Variation in the response of melon genotypes to Fusarium oxysporum f.sp. melonis race 1 determined by inoculation tests and molecular markers     

Y. Burger  N. Katzir  G. Tzuri  V. Portnoy  U. Saar  S. Shriber  R. Perl-Treves  R. Cohen † 《Plant pathology》2003,52(2):204-211

Screening of genotypes of melon ( Cucumis melo ) for resistance to wilt caused by Fusarium oxysporum f.sp. melonis is often characterized by wide variability in their responses to inoculation, even under carefully controlled conditions. The variability at the seedling stage of 17 genotypes susceptible to race 1 was examined in growth-chamber experiments. Disease incidence varied from 0 to 100% in a genotype-dependent manner. Using four combinations of light (60 and 90  µ E m⁻² s⁻¹) and temperatures of (27 and 31°C), only light intensity showed a statistically significant effect. Marker-assisted selection for fusarium resistance breeding using cleaved amplified polymorphic sequence (CAPS) and sequence-characterized amplified region (SCAR) markers were compared using a single set of genotypes that included 24 melon accessions and breeding lines whose genotype regarding the Fom-2 gene was well characterized. The practical value of the markers for discriminating a range of genotypes and clarifying the scoring of phenotypes was also tested using a segregating breeding population which showed codominant SCAR markers to be useful in marker-assisted selection.  相似文献   

Distribution of citrus viroids and <Emphasis Type="Italic">Apple stem grooving virus</Emphasis> on citrus trees in Japan using multiplex reverse transcription polymerase chain reaction     

Takao Ito  Nobuyuki Namba  Tsutae Ito 《Journal of General Plant Pathology》2003,69(3):205-207

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Further suppression of<Emphasis Type="Italic">Botrytis cinerea</Emphasis> disease in cucumber seedlings by chitosan-copper complex as compared with chitosan alone     

N. Ben-Shalom  E. Fallik 《Phytoparasitica》2003,31(1):99-102

Chitosan-copper complex compared with chitosan alone enhanced suppression ofBotrytis cinerea rot development on four-true-leaf cucumber seedlings in controlled growth chambers. This paper constitutes the first report of such enhancement. The optimal concentrations for the most effective suppression ofBotrytis development were 0.2 gl ⁻¹ chitosan and 1.6 mmole copper. After 12 days’ incubation, marked and significantly better disease suppression was obtained with chitosan-copper complex (75% suppression) than with chitosan alone. The chitosan-copper complex could be a very promising decay control agent for use in both conventional and organic agriculture. http://www.phytoparasitica.org posting Dec. 18, 2002.  相似文献   

Indole-3-acetic acid biosynthesis in <Emphasis Type="Italic">Aciculosporium take</Emphasis>, a causal agent of witches' broom of bamboo     

Eiji Tanaka  Chihiro Tanaka  Atsushi Ishihara  Yasumasa Kuwahara  Mitsuya Tsuda 《Journal of General Plant Pathology》2003,69(1):1-6

 Aciculosporium take (Ascomycota; Clavicipitaceae) is a causal agent of witches' broom of bamboo plants. The symptoms of this disease are believed to be induced by plant hormones, particularly auxins. Indole-3-acetic acid (IAA) was identified in cultures of this fungus in an l-tryptophan-supplemented liquid medium. IAA production was confirmed on 30 isolates of A. take from various hosts and locations at levels up to 1 mg/l. The biosynthetic pathway of IAA in A. take culture was examined by analyzing intermediate products and by feeding experiments. The results showed that the indole-3-pyruvic acid pathway (l-tryptophan → indole-3-pyruvic acid → indole acetaldehyde → IAA) was the dominant pathway in A. take. Received: June 3, 2002 / Accepted: July 25, 2002  相似文献   

Inconspicuous restraint of rice seedling growth by root-infecting fungi in soil of a rice paddy field     

Hiromitsu Furuya  Tsutomu Matsumoto  Shin-ichi Fuji  Hideki Naito 《Journal of General Plant Pathology》2003,69(2):115-119

 Rice seedling growth, estimated by plant height and root development and discoloration, was better in pasteurized soil than in unpasteurized soil obtained from a flooded rice field. Rice seedlings also grew better in sterilized soil modified by adding roots harvested from the pasteurized soil than in soil modified by adding roots harvested from the unpasteurized soil. The results demonstrate that seedling growth in the rice field soil was inhibited by soil microorganisms, even though no typical symptoms such as seedling blight or damping-off appeared. Pythium aristosporum is suggested to be involved in the inhibition. Thus, it appears that inconspicuous restraint of rice seedling growth could occur in soils of rice paddy fields. Received: May 20, 2002 / Accepted: October 16, 2002 Acknowledgments The authors thank Dr. T. Ichitani, former professor at Osaka Prefectural University, for providing an isolate of Pythium aristosporum for comparison, and Mr. Mitsuaki Sato of Akita Prefectural College of Agriculture for technical assistance.  相似文献   

Comparison of two sampling methods for leafhoppers (Homoptera, Cicadellidae) associated with sesame in the east Mediterranean region of Turkey     

U. Kersting  H. Bapinar  N. Uygun  S. Satar 《Anzeiger für Sch?dlingskunde》1997,70(7):131-135

Yellow sticky-traps and a modified Johnson-Taylor suction-trap were used to index the relative population dynamic of leafhoppers associated with sesame in the east Mediterranean region of Turkey. Comparison of the obtained results signified important differences between both traps. 32 leafhoppers species were caught in the suction-trap while only 18 species were determined on yellow sticky-traps. For most of the leafhopper species, relatively more males were determined on the yellow-traps than in the suction-trap, indicating a higher activity of male leafhoppers during daytime hours. A close relationship between the seasonal flight pattern as indexed by sticky-traps and by suction-trap was only observed forAsymmetrasca decedens (Paoli) andEmpoasca decipiens Paoli. For most other leafhopper species no or only a very poor correlation for the relative population dynamic was determined between both traps. Important leafhopper vector species, e.g.,Circulifer haematoceps (Mulsant et Rey) andOrosius orientalis (Matsumura) were better represented in yellow sticky-trap catches than they were in the suction trap.

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Zusammenfassung  Die relative Populationsdynamik der mit Sesam assozüerten Zwergzikaden wurde mit beleimten Gelbtafeln und einer stationären Johnson-Taylor-Saugfalle an der südöstlichen Mittelmeerküste der Türkei untersucht. Beim Vergleich beider Methoden zeigten sich deutliche Unterschiede zwischen den Fallentypen. In der Saugfalle konnten 32 Zwergzikadenarten erfaßt werden, während dies auf den Gelbtafeln nur 18 Arten waren. Die meisten Zwergzikadenarten zeigten auf den Gelbtafeln ein stark in Richtung der Männchen verschobenes Geschlechterverhältnis, was eine erhöhte Flugaktivität der Männchen während des Tageslichts vermuten läßt. Auch der Verlauf der saisonalen Flugaktivität war für die meisten Zwergzikadenarten zwischen den beiden Fallentypen sehr unterschiedlich, und es konnten zwischen Saug- und Gelbfalle keine deutlichen Korrelationen hergestellt werden. Nur für die beiden zusammen erfaßten ArtenAsymmetrasca decedens (Paoli) undEmpoasca decipiens Paoli wurde ein enger Zusammenhang zwischen der mit der Saugfalle und den gelben Leimtafeln erfaßten relativen Populationsdynamik festgestellt. Wichtige Vektorenarten unter den Zwergzikaden, z. B.Circulifer haematoceps (Mulsant et Rey) undOrosius orientalis (Matsumura) waren auf den Gelbtafeln besser repräsentiert als in der Saugfalle.

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Functional heterogeneity in resources within landscapes and herbivore population dynamics     

Norman Owen-Smith 《Landscape Ecology》2004,19(7):761-771

Large mammalian herbivores are notorious for their propensity towards population irruptions and crashes, yet many herbivore populations remain relatively stable. I explore how resource heterogeneity within landscapes dampens population instability, using a metaphysiological modelling approach considering patch state distributions. Resource heterogeneity is functionally stabilizing through spreading consumption away from preferred resources before these become critically depleted. Lower-quality resources act as a buffer against starvation during critical periods of the seasonal cycle. Enriching resource quality is destabilizing, even if patch diversity is maintained, because food quantity then becomes the limitation. The potential consequences of landscape fragmentation are explored using the Serengeti ecosystem, characterised by broadscale resource gradients, as a hypothetical example. Further insights provided by the model are illustrated with specific examples concerning the effects of patch scales and waterpoint distribution. A metaphysiological modelling approach enables the basic consequences of landscape heterogeneity to be distinguished from further effects that may arise from specific patch scales and configurations, without the distracting detail of spatially explicit models.  相似文献   

Auxins increase the occurrence of leaf-colour variants in Caladium regenerated from leaf explants     

E. U. Ahmed  T. Hayashi  S. Yazawa 《Scientia Horticulturae》2004,100(1-4):153-159

Leaf explants of Caladium ‘Pink Cloud’ were cultured in vitro on MS medium containing various auxins (NAA, IBA, IAA, 2,4,5-T and 2,4-D) in combination with cytokinin (BA). NAA gave the most vigorous in vitro propagation of this plant, and only 15% of the plants were leaf-colour variants on the medium containing 0.5 μmol NAA. Leaf colour variation was observed in all plants regenerated on the medium containing 2,4-D at 0.5–4.5 μmol. In hormone-free medium, only a few leaf-colour variants (6%) occurred, but the rate of plant regeneration was very low. Application of 0.5 μmol NAA together with 4.5 μmol BA seemed to be the most appropriate for in vitro propagation of Caladium ‘Pink Cloud’ with only a few leaf-colour variants.  相似文献   

Factors affecting the development of disease symptoms in potatoes infected by <Emphasis Type="Italic">Tobacco rattle virus</Emphasis>     

D.J. Robinson  M.F.B. Dale  D. Todd 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(9):921-928

Infection of potato plants with Tobacco rattle virus by its nematode vector can have different outcomes, including the development of spraing symptoms in progeny tubers. A novel syndrome described here comprises a generalized mottle in leaves on all stems, together with virtually total failure to produce daughter tubers. The outcome of infection depends partly on the potato genotype, but field trials with 15 varieties showed that the incidence and severity of spraing symptoms at three sites differed. There was no evidence that this was due to differences in virulence among the virus isolates at the sites, but it was probably the result of environmental differences that influenced the numbers and activity of the vector nematodes. At the most severely affected site, spraing symptoms were found in all varieties tested, except Record, including several that were not affected at the other two sites. Taking both severity and incidence of symptoms into account, the ranking of varieties was similar at each site. The incidence of spraing symptoms was greater in larger than in smaller tubers, and increased with later harvest dates, but did not increase when early harvested tubers were stored. Tobacco rattle viruswas detected in the roots of many of the weeds growing at one of the sites and in the roots of a few plants of the subsequent barley crop.  相似文献   

Validation of the specificity and sensitivity of species-specific primers that provide a reliable molecular diagnostic for <Emphasis Type="Italic">Xiphinema diversicaudatum</Emphasis>, <Emphasis Type="Italic">X. index</Emphasis> and <Emphasis Type="Italic">X. vuittenezi</Emphasis>     

Judith Hübschen  Lilo Kling  Ulrike Ipach  Volker Zinkernagel  Nathalie Bosselut  Daniel Esmenjaud  Derek J.F. Brown  Roy Neilson 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(8):779-788

Xiphinema diversicaudatum and X. index are vector nematode species of economic importance in viticulture regions as they can transmit Arabis Mosaic, Grapevine Fanleaf and Strawberry Latent Ringspot viruses to grapevine. Wang et al. (2003) designed species-specific diagnostic primers from ribosomal genes for both these vector species as well as a vector and a non-vector species X. italiae and X. vuittenezi, respectively. Our study aimed to confirm the specificity and determine the sensitivity and reliability of the primers for the two vector species, X. diversicaudatumand X. indexwhen challenged with closely related longidorid species and general nematode communities typical of vineyard soil. With one exception, no PCR product was observed when the primers were tested against six Longidorus, one Paralongidorus and one Xiphinema non-target species. Occasionally (three out of eight replicate PCR reactions) a weak PCR product was noted when primers for X. index were tested with L. elongatus. Furthermore, when challenged with a range of non-target nematode species comprising the nematode community typical of viticulture soil, no PCR product was amplified. An experimental dilution series of extracted DNA rigorously demonstrated that DNA from an equivalent single specimen of the target virus-vector species, X. diversicaudatum and/or X. index, could be detected amongst 1000 equivalent non-targetX. vuittenezi. Also, extracted DNA from an equivalent single target specimen was detected when added to DNA extracted from the overall soil nematode community. The primers were assessed further by using serial mixtures of actual nematodes rather than extracted DNA to simulate field soil. Using this method, a single target nematode could be detected amongst 200 non-target specimens. Given their specificity, sensitivity and reliability, it appears that these diagnostic primers will be of great benefit to phytosanitary/quarantine services related to the viticulture industry.  相似文献