Polygalacturonase isoenzymes and oxalic acid produced by Sclerotinia sclerotiorum in soybean hypocotyls as elicitors of glyceollin     

F. Favaron  P. Alghisi  P. Marciano  P. Magro 《Physiological and Molecular Plant Pathology》1988,33(3)

The polygalacturonases (PG) and oxalic acid produced by Sclerotinia sclerotiorum in infected soybean hypocotyls were investigated as elicitors of the phytoalexin glyceollin I.Purification to homogeneity through isoelectrofocusing and ion-exchange fast protein liquid chromatography revealed three endo-PG isoenzymes (PG-I, PG-II and PG-IV) and one exo-PG (PG-III) in 6-day-old etiolated soybean hypocotyls infected with the B-24 isolate of S. sclerotiorum.PG-I and PG-III, in the range of concentrations tested (0·15–1·2 reducing units ml⁻¹), did not act as elicitors of glyceollin I synthesis. Some elicitor activity was shown by PG-II at 0·6–1·2 reducing units ml⁻¹. PG-IV, at lower doses (0·038–0·30 reducing units ml⁻¹), was even more effective in inducing phytoalexin synthesis. However higher concentrations of PG-IV induced tissue softening and decreased phytoalexin accumulation.PG-II and PG-IV released heat-stable elicitors from purified soybean cell walls supporting the evidence that uronides are intermediate inducers in elicitation by endo-PGs. Oxalic acid was an active elicitor of glyceollin I over the range of concentrations tested (0·31–20 m ) with the maximum at a concentration of 5 m . The inability of oxalic acid to release uronides from purified cell walls makes it unlikely that uronide intermediate elicitors are involved in elicitation by oxalic acid.  相似文献   

The pyrethrins and related compounds. Part XXXIV. Optimisation of insecticidal activity in non-esters     

Ahmet E. Baydar  Michael Elliott  Andrew W. Farnham  Norman F. Janes  Bhupinder P. S. Khambay 《Pest management science》1988,23(3):247-257

Optimisation of activity within the structural constraints defined by the preceding work, by varying the substituents on phenyl in the acid fragment (10 variations), the nature of the group fulfilling the dimethyl function (three variations), the central linking group (four variations) and the presence or absence of a 4-fluoro substituent in the alcohol fragment, has led to achiral compounds as active as bioresmethrin against houseflies and mustard beetles. Statistical analysis of the effects has shown that particular combinations, for instance the cyclopropyl form of dimethyl with a central E-alkene group (but not a central ether group), lead to higher activity than expected. 4-Fluoro substitution enhances activity more strongly against mustard beetles. Difluorocyclopropyl compounds are on average slightly more active than cyclopropyl analogues.  相似文献   

Leaching potential and decomposition of fluroxypyr in Swedish soils under field conditions     

Lars F. Bergstrm  Alec S. McGibbon  Steve R. Day  Marten Snel 《Pest management science》1990,29(4):405-417

The mobility and decomposition of the herbicide fluroxypyr (4-amino-3,5-dichloro-6-fluoro-2-pyridyloxyacetic acid) was studied under field conditions in a sandy soil and a clay soil. Leachate was collected in lysimeters with undisturbed soil (sand) and in tile-drained plots (clay). Soil samples to a depth of one metre were also collected in both soils to characterize the temporal depth distribution of fluroxypyr in the profiles. The herbicide was applied as the I-methylheptyl ester of fluroxypyr at two rates, 187.5 and 375.0 g a.e. ha^?1, representing the normal and double the dose of the compound used for spring cereals. Some lysimeters received supplementary watering. Only two leachate samples (one from each soil) had concentrations of fluroxypyr above the detection limit (1 μg litre^?1), i.e. 2 and 5 μg litre^?1. Both samples were collected within two months after application, when less than 2 mm of drainage had been collected. The methylheptyl ester of fluroxypyr was not found in any of the samples. Fluroxypyr levels above the detection limit in soil (5 μg kg^?1 dry soil), were never found below the topsoil (0.2 m) in the clay profile, while, in the sandy profile, levels just above the detection limit were found occasionally in deeper soil layers. Concentrations were reduced to undetectable or very low levels within three months after spraying.  相似文献   

Synopsis of type specimens deposited in the helminthological collection of the Institute of Parasitology, Czechoslovak Academy of Sciences, in Ceské Bud?jovice. III. Nematoda     

F Moravec 《Folia parasitologica》1990,37(4):367-383

The paper comprises a list of the nematode type specimens deposited in the helminthological collection of the Institute of Parasitology, Czechoslovak Academy of Sciences, in Ceské Bud?jovice. These materials include a total of 110 species and subspecies.  相似文献   

First record of the nematode Syncuaria squamata (Linstow, 1883) from common cormorants (Phalacrocorax carbo (L.)) in Czechoslovakia     

F Moravec 《Folia parasitologica》1990,37(4):365-366

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Achievements of ichthyoparasitological research in the Institute of Parasitology of the Czechoslovak Academy of Sciences     

F Moravec  J Lom 《Folia parasitologica》1990,37(4):289-294

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Additional records of nematode parasites from Papua New Guinea amphibians with a list of recorded endohelminths by amphibian hosts   总被引：1，自引：0，他引：1  

F Moravec 《Folia parasitologica》1990,37(1):43-58

An examination of a small sample of four species of frogs (Cophixalus riparius, Phrynomantis humicola, Ph. stictogaster, Ph. wilhelmana) from Papua New Guinea yielded altogether 5 species of nematodes, 2 of them being new to science. These include: Cosmocercella phrynomantisi sp. n. (type host Ph. humicola), Spinicaudinae gen. sp., Parathelandros andersoni sp. n. (type host C. riparius), Oswaldocruzia bakeri, and Paracapillaria spratti. C. phrynomantisi sp. n. differs from congeneric species mainly in the length of spicules (0.180 mm) and the character, arrangement and number of caudal papillae in the male, while P. andersoni sp. n. is characterized mainly by the presence of four well developed spines on the male tail. Pseudocapillaria spratti is redescribed in detail and it is transferred to Paracapillaria as P. spratti (Moravec et Sey, 1986) comb. n. Capillaria combesi Chabaud et Knoepffler, 1985 is transferred to Amphibiocapillaria Moravec, 1982 and Capillaria petiti Justine et Bain, 1987 to Pseudocapillaria Freitas, 1959. A survey of the endohelminths (excluding Hirudinea) hitherto reported from New Guinea amphibians is presented.  相似文献   

Tobacco rattle virus serotypes and associated nematode vector species of Trichodoridae in the bulb-growing areas in the Netherlands   总被引：1，自引：0，他引：1  

A. T. Ploeg  C. J. Asjes  D. J. F. Brown 《European journal of plant pathology / European Foundation for Plant Pathology》1991,97(5):311-319

Soil samples from the coastal bulb-growing areas in the provinces of North- and South-Holland and the North-East Polder in the Netherlands were examined for trichodorid nematodes and tobacco rattle virus (TRV) serotypes. At least one of a total of eight species of Trichodoridae, of whichParatrichodorus pachydermus was most prevalent, was found in 93% of the samples from the provinces of North- and South-Holland and TRV, including four serotypes, was obtained from 49% of these samples. In the North-East Polder one of three species of trichodorids, of whichP. teres occurred most frequently, was present in 72% of the samples, and TRV of one serotype was obtained from 28% of these samples. The TRV isolates recovered from these samples reacted serologically with one of four antisera to strains of TRV. Virus transmitted byP. pachydermus reacted to the PRN-, byTrichodorus viruliferus to the RQ-, byP. teres to the N5- and byT. similis, to the TS-antiserum, respectively.  相似文献   

Growth of the mycoparasitic fungus Verticillium biguttatum from different geographical origins at near-minimum temperatures     

P. H. J. F. van den Boogert  T. A. W. M. Saat 《European journal of plant pathology / European Foundation for Plant Pathology》1991,97(2):115-124

Sclerotia ofRhizoctonia solani collected from potato tubers from different countries were assayed for the presence of mycoparasites. Among the mycoparasites observedVerticillium biguttatum predominated. Its geographical distribution was not restricted to certain latitudes or soil types;V. biguttatum occurred worldwide in potato fields.The minimum growth temperature of 57V. biguttatum isolates was found to be in the narrow range from 10 to 13°C, irrespective of their geographical origin. A non-linear logistic growth model was used to describe the radial growth onRhizoctonia mycelium and nutrient agar plates. At near-minimum temperature the maximum colony radii varied considerably; they were up to 3.8 times that of the reference isolate M73. Based on parameter values for logistic growth, fast-and slow-growing isolates could be distinguished. Although the growth properties ofV. biguttatum isolates from different locations varied, the presence of fast- and slow-growing isolates was not restricted to particular areas and both types could be found in the same field. However, bioassays with selected fast- and slow-growing isolates do not support the assumption that growth at near-minimum temperatures is a relevant criterion for screening isolates ofV. biguttatum in terms of effectiveness for biological control ofR. solani.  相似文献   

Phenotypic instability of flusilazole sensitivity in Venturia inaequalis   总被引：2，自引：0，他引：2  

W. KÖLLER  F. D. SMITH  K. L. REYNOLDS 《Plant pathology》1991,40(4):608-611

Sensitivities of 16 monoconidial isolates of Venturia inaequalis to the sterol demethylation inhibitor flusilazole were found to be stable, when cultures which had been successively transferred to inhibitor-free nutrient agar and maintained at 20 C were retested 6 months after isolation. In contrast, with storage of these isolates at 2 C for 7 additional months, phenotypic sensitivities were subject to change. A high degree of phenotypic instability was also observed for 77 representative strains which had been subcultured for 10 months. In both cases, the majority of strains became more sensitive to flusilazole. The frequency and magnitude of these changes were most pronounced for strains with moderate levels of resistance. More than 70% of the strains investigated were collected from wild-type populations, suggesting that the reversion of resistant strains was not related to a process of unstable adaptation but to a high degree of plasticity in the genetic control of sensitivities to sterol demethylation inhibitors.  相似文献