摘要:

AbstractFour winter wheat cultivars with different levels of resistance toSeptoria nodorumwere investigated at four locations during two vegetation periods. Forty plants per cultivar and site were collected at random at seven defined growth stages from crop emergence to harvest. Samples from roots, culms, leaves, glumes and kernels were examined for the occurrence of endophytic fungi after surface sterilization. 83% of the 26944 isolates sporulated and were assigned to 213 species. The most frequent were:Septoria nodorum(20.1%),Alternaria tenuissima(9.8%),Epicoccum purpurascens(9.1%),Idriella bolleyi(6.9%),Fusarium graminearum(5.3%),Fusarium culmorum(4.0%),Cladosporium oxysporum(3.7%),Didymella exitialis(3.1%),Fusarium nivale(2.8%) andRhizoctonia solani(2.1%). Each species occurred preferentially in one or more plant organs. A factorial analysis of variance showed that plant organ, sampling site, vegetation, period and cultivar in decreasing order of importance influenced the quantitative and qualitative composition of the fungal populations. No relationship between endophytic fungi was found to be constantly antagonistic or mutualistic.Septoria nodorumwas isolated mainly from culms. The number ofS. nodorumisolates differed significantly between cultivars in culms and glumes but not in flag leaves. The results are discussed in relation to resistance breeding and the effect endophytic fungi, might have on yield.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01021.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractFollowing inoculation of pods of several cultivars of French bean (Red Kidney Selections W 243, 244, 245), withColletotrichum lindemuthianum(Sacc.&Magn.) Bri. and Cav. ANZ races 1 and 2, phaseollin, phaseollidin and 6‐α‐hydroxyphaseollin were estimated in infection‐droplets and tissue extracts by u.v. spectrophotometry and HPLC. The examples represented both compatible and incompatible cultivar‐race interactions and confirmed a positive correlation between degree of incompatibility andphaseollin concentration or content. The data supported the concept that a phytoalexin index may be of value in selecting for disease resistance or studying the quantitative inheritance of phaseollin in studies of anthracnose resistance in French beans.Concentrations of phaseollidin and 6‐α‐hydroxyphaseollin were low and were not correlated with degree of compatibility of cultivar‐race interactions. The evidence did not support the putative role of 6‐α‐hydroxyphaseollin as anin plantadegra, dative phaseollin metabolite associated with French bean –C. lindemuthianumc

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01022.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractConidiation inBotrytis fabaewas stimulated by irradiating 1 to 3 day old, but not 4 to 5 day old mycelium. Three cycles of 12 h irradiation + 12 h darkness stimulated the production of about twice as many spores compared with only 12 h irradiation. At 18°C all the spores had been produced within 3 days but not within 2 days from the start of irradiation. Near‐u.v. irradiation at wavelengths of 375–400 nm induced most sporulation. Red light at 600–650 nm also stimulated conidiation but irradiation at other wavelengths from 300 to 700 nm was ineffective. Fewer conidia were produced when the fungus was kept in darkness at 4°C between periods of irradiaton at 18°C compared with continuous 18°C. The optimum osmotic potential of the culture, medium for conidiation was about‐27 bar although more mycelium grew at even lower osmotic potentials. Abundant spore production occurred when the fungus was grown in media with a wide range o

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01023.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractAfter inoculation of petiole stumps of tomato plants with a tomato isolate ofB. cinerea, a transition zone between water‐soaked and apparently healthy tissue became clearly visible. Hyphal colonization occurred up to approximately 2 mm beyond this zone. In the colonized tissue the pH values were lower than in the healthy tissue. In the region with most of the tips of the advancing hyphae, however, pH values were slightly, but consistently, higher. In the colonized tissue concentrations of oxalic, citric and succinic acid were higher than in the tissue of healthy, non‐inoculated petioles.In vitrothis isolate ofB. cinereaproduced citric, malic and succinic acid. Oxalic acid, however, could not be detected. In media enriched, with citric or malic acid, mycelial production was higher than in media without this enrichm

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01024.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractIncidence of African cassava mosaic (ACMD), cassava bacterial blight (CBB), and cassava anthracnose (CA) on local susceptible cassava cultivars planted in December, February, and April was investigated. December cassava planting had a higher incidence of ACMD, CBB, and CA diseases compared with February and April plantings. CA seemed to be more prevalent at an older stage (8 months old) of plant growth. April planting had significantly lower incidence of major cassava diseases, and higher mean tuber, yield than the same cassava cultivars planted earlier. The length of exposure of cassava plants to the inocula and/or to the vector during the rainy season determines the occurrence of diseases. In the absence of resistant cassava cultivars and through, partial disease escape of susceptible cultivars from ACMD, CBB, and CA, planting the same cultivars in April can still produce a profitable cassava crop.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01025.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractPrior inoculation of wounded tomato petioles with a minimum concentration of 5 × 104cells per wound of variousPseudomonas syringaepathovars completely protected plants against subsequent infection withCorynebacterium michiganensepv.michiganenseinoculated on the same site. Only living cells induced effective protection. In protected tissue, cells ofCorynebacterium michiganensepv.michiganenseremained localized at the inoculation site and their multiplication was restricted. Irrespective of the cell number introduced, initial population decreased slowly and then levelled off below the initial inoculum level. This level remained constant throughout the experimental period (15 days). Similarly, the, cell number of the inducerPseudomonas syringaepv.phaseolicolalevelled off at ca. 106cells per plant. The protection was not systemic and could be eliminated by removing the upper 5 mm of the inoculated wound tissues containing, the inducer

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01026.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe hypothesis of superoxide anion generation as a direct bactericidal mechanism exercised by hypersensitive tobacco leaf tissue against an incompatible phytopathogenic pseudomonad was tested.The detection of O2−was made directly by reducing Cytochrome c and by producing nitrite from hydroxylamine chloride and indirectly by measuring the death of endophytic bacteria in the presence of superoxide dismutase.At 4 h and 6 h the low net specific reduction of Cytochrome c in the hypersensitive tissue was not confirmed by the specific production of nitrite. At the same time active superoxide dismutase did not give significant protection to the incompatible bacteria as compared to inactive superoxide dismutase. The protection provided by active superoxide dismutase as compared with the controls (bovine serum albumine treated tissue and non‐treated tissue) at 4 h and at 6 h was not correlated to its superoxide anion scavenger activity.The results indicated that the death of the incompatible pseudomonad during the hypersensitive reaction was not directly linked to O2−gener

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01027.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractTwo potyvirus isolates from the eggplant (Solanum melongenaL.) cultivars ‘Ex Benin’ and ‘Ex Jos’, respectively, in Nigeria proved to be almost identical in host range, symptomatology and reactivity with antisera to various potyviruses. In eggplant they caused a severe systemic mottle, blistering and malformation of leaves and an abnormal serration of the leaf margins. A potyvirus isolate from tomato showing mosaic symptoms was similar, but not identical to the eggplant isolates. In the slide, precipitin test the serological differentiation indices were between 1 and 3 for the eggplant and tomato isolates. In the immunoelectron microscopical decoration test all three virus isolates showed some reactivity with antisera to the following potyvir, uses: dioscorea green banding mosaic, groundnut eyespot, a mungbean isolate of peanut stripe, pepper veinal mottle, telfairia mosaic and a tomato isolate from Taiwan. No reactions were observed with antisera to other potyviruses. Cytopathogenic effects w,ere similar for all three isolates in the arrangement of virus particles, the structure of the cylindrical inclusions and the occurrence of clusters of small vesicles. However, other cytological alterations like accumulations of rod‐shaped aggregates of,granular material, formation of giant mitochondria, degeneration of mitochondria and occurrence of a nucleolar inclusion differentiated the

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01028.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractApple mosaic virus and raspberry bushy dwarf virus were detected by ELISA in plantlets of red raspberry still growingin vitro.The plantlets were derived from explants which were excised from plants infected by either of the viruses mentioned. Detection by ELISA of prune dwarf virus in 4‐month‐oldin vitrocultures of sour cherry was reported earlier. Thus, application of ELISA to tissue cultured plantsin vitroseems to be an appropriate method for early detection of virus‐infected plant cul

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01029.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Book Reviewed in this article:Henseler, K., Der Pflanzendoktor für den Hausgarten, Krankheiten und Schädlinge an Obst, Gemüse und Zierpflanz

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1988.tb01030.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY