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1.
The relative virulence ofPhytophthora cactorum andP. syringae originating from almond trees, and ofP. citrophthora originating from citrus, to apple, pear, peach, cherry and plum rootstocks, was studiedin vivo andin vitro. Results of the different experiments were in good agreement. All testedPhytophthora isolates showed little virulence to pear rootstocks-causing only minor crown rot symptoms - and no virulence at all to apple rootstocks. In contrast, they were highly virulent to stone fruit rootstocks, causing crown rot disease. The non-pathogenicity of these isolates to pome rootstocks could be interpreted as strict host specificity.  相似文献   

2.
梨和苹果腐烂病菌不同培养表型菌株的致病性分析   总被引：3，自引：0，他引：3  
The pathogenicity of three strains (F-SD-8, F-BJ-2c-2 and F-HN-2a-1) of Valsa mali var. pyri causing pear canker and one strain (F-SX-A6) of V. mali var. mali causing apple canker in China were comparatively tested by wound inoculation on in vitro twigs of pear, apple and some other woody plants, and in vivo twigs of pear. Significant pathogenicity differentiation was detected in V. mali var. pyri. Generally strains F-SD-8 and F-BJ-2c-2 were highly pathogenic on pear although their culturing characteristics differed greatly. The strain F-SX-A6 was more aggressive on apple than on pear, and the strain F-HN-2a-1 showed significant lower pathogenicity on ten pear cultivars and other seven species of woody plants. Our results confirmed that two variants of V. mali had host preference and were also aggressive to crabapple, apricot, and peach besides apple and pear. Meanwhile, strains F-SD-8 and F-BJ-2c-2 could induce the formation of pycnidia on in vivo twigs of pear, which was not observed on in vivo twigs inoculated with F-HN-2a-1 and F-SX-A6.  相似文献   

3.
A survey of wild cherry (Prunus avium) woodland plantations and nurseries was carried out in 2000/01. Trees with symptoms of bacterial canker were found in 20 of the 24 plantations visited and in three of seven nurseries. Fifty-four Pseudomonas syringae isolates from wild cherry together with 22 representative isolates from sweet cherry and 13 isolates from other Prunus spp., pear and lilac were characterised by physiological, biochemical, serological and pathogenicity tests. Isolates from wild cherry were predominantly P. syringae pv. syringae (Pss), but P. syringae pv. morsprunorum (Psm) races 1 and 2 were also found. Physiological and biochemical tests discriminated Psm races 1 and 2 from other P. syringae isolates. Agglutination and indirect-enzyme-linked immunosorbent assay tests with three different antisera showed that Psm race 1 and race 2 were very uniform and indicated high variability amongst other P. syringae isolates. However, pathogenic Pss isolates could not be distinguished from non-pathogenic isolates of P. syringae on the basis of physiological, biochemical or serological tests. Pathogenicity tests on rooted lilac plants and on micropropagated plantlets of lilac and two wild cherry clones differentiated Pss and Psm isolates and demonstrated a range of aggressiveness amongst Pss isolates. Serological tests could be used as an alternative to the classical physiological and biochemical tests to increase the speed of detection and discrimination of isolates, but pathogenicity tests are still necessary to discriminate the pathogenic Pss isolates.  相似文献   

4.
The pathogenicity of 99 Belgian Pseudomonas syringae strains representative of the genetic diversity encountered in Belgian fruit orchards was evaluated by using 17 pathogenicity tests conducted on pear, cherry, plum, lilac, sugar beet and wheat. The P. syringae pv. morsprunorum strains were pathogenic to stone fruit species but the race 1 strains possessing the cfl gene involved in coronatine production were pathogenic in more tests than those lacking the gene. Also, sweet cherry twigs were a better material to detect pathogenic strains of race 1 and sour cherry twigs of race 2, which accorded with race 2 presence in sour cherry orchards in Belgium. Three groups were defined in the pv. syringae based on pathogenicity. One group pathogenic in 71.1% of the tests and to lilac included toxic lipodesipeptide-producing (TLP+) strains. The second group pathogenic in 26.8% of the tests and non-pathogenic to lilac included TLP+ strains. The thirth group pathogenic in 9.1% of the tests and almost specifically pathogenic to pear included TLP− strains. The three groups were genetically heterogeneous. Although strain-host relationships were noted within the pv. syringae, aptata and atrofaciens when considering the strain origins, such relationships were not found in the pathogenicity tests, suggesting that pathogenicity tests could probably not reproduce all the aspects of the host-pathogen interactions. None of the pathogenicity tests was able to provide all the information provided by the complete study. A test on pear buds indicated that strains different from the pv. syringae were pathogenic to pear.  相似文献   

5.
Bacterial strains isolated from cankers of wild cherry trees (Prunus avium) in France were characterized using numerical taxonomy of biochemical tests, DNA–DNA hybridization, repeat sequence primed-PCR (rep-PCR) based on REP, ERIC and BOX sequences, heteroduplex mobility assay (HMA) of internal transcribed spacer (ITS) as well as pathogenicity on wild cherry trees and other species of Prunus. They were compared to reference strains of Pseudomonas syringae pathovars isolated from wild and sweet cherry and various host plants. Wild cherry strains were closely related to P. syringae (sensu lato) in LOPAT group Ia (+ - - - +). Wild cherry strains were pathogenic to wild cherry trees and produced symptoms similar to those observed in orchards. They were pathogenic also, but at a lesser extent, to sweet cherry trees (cv. Napoléon). The wild cherry strains were collected from five different areas in France and appeared to constitute a very homogeneous group. They showed an homogenous profile of a biochemical and physiological characteristics. They were closely related by DNA–DNA hybridization and belonged to genomospecies 3 `tomato'. Rep-PCR showed that wild cherry strains constitute a tight group distinct from P. s. pv. morsprunorum races 1 and 2 and from other P. syringae pathovars. HMA profiles indicated that the ITS of all wild cherry strains were identical but different from P. s. pv. persicae strains since the two heteroduplex bands with reduced mobility were generated by hybridization with the P. s. pv. persicae pathotype strain CFBP 1573. The 8 genomospecies of Gardan et al. (1999) have not been converted into formal species as they cannot be differentiated by biochemical tests. Therefore, the pathovar system within P. syringae was currently used. P. syringae pv. avii is proposed for this bacterium causing a wild cherry bacterial canker and strain CFBP 3846 (NCPPB 4290, ICMP 14479) is designated as the pathotype.  相似文献   

6.
The susceptibility of thirty-three pear cultivars and two pear rootstocks to four virulent strains of Pseudomonas syringae pv. syringae was evaluated by inoculating detached immature fruits and young leaves. The four strains were similarly virulent and did not show cultivar specificity although they were isolated from different pear cultivars and exhibited different biochemical profiles. The most frequently planted pear cultivars, Conference, Abate Fetel, General Leclerc, Williams, D. Comice, El Dorado, Alexandrine, B. Anjou, Passe Crassane and the rootstock OHxF 333 were susceptible to P. syringae pv. syringae. Maximal severity values were obtained on 'Preguystar' leaves (about 90%). The rootstock Winter Nelis was less susceptible. Results with immature fruit and detached leaf assays agreed with field observations on cultivar susceptibility to bacterial blast. However, the detached leaf test gave a more accurate prediction and has the advantages that symptoms develop quickly (48 h), and leaves are available for a longer period of time than fruits. This method is proposed as a rapid and reproducible screening system of cultivar susceptibility to bacterial blast of pear.  相似文献   

7.
Infection of fruit trees by Pseudomonas syringae is a potentially serious problem that may limit the establishment and sustained productivity of pome and stone fruit orchards in Serbia. To estimate possible diversity of Pseudomonas syringae fruit trees strains, we collected a set of strains in several areas of Serbia. The samples were taken from infected orchards with raspberry, plum, cherry, sour cherry, peach, pear and apple trees. Genetic diversity of P. syringae strains isolated from fruit trees was determined by using SpeI macrorestriction analysis of genomic DNAs by pulsed-field gel electrophoresis (PFGE) and REP-PCR. Molecular analysis showed that most of isolates had unique profiles, with the exception of isolates from plum and cherry that displayed profiles identical to each other and similar to P. syringae pv. morsprunorum. The study presented here clearly demonstrates the discriminative power of molecular techniques in enabling a detailed analysis of the genetic variations between strains of P. syringae from different pome and stone fruit hosts in Serbia.  相似文献   

8.
A total of 101 Pseudomonas syringae pv. syringae strains, obtained from international culture collections or isolated from diseased tissues of herbaceous and woody plant species, were assessed by repetitive PCR using the BOX primer, and for the presence of the syrB gene. Representative strains were also tested for pathogenicity to lilac, pear, peach, corn and bean, as well as for virulence to lemon and zucchini fruits. The unweighted pair-group method using arithmethic averages analysis (UPGMA) of genomic fingerprints revealed 17 different patterns which grouped into three major clusters, A, B and C. Most of the strains (52·4%) were included in patterns 1–4 of group A. These patterns comprised strains obtained from either herbaceous or woody species, and showed four fragments of similar mobility. Genetic variability was ascertained for strains isolated from apple, pear, apricot, Citrus spp. and cereals. No clear relationship was observed between host plant and bacterial genomic fingerprint. Variability was also observed in pathogenicity and virulence tests. The inoculation of pear leaves discriminated strains isolated from pear as well as the very aggressive strains, whereas inoculation of lilac, peach and corn did not discriminate the host plant from which the strains were originally isolated. Lemon fruit inoculation proved very effective for P. syringae pv. syringae virulence assessment. The syrB gene was present in almost all strains.  相似文献   

9.
A collection of Pseudomonas syringae and viridiflava isolates was established between 1993 and 2002 from diseased organs sampled from 36 pear, plum and cherry orchards in Belgium. Among the 356 isolates investigated in this study, phytotoxin, siderophore and classical microbiology tests, as well as the genetical methods REP-, ERIC- and BOX- (collectively, rep-) and IS50-PCR, enabled identification to be made of 280 isolates as P. syringae pv. syringae (Pss), 41 isolates as P. syringae pv. morsprunorum (Psm) race 1, 12 isolates as Psm race 2, three isolates as P. viridiflava and 20 isolates as unclassified P. syringae. The rep-PCR methods, particularly BOX-PCR, proved to be useful for identifying the Psm race 1 and Psm race 2 isolates. The latter race was frequent on sour cherry in Belgium. Combined genetic results confirmed homogeneities in the pvs avii, and morsprunorum race 1 and race 2 and high diversity in the pv. syringae. In the pv. syringae, homogeneous genetic groups consistently found on the same hosts (pear, cherry or plum) were observed. Pathogenicity on lilac was sometimes variable among Pss isolates from the same genetic group; also, some Psm race 2 and unclassified P. syringae isolates were pathogenic to lilac. In the BOX analyses, four patterns included 100% of the toxic lipodepsipeptide (TLP)-producing Pss isolates pathogenic to lilac. Many TLP-producing Pss isolates non-pathogenic to lilac and the TLP-non-producing Pss isolates were classified differently. Pseudomonas syringae isolates that differed from known fruit pathogens were observed in pear, sour cherry and plum orchards in Belgium.  相似文献   

10.
The hrpS to hrpB regions from strains of Pseudomonas syringae were amplified by polymerase chain reaction (PCR) and the DNA sequence determined. The order of hrpS, hrpA, hrpZ, and hrpB was consistent among P. syringae strains. The sequence of hrpS was highly conserved. In a cluster analysis with the hrpS sequence, P. syringae strains were divided into four groups (I, II, III, and IV) and one undetermined strain, in agreement with previous studies. In contrast, the hrpZ sequences contained insertions, deletions, and base substitutions followed by changes in amino acids. Based on cluster analysis of hrpA, hrpZ, and hrpB, P. syringae strains could be divided into five groups. One of the four groups (group I) in the cluster analysis of hrpS could be further divided into two subgroups (groups IA and IB). Groups II, III, and IV were the same in the two analyses. Group-specific primers were designed, based on the DNA sequences of hrpZ, that could differentiate the groups of P. syringae strains. The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under the accession numbers AB112552 to AB112581  相似文献   

11.
Bacterial canker is a major disease of Prunus avium (cherry), Prunus domestica (plum) and other stone fruits. It is caused by pathovars within the Pseudomonas syringae species complex including P. syringae pv. morsprunorum (Psm) race 1 (R1), Psm race 2 (R2) and P. syringae pv. syringae (Pss). Psm R1 and Psm R2 were originally designated as the same pathovar; however, phylogenetic analysis revealed them to be distantly related, falling into phylogroups 3 and 1, respectively. This study characterized the pathogenicity of 18 newly genome‐sequenced P. syringae strains on cherry and plum, in the field and laboratory. The field experiment confirmed that the cherry cultivar Merton Glory exhibited a broad resistance to all clades. Psm R1 contained strains with differential specificity on cherry and plum. The ability of tractable laboratory‐based assays to reproduce assessments on whole trees was examined. Good correlations were achieved with assays using cut shoots or leaves, although only the cut shoot assay was able to reliably discriminate cultivar differences seen in the field. Measuring bacterial multiplication in detached leaves differentiated pathogens from nonpathogens and was therefore suitable for routine testing. In cherry leaves, symptom appearance discriminated Psm races from nonpathogens, which triggered a hypersensitive reaction. Pathogenic strains of Pss rapidly induced disease lesions in all tissues and exhibited a more necrotrophic lifestyle than hemibiotrophic Psm. This in‐depth study of pathogenic interactions, identification of host resistance and optimization of laboratory assays provides a framework for future genetic dissection of host–pathogen interactions in the canker disease.  相似文献   

12.
A collection of 205 strains ofErwinia amylovora isolated in Israel over a period of 12 years has been established. The strains were isolated from different varieties of pear, apple, loquat and quince grown in Israel, and collected from different locations in the country. They were characterized in respect to degree of virulence on several hosts and serological and molecular characters. Pathogenicity tests carried out on flowering branches of pear and apple, shoots of pears, and on trees of pear and loquat grown in containers outdoors, revealed no significant differences in the severity of blossom blight or shoot blight among the various strains. ELISA and immunofluorescence assays revealed no serotypic groups among the Israeli strains. Genomic diversity was studied by random amplified polymorphic DNA (RAPD) analysis using 24 arbitrary 10-base primers. All the strains examined (45 Israeli and 11 from Egypt, Cyprus and Greece) produced the same RAPD patterns with each of the primers used. Amplification patterns were indistinguishable from those produced by strains isolated from the neighboring countries. Results presented in this study suggest that the population ofE. amylovora in Israel is homogenous.  相似文献   

13.
We have previously shown that flagellin of Pseudomonas syringae pv. tabaci is an elicitor that induces a hypersensitive reaction (HR) in nonhost tomato cells. Flagellin is the major HR elicitor produced by this pathogen, as shown by the inability of a flagellin-defective mutant, ΔfliC, to induce HR. Also, a ΔfliD mutant that secretes large amounts of monomer flagellins induces a strong HR in tomato. In this study, the possible involvement of an Hrp type III secretion system (TTSS) in flagellin-induced HR was investigated using flagella-defective mutants or Hrp TTSS-defective mutants. The hrcC gene encodes HrcC protein, which is required for Hrp pilus formation in the outer membrane. An hrcC mutation, introduced into the wild-type, ΔfliC, and ΔfliD mutants of P. syringae pv. tabaci did not affect swimming motility or flagellin secretion, whereas all ΔhrcC, ΔfliC, and ΔfliD mutants lost the ability to cause disease on host tobacco leaves. However, the ΔhrcC mutant and the ΔfliD/ΔhrcC double mutant were still able to induce HR cell death, expression of one of the defense-related genes hsr203J, and the generation of hydrogen peroxide in nonhost tomato cells. Thus, flagellin is required for both pathogenicity in host tobacco and HR in nonhost tomato. On the other hand, hrp TTSS is necessary for pathogenicity on host tobacco but is not indispensable to induce HR in nonhost tomato. These results clearly show that flagellin-induced HR is hrp-independent in tomato.The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under the accession number AB049570  相似文献   

14.
Pseudomonas syringae pv. papulans (PSP) the causal agent of blister spot, on the apple cultivar Mutsu in the USA, Canada and Italy, has not been described in France. A study on epiphytic populations of P. syringae isolated from French apple orchards revealed two isolates called KA54 and E121, whose biochemical characterisation showed high similarities with PSP strains. Identical symptoms were obtained with KA54, E121 and PSP strains, after vacuum inoculation of detached immature fruits of the cultivar Fuji, and young leaves of the cultivars Fuji, Mutsu, Gala and Golden Delicious. Koch's postulate was verified. These results indicate the presence of PSP in France. Differential characterisation criteria including serological, molecular and pathogenicity tests are proposed.  相似文献   

15.
Copper-containing bactericides have been used to control bacterial canker of kiwifruit, caused by Pseudomonas syringae pv. actinidiae. However, the efficacy of copper has been reduced by the occurrence of copper-resistant strains. Analysis of the DNA sequence of a cluster region containing the copper-resistance genes from P. syringae pv. actinidiae suggested the presence of three possible different systems for copper resistance: copper-trapping, copper-efflux and copper-transport systems. Transposon insertional inactivation analysis indicated that the copper-trapping system was essential for copper resistance.  相似文献   

16.
Bacterial canker is one of the most important diseases of cherry (Prunus avium). This disease can be caused by two pathovars of Pseudomonas syringae: pv. morsprunorum and pv. syringae. Repetitive DNA polymerase chain reaction-based fingerprinting (rep-PCR) was investigated as a method to distinguish pathovars, races and isolates of P. syringae from sweet and wild cherry. After amplification of total genomic DNA from 87 isolates using the REP (repetitive extragenic palindromic), ERIC (enterobacterial repetitive intergenic consensus) and BOX primers, followed by agarose gel electrophoresis, groups of isolates showed specific patterns of PCR products. Pseudomonas syringae pv. syringae isolates were highly variable. The differences amongst the fingerprints of P. syringae pv. morsprunorum race 1 isolates were small. The patterns of P. syringae pv. morsprunorum race 2 isolates were also very uniform, with one exception, and distinct from the race 1 isolates. rep-PCR is a rapid and simple method to identify isolates of the two races of P. syringae pv. morsprunorum; this method can also assist in the identification of P. syringae pv. syringae isolates, although it cannot replace inoculation on susceptible hosts such as cherry and lilac.  相似文献   

17.
Occurrence of Pseudomonas syringae pv. actinidiae on kiwifruit in Italy   总被引：2，自引：0，他引：2  
Pseudomonas syringae pv. actinidiae has been isolated from kiwifruit plants for the first time in Italy. Biochemical tests were consistent with those characterizing the type-strain; pathogenicity tests yielded severe blights in the inoculated kiwifruit plants and no symptoms on lilac, pear and peach. Nutritional tests as well as whole-cell protein profiles revealed slight differences between the strains isolated in Japan and those of the present study. The main symptoms observed in the field are a red-rusty exudation covering the bark of twigs and trunks, blight of young canes and plants, angular leaf spots surrounded by chlorotic haloes and tiny cankers along the twigs.  相似文献   

18.
The pathogenicity and taxonomy of 15 isolates of Alternaria spp. from pear and apple were compared. Only isolates from Asian pear ( Pyrus pyrifolia ) from Italy and Korea were virulent on leaves and young fruits of the susceptible Asian pear cv. Nijisseiki. Their conidial morphology was typical of A. gaisen (= A. kikuchiana ). Only isolates of A. mali from USA were virulent on susceptible American apple cvs Indo and Red Gold. No virulence was demonstrated in any isolate/host combination among isolates from stem infections of Asian and European pear ( Pyrus communis ), leaf spots of European apple, and ripe fruit rots of Chinese pear ( Pyrus ussuriensis ), European pear and apple. These non-virulent isolates could be readily distinguished from A. gaisen and A. mali by their pattern of branching of conidial chains, the branching associated with A. alternata sensu stricto being most common among non-virulent isolates. This limited survey implies that A. gaisen is only virulent to Asian pear and the toxigenic form of A. mali to certain American apple cultivars; also that A. gaisen is not established outside eastern Asia or the toxigenic form of A. mali outside eastern Asia and parts of USA.  相似文献   

19.
A bacterial strain, CFBP 3388, isolated from Vetch (Vicia sativa, L.) was identified asP. s. pv.syringae on the basis of nutritional and biochemical patterns which were obtained with classical tests and the Biolog system. It caused necrotic symptoms typical ofP. s. pv.syringae on bean leaves and pods after artificial inoculation. However, the isolate caused a citrulline-reversible inhibition ofE. coli in phaseolotoxin bioassay. Furthermore, with CFBP 3388 DNA as template a 1900 bp DNA fragment, specific for the phaseolotoxin DNA cluster ofP. s. pv.phaseolicola, was amplified by PCR. This is the first demonstration that an isolate ofP. syringae that is not pv.phaseolicola can produce phaseolotoxinAbbreviations bp base pair - kb kilobase - OCT Ornithine Carbamoyl Transferase  相似文献   

20.
Bacterial canker is a major disease of stone fruits and is a critical limiting factor to sweet cherry (Prunus avium) production worldwide. One important strategy for disease control is the development of resistant varieties. Partial varietal resistance in sweet cherry is discernible using shoot or whole tree inoculations; however, these quantitative differences in resistance are not evident in detached leaf assays. To identify novel sources of resistance to canker, we used a rapid leaf pathogenicity test to screen a range of wild cherry, ornamental Prunus species and sweet cherry × ornamental cherry hybrids with the canker pathogens, Pseudomonas syringae pvs syringae, morsprunorum races 1 and 2, and avii. Several Prunus accessions exhibited limited symptom development following inoculation with each of the pathogens, and this resistance extended to 16 P. syringae strains pathogenic on sweet cherry and plum. Resistance was associated with reduced bacterial multiplication after inoculation, a phenotype similar to that of commercial sweet cherry towards nonhost strains of P. syringae. Progeny resulting from a cross of a resistant ornamental species Prunus incisa with susceptible sweet cherry (P. avium) exhibited resistance indicating it is an inherited trait. Identification of accessions with resistance to the major bacterial canker pathogens is the first step towards characterizing the underlying genetic mechanisms of resistance and introducing these traits into commercial germplasm.  相似文献   

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