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1.
During recent years, recurrent attacks of basal glume rot/leaf blight attributed to Pseudomonas syringae pv. atrofaciens have been observed on cultivars of durum wheat grown in the Po valley (IT). The main aim of this study was to test for this pathogen and Xanthomonas campestris pathovars in commercial seed lots of cereals produced in different regions of Italy, as well as in symptomatic plants collected in the field. None of the analyses led to the detection of xanthomonads. In testing for P.s. atrofaciens , representative bacterial isolates were selected and characterized; this was done by combining conventional identification tests and computerized densitometric analysis of electrophoretic patterns of cell proteins obtained using the SDS-PAGE technique. P.s. atrofaciens was detected in seed samples (barley, wheat and durum wheat) and symptomatic plants (durum wheat) grown in northern and central Italy. The possible pathogenic role of other unrelated fluorescent pseudomonads in this interaction was also examined. Difficulties in discriminating pvs syringae and atrofaciens of P. syringae are discussed and the uncertain taxonomic relationship between these two pathovars is emphasized. 相似文献
2.
ABSTRACT In 1993, a bacterial blight caused important losses of cantaloupe (Cucumis melo var. cantalupensis) in southwestern France and has now been reported in all cantaloupe-growing regions of France. The causal agent of this blight is Pseudomonas syringae, although on a worldwide basis this bacterium has not been a major pathogen of melon for over 50 years. To identify the pathovar of the cantaloupe pathogen, we employed biochemical tests, plasmid and chromosomal profiling, and host range studies for 23 strains from cantaloupe and 47 reference strains of 14 pathovars of P. syringae. Numerical analysis of 119 traits, serological typing, syringomycin production, and BOX-polymerase chain reaction profiles did not allow us to differentiate among pathovars related to P. syringae pv. syringae. Host range studies of cantaloupe and references strains on 18 plant species showed that virulence to sugar beet was a common feature of strains virulent on cantaloupe, but was not common to strains avirulent on cantaloupe. Virulence to other species of plants varied among strains, but the overall extent of the host range was proportional to aggressiveness to cantaloupe. We propose that the strains attacking cantaloupe in France be considered P. syringae pv. aptata and that adequate host range testing may reveal that this pathovar is the cause of cantaloupe blight reported in other parts of the world. 相似文献
3.
The recent finding that syringomycin (SR) and syringotoxin (ST)-producing isolates of Pseudomonas syringae pv. syringae also synthesize syringopeptins (SPs), another class of phytotoxic lipodepsipeptides, prompted studies of the biological properties and comparisons of the activities of the two groups of metabolites. The present paper reports the effects of two forms of SP on stomatal movement in detached leaves of Xanthium strumarium and in epidermal strips of Vicia faba and shows that these phytotoxins, as does the previously investigated SR, promote stomatal closure. SPs are at least 10-fold more efficient than SR in both tissues. In epidermal strips, the toxin-induced closure was not reversed by fusicoccin, a fungal metabolite that reversed the closing effects of abscisic acid. As reported in previous papers, these amphiphilic toxins affect several functions of biological membranes. A marked decrease in the rate of photosynthesis recorded in X. strumarium leaves treated with SPs is consistent with effects on biological membranes. 相似文献
4.
豆薯细菌性角斑病的病原鉴定 总被引：2，自引：1，他引：1
在安徽滁州的豆薯叶片上发现一种由细菌侵染引起角斑症状的病害,从角斑上分离到具有致病性的非荧光的杆状细菌,菌株的表型特征、细菌学特征、LOPAT试验和生理生化试验表明该细菌与丁香假单胞菌(Pseudomonas syringae van Hall)相似,BIOLOG系统鉴定结果与丁香假单胞菌豌豆致病变种(P.syringae pv.pisi)相近,接种试验表明豆薯菌株能侵染大豆、菜豆和眉豆,但对豌豆的致病性差;在豇豆、绿豆和蚕豆上不表现症状。结果表明豆薯细菌性角斑病是一种新病害,病原菌属于丁香假单胞菌群的一个新的致病变种,命名为P.syringae pv.pachyrhizus nov. 相似文献
5.
Activation of systemic disease resistance in pea by an avirulent bacterium or a benzothiadiazole, but not by a fungal leaf spot pathogen 总被引：4，自引：0，他引：4
Inoculation of first expanded leaves of pea seedlings with an avirulent strain of Pseudomonas syringae pv. pisi , or treatment with sprays of a benzothiadiazole (20 or 100 μ g a.i. mL−1 ), decreased the susceptibility of subsequent leaves 7 or 14 days later to challenge inoculation with Mycosphaerella pinodes . Inoculation of first leaves with a virulent strain of P. syringae pv. pisi or with M. pinodes did not decrease the susceptibility of plants to M. pinodes . Treatments effective in decreasing susceptibility to M. pinodes were similarly active against Uromyces viciae-fabae and virulent P. syringae pv. pisi . Effective treatments also enhanced the activities of the enzymes β-1,3-glucanase and chitinase in untreated upper leaves 6 days later. Ineffective treatments for decreased susceptibility had no effect on the activity of the enzymes. None of the treatments enhanced peroxidase activities. The results are discussed in relation to the reported signalling effects of the benzothiadiazole and in relation to a suggested high activity of the avirulent P. syringae pv. pisi strain and inactivity of M. pinodes in enhancing natural signalling. 相似文献
6.
H. Olczak-Woltman A. Masny G. Bartoszewski A. P&#;ucienniczak K. Niemirowicz-Szczytt 《Plant pathology》2007,56(3):373-382
Several strains of Pseudomonas syringae pathovar (pv.) lachrymans and related bacterial pathogens were isolated from cucumber ( Cucumis sativus ) leaves collected in central and southern Poland in 2001 and 2002. Twenty five original strains, together with five reference strains of P. syringae pv. lachrymans , pv. syringae and pv. tomato , were genetically characterized by PCR-RFLP (polymerase chain reaction − restriction fragment length polymorphism), ADSRRS (amplification of DNA fragments surrounding rare restriction sites), and PCR-MP (PCR − melting profiles) fingerprinting techniques. Genetic similarity analyses of the PCR-RFLP and ADSRRS fingerprints showed that strains of P. syringae pv. lachrymans form distinct clusters. The results also indicated that the ADSRRS and the PCR-MP fingerprinting techniques may serve as more efficient tools for evaluating genetic similarity among pathovars and strains of P. syringae than PCR-RFLP. The 25 strains showed diverse pathogenicity to cucumber seedlings and biochemical tests were varied. The syrB gene was identified in four cucumber strains, characterized as P. syringae pv. syringae . 相似文献
7.
8.
广东南瓜细菌性叶枯病及其病原鉴定 总被引：1，自引：0，他引：1
在广东省雷州市发生一种南瓜(Cucurbita moschata)叶枯病,病株叶片边缘开始出现水渍状病斑,逐步发展成大病斑,后期病斑焦枯;在叶片上也可形成近圆形水渍状病斑,伴有黄色晕圈,后期病斑联合形成不规则大枯斑;叶柄和匍匐茎被侵染后呈水渍状腐烂。从病斑上分离到一种细菌,在KB培养基上,菌落为椭圆形,乳白色,半透明,边缘参差不齐,紫外灯照射下产生荧光反应。致病性测定结果表明,该病原细菌可侵染6个南瓜品种引起与田间症状相同的叶枯病。生理生化试验结果表明,该病原细菌与丁香假单胞丁香致病变种(Pseudomonas syringae pv. syringae)的特性一致。应用假单胞菌属特异引物Ps-for/Ps-rev和丁香假单胞丁香致病变种组群特异性引物Group III-F/Group III-R,可从该病原细菌中扩增出预期大小分别为1 018 bp和750 bp的目的片段。应用丁香致病变种syrB基因特异性引物B1/B2,可从该病原菌中扩增出预期大小为750 bp的丁香霉素基因片段。基于16S rDNA与gyrB基因序列系统进化分析均表明,南瓜叶枯病菌株与已报道的P. syringae pv. syringae菌株HS191(CP006256)亲缘关系最近,二者聚类在一起形成一个小分支。人工接种条件下,该病原细菌还可侵染西葫芦、丝瓜、茄子、番茄、菜豆、扁豆等植物。这些结果表明,引起广东省南瓜叶枯病的病原为丁香假单胞丁香致病变种(Pseudomonas syringae pv. syringae)。这是首次在中国发现丁香假单胞丁香致病变种引起南瓜叶枯病。 相似文献
9.
ABSTRACT The dynamics of the adherent and nonadherent populations of three bacterial species on maize leaves were examined to identify the extent to which bacteria adhere to leaves and the importance of this adhesion to leaf colonization. Pantoea agglomerans strain BRT98, Clavibacter michiganensis subsp. nebraskensis strain GH2390, and Pseudomonas syringae pv. syringae strain HS191R all rapidly adhered to maize leaves following inoculation, but differed in the percentage of cells that adhered to the leaves. Immediately following inoculation, the percentage of adherent cells was highest for the saprophyte P. agglomerans (8 to 10%) and was much lower for the pathogens C. michiganensis subsp. nebras-kensis and P. syringae pv. syringae (2 to 3 and <1%, respectively), although the results for P. syringae pv. syringae HS191R were based on only one experiment. In the 4 days following inoculation, the percentage of the P. agglomerans populations that adhered to the leaves increased to approximately 70%. Similarly, the percentage of C. michiganensis subsp. nebraskensis and P. syringae pv. syringae cells that resisted removal steadily increased in the days following inoculation, although these increases probably reflected both adherence and localization to endophytic sites. Based on differences in the percentage of cells adhering to several cuticular wax mutants of maize, the rapid adherence of C. michiganensis subsp. nebraskensis cells to maize leaves was influenced by the cuticular wax properties, while the rapid adherence of P. agglomerans was not. Finally, bacterial adherence to leaves was advantageous to P. agglomerans survival and growth on leaves based on the finding that the nonadherent populations of the P. agglomerans strain decreased significantly more than did the adherent populations in the 24 h following inoculation, and increased much less than did the adherent populations over the next 3 days. Similar results with the C. michiganensis subsp. nebraskensis and P. syringae pv. syringae strains indicate that bacterial adherence to leaves, bacterial movement to endophytic sites, or both were advantageous to the survival and growth of these strains on leaves. 相似文献
10.
Cazorla FM Torés JA Olalla L Pérez-García A Farré JM de Vicente A 《Phytopathology》1998,88(7):614-620
ABSTRACT A necrotic bacterial disease of mango trees (Mangifera indica) in Spain affecting buds, leaves, and stems is described for the first time. Necrosis of flower and vegetative buds on commercial trees during winter dormancy was the most destructive symptom of the disease. The apical necrosis is caused by Pseudomonas syringae, which was always isolated from mango trees with disease symptoms. Of 95 bacterial strains isolated from symptomatic tissues and characterized from 1992 to 1997, over 90% were identified as P. syringae pv. syringae. Additional strains were isolated from healthy mango trees, and they were identical to the isolates from diseased tissues. Pathogenicity tests on mango plants showed that P. syringae pv. syringae incited the apical necrosis, but that climatic conditions determined the onset of disease development. Populations of total bacteria and of P. syringae and the number of active ice nuclei were monitored over a 3-year period. The largest populations of P. syringae were associated with cool, wet periods that coincided with the highest disease severity, whereas P. syringae was only occasionally detected on healthy trees. The median effective dose was estimated from infectivity titration assays. 相似文献
11.
黄瓜细菌性角斑病是我国黄瓜生产上的重要病害之一,其病原菌为Pseudomonas syringae pv.lachrymans。根据该病原菌甘油醛-3-磷酸脱氢基因保守序列设计引物和探针,建立了交叉引物恒温扩增和核酸试纸条检测技术。菌体DNA检测灵敏度可达0.55 ng,纯菌直接检测灵敏度基本可达到单个细菌。所测试的5株黄瓜细菌性角斑病菌和染病黄瓜叶片均为阳性,其他13株对照菌株均为阴性。该方法灵敏度高,且操作简单,对设备要求低等,适合基层实验室应用。 相似文献
12.
ABSTRACT Strains of Pseudomonas syringae pv. pisi and Ralstonia solanacearum produced ethylene at rates 20- and 200-fold lower, respectively, than strains of P. syringae pvs. cannabina, glycinea, phaseolicola, and sesami. In the current study, we investigated which ethylene biosynthetic pathways were used by P. syringae pv. pisi and R. solanacearum. Neither the activity of an ethylene-forming enzyme nor a corresponding efe gene homolog could be detected in R. solanacearum, suggesting synthesis of ethylene via 2-keto-4-methyl-thiobutyric acid. In contrast, 2-oxoglutarate-dependent ethylene formation was observed with P. syringae pv. pisi, and Southern blot hybridization revealed the presence of an efe homolog in this pathovar. The efe genes from P. syringae pvs. cannabina, glycinea, phaseolicola, pisi, and sesami were sequenced. Nucleotide sequence comparisons indicated that the efe gene in pv. pisi was not as highly conserved as it was in other P. syringae pathovars. The pv. pisi efe homolog showed numerous nucleotide substitutions and a deletion of 13 amino acids at the C-terminus of the predicted gene product. These sequence alterations might account for the lower rate of ethylene production by this pathovar. All ethylene-producing P. syringae pathovars were virulent on bush bean plants. The overlapping host range of these pathovars suggests that horizontal transfer of the efe gene may have occurred among bacteria inhabiting the same host. 相似文献
13.
ABSTRACT The identification and detection of Pseudomonas syringae pv. papulans, the causal agent of blister spot of apple, on apple leaves and fruit was achieved by polymerase chain reaction amplification of a specific DNA fragment of the hrpL sequence. The consensus primers hrpL(1) and hrpL(2) were designed based on the alignment of pseudomonad hrpL gene sequences available in nucleic acid data banks. This primer set produced a 631-bp amplicon from 37 of the 57 pseudomonads strains tested. These strains belonged to genomospecies 1 and 2, as described by Gardan et al. (8). The amplicon obtained from 30 of these strains was digested with eight restriction enzymes. Three different restriction patterns were produced from strains belonging to genomospecies 1, resulting in A1 and A2 patterns, while strains belonging to genomospecies 2 were characterized by a B pattern. Patterns A1 and A2 differed at only two sites, a Bsp 143I site located at nucleotide 360 and a MseI site located at nucleotides 22-24. Group A2 consisted solely of P. syringae pv. papulans strains. The hrpL gene in P. syringae pv. papulans strain CFBP3323 was sequenced. Two primer sets, Pap1/Pap2 and Pap1/Pap3, were designed and tested for specificity to P. syringae pv. papulans. These primers amplified expected fragments of 242 and 303 bp, respectively. Pap1/Pap2 amplified a fragment only with P. syringae pv. papulans DNA, while Pap1/Pap3 amplified all tested strains belonging to genomospecies 1. A diagnostic procedure using the Pap1/Pap2 primer set was successful for the detection of P. syringae pv. papulans in diseased fruit and artificially inoculated leaves. 相似文献
14.
A study on the pathogenicity of 81 strains of Pseudomonas syringae pv. syringae (PSS) isolated from 16 different hosts was conducted on lilac plants, bean pods and pear seedlings, using artificial inoculation.
Only 55 among the 81 strains induced a necrotic lesion when inoculated on lilac leaves. On bean pods, all but one of the bean isolates, and only eight strains among the 52 strains isolated from other hosts, induced typical green water-soaked lesions. On pear leaves, only pear isolates incited a typical progressive necrotic reaction, the isolates from other origins inducing no symptoms or a weak reaction limited to the inoculation point. This study indicates that in addition to the large variability observed in aggressiveness of PSS strains, host specificity occurred on bean and pear. 相似文献
Only 55 among the 81 strains induced a necrotic lesion when inoculated on lilac leaves. On bean pods, all but one of the bean isolates, and only eight strains among the 52 strains isolated from other hosts, induced typical green water-soaked lesions. On pear leaves, only pear isolates incited a typical progressive necrotic reaction, the isolates from other origins inducing no symptoms or a weak reaction limited to the inoculation point. This study indicates that in addition to the large variability observed in aggressiveness of PSS strains, host specificity occurred on bean and pear. 相似文献
15.
ABSTRACT Bacterial speck of tomato, caused by Pseudomonas syringae pv. tomato, continues to be a problem for tomato growers worldwide. A collection of nonpathogenic bacteria from tomato leaves plus P. syringae strains TLP2 and Cit7, P. fluorescens strain A506, and P. syringae pv. tomato DC3000 hrp mutants were examined in a greenhouse bioassay for the ability to reduce foliar bacterial speck disease severity. While several of these strains significantly reduced disease severity, P. syringae Cit7 was the most effective, providing a mean level of disease reduction of 78% under greenhouse conditions. The P. syringae pv. tomato DC3000 hrpA, hrpH, and hrpS mutants also significantly reduced speck severity under greenhouse conditions. The strains with the greatest efficacy under greenhouse conditions were tested for the ability to reduce bacterial speck under field conditions at locations in Alabama, Florida, and Ontario, Canada. P. syringae Cit7 was the most effective strain, providing a mean level of disease reduction of 28% over 10 different field experiments. P. fluorescens A506, which is commercially available as Blight-Ban A506, provided a mean level of disease reduction of 18% over nine different field experiments. While neither P. syringae Cit7 nor P. fluorescens A506 can be integrated with copper bactericides due to their copper sensitivity, there exist some potential for integrating these biological control agents with "plant activators", including Actigard. Of the P. syringae pv. tomato DC3000 hrp mutants tested, only the hrpS mutant reduced speck severity significantly under field conditions. 相似文献
16.
17.
Since 2002, severe leaf spotting on parsley (Petroselinum crispum) has occurred in Monterey County, CA. Either of two different pathovars of Pseudomonas syringae sensu lato were isolated from diseased leaves from eight distinct outbreaks and once from the same outbreak. Fragment analysis of DNA amplified between repetitive sequence polymerase chain reaction; 16S rDNA sequence analysis; and biochemical, physiological, and host range tests identified the pathogens as Pseudomonas syringae pv. apii and P. syringae pv. coriandricola. Koch's postulates were completed for the isolates from parsley, and host range tests with parsley isolates and pathotype strains demonstrated that P. syringae pv. apii and P. syringae pv. coriandricola cause leaf spot diseases on parsley, celery, and coriander or cilantro. In a multilocus sequence typing (MLST) approach, four housekeeping gene fragments were sequenced from 10 strains isolated from parsley and 56 pathotype strains of P. syringae. Allele sequences were uploaded to the Plant-Associated Microbes Database and a phylogenetic tree was built based on concatenated sequences. Tree topology directly corresponded to P. syringae genomospecies and P. syringae pv. apii was allocated appropriately to genomospecies 3. This is the first demonstration that MLST can accurately allocate new pathogens directly to P. syringae sensu lato genomospecies. According to MLST, P. syringae pv. coriandricola is a member of genomospecies 9, P. cannabina. In a blind test, both P. syringae pv. coriandricola and P. syringae pv. apii isolates from parsley were correctly identified to pathovar. In both cases, MLST described diversity within each pathovar that was previously unknown. 相似文献
18.
ABSTRACT Successful spread of an organism to a new habitat requires both immigration to and growth on that habitat. Field experiments were conducted to determine the relative roles of dispersal (i.e., immigration) and bacterial multiplication in spread of Pseudomonas syringae pv. syringae in the phyllosphere. To study spread, individual plots consisted of three nested concentric squares with the inner 6 m(2) planted to snap beans serving as the sink. Each sink, in turn, was surrounded by a barrier zone, usually 6 m wide, which was surrounded by a 6-m-wide source area. The source areas were planted with snap bean seeds inoculated with doubly marked strains derived from wild-type P. syringae pv. syringae B728a. The treatments were designed to test the effects of the nature and width of the barrier zone and suitability of the habitat in the sinks on spread of P. syringae pv. syringae. The marked strains introduced into the source areas at the time of planting were consistently detected in sink areas within a day or two after emergence of bean seedlings in the sources as assessed by leaf imprinting and dilution plating. The amounts of spread (population sizes of the marked strain in sinks) across barrier zones planted to snap bean (a suitable habitat for growth of P. syringae pv. syringae), soybean (not a favorable habitat for P. syringae pv. syringae), and bare ground were not significantly different. Thus, the nature of the barrier had no measurable effect on spread. Similarly, spread across bare-ground barriers 20 m wide was not significantly different from that across barriers 6 m wide, indicating that distance on this scale was not a major factor in determining the amount of spread. The suitability of the sink for colonization by P. syringae pv. syringae had a measurable effect on spread. Spread to sinks planted to clean seed was greater than that to sinks planted with bean seeds inoculated with a slurry of pulverized brown spot diseased bean leaves, sinks planted 3 weeks before sources, and sinks planted to a snap bean cultivar that does not support large numbers of P. syringae pv. syringae. Based of these results, we conclude that the small amount of dispersal that occurred on the scale studied was sufficient to support extensive spread, and suitability of the habitat for multiplication of P. syringae pv. syringae strongly influenced the amount of spread. 相似文献
19.
A new bacterial disease of tall goldenrod (Solidago altissima L., “Seitaka-awadachiso” in Japanese), one of the most serious weeds in non-agricultural land, was discovered in Ibaraki Prefecture,
Japan. Characterized by angular or round, dark brown necrotic spots on leaves, this disease resulted in defoliation and terminal
dieback of the plants in severe cases. The disease was named “bacterial leaf spot”. The causal bacterium was identified as
Pseudomonas syringae based on its bacteriological properties including those determined by LOPAT tests. The present bacterium was pathogenic to
tall goldenrod alone but not to many other tested plants including weeds, flowers, trees and crops. In addition, P. syringae pv. syringae and other pathovars did not show any pathogenicity to tall goldenrod. Because no pathovars of P. syringae pathogenic to tall goldenrod have been reported, the present bacterium was concluded to be a new pathovar of P. syringae. We propose the name P. syringae pv. solidagae pv. nov. , and strain Sei 1 (MAFF 810063) is designated as the pathotype strain and has been deposited in the MAFF collection
with two reference strains (MAFF 810064 and MAFF81066).
Received 9 May 2001/ Accepted in revised form 18 June 2001 相似文献
20.
ABSTRACT Forty bacterial strains isolated from leek blight (Allium porrum) in France and other countries were studied by conventional biochemical methods, serological reactions, numerical taxonomy, DNA-DNA hybridization, and ice nucleation activity, as well as by pathogenicity on leek and other host plants. They were compared with reference strains of Pseudomonas, mainly pathotype strains of P. syringae pathovars and strains of P. syringae pv. syringae isolated from various host plants including onions. Leek strains sorted with P. syringae species (sensu lato) by LOPAT tests (production of levan-sucrase, oxidase, pectinase, arginine dihydrolase, and hypersensitive reaction on tobacco). Leek strains were pathogenic to leek and produced symptoms identical to those observed in the field. They were the only strains in our study that could cause blight of leek. Thus, our results justify the creation of a new pathovar. Leek strains constituted a highly homogeneous DNA group and a discrete phenon by numerical taxonomy, and they belonged to O-serogroup POR. The name of P. syringae pv. porri is proposed for the bacterium causing leek blight. Criteria for routine identification are presented and taxonomic status is discussed. 相似文献