摘要:

AbstractIn vitroinvestigations and microscopic studies about the development ofPhoma chrysanthemicolaHollos f. sp.chrysanthemicola, the causal pathogen of a collar and root rot of chrysanthemumsDifferent media were tested for cultivation ofPhoma chrysanthemicola.The pathogen grew best on PDA and carrot‐Agar at a temperature of 25°C. The three strains used showed many variations, concerning the structure and colour of the mycelium. Fructification has been promoted by irradiation (ultra‐violer ray). The morphogenesis, especially the formation of pycnidia, conidia and sclerotial structures has been examined with help of the scanning electrone microscope (SEM), results are presented., So far unknown organs probably belonging to the fungus were observed, their identity is still not c

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00923.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe productionin vitroof cutin hydrolyzing enzymes by five isolates ofB. cinereawas studied, using cutin of tomato fruits as a carbon source. Chemical depolymerisation of the cutin yielded 10,16‐dihydroxyhexadecanoic acid as the main component. The same fatty acid was found after incubation of cutin with a crude enzyme preparation from a culture filtrate ofB. cinerea.Hydrolysis was optimal at pH 5.5–6.0. In cultures with glucose as the only carbon source no cutinase activity was detected. Crude enzyme preparations which hydrolyzed cutin, also hydrolyzed para‐nitrophenylbutyrate, with an optimum activity at pH 8. All five isolates showed para‐nitrophenylbutyrate hydrolyzing activity when grown on tomato cutin, but the activity varied with the isolate used. No correlation was found between para‐nitrophenylbutyrate‐hydrolyzing activity of an isolate and its production of small lesions on young to

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00924.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractSeveral yellow pigmented, rod‐shaped bacterial strains with antagonistic activity againstE. amylovorahad been isolated from blighted ornamental shrubs. Criteria of the mode of action have been investigated underin‐vitroconditions and in inoculation experiments. In contrast to the noninhibitory isolates of the same host origin the active forms obviously produce a substantial principle. This is active only under acid conditions, it is heat‐stabile, it can be dialyzed and is solublein water and methanol. It is not a phenolic compound.In disease control experiments using culture filtrates of the antagonistic bacterial isolates fireblight could be reduced to a limited extend following shoot tip inoculation ofCotoneaster bullatusunder controlled conditions. Compared to application of the living antagonists in the control experiments disease reduction, however, was considerably less expr

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00925.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractUntrastructural interactions betweenVenturia inaequalisand callus cultures from scab susceptible and resistant apple varieties, were similar. Host cell wall changes, appositions, and invagination of host plasmamembrane at sites of close contact with fungal hyphae were regularly observed. The ultrastructural observations are described and discussed. The host cell alterations as well as many fungal structures corresponded to those known in young leaves of susceptible apple varieties.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00926.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractInfection of lower leaves of tomato plants withPhytophthora infestansfollowed by a period unfavourable to disease development increased the general resistance of the plants against the pathogen. Induced resistance to a second infection of upper leaves was expressed in the development of necrotic lesions that were sharply defined and reduced in size. Sporulation of the pathogen was suppressed. Lesions on unprotected plants expanded with a sporulating zone passing gradually to the healthy tissue under the same conditions. Induced resistance delayed and reduced penetration of the pathogen into the epidermis and subsequent colonisation of the mesophyll by formation of papillae in epidermal cells and hypersensitive‐like reactions of penetrated, mesophyll cell

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00927.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractPossible participation of the peroxidation system in the cultivar‐race specificity was studied for the oat‐crown rust system. The levels of lipid peroxidation and total lipoxygenase (LOX) activity were extensively increased in leaves of cv. Shokan l responding with resistance to race 226. One anionic and one cationic LOX isozyme was detected in the extract of Shokan 1 leaves inoculated with race 226. In addition, three anionic and one cationic isozymes were consistently found in the extract of uninoculated and compatible race 203‐inoculated leaves. The blockage experiments with race 226‐inoculated leaves using RNA and protein synthesis inhibitors indicated that the two LOX isozymes characteristic of the incompatible combination arede novosynthesized and their activity is causally linked to the resistance expression. Production of the two isozymes was also demonstrated in the five resistantPcoat lines, but not in the two susceptible

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00928.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe antimycotic activity of saponin A fromStyraxand of its debenzoylated derivative, Saponin B, was studied on a number of plant pathogens and onTrichoderma viride.Saponin A demonstrated activity againstTrichoderma viride, Fusarium oxysporum, Aspargillus nigerandRhizopus mucco.At the concentration tested, Saponin B had low activity only onTrichoderma viride‐ a result discussed in terms of mechanism of actio

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00929.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractResistance of different cultivated and wild tomato plants (Lycopersiconspp.) toBotrytis cinereaPers.20 provenances of different cultivated and wild tomato plants (Lycopersiconspp.) were screened for resistance toBotrytis cinereaPers. using anin vitro‐leaf necrosis test.TheBotrytisresistance decreased with increasing age of the leaves corresponding to their insertion height (relative youth resistance respectively senescence susceptibility).The 6B. cinerea‐isolates used for inoculation differed significantly in virulence. With increasing inoculum age a virulence reduction of the variousB. cinerea‐isolates occurred. Within the investigated test plant collection 2 wild species –L. columbianumandL. hirsutum– proved to be resistant in each stage of development to allB. cinerea‐isolates and additionally showed field

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00930.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe fungusEutypa lata(syn.E. armeniacae), known as the causal agent of the death of many different woody plants, was found on dead branches of pistachio (Pistacia veraL.) in Greece. Isolations from diseased branches yielded consistently typical colonies of the asexual stage of the fungus (Libertella blepharis, syn.Cytosporinasp.), which proved to be undistinguishable from other cultures of the pathogen obtained from 15 different hosts. Furthermore, all isolates from pistachio tested for pathogenicity on apricot were pathogenic and yielded characteristic cankers.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00931.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractPlants of the mildew susceptible barley cultivar Peruvian and the adult plant resistant cultivar Osiris were inoculated withErysiphe graminisf. sp.hordeiat the first and fifth leaf stages. Samples taken at 32 hr after inoculation were examined by electron microscopy to compare papillae associated either with penetration failure or with successful penetration of the fungus into the epidermal cell and haustorium formation. Four types of papillae with ultrastructural differences could, be classified. Although their definite association with fungal ingress or failure is not possible, our data suggest that papillae with larger, more compacted and amorphous or globular structures may be more effective as penetration barriers than others, with more or less uniform distribution of irregular, smaller electrondense structures.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1986.tb00932.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY