ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1989.tb00123.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Results are reported for several international collaborative experiments which examined methods of assessing degrees of partial resistance in potato and virulence in potato cyst nematode (PCN,Globodera pallida).It was demonstrated that absolute rates of multiplication can be extremely variable on both susceptible and partially resistant clones, even when the same population and test procedures are employed. It was therefore concluded that, on clones with quantitatively inherited resistance (i.e. partially resistant), absolute rates of multiplication cannot be used to separate pathotypes. Expression of these rates as percentages of those on the susceptible controls reduced the absolute differences between tests, but the values obtained were still too variable for statutory use. However, whatever the environment or nematode population used, it was observed that the resistance of the test clones and virulence of the nematode populations were generally ranked in a similar order. The main exceptions to this were: (1) a Petri‐dish test where cv. Vantage was less resistant than in canisters or pots and (2) a pot test where cv. Darwina tended to be more interactive with environmental factors than the other test clones. It was also observed that with some populations of PCN in pots the susceptible cv. Bintje was a less good host than cv. Désirée. On the basis of these results it is suggested that certain partially resistant clones should be used as internal references in statutory, recommended list and breeders' assessment tests against which the resistance of the test clones are compared. For international comparability it is necessary that the different centres conducting such tests use the same reference clones and nematode populations, and similar test meth

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1989.tb00124.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

In support of the work of the EPPO Panel on Certification of Pathogen‐tested Ornamentals, new techniques of diagnosis (since 1980) are presented for viruses of carnation, chrysanthemum, iris, lily, narcissus and pelargoniu

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1989.tb00125.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Bacterial pathogens of Gramineae principally belong to the generaClavibacter, Erwinia, PseudomonasandXanthomonas, the last being the most important. A general survey of these pathogens is given, with details on nomenclature, symptoms, natural host range, geographical distribution and potential quarantine significance for the EPPO region. The status ofXanthomonas campestrispathovars with overlapping broad and narrow host ranges on Gramineae is discussed. It is proposed to adopt a broad concept ofX. campestrispv.translucensand evaluate it as a potential quarantine hazard for the EPPO region.

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1989.tb00126.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Des enquêtes concernant le dessechement àXanthomonas campestrisdes graminées cultivées ont été menées en France. Ľanalyse bactériologique ďéchantillons deLolium italicum, L. multiforum, L. perenne, Dactylis glomerataetFestuca arundinaceaa permis de trier les criteres ďidentification utilisables en routine pour identifier lesX. campestrisdu groupegraminis.Les bactéries ont également été comparées aux références ďautresXanthomonas, dont les pathotypes du groupetranslucens, parasites foliaires des céréales non identifiés en France. L'aspect colonial, mucoïde et butyreux, àľisolement est un élément distinctif essentiel vis‐à‐avis des saprophytes présents sur les graminées. Parmi les caractères physiologiques, les tests Amidon et Tween 80 font des groupestranslucensetgraminis(deLolium, DactylisetFestuca)desXanthomonasdifférents du reste de ľespèceX. campestris.En immunodiffusion, on distingue un sérogroupegraminisincluant les isolats deLolium, Festuca, Dactylis, ainsi que les pathotypes des pvsgraminis, arrhenatherietpoae.Un deuxième sérogroupe,undulosa, distinct du premier, contient les pathotypes des pvsundulosa,

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1989.tb00127.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

More than 120Xanthomonas campestrisstrains pathogenic for grasses and cereals were compared by polyacrylamide gel electrophoresis (SDS‐PAGE) of their whole‐cell proteins. Genotypic relationships between representative strains of the electrophoretic groups were determined by DNA:DNA hybridizations. Two major groups of bacteria were delineated. The first includedX. campestrispv.graminis, pv.arrhenatheriand some isolates fromBromus, which could be differentiated from each other by their protein fingerprints, and also the following pathovars which it was impossible to differentiate by SDS‐PAGE:cerealis, hordei, poae, secalis, translucensandundulosa.DNA:DNA hybridizations indicated that significant degrees of DNA‐binding (>60% D) exist between all these pathovars. In the second group, strains ofX. campestrispv.holcicola, pv.vasculorumand pv.oryzaewere related at 40–45% DNA‐binding, while strains of pv.oryzaeand pv.oryzicolawere genotypically highly related (85% D). All the pathovars of this second group could be differentiated from each other by their protein electrophoretic f

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1989.tb00128.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Fatty acid profiles were prepared for a range of strains representing all 14Xanthomonas campestrispathovars from the Gramineae. Profiles were complex, containing up to 40 acids, most of which were iso‐ and anteiso‐branched acids. Grouping of profile types generally correlated with pathovar, although pvstranslucens, hordei, cerealis, secalisandundulosacould not be differentiated. Pvsgraminis, arrhenatheri, poaeandphleiformed another profile type although there were some differences between the pathovars. Thesegraminisandtranslucensgroups had similar profiles but could usually be differentiated by the ratios of 15:0 iso/16:0 iso and 15:0 iso/15:0 anteiso fatty acid methyl esters. The other pathovars each had a very different profile type. Pvsoryzaeandoryzicolahad profiles which were very different from all others. Pv.vasculorumcomprised at least two distinct profile types. This did not correlate with host species or geographic distribution. Fatty acid profiling can be used to identify strains ofX. campestrispathovars from Gramin

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1989.tb00129.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

In Norway seven different grass species were found to be attacked byXanthomonas campestrispv.graminis(bacterial wilt of forage grasses). Among these,Phleum pratenseis the most susceptible and common host. Considerable damage may occur after long periods of hot and dry weather, while in cool and wet periods hardly any diseased plants are found. The pathogen may be identified by isolation and biochemical tests. Specific antibodies used in immunofluorescence and ELISA had a high degree of sensitivity and specificity against the target bacterium. The two methods were used for screening pure cultures and detecting bacteria directly in plant tissue extracts. Their application revealed the presence of low numbers of bacteria in symptomless plants and a discontinuous distribution within the plant.

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1989.tb00130.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Plantsof Lolium multiflorumcv. Remy were infected byXanthomonas campestrispv.graminisin the greenhouse by clipping their leaves with scissors the blades of which had been dipped in a bacterial suspension. Inoculation of the cut leaves resulted in intense bacterial proliferation in the protoxylem lacunae.X. c. graminiscaused cell wall dissolution early in the infection process. Bacteria were observed to exist within the protoxylem lacunae in a matrix of amorphous substance, presumably partly dissolved cell wall material and extracellular polysaccharide. They spread out into the adjacent xylem parenchyma cells after having dissolved the parenchyma cell walls, and into the xylem vessels. Long‐distance transport ofX.c. graminisoccurred in the xylem. The bacteria invaded neighbouring vascular bundles by penetrating through intercellular spaces developed from dissolved primary cell walls between leaf mesophyll cells. Six weeks after inoculation most bacteria could be found in the xylem of the outermost leaf sheat

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1989.tb00131.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Scanning electron‐microscopy observations made on the leaves of Italian ryegrass and maize, inoculated withXanthomonas campestrispvsgraminis, oryzaeandoryzicolaclearly showed a difference in the distribution pattern among the different pathovars tested. Pvsoryzaeandoryzicolacould be detected on the leaf trichomes of ryegrass, while pv.graminiswas not. On maize leaves, the attachment of pvsoryzaeandoryzicolato trichomes was much more pronounced than on ryegrass. In addition, pv.oryzaespread further into leaves of maize than did pvsgraminisandoryzicolaand could be detected in masses until at least the sixth day after inoculation. These observations suggest that non‐host plants such as maize could function as alternate inoculum sources of pv.oryzaefor nearby rice pla

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1989.tb00132.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY