Assessment of biological and molecular variability between and within field isolates of Plasmodiophora brassicae     

M. J. Manzanares-Dauleux†  I. Divaret  F. Baron  G. Thomas 《Plant pathology》2001,50(2):165-173

Plasmodiophora brassicae is an obligate biotroph that causes clubroot, one of the most damaging diseases of crucifers. Differential cultivars and random amplified polymorphic DNA markers were used to assess the extent of genetic diversity among nine single-gall populations of P. brassicae and 37 single-spore isolates (SSI) derived from four of those field samples. Isolates were classified into eight pathotypes, and each isolate was associated with a unique molecular genotype. Virulence and DNA polymorphisms were detected within and between field isolates, and among SSIs from different pathotypes, hosts and geographical origins. The relatively high level of genetic diversity among field isolates was similar to that among SSIs derived from a single-club field isolate. Molecular and pathogenicity-based classifications were not clearly correlated, but isolates belonging to pathotype P1 were clustered. Two RAPD markers were specific to pathotype P1. The finding that genetic differences can occur in P. brassicae field isolates will be an important consideration in resistance genetic studies and in choosing breeding strategies to develop durable clubroot resistance.  相似文献   

Severe outbreak of bacterial speck, caused by Pseudomonas syringae pv. tomato, on field-grown tomatoes in the eastern Anatolia region of Turkey   总被引：1，自引：0，他引：1  

F. &#;ahin 《Plant pathology》2001,50(6):799-799

  相似文献   

Biological evidence for a 1:1 Ca²⁺:glyphosate association in deposit residuals on the leaf surface of barley     

C Gauvrit  J-C Gaudry  T Lucotte  & F Cabanne 《Weed Research》2001,41(5):433-445

It has long been known that calcium ion antagonizes glyphosate, but it was not clear whether the stoichiometry of their interaction is 1:1 or 1:2. Two independent methods were used to determine which stoichiometry was the most probable. First, dose–response curves of barley ( Hordeum vulgare L.) plants treated with glyphosate were determined in the presence of 0, 1.25, 2.5, 5 and 10 mM CaCl₂. The doses of 'free' glyphosate (=not inactivated by calcium ion) were computed using the assumptions of 1:1 and 1:2 stoechiometries. The response curves were redrawn as a function of 'free' glyphosate. Analysis showed that the 1:2 hypothesis could be rejected, whereas the 1:1 hypothesis was highly probable. Second, kinetics of glyphosate penetration into barley leaves were determined in the presence of 0, 2.5 and 10 mM CaCl₂. The concentrations of 'free' glyphosate were computed as above. The kinetics of glyphosate penetration at these concentrations were established and were compared to the kinetics of glyphosate penetration in the presence of CaCl₂. Again, the 1:2 hypothesis was rejected, whereas the 1:1 hypothesis was more probable. These results strongly suggest that the stoichiometry of the Ca²⁺:glyphosate association is 1:1 in deposit residuals on the leaf surface.  相似文献   

Suppression of development of Callosobruchus maculatus (F.) (Col.: Bruchidae) in bambara groundnut seeds exposed to solar heat in the Nigerian savanna     

N. E. S. Lale  F. A. Ajayi 《Anzeiger für Sch?dlingskunde》2001,74(5):133-137

The effect of solarization on the development of Callosobruchus maculatus was investigated in the Nigerian savanna during the hot season from April to May, 1999. Development of C. maculatus adult progeny was completely suppressed in seeds of bambara groundnut, Vigna subterranea bearing bruchid eggs or harbouring first and second instar larvae that were exposed to the sun in metal tins, clay pots or polypropylene sacks for 7, 14 or 28 h. Adults of C. maculatus developed only in seeds that were not exposed to sun. Solarization did not have a significant adverse effect on germinability of bambara groundnut seeds.  相似文献   

Suppression of development of Callosobruchus maculatus (F.) (Col.: Bruchidae) in bambara groundnut seeds exposed to solar heat in the Nigerian savanna     

N. E. S. Lale  F. A. Ajayi 《Anzeiger für Sch?dlingskunde》2001,22(1):133-137

  相似文献   

Characterisation ofFusarium oxysporum isolated from carnation in Australia based on pathogenicity,vegetative compatibility and random amplified polymorphic DNA (RAPD) assay     

G. F. Kalc Wright  D. I. Guest  D. L. S. Wimalajeewa  R. van Heeswijck 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(5):451-457

Isolates ofF. oxysporum collected from symptomless carnation cuttings from Australian carnation growers properties, together with isolates from national collections, were screened for pathogenicity and grouped according to vegetative compatibility and random amplified polymorphic DNA (RAPD) patterns. The collection of 82 Australian isolates sorted into 23 different vegetative compatibility groups (VCGs). Of 69 isolates tested for pathogenicity, 24 were pathogenic to carnations, while the remaining 45 were non-pathogenic. All pathogenic isolates were within two VCGs, one of which was also compatible with an isolate obtained from an international culture collection, and which is known to represent VCG 0021 and race 2. Race status of the two pathogenic VCGs remains unknown. The RAPD assay revealed distinct DNA banding patterns which could distinguish pathogenic from non-pathogenic isolates as well as differentiate between isolates from the two pathogenic VCGs.  相似文献   

Effects of accumulate dead and alive insects in trap on the capture ofTribolium castaneum (herbst)     

P. Trematerra  F. Fontana  M. Mancini 《Anzeiger für Sch?dlingskunde》1996,69(1):3-9

In the trapping ofTribolium castaneum (Herbst), the activity of traps baited or not baited with aggregation pheromone 4,8-dimethyldecanal is influenced by the presence in the traps of accumulate specimens trapped. This fact has been observed both in trap containing alive or dead specimens. Interactions in the different substances produced by adults of Red Flour Beetle during their communication relationship are involved in this behaviour.The results obtained in the trials suggests that the presence of alive insects in traps is attractive for other free specimens, but under conditions of overcrowding quinone produced by them regulate population density by counteracting the effect of the aggregation pheromone, causing the insects to disperse or suppressing aggregation behaviour.  相似文献   

Specificity of polycllonal and monoclonal antibodies for the identification of Xanthomonas campestris pv. campestris     

A. A. J. M. Franken  J. F. Zilverentant  P. M. Boonekamp  A. Schots 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(2):81-94

Polyclonal and monoclonal antibodies (PCAs and MCAs), produced to whole cells and flagellar extracts ofXanthomonas campestris pv.campestris (Xcc), respectively, were tested for specificity. In immunofluorescence microscopy (IF) the three PCAs tested, reacted at low dilutions with all Xcc strains, some other xanthomonads and non-xanthomonads. At higher dilutions most cross-reactivity with non-xanthomonad strains disappeared. However, the cross-reactivity with strains ofX. c. pv.vesicatoria (Xcv),X. c. pv.amoraciae (Xca) andX. c. pv.phaseoli var. fuscans (Xcpf) remained.Six MCA-producing cell clones viz. 20H6, 2F4, 18G12, 10C5, 17C12 and 16B5 were selected for specificity tests with an enzyme immunoassay (EIA), IF and a dot-blot immunoassay (DBI). None of the MCAs reacted with all Xcc strains in IF and EIA. In DBI, only MCAs 17C12 and 16B5 reacted with all Xcc strains. All six MCAs tested, cross-reacted in one of either tests with other pathovars ofX. campestris, such as Xcv or Xca. The MCAs were also tested in immunoblotting experiments using total bacterial extracts, cell envelope and flagellar extracts. MCAs 20H6, 2F4, 18G12 and 10C5 reacted with the lipopolysaccharide (LPS) of Xcc. MCAs 16B5 and 17C12 reacted with a 39 kilodalton and a 29 kilodalton protein, respectively.It is concluded that the PCAs and MCAs discussed in this study may be used for routine identification and differentiation of (a group of) Xcc strains. The significance of the cross-reactions with other pathovars ofX. campestris needs to be determined by testing seed lots.  相似文献   

Parry's disease of pears is similar to pear decline and is associated with mycoplasma-like organisms transmitted by Cacopsylla pyricola   总被引：1，自引：1，他引：1  

D. L. DAVIES  C. M. GUISE  M. F. CLARK  A. N. ADAMS 《Plant pathology》1992,41(2):195-203

Mycoplasma-like organisms (MLOs) were detected by fluorescence microscopy in a number of pear cultivars and pear seedlings growing under a range of different conditions. In the cultivar Conference, MLOs were consistently associated with symptoms of Parry's disease, a decline-like disease of young trees with quince rootstocks. MLO-free pear seedlings rapidly became infected when they were planted outside. Experimental transmission of MLOs to pear seedlings and Conference trees was achieved using pear psyllids, caught outside or raised on infected plants under controlled conditions. Conference trees in an orchard trial remained free from the severe spring symptoms of Parry's disease when they were protected from feeding insects during spring of the previous year. MLOs were graft transmissible, but were not perpetuated by the standard propagation practices of budding or grafting when quince rootstocks were used. Parry's disease appears to be similar to pear decline, an MLO-induced disease well established in several other parts of the world. It is suggested that Parry's disease should be referred to as pear decline.  相似文献   

Development of a monoclonal antibody-based immunodetection assay for Botrytis cinerea   总被引：1，自引：2，他引：1  

R. BOSSI  F. M. DEWEY 《Plant pathology》1992,41(4):472-482

Three hybridoma cell lines secreting antibodies that specifically recognize Botrytis cinerea and B.fabae , but not B. allii, have been raised from splenocytes of mice immunized with a low molecular-weight fraction (30 kDa) from surface washings of B. cinerea. Antibodies from these cell lines have been used to develop an antigen-based elisa test that will detect B. cinerea in strawberries. This monoclonal antibody immunoassay detection assay should prove useful to both the cut-flower and wine industries. Supernatants from the three specific cell lines recognize mycelial fragments, saline extracts of mycelia and germinating conidia by both ELISA and immunofluorescence. Recognition of non-germinating spores is poor. Supernatants from the specific cell lines did not recognize other fungi normally involved in post-harvest spoilage of fruits and vegetables. Supernatants from KH4 gave the lowest background values with healthy tissue. Indirect evidence from heat, protease and periodate treatment of the antigens indicates that antibodies from all three specific cell lines are recognizing carbohydrate epitopes on a glycoprotein.  相似文献