摘要:

AbstractVariations in pH, cell ultrastructure, conductivity, calcium ion molarity, reducing sugars, uronic acids and in protein of the intercellular washing fluid were studied at 0, 12, 24 and 48 h in tobacco leaf halves intercellularly injected with a bacterial pr‐LPS complex (250 μg‐ml−1). These injections induced a localized cellular reaction (LCR) in points opposite to intercellular structured deposits on the plant cell walls. The intercellular fluid pH was higher at 24 h than in the control, but not at 12 and 48 h. The conductivity, the calcium ion molarity, the free and hydrolyzed sugar content were higher at 12, 24 and 48 h than in the control tissue; the uronic acid content was higher at 24 and 48 h, but not at 12 h. There was a peak for, all 5 parameters at around 24 h, when LCR showed its highest activity. The protein content was significantly higher at 24 and 48 h than in the control intercellular fluid.The increase in conductivity, calcium ions, sugar, uronic acids and proteins in the intercellular fluids of the pr‐LPS injected tissue were interpreted as direct or indirect effects of the LCR, i.e. as an exocytosis induced by pr‐LPS injections. The associated high sugar and uronic acid content of the intercellular fluid at 12 and 24 h was not correlated to its capacity to prevent the hypersensitive confluent necrosis when injected intercellularly into toba

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04445.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA mosaic disease of Johnsongrass characterized by the presence of short and long chlorotic stripes in leaves and stunting of plants was found in two locations about 300 km apart in the Fars Province of Iran. The disease occurred in patches or along the irrigation ditches. The disease agent could not be transmitted mechanically or by certain insects and mites. About 0.5% of the seedlings, grown in soil from the root zone of diseased plants, developed the disease after 1–8 months. Electron microscopy, of leaf‐dip preparations showed presence of isometric viruslike particles (VLPs) of about 35 nm diameter in unusually high concentrations in diseased plants but not in healthy plants. VLPs from diseased leaves were purified by low‐pH clarification followed by differential and densitygradient centrifugation. Purified VLP preparations showed UV absorption spectrum typical of nucleoproteins. A260/A280 was 1.48. High titered antisera obtained by injecting rabbits with purified VLPs reacted with sap from diseased plants but not healthy plants. Purified VLP preparations and sap from diseased plants did not react with antisera to Bermuda grass etched line,Brachypodium sylvaticum, brome mosaic, maize chlorotic dwarf, maize rayado fino, maize white line mosaic and tobacco necrosis vi

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04446.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractAntigen‐antibody reactions in agar gel, as demonstrated by the double diffusion technique, between cotton seed globulins and the antisera specific to each of the testedFusarium oxysporumf. sp.vasinfectumisolates as well as the antiserum ofF. moniliformerevealed that all the tested antisera ofF. oxysporumf. sp.vasinfectumreacted with seed globulins except the Menoufi cultivar globulins. No precipitin lines were detected in the reaction between the antigenof the cotton cultivar Acala SJ2 versus the antiserum of P10 isolate. The 5 cultivars behaved differently with each fungal antiserum to the extent that they could be distinguished accordingly. When the seed globulins of the susceptible cultivars (Giza 74, and Bahtim 110) reacted with antiserum of the testedF. oxysporumf. sp.vasinfectumisolates, more precipitin lines were formed than the resistant cultivars. On the other hand, no obvious reaction was detected in case ofF. moniliformeantiseru

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04447.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractRubigan (a systemic fungicide) inhibited the growth ofRhizoctonia solani in vitrowhen used at concentrations of 6, 12 and 24 μg/ml respectively. Application of Rubigan as a soil drench significantly reduced the damping‐off incidence on cowpea (Vigna sinensis) plants.Symptoms of growth retardation appearing on cowpea plants treated with Rubigan could be mimiced using an ethylene releasing compound (Ethrel). Ethrel at 10 and 20 μl/ml added to the soil around the seeds induced severe dwarfing as evidenced from measurements of plant length, dry weight and leaf area. Gas chromatographic analysis revealed that ethylene was released either from Rubigan mixed or not with the soil. Rates of ethylene production from soils drenched with Rubigan were relatively inferiorto those produced by authentic Rubigan solutions not added to the soil. Moreover, in all cases ethylene was released at rates proportional to the Rubigan concentrations applied.Factors involved in growth retardation of Rubigan‐treated cowpea plants were discussed in the light of the possible interaction between ethylene and endogenous gibberellin l

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04448.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractIsometric virus‐like particles (VLPs) have been purified from cucumber leaf tissue. Three dsRNA segments with estimated molecular weights of 1.8, 1.1 and 1.0 × 106d have been isolated from VLPs occurring in CsCl density gradient fractions but were also readily detected in preparations from as little as 1 g of fresh leaf tissue. The VLPs resemble dsRNA containing cryptic viruses and have been namedCucumis sativuscryptic virus (CsC

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04449.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA virus isolated fromAnagyris foetidaand infecting species in the Leguminosae and Solanaceae had typical properties of a tymovirus. It sedimented as two components (49 S and 103 S) and induced the formation of double membrane‐bounded invaginations in the chloroplasts of infected cells. Large numbers of ‘empty shells’ were found in the nuclei. The coat protein had a molecular weight of c. 20.000 and the RNA consisted of c. 5500 nucleotides. Crystallization of the virus in laminal crystals could be achieved by precipitation with 10 % polyethylenglycol 6000 and 1 % NaCl. Serologically, the virus was closely related toScrophulariamottle,Ononisyellow mosaic andPlantagomottle viruses. The four viruses which all infect leguminous hosts are separated by serological differentiation indices which are mostly between 1 and 3. It is therefore suggested that they all should be considered as strains of the same virus which for reasons of priority should have the nameScrophulariamottle virus (ScrMV). The proposedAnagyrisstrain clearly differs from theScrophulariamottle,Ononisyellow mosaic andPlantagomottle strains of ScrMV in host range, symptomatology, electrophoretic mobility serological properties and some cytopathogenic effects. It is not clear why theAnagyrisstrain infectsA. foetidasystemically in nature, but only locally under greenhouse condi

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04450.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractEffect of leaf position on the susceptibility of melon plants to artificial infection with powdery mildew,Sphaerotheca fuligineaThe leaf position of melon plants seems to play a role on their susceptibility when they are artificially infected with powdery mildewSphaerotheca fuliginea.The cotyledons are generally very susceptible, while the first leaf relatively resistant; the susceptibility again continues up to the 4th–5th leaf (but less susceptible than the cotyledons) and then after it decreases; these results can be obtained on plants in greenhouse or on detached leaves in Petri dishes.From this observation, we think that the screening of melon genotypes for resistance to powdery mildew can be evaluated neither on the cotyledons which are very susceptible nor on the first leaf which is resistant, but on the third leaf which is moderately susceptible. In fact, there is a good correlation between the reaction of the third leaf and the resistance or susceptibility of genotype

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04451.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractLocalized infections produced by tobacco necrosis virus (TNV) or tomato mosaic virus (ToMV) in White Burley tobacco induced a systemic acquired resistance in upper, uninoculated leaves. This resistance was effective against challenge infection by TNV or ToMV but not by potato virus Y, necrotic strain (PVYn), tobacco mosaic virus (TMV) or tobacco rattle virus (TRV), viruses giving systemic infections.Systemic acquired resistance against TNV or ToMV was expressed as a reduction in lesion size but not in viral antigen content of the resulting necrotic local lesions. The acquisition of resistance was concurrent with an increased capacity of the resistant leaves to convert 1‐aminocyclopropane‐1‐carboxylic acid into ethylene.Systemic acquired resistance was ineffective to contrast or minimize in whatever way the systemic challenge infection produced by PVYN, TMV or TRV. Severity of symptoms and virus multiplication did not differ in resistant leaves from controls. This result does not allow any optimistic promise on possible application of the systemic acquired resistance against severe viral diseases of

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04452.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractTotal cellular fatty acids for 20 strains ofErwinia amylovoragrown on trypticase soy agar (TSA) for 3 days at 27°C, and for 3 strains grown on nutrient agar (NA), King's B (KB), glucoseyeast extract carbonate (GYCA) and TSA for 1, 3 and 6 days were analyzed by gas‐liquid chromatography. Forty one percent of total fatty acids were saturated even‐carbon straight chains, 6 % were saturated odd‐carbon chains, 34 % unsaturated acids, 6 % hydroxy‐substituted acids, 1 % branched chains, 7 % cyclic acids, and 4 % unidentified components. Composition was affected by growth medium, physiological age of cells, and chromatograph sensitivity. On TSA and NA saturated odd‐carbon and cyclic acids of the 3 strains (combining 1, 3 and 6‐day data) were higher than on KB and GYCA. Cyclic acids increased with physiological age on GYCA and KB medium. Even‐carbon straight chain and unsaturated fatty acids (major components) constituted a significantly lower percentage of total fatty acids in chromatograms of high sensitivity (30–50 components) than of low instrument sensitivity (1

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04453.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractHypersensitive browning, host cell death and phytoalexins (rishitin) synthesis in both callus cultures and cotyledons have been observed in a susceptible tomato cultivar following treatment with high molecular weight cell wall components fromPhytophthora infestansrace 1B. The growth of the pathogen was restricted on both elicited differentiated and undifferentiated tomato tissues. Subtance(s) released by germinating sporangia, but not by the mycelium, suppressed the hypersensitive reaction.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04454.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY