摘要:

AbstractThe protective effect of homologues of host‐specific AF‐toxin I fromAlternaria alternatastrawberry pathotype on susceptible strawberry cells was quantitatively examined by using the cultured cells. Among three AF‐toxin molecules, AF‐toxin II did not exhibit toxicity to strawberry cells, although AF‐toxin I and III were highly toxic to the cells. AF‐toxin II protected strawberry cells from AF‐toxin I action. The protection was remarkable when the cultured cells were exposed to excess amounts of AF‐toxin II both prior to and simultaneously with AF‐toxin I addition. The simultaneous treatment, however, was most effective at preventing AF‐toxin I action: it gave complete protection at a 50 : 1 (toxin II : toxin I) ratio on a molar basis. The epoxy‐decatrienoic acid moiety of the AF‐toxins also prevented the cell death caused by AF‐toxin I, but was less effective than AF‐toxin II. Protection was apparent when the cultured cells were exposed to AF‐toxin II for 3 h, rinsed to remove free AF‐toxin II and then exposed to AF‐toxin I. These results suggest that the toxoids of AF‐toxin I, such as AF‐toxin II and the decatrienoic acid, act as

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01264.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractMycoplasma‐like organisms (MLOs) were found in sieve tubes ofSolanum lycocarpumaffected with prolferation and big bud. The MLOs were graft‐transmitted to tomato plants which developed similar symptoms. The association of MLOs with affected but not with symptomlessS. lycocarpumand tomato suggests that the abnormality is induced by MLOs. The possible role ofS. lycocarpumas a reservoir of a strain of the tomato big bud is discus

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01265.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractWe studied the behaviour of tomato mosaic tobamovirus (ToMV) in a recirculating nutrient solution. Particles of tomato mosaic virus were found in the nutrient solution 3 days after leaf inoculation of plants and we demonstrated that the level could increase to a concentration readily detectable by electron microscopy. Virions remained infective in nutrient solution for at least 6 months, could infect bait plants and induced systemic symptoms within 10 days. This is the first report of measurement of infective virions in recirculating nutrient solutions. Hydroponic producers should be aware of the potential for rapid spread of virus diseases in soilless growing systems as one infected plant can serve as a source of inoculum that can ultimately result in an epidemic.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01266.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe effects and risks involved with the small tuber assay in plant breeding programmes with potato seedlings for resistance toPhytophthora infestansIn an assay which involved 838 potato seedlings, the relative resistance to leaf‐Phytophthora(KRG) was tested at the 4–6 leaf growth stage, and the relative tuber resistance to infection was determined on small pot‐grown tubers (BK) and, in the following 2 years, in slices from field‐grown potatoes (Bs). The small tuber assay is described and its value as a measure of disease resistance, compared with the potato slice assay, discussed. Among 357 leaf‐Phytophthorasusceptible clones (KRG≤ 5) were 10 clones with a good to very good tuber resistance. 18 of 204 leaf‐Phytophthorahighly resistant idiotypes were extremely susceptible to tuber rot. After discarding those seedlings which showed KRG‐values ≤ 5 and BX‐values ≤ 5, 208 of the remaining 241 (= 86 %) tuber rot resistance carrying seedlings were selected. 14 % of the clones which showed adequate resistance in the potato slice assay were falsely discarded according to the small tuber assay. 80 clones remained as ballast in the field trials (BK≤ 5, Bs≤ 6.4), 160 (33 % of the idiotypes tested) had been correctly eliminated. The work‐intensive small tuber assay presents a possibility by which breeding material can already be reduced in the seedling stage. In this respect there must be a pronounced genetic differentiation present in the potato population and the selection procedure carrie

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01267.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractAllopurinol [4‐hydroxypyrazolo(3,4‐d)pyrimidine], a specific, potent inhibitor of xanthine oxidoreductase, effectivein vitroandin vivo, was applied to bean plants as soil drench at a 400 μM concentration 8–10 days before inoculation and strongly reduced the development ofUromyces phaseoliin bean leaves. Allopurinol was ineffective on uredospore germination, presumably due to the absence of any xanthine oxidoreductase activity in the extract of germinated uredospores. The concentration of allopurinol used for the treatment did not significantly influence the level of ureides in leaves mainly because low concentration of these compounds were found in leaves and also probably because allopurinol‐insensitive biosynthetic route/s of these compounds are active in bean plants. This paper examines the possibility that host xanthine oxidase is in some way involved in the biotrophic nutritional process leading to the growth of bean rus

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01268.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractOospores ofPeronospora ducometi, the causal agent of downy mildew of buckwheat (Fagopyrum esculentum), were found in the calyx remnant attached to the seed, on the inside of the seedcoat and in the spermoderm layer between the seedcoat and the endosperm. This constitutes a first report documenting the location of oospores in buckwheat seed. Systemic infection of seedlings occurred from oospore‐infested seed. Conidial germination was greater at 14°C than 25°C. Systemic infection also occurred as the result of conidial infection of leaves.It is proposed that primary infection of buckwheat occurs by the germination of seed‐borne oospores resulting in systemic invasion of the seedling by the germtubes, and followed by conidial formation on the cotyledons. Secondary infection occurs initially from conidia produced on the cotyledons as a result of the systemic infection from seed and subsequently as the result of repeated infections by conidia produced on leaf lesions as the disease progresses up the

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01269.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractEffect of the Bacterial Phytotoxin Coronatine on Plant Cell CulturesThe influence of the bacterial phytotoxin coronatine on cell cultures ofLycopersicon peruvianumandChenopodium albumwas studied. It was detectable that the cell cultureL. peruvianummore related to the host plant of the phytopathogenic bacteria reacts more sensitive to coronatine. Concentrations of 3.5 ng coronatme/ml culture liquid mduce reductions in growth and the TTC‐activity. In the case of the other used cell culture the critical amount of coronatine was higher than 7 ng/ml culture liquid. In further experiments the concentrations of free amino acids and proteins within the cell were followed. After 6–7 days of culture a slightly recovery of the cultures treated with coronatine was detecta

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01270.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA severe isolate (BL) of tomato spotted wilt virus (TSWV) that originated from Hawaii was treated with nitrous acid in an effort to obtain mild mutants. The standardized procedure used in mutation experiments was: extracting infectedGomphrena globosaL. leaf tissue in 0.01 M Na2SO3, 0.125 M sodium acetate and 0.4 M sodium nitrite at pH 5.5 and incubating the extract for 20 min at room temperature. The extract was inoculated to tobacco (Nicotiana tabacumL. cv. Havana 423) and local lesions were subsequently transferred to lettuce (Lactuca sativaL. cv. Minetto). One isolate (R27G) that incited mild symptoms in lettuce was obtained out of 868 local‐lesion‐transfers. Under greenhouse conditions, the isolate induced mild symptoms on tomato (Lycopersicon esculentumMill.) but was severe on peppers (Capsicum annuumL.). The effect of the R27G isolate on growth of potted tomatoes kept outdoors was variable. In one trial, only 15 % of the fruit had symptoms versus 67 % in another trial. R27G fully protectedDatura stramoniumL. plants that were challenge inoculated with the severe parent BL isolate. Less effective cross protection was observed against a severe isolate from Oklah

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01271.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractExtracts of culture filtrate of the phytopathogenic fungusAlternaria alternata(Fries) Keissler cause distinct wilting of cuts of the problem weedGalium aparineL. We were able to demonstrate that the cyclic tetrapeptides tentoxin and dihydrotentoxin were reponsible for this effect. A tentoxin derivative, isolated from the culture filtrate, shows a similar, but stronger wilting activity.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01272.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe specific activities of enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPOX) and glutathione reductase (GR), which are involved in protection against toxic species of oxygen, were determined in mycelia extracts of pentachloronitrobenzene (PCNB)‐tolerant and susceptible soil fungi. The organisms assayed were the highly PCNB‐sensitiveRhizoctonia solaniandRhizopus arrhizus; Sclerotium rolfsiiandTrichoderma harzianum, which are moderately susceptible to PCNB, and the fungicide‐tolerantFusarium oxysporumf. sp.melonisandPythium aphanidermatum. No GPOX activity was detected in the six examined fungi. Significant differences in the specific activities of the other enzyme systems among the fungi were evident. Remarkably low levels of CAT activities were measured inR. solani. Except forT. harzianum, no meaningful differences regarding SOD, CAT and GR activities with age of the fungi cultures were observed. The electrophoretic patterns of SOD and CAT displayed dissimilarities among the fungi under study.P. aphanidermatumis more polymorphic with respect to both SOD and CAT enzyme systems as compared to the other fungi. The SOD ofF. oxysporumf. sp.melonis, R. arrhizusandT. harzianumis a cuprozinc enzyme, while the mangano‐SOD species was detected inS. rolfsii, R. solaniandT. ha

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1992.tb01273.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY