. Spring barley cultivar ‘Proctor’ was significantly less infected than ‘Golden Promise”. Using these two cultivars (having no effective major resistance gene) as controls, MO‐ and AR‐resistant cultivars were inoculated with virulent mildew isolates. ‘Mona”, ‘Grit’ and ‘Nudinka’ had a higher or, at least, the same level of quantitative resistance as ‘Proctor”. None of the remaining cultivars showed the high susceptibility expressed by ‘Golden Promise”. Ranking of host genotypes was nearly constant while that of mildew isolates varied considerably. Only a small portion of the observed variance was due to interaction between host cultivars and pathogen isolates.‘Triesdorfer Diva’ gave a resistant infection type after inoculation with different AR‐virulent isolates, indicating that this cultivar has major resistance

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00880.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractComplementary deoxyribonucleic acids (cDNAs) to the four ribonucleic acid (RNA) species of isolate YU2 of beet necrotic yellow vein virus (BNYVV) were prepared by reverse transcription. The duplexes of these cDNAs were incorporated in the plasmid pBR322 and cloned into E. coli strain 5K. The insert sizes of the cDNA clones ranged from 280 to 2100 base pairs. In Southern blot hybridizations not all cDNAs specific for a particular RNA of BNYVV cross‐reacted. This suggests that they are complementaryto different regions of the respective RNA. In dot blot hybridization experiments sixteen out of eighteen cDNA clones detected all thirteen BNYVV isolates which were obtained from sugar beets originating from Yugoslavia, Italy, Switzerland, France and various regions in Germany and which were maintained inChenopodium quinoa.Two cDNA clones specific for RNA‐3 failed to detect one German isolate. Pronounced differences between the thirteen virus isolates were seen when the electrophoretic migration of their RNAs was compared in Northern blot hybridizations. RNA‐1 and RNA‐2 of all isolates had the same sizes of 7100 and 5200 bases, respectively. The size, number and relative concentration of the smaller RNAs, however, varied greatly with different, i

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00881.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractFluorescence and electron microscopical studies show that the detection of structures associated with theAbutilonMosaic Virus disease is dependent on the sampling daytime. Moreover the infectivity of plant sap may vary during the day. The results emphasize the importance to consider the daytime as an essential parameter in experimental design in virological research.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00882.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractInvestigations on the susceptibility of head lettuce (Lactuca sativa) to downy mildew (Bremia lactucae) III. Activities of peroxidase, catalase and polyphenoloxidaseHost cell walls in contact with intercellular hyphae ofBremia lactucaestain electron positively in susceptible and incompletely resistant varieties of lettuce after appropriate electron microscopy preparation for peroxidase activity. The outer membranes of the mitochondria of the parasite also stained darkly in susceptible varieties whereas in incompletely resistant plants Bremia innermost mitochondrial membranes and host cell mitochondria were darkly stained. This latter observation suggests increased respiration and could be explained as a resistance reaction. Catalase activity was observed in the microbodies of susceptible, in incompletely resistant and healthy varieties. There were no differences in stain intensity in the three kinds of varieties suggesting that catalase activity is not involved in resistance reactions.Polyphenoloxidase activity was infrequently observed on the host cell wall in susceptible and healthy plants, whereas strong activity in incompletely resistant varieties was observed in vesicles in the haustorial sheath. These vesicles werenotsurrounded by unit membranes and therefore could not have originated from the unit membranes of the extrahaustorial matrix or from the host plasmalemma. They may have been derived from the host protoplast and involved in inactivation of parasite produced toxins thereby contributing to resistance.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00883.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractOn the occurrence ofPhoma nigrificans(P. Karst.) comb. nov. (teleomorphDidymella macropodiiPetrak) on winterrape (Brassica napusL. var.oleiferaMetzger)With a screening for resistence of winterrape toPhoma lingam(teleomorphLeptosphaeria maculans), in various places in North Germany, another species ofPhomawas repeatedly isolated from plants with blackleg symptoms. ThisPhomaspecies could easily be distinguished fromP. lingamby its larger conidia and its lower optimal temperature. Comparative study with isolates in thePhoma‐collection of the “Plantenziektenkundige Dienst” (Wageningen) showed that it, represents the anamorph ofDidymella macropodii, an Eurasian Ascomycete occurring on different wild crucifers and originally described fromMacropodium nivalein Siberia. ThePhoma‐anamorph of this fungus was first described in Finl, and fromArmoracia rusticanaasSphaeronaema nigrificans.This binomial is now transferred toPhoma(“sectionSclerophomella”). Inoculation of rape seedlings withPhoma nigrificans(Didymella macropodii) resulted, in dark discolorations and constrictions of the hypocotyls of th

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00884.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe study of the agent associated with the mild type ofHydrangea virescencein France involved three steps, with the aid of transmission electron microscope (TEM). In the first step, we observed the presence of polymorphic procaryotes in thephloem sieve tubes of diseased plants and their absence from corresponding healthy plant parts. The procaryotes were detected in the areas suspected in 1000 nm thick sections stained with thionin‐acridine orange. In the next step, the ultrastructure of their unit membrane was studied at magnifications higher than 100 000. The two osmiophilic layers of the membrane were 6 nm distant and no preliminary parietal shape was detected. These observations on ultrathin (60 nm) sections allowed us to classify the, particles into the class “Mollicutes”. The third step involving the examination of 350–1000 nm thick sections revealed the absence of spiral forms.The TEM observations are consistent with the hypothesis that the agents associated with the mild type ofHydrangeavirescence observed in France should be included within the MLO group. A method specially adjusted to the fixation of MLO inside sieve tubes has been me

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00885.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractStructure‐activity relationships of the phytotoxins stemphyloxin I and II fromStemphylium botryosumf. sp.lycopersiciwere investigated by quantitative comparison of their biological activity with chemically related phytotoxins fromPhoma betae, betaenones A, B and C. Phytotoxicity was estimated by inhibition of incorporation of14C‐leucine into proteins of exponentially growing tomato cells. The values of 50 % inhibition for stemphyloxin I and II and for betaenones A, B and C were 0.075, 16, 55, 350 and 1 μM respectively. The β‐ketoaldehyde moiety appeared to be essential in, conferring biological activity and its toxicity was influenced by its spatial orientation. The presence of an hydroxyl group in stemphyloxin I and II enhanced activity in comparison with the respective compounds betaenones C and A which lack thi

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00886.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY