摘要:

AbstractChanges in the soluble protein pattern of leaves of eight lines of barley, carrying different resistance genes to mildew, were analysed by SDS‐polyacrylamide gel electrophoresis and isoelectric focusing. Apparently new host proteins were induced byErysiphe graminisf. sp.hordeiin the incompatible reaction which were not present in the immune or susceptible response. These proteins are of low molecular weight, 13,500–27,500 d, and have either very low or very high isoelectric points. Thus, they resemble the pathogenesis‐related proteins found in many dicotyledonous sp

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04467.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractAn isolate ofNeocosmospora vasinfectavar.africana(F‐2) was assayed for its antagonistic activity against 15 soil‐borne fungi; 14 of them were important plant pathogens. The fungus exhibited a strong antibiotic effect against most of the fungi under test. WhilePythium debaryanum, Macrophomina phaseolina, Phytophthora capsici, Sclerotinia sclerotiorum, Cochliobolus sativusandAlternaria alternatashowed a very high degree of sensitivity as evidenced by the respectivezones of inhibition caused by the antagonist,Phoma betae, Rhizoctonia solaniandVerticillium dahliaeproved to be the most resistant. A mutual antibiosis existed betweenN. vasinfectavar.africanaand five of the test fungi.The culture filtrate of the antagonist, diluted ten times with PDA, suppressed the mycelial growth ofP. debaryanumandP. capsicicompletely. Whereas in this testR. solaniproved to be the least sensitive, the remaining test fungi showed some differences in their susceptibility, but in any case their growth was inhibited significantly as compared to the contr

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04468.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractSalicylate watered onto soil in which White Burley tobacco plants were grown represents a reversible stress characterized by stomatal closure, slight slackening of plant growth and low chlorophyll loss. Salicylate affected viral pathogenesis in opposite ways. It had no effect against local and systemic infections by potato virus X (PVX), potato virus Y0(PVY0) or tobacco mosaic virus (TMV), whereas it completely prevented systemic infection by alfalfa mosaic virus (AIMV) or tobacco, rattle virus (TRV) in a high proportion of treated plants. When infection moved from leaves inoculated with AIMV or TRV, the tendency to limit systemic spread was shown by the restriction of systemic infection to very limited areas erratically distributed in some uninoculated leaves.The salicylate‐induced restriction of AIMV or TRV infectivity to inoculated leaves did not appear due to inhibition of virus multiplication because the inoculation of potentially resistant leaves of salicylate‐reated plants resulted in virus antigen accumulation comparable to that of untreated controls. Salicylate may therefore inhibit some long distance virus transport function.Salicylate appears able to evoke true hypersensitivity only against systemic viruses able to induce local necrotic lesions, probably by activating some genetic information for resistance that is normally not expres

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04469.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractCellulase and β‐D‐glucosidase activity have been identified inVenturia inaequalis, the causal agent of apple scab. Most of the activity of the enzymes was associated with the mycelium after homogenization. The activities were relatively weakin vitrocompared to those of other plant pathogens. With a new screening technique, β‐D‐glucosidase hyperproducing mutants were

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04470.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractAs indicated by reduced cellulolysis,Zygorrhynchus moellerisuppressed mycelial growth inRhizoctonia solaniandSclerotinia sclerotiorum.Sclerotium production by both pathogenic fungi was also reduced byZ. moelleriin dual sand‐oatmeal cultures. The viability of sclerotia produced byS. sclerotiorum, but not those produced byR. solani, was greatly reduced. Sclerotium production byS. sclerotiorumon celery and tomato segments was reduced to a much greater extent whenZ. moelleriwas applied to the plant tissue 24 h before the pathogen than when applied at the same time or 24 h after the pathoge

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04471.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe interaction betweenPratylenchus coffeaeandPythium aphanidermatumand/orRhizoctonia solanion chrysanthemum and the influence of farmyard manure (FYM) on it was studied under pot conditions. The disease caused byP. aphanidermatumorR. solaniwas significantly high at varying inoculum levels ofPratylenchus coffeae.The severiy further increased when nematode infected plants were inoculated with both the fungi together. Organic manuring also influenced the disease severity which was greatest in soils containing 200% organic manure.The nematode population significantly increased in presence ofR. solani, decreased in presence ofP. aphanidermatumand remained unaffected when both the fungi occurred together around the plants. The nematode population was greatly reduced in soils containing 200% organic manure.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04472.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe seed‐borne inoculum ofP. manshuricais described using various microscopic techniques and staining reactions. The inoculum, in addition to the oospores, consists of a thin walled mycelium under the hourglass cell layer of the seed coat and a thick walled resting mycelium in the oospore crust on the seed surface. By a modified Feulgen staining technique it was possible to demonstrate that the thin walled and the thick walled resting mycelium as well as thin and thick walled oogonia contain nuclei which are Feulgen positive suggesting that portions of the mycelium ofP. manshuricamay survive even on the surface of dry, mature seed

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04473.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractOospores ofPeronospora manshurica, the causal agent of soybean downy mildew, were stained by a variety of techniques. TTC (tetrazolium chloride) and NBT (nitroblue tetrazolium chloride) primarily stained oospores which were cytologically abnormal and appeared degenerating. Cytological normal oospores were not stained by these compounds presumably because the dyes were excluded from the oospore cytoplasm by the oospore wall or the plasmalemma. Strong autofluorescence of dead/degenerating oospores in the FDA test (fluorescein diacetate) made scoring of the oospore viability by this technique unreliable. Phloxine B was found in a consistent way to stain the degenerating oospores and a small proportion of the oospores which by light microscopic, observations could not be scored cytologically abnormal. Control experiments with live and dead cells of yeast (Saccharomyces cerevisiae) confirm that phloxine B is excluded from live cells and dead cells become stained. The presumed mode of action is that the semipermeability of the plasma membrane of live cells excludes the stain. The phloxine B test described here appears a promising technique for the determination of oospore viability ofP. manshurica.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04474.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe inheritance of hypersensitive resistance toLeptosphaeria maculansin a cross betweenB. oleraceavar.alboglabraandB. insulariswas studied. Analyses of F1and F2progeny suggested that resistance is determined by two dominant, independently‐segregating genes. F1hybrids were semifertile but normal levels of fertility were restored in a proportion of the F2progen

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04475.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractMost uredospores of rust fungi develop infection structures in a typical pattern so that they can infect the host plant. The function of these infection structures is divided into the following three phases:1In the recognition phase, the germ tube recognizes the cuticle and the stoma. This process may occur independently from the host plant since copies of the cuticle induce similar reactions of the fungus. During fungal growth on the epidermis, unspecific stress responses of the plant are triggered.2In the signal phase, the fungal substomatal vesicle and infection hypha(e) contact the host cells within the leaf parenchyma. A signal from the host induces further development of the fungus. Haustorium mother cell differentiation is effected and haustorium formation is initiated. At the same time, the fungus suppresses the synthesis of stress metabolites by the plant.3In the parasitic phase, the fungus penetrates the host cell and complex interactions between host and parasite begin. A highly specialized interface around the haustorium develops presumably in order to allow a more efficient nutrient transfer from host to parasite. Eventual defence reactions of the plant, generally on the race‐cultivar level, fail to be evoked or are suppressed in compatible combination

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb04476.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY