Previous Article | Next Article 
Applied and Environmental Microbiology, October 1998, p. 3818-3823, Vol. 64, No. 10
Department of Plant Pathology, University of
California, Davis, California 95616
Received 30 January 1998/Accepted 16 July 1998
Strains of Pseudomonas syringae pv. syringae were
isolated from healthy and diseased stone fruit tissues sampled from 43 orchard sites in California in 1995 and 1996. These strains, together with P. syringae strains from other hosts and pathovars,
were tested for pathogenicity and the presence of the syrB
and syrC genes and were genetically characterized by using
enterobacterial repetitive intergenic consensus (ERIC) primers and PCR.
All 89 strains of P. syringae pv. syringae tested were
moderately to highly pathogenic on Lovell peach seedlings regardless of
the host of origin, while strains of other pathovars exhibited low or
no pathogenicity. The 19 strains of P. syringae pv.
syringae examined by restriction fragment length polymorphism analysis contained the syrB and syrC genes, whereas no
hybridization occurred with 4 strains of other P. syringae
pathovars. The P. syringae pv. syringae strains from stone
fruit, except for a strain from New Zealand, generated ERIC
genomic fingerprints which shared four fragments of similar mobility.
Of the P. syringae pv. syringae strains tested from other
hosts, only strains from rose, kiwi, and pear generated genomic
fingerprints that had the same four fragments as the stone fruit
strains. Analysis of the ERIC fingerprints from P. syringae
pv. syringae strains showed that the strains isolated from stone fruits
formed a distinct cluster separate from most of the strains isolated
from other hosts. These results provide evidence of host specialization
within the diverse pathovar P. syringae pv. syringae.
Bacterial canker and blast of
stone fruit trees, caused by Pseudomonas syringae pv.
syringae, affects all commercially grown Prunus species in
California including peach (Prunus persica), European plum
and French prune (P. domestica), Japanese plum (P. salicina), sweet cherry (P. avium), apricot
(P. armeniaca), and almond (P. dulcis). Losses
can result from a direct reduction in yield due to cold-induced blast
or death of buds and flowers or from tree decline and death due to the
development of cankers in branches and major scaffold limbs
(20).
P. syringae pv. syringae is unique among most P. syringae pathovars in its ability to cause disease in over 180 species of plants in several unrelated genera (1). Strains
of P. syringae pv. syringae are identified on the basis of
biochemical and nutritional tests and symptom expression in host
plants. In many cases, strains of P. syringae that are found
infecting a previously unreported host and are biochemically similar to
P. syringae pv. syringae strains have been placed in this
pathovar without establishment of a common host range (34).
The relationship between P. syringae pv. syringae strains
infecting Prunus species and strains that infect other crops
such as tomato, cereals, citrus, and kiwi fruit is unknown and needs to
be elucidated. Biochemical tests are not reliable for differentiating strains at or below the pathovar level (12, 25), and
pathogenicity tests in greenhouses are not reliable indicators of
natural host preferences (2). Peach seedlings
(22) and cowpea leaves (14) were found to
be susceptible to P. syringae pv. syringae strains from
various hosts. There is, however, evidence of host specificity among P. syringae pv. syringae strains infecting beans
(26, 27) and grasses (10) based on the results of
pathogenicity tests.
Molecular analysis of genomic variability has been used to
differentiate and classify bacterial strains below the level of species. Analysis of restriction fragment length polymorphisms (RFLP)
of the chromosomal DNA of P. syringae strains detected differences between and within the pathovars (5, 11, 16). More recently, enterobacterial repetitive intergenic consensus (ERIC) sequences and repetitive extragenic palindromic (REP)
sequences, which are short repetitive DNA sequences with highly
conserved central inverted repeats that are dispersed throughout the
genomes of diverse bacterial species (32), have been used to
design universal PCR primers that generate highly reproducible,
strain-specific fingerprints that can differentiate bacterial strains
below the level of species or subspecies (4, 19).
The objective of this study was to identify and characterize strains of
P. syringae pv. syringae isolated from various
Prunus species and other plant hosts by using pathogenicity
testing and RFLP and ERIC-PCR analyses.
Bacterial strains.
The bacterial strains used in this study
are listed in Table 1. Many of these
strains have been well characterized in previous pathogenicity,
biochemical, and genetic studies (6, 9, 23). Strains were
maintained in 15% glycerol at
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Genetic Characterization of Pseudomonas
syringae pv. syringae Strains from Stone Fruits in
California
ABSTRACT
Top
Abstract
Introduction
Materials & Methods
Results
Discussion
References
INTRODUCTION
Top
Abstract
Introduction
Materials & Methods
Results
Discussion
References
MATERIALS AND METHODS
Top
Abstract
Introduction
Materials & Methods
Results
Discussion
References
80°C and subcultured on King's
medium B (KB) (13) as needed.
TABLE 1.
Bacterial strains used in this study
Strain isolation. In 1995 and 1996, samples of both healthy and diseased tissues from stone fruit trees were collected from orchard sites in the Sacramento and San Joaquin valleys of California. Samples included healthy flowers, healthy and diseased dormant buds, diseased leaves, twigs, and branches. In addition, samples of weeds were collected during the winter of 1996 from orchards with a history of bacterial canker. Healthy tissues were washed in 0.01 M potassium phosphate buffer (PB) with 0.02% Tween 20 (ca. 3 g of flowers or 5 g of dormant twigs/25 ml of PB; 5 g of weed leaf tissue/100 ml of PB) on a platform shaker at 250 rpm for 30 min, and 100 µl of the wash liquid was spread onto KB plates containing 50 µg of cycloheximide per ml. Three to five healthy buds were ground in 2 ml of PB in a Pyrex tissue grinder, and 100 µl of either undiluted or 1:10-diluted (in PB) wash liquid was plated onto KB or KB with 50 µg of cycloheximide per ml. Diseased tissues were surface sterilized in 0.5% sodium hypochlorite for 1 min, rinsed in sterile water, and ground in a small amount of PB, and the liquid suspension was spread onto KB. The plates were incubated for 3 days, and then blue fluorescent colonies were counted, purified, and tested for the oxidase reaction, the ability to rot potato slices, the presence of arginine dihydrolase, levan production, and tobacco hypersensitivity (17).
Pathogenicity tests. Bacterial cells grown for 24 h on solid KB at 24°C were suspended in PB to a concentration of ~5 × 107 CFU/ml. Bacterial suspensions (~0.1 ml) were injected into the stems of 10- to 12-week-old Lovell peach seedlings by using a 22-gauge needle inserted tangentially under the cambium. PB was injected as a control. The plants were maintained in a greenhouse at 28°C and rated after 10 days for disease development on a scale of 0 to 3 as follows: 0, light necrosis associated with wounding at the area of inoculation; 1, dark, water-soaked necrosis confined to the immediate area of inoculation, with some streaking in the cambium; 2, streaking in the cambium extending away from the site of inoculation, necrosis around the wound up to 2 mm above and below the wound with gumming; and 3, necrotic lesion and streaking involving the entire stem, often with girdling and death of distal portions and extensive gumming. Each seedling was inoculated in three places with a strain, and an average pathogenicity rating for each strain was used to determine the mean and standard deviation of the pathogenicity for all strains isolated from a particular host.
DNA preparation. Total genomic DNA was extracted from 10 ml of 24-h shake cultures of bacterial cells. After centrifugation at 10,000 × g for 10 min, the bacterial pellet was resuspended in 1.5 ml of buffer (100 mM Tris-HCl [pH 7.5], 100 mM EDTA [pH 8.0]). Freshly prepared lysozyme (Sigma, St. Louis, Mo.) was added to a final concentration of 25 µg/ml, the volume of the solution was brought to 3 ml with sterile distilled water, and the mixture was incubated on ice for 10 min. Sodium dodecyl sulfate and proteinase K (Gibco BRL, Gaithersburg, Md.) were added to final concentrations of 1% and 200 µg/ml, respectively. The suspension was incubated for 1 h at 50°C and extracted four times with 5 ml of phenol-chloroform (1:1). The nucleic acids were precipitated with 0.1 volume of 3 M sodium acetate (pH 5.2)-1 volume of isopropanol, washed in 70% ethanol, and resuspended overnight in 200 µl of TE buffer (10 mM Tris-HCl [pH 7.5], 1 mM EDTA [pH 8.0]) with 30 µg of RNase (Amresco, Solon, Ohio) per ml. The DNA solution was extracted again with an equal volume of phenol-chloroform (1:1) followed by an equal volume of chloroform-isoamyl alcohol (24:1). The nucleic acids were precipitated with 0.1 volume of sodium acetate-2 volumes of 100% ethanol, rinsed in 70% ethanol, and resuspended in 200 µl of TE buffer. DNA concentrations were determined with a TKO 100 fluorometer (Hoefer Scientific Instruments, San Francisco, Calif.).
RFLP analysis. Approximately 1 µg of total genomic DNA was digested at 37°C overnight with EcoRI (Pharmacia Biotech, Uppsala, Sweden), and nucleic acid fragments were electrophoresed in 1% agarose gels at 45 V for 5 to 6 h with TAE (0.04 M Tris acetate, 0.001 M EDTA). The DNA was transferred to Nytran (Schleicher & Schuell, Keene, N.H.) nylon membranes, and Southern hybridization analysis was performed as previously described (8) with a [32P]dATP-labeled 7-kb HindIII fragment containing the syrB and syrC genes from plasmid p601D, which was kindly provided by D. Gross (23). The size of restriction fragment(s) that hybridized with the probe was estimated relative to the mobility of 1-kb DNA standards (Gibco BRL).
Oligonucleotide primers and PCR conditions.
ERIC
oligonucleotide primers (ERIC1R [5'-ATGTAAGCTCCTGGGGATTCAC-3']
and ERIC2 [5'-AAGTAAGTGACTGGGGTGAGCG-3']) were
purchased from Oligos Etc. (Wilsonville, Oreg.). The PCR conditions
were as previously described (21, 32). Bacterial strains
were streaked onto plates of KB and incubated for 2 days at 25°C. A
small portion of a single colony was transferred to 25 µl of a PCR
mixture containing 50 pmol of each primer, 1.25 mM each deoxynucleoside
triphosphate, 10% dimethyl sulfoxide, 4 µg of bovine serum albumin
(Boehringer Mannheim, Indianapolis, Ind.), 2 U of AmpliTaq
DNA polymerase (Perkin-Elmer Cetus, Norwalk, Conn.), 16.6 mM ammonium
sulfate, 67 mM Tris HCl (pH 8.0), 6.7 mM magnesium chloride, 6.7 µM
EDTA, and 30 mM 
-mercaptoethanol. The mixture was overlaid with
silicone oil (Aldrich Chemicals, Milwaukee, Wis.), and PCR was
performed in a no. 480 DNA thermal cycler (Perkin-Elmer Cetus) under
the following conditions: 1 cycle at 95°C for 6 min; 35 cycles at 94°C for 1 min, 52°C for 1 min, and 65°C for 8 min; and a final extension cycle at 68°C for 16 min. Aliquots (8 µl) of the reaction mixture were electrophoresed on 1.5% TAE agarose gels at room temperature at 5 V/cm for 4 h. The DNA fragments in the gel were visualized by staining with ethidium bromide.
Data analysis. The amplified fragments of each strain were scored as 1 (present) or 0 (absent), and pairwise comparisons were made of each unique pattern by using the Jaccard similarity coefficient (30) and the NTSYS program (Exeter Software, Setauket, N.Y.). A similarity matrix was generated by using the unweighted pair-group method with averages. Phenograms were constructed with the tree display option (TREE). A cophenetic value matrix was calculated by using the COPH option and compared with the original similarity matrix by using the MXCOMP option to test the goodness of fit of the cluster analysis.
| |
RESULTS |
|---|
|
Top
Abstract
Introduction
Materials & Methods
Results
Discussion
References
|
|---|
Strain collection and identification. Ninety-one strains of P. syringae pv. syringae collected from 43 almond, prune, plum, peach, apricot, and cherry orchard sites in the San Joaquin and Sacramento valleys were used in this study. Each strain was collected from separate tissue samples within an orchard site. The bacterium was detected in diseased samples and as an epiphyte on apparently healthy twigs, flowers, and buds. In addition, P. syringae pv. syringae was washed from the leaves of two weeds, a Geranium sp. and a Malva sp., that were growing in a prune orchard with trees showing symptoms of bacterial canker. All P. syringae pv. syringae strains used in this study were negative for oxidase, potato rotting, and arginine dihydrolase and positive for levan production and the hypersensitive response on tobacco.
A total of 76 strains of P. syringae pv. syringae isolated in 1995 and 1996 from Prunus hosts were tested for pathogenicity on Lovell peach seedlings. In addition, four strains from orchard weeds, nine strains from nine other hosts, and five strains of three other P. syringae pathovars were tested. All of the P. syringae pv. syringae strains were moderately to highly pathogenic on peach, as evidenced by a pathogenicity rating of 2 or more, except for wheat strain 61, which had a rating of 1.0. The stone fruit strains, together with the bean and lemon strains, had pathogenicity ratings in the range of 2.6 to 3.0, while the grass, millet, pear, tomato, and weed strains had ratings of 2.0. The rose and kiwi strain ratings were 2.5 and 2.3, respectively. P. syringae pv. tomato, morsprunorum, and coriandricola were of low virulence on peach (0.5, 1.1, and 1.0 disease rating, respectively), and each incited only a mild necrotic reaction around the site of inoculation. A total of 23 strains, including 19 strains of P. syringae pv. syringae and 4 strains of four other pathovars, were tested for the presence of the syrB and syrC genes. DNA isolated from all of the P. syringae pv. syringae strains, but not the DNA from the other pathovars, hybridized with the syrB and syrC probe (Fig. 1). The kiwi (84-160), rose (B37), Geranium (073), tomato (321), and beet (142) strains and all of the stone fruit strains except for the peach strain from New Zealand (B36) had a similar RFLP pattern.
|
ERIC analysis. The DNA fingerprints of 104 strains isolated in 1995 and 1996 from 43 orchard sites, including 4 epiphytic weed strains of P. syringae and strains obtained from other hosts and/or sources (Table 1), were determined by using ERIC-PCR. The stone fruit strains (except for strain B36, isolated from peach in New Zealand), rose strain B37, kiwi strain 84-160 and pear strain B301 each generated 1 of 11 distinct ERIC genomic fingerprint patterns, which all shared four fragments of similar mobility (Table 2). These 11 patterns could be differentiated by polymorphisms in one or more of the other amplified DNA fragments (Fig. 2). Ninety-three percent of the stone fruit strains isolated in this study produced either pattern 2, 3, 5, or 6 (Table 2). Pattern 10 was represented by the epiphytic Geranium sp. weed strains and by an epiphytic strain recovered from a healthy prune bud, each from a different orchard site with a history of bacterial canker disease. The Malva sp. weed strains generated a unique pattern, which did not contain the four fragments shared by the stone fruit strain patterns. A strain from a healthy prune flower isolated in the same orchard as the weed strains was the only strain to generate pattern 11. However, 15 other strains isolated from apparently healthy tissues collected in various orchards each generated one of the four most common stone fruit fingerprint patterns.
|
|
|
|
| |
DISCUSSION |
|---|
|
Top
Abstract
Introduction
Materials & Methods
Results
Discussion
References
|
|---|
In this study, the P. syringae pv. syringae strains isolated from Prunus hosts in California generated similar genetic profiles in ERIC-PCR whereas most strains of P. syringae pv. syringae isolated from other hosts generated dissimilar patterns. This suggests a host specialization of the stone fruit strains within the heterogeneous pathovar syringae. Specialization of P. syringae pv. syringae strains toward a particular host has been observed in previous studies. Saad and Hagedorn (27) used a bean pod pathogenicity assay and found that strains of P. syringae pv. syringae isolated from beans or as epiphytes from weeds near bean fields, but not strains isolated from other hosts, caused a pathogenic reaction. The same result was observed in other studies of the strains isolated from beans (2, 7, 26), which led Rudolph (26) to propose designating the bean strains P. syringae pv. phaseoli. Legard et al. (16), using RFLP analyses of P. syringae pv. syringae strains from various hosts, found that the bean strains formed a separate cluster within the pathovar, substantiating the results of the greenhouse pathogenicity assays. Gross and DeVay (10) found a tendency for grass strains of P. syringae pv. syringae to be highly virulent on inoculated maize plants and to reach higher populations in maize leaf tissues than did strains isolated from nongrass hosts. In our study, pathogenicity tests with peach seedlings in the greenhouse failed to distinguish between stone fruit strains and strains from other hosts but were useful in differentiating P. syringae pv. syringae strains from strains of other pathovars. Similarly, Otta and English (22) found that P. syringae pv. syringae strains from 30 different hosts induced similar cankers on wound-inoculated peach seedling stems.
Syringomycin functions as a nonspecific virulence factor in strains of P. syringae pv. syringae (6, 10). Genes for the synthesis and export of the phytotoxin are found in P. syringae pv. syringae strains but not in several other related pathovars (23). Some other phytotoxin genes are highly pathovar specific and have been used to develop DNA probes to identify coronatine-producing (3) or phaseolotoxin-producing (28) strains. In addition, the production of syringomycin has been used as a determinative characteristic in identifying strains of P. syringae pv. syringae (29, 34). Therefore, the syrB and syrC genes were used as hybridization probes to confirm the identity of a representative group of the P. syringae pv. syringae strains used in this study. The stone fruit strains, except for the New Zealand peach strain (B36), had a similar hybridization pattern to the pear, rose, bean, and kiwi fruit strains (strains which had a similar ERIC pattern), as well as to the strains from millet, beet, and tomato. However, the ubiquitous presence of syringomycin in this pathovar indicates that although strains can be genetically heterogeneous by methods such as ERICs and RFLPs, all of the P. syringae pv. syringae strains tested have the genetic potential to produce syringomycin.
Weed hosts within or near orchards or fields have been hypothesized to provide overwintering sites for P. syringae pv. syringae and to serve as an inoculum source for disease outbreaks (7, 15, 24). In this study, the ERIC patterns of P. syringae pv. syringae strains recovered from weed species were dissimilar to those of strains causing cankers on Prunus hosts. Thus, the role played by P. syringae pv. syringae epiphytes on weeds in the initiation and development of bacterial canker disease of prune in California remains uncertain. Strains from one of the weed species and two epiphytic strains isolated from healthy prune tissues were the only strains to generate two of the ERIC patterns (patterns 10 and 11). Another 15 epiphytic strains generated the same banding patterns as the strains isolated from diseased tissues. Therefore, healthy tissues appear to harbor a heterogeneous population of epiphytic strains, with at least some of these strains being capable of causing bacterial canker in susceptible tissues.
ERIC and REP PCR has been shown to be a rapid and reliable method to differentiate plant-pathogenic bacteria at or below the pathovar level with highly reproducible results (19). In a study which used REP PCR to compare 100 P. syringae pv. syringae strains from ornamental pear trees with 6 strains from peach, wheat, tomato, and maize, all of the ornamental-pear strains clustered into one of two closely related groups while none of the strains from other hosts had any similarities to the pear strains or to each other (31). These results are similar to what was observed in this study when P. syringae pv. syringae strains isolated from stone fruits in California were compared to strains isolated from other hosts and support the theory that some, if not all, strains within the heterogeneous pathovar syringae have adapted genetically to a particular host. In addition, similar to what was observed in this study, previous research has demonstrated a close relationship between strains causing disease on pome fruits, such as pear, and stone fruits (9, 25). Weingart and Völksch (33), however, found few similarities in the ERIC banding patterns of five strains of P. syringae pv. syringae isolated from pear, apple, and cherry trees in Western Europe. This apparent high diversity might be expected in an area with a long history of cultivating Prunus species, where, presumably, the associated microflora would have evolved with and adapted to the various Prunus hosts over time. In our study, a peach strain (B36) isolated in New Zealand generated an ERIC pattern unlike those from all of the other P. syringae pv. syringae strains tested; this strain may be the result of an evolutionary adaptation separate from North American and European P. syringae pv. syringae strains.
Louws et al. (19), using ERIC PCR, found evidence of intrapathovar diversity among strains of Xanthomonas campestris pv. vesicatoria and campestris, pathovars which also have more than one host. Other pathovars with a more restricted host range, such as P. syringae pv. morsprunorum and tomato, had low or no diversity in their ERIC profiles. Additional studies by other genetic characterization methods support the hypothesis that variation was greater among strains from pathovars with wide host ranges, such as P. syringae pv. syringae. Denny et al. (5) used RFLP to analyze six P. syringae pv. syringae strains and found that the strains clustered into two groups which contained strains either from monocots or from dicots whereas strains of P. syringae pv. tomato were less genetically diverse. In another study involving RFLP and randomly amplified polymorphic DNA analyses (18), strains of P. syringae pv. apii, which infect only celery, were more genetically homogeneous than were strains of P. syringae pv. maculicola, which infect a wide range of crucifer hosts. Overall, our results suggest that strains of P. syringae pv. syringae that are adapted to a specialized niche, such as California stone fruits, may be the result of a recent adaption and/or genetic isolation, resulting in the genetically homogeneous population of P. syringae pv. syringae strains from stone fruits observed in this study, which formed a distinct group from strains isolated from other hosts.
| |
ACKNOWLEDGMENT |
|---|
This work was supported by a grant from the California Prune Board.
| |
FOOTNOTES |
|---|
* Corresponding author. Mailing address: Department of Plant Pathology, University of California, Davis, CA 95916. Phone: (530) 752-2831. Fax: (530) 752-5674. E-mail: bckirkpatrick{at}ucdavis.edu.
Present address: Department of Crop and Soil Sciences, University
of Georgia, Athens, GA 30602.
| |
REFERENCES |
|---|
|
Top
Abstract
Introduction
Materials & Methods
Results
Discussion
References
|
|---|
| 1. | Bradbury, J. F. 1986. Pseudomonas syringae pv. syringae, p. 175-177. In Guide to Plant Pathogenic Bacteria. CAB International Mycological Institute, Kew, England. |
| 2. | Cheng, G. Y., D. E. Legard, J. E. Hunter, and T. J. Burr. 1989. Modified bean pod assay to detect strains of Pseudomonas syringae pv. syringae that cause bacterial brown spot of snap bean. Plant Dis. 73:419-423. |
| 3. |
Cuppels, D. A.,
R. A. Moore, and V. L. Morris.
1990.
Construction and use of a nonradioactive DNA hybridization probe for detection of Pseudomonas syringae pv. tomato on tomato plants.
Appl. Environ. Microbiol.
56:1743-1749 |
| 4. |
de Bruijn, F. J.
1992.
Use of repetitive (repetitive extragenic palindromic and enterobacterial repetitive intergeneric consensus) sequences and the polymerase chain reaction to fingerprint the genomes of Rhizobium meliloti isolates and other soil bacteria.
Appl. Environ. Microbiol.
58:2180-2187 |
| 5. |
Denny, T. P.,
M. N. Gilmour, and R. K. Selander.
1988.
Genetic diversity and relationships of two pathovars of Pseudomonas syringae.
J. Gen. Microbiol.
134:1949-1960 |
| 6. | DeVay, J. E., F. L. Lukezic, S. L. Sinden, H. English, and D. L. Coplin. 1968. A biocide produced by pathogenic isolates of Pseudomonas syringae and its possible role in the bacterial canker disease of peach trees. Phytopathology 58:95-101. |
| 7. | Ercolani, G. L., D. J. Hagedorn, A. Kelman, and R. E. Rand. 1974. Epiphytic survival of Pseudomonas syringae on hairy vetch in relation to epidemiology of bacterial brown spot of bean in Wisconsin. Phytopathology 64:1330-1339. |
| 8. | Gilbertson, R. L., D. P. Maxwell, D. J. Hagedorn, and S. A. Leong. 1989. Development and application of a plasmid DNA probe for detection of bacteria causing common bacterial blight of bean. Phytopathology 79:518-525. |
| 9. | Gross, D. C., Y. S. Cody, E. L. Proebsting, Jr., G. K. Radamaker, and R. A. Spotts. 1984. Ecotypes and pathogenicity of ice-nucleation-active Pseudomonas syringae isolated from deciduous fruit tree orchards. Phytopathology 74:241-248. |
| 10. | Gross, D. C., and J. E. DeVay. 1977. Population dynamics and pathogenesis of Pseudomonas syringae in maize and cowpea in relation to the in vitro production of syringomycin. Phytopathology 67:475-483. |
| 11. | Henson, M., D. C. Hildebrand, and M. N. Schroth. 1992. Relatedness of Pseudomonas syringae pv. tomato, Pseudomonas syringae pv. maculicola and Pseudomonas syringae pv. antirrhini. J. Appl. Bacteriol. 73:455-464. |
| 12. | Hildebrand, D. C., M. N. Schroth, and O. C. Huisman. 1982. The DNA homology matrix and non-random variation concepts as the basis for the taxonomic treatment of plant pathogenic and other bacteria. Annu. Rev. Phytopathology 20:235-256. |
| 13. | King, E. O., M. K. Ward, and D. E. Raney. 1954. Two simple media for the demonstration of pyocyanin and fluorescein. J. Lab. Clin. Med. 44:301-307[Medline]. |
| 14. | Lai, M., and B. Hass. 1973. Reaction of cowpea seedlings to phytopathogenic bacteria. Phytopathology 63:1099-1103. |
| 15. | Latorre, B. A., and A. L. Jones. 1979. Evaluation of weeds and plant refuse as potential sources of inoculum of Pseudomonas syringae in bacterial canker of cherry. Phytopathology 69:1122-1125. |
| 16. |
Legard, D. E.,
C. F. Aquadro, and J. E. Hunter.
1993.
DNA sequence variation and phylogenetic relationships among strains of Pseudomonas syringae pv. syringae inferred from restriction site maps and restriction fragment length polymorphism.
Appl. Environ. Microbiol.
59:4180-4188 |
| 17. | Lelliott, R. A., E. Billing, and A. C. Hayward. 1966. A determinative scheme for the fluorescent plant pathogenic pseudomonads. J. Appl. Bacteriol. 29:470-489[Medline]. |
| 18. | Little, E. L., and R. L. Gilbertson. 1997. Phenotypic and genotypic characters support placement of Pseudomonas syringae strains from tomato, celery, and cauliflower into distinct pathovars, p. 542-547. In K. Rudolph, T. J. Burr, J. W. Mansfield, D. Stead, A. Vivian, and J. von Kietzell (ed.), Pseudomonas syringae pathovars and related pathogens. Kluwer Academic Publishers, Dordrecht, The Netherlands. |
| 19. |
Louws, F. J.,
D. W. Fulbright,
C. T. Stephens, and F. J. de Bruijn.
1994.
Specific genomic fingerprints of phytopathogenic Xanthomonas and Pseudomonas pathovars and strains generated with repetitive sequences and PCR.
Appl. Environ. Microbiol.
60:2286-2295 |
| 20. | Ogawa, J. M., and H. English. 1991. Diseases of temperate zone tree fruit and nut crops. Publication 3345. University of California Division of Agriculture and Natural Resources, Oakland. |
| 21. | Opgenorth, D. C., C. D. Smart, F. J. Louws, F. J. de Bruijn, and B. C. Kirkpatrick. 1996. Identification of Xanthomonas fragariae field isolates by rep-PCR genomic fingerprinting. Plant Dis. 80:868-873. |
| 22. | Otta, J. D., and H. English. 1971. Serology and pathology of Pseudomonas syringae. Phytopathology 61:443-452. |
| 23. | Quigley, N. B., and D. C. Gross. 1994. Syringomycin production among strains of Pseudomonas syringae pv. syringae: conservation of the syrB and syrD genes and activation of phytotoxin production by plant signal molecules. Mol. Plant-Microbe Interact. 7:78-90[Medline]. |
| 24. | Roos, I. M. M., and M. J. Hattingh. 1986. Weeds in orchards as potential source of inoculum for bacterial canker of stone fruit. Phytophylactica 18:5-6. |
| 25. | Roos, I. M. M., and M. J. Hattingh. 1987. Pathogenicity and numerical analysis of phenotypic features of Pseudomonas syringae strains isolated from deciduous fruit trees. Phytopathology 77:900-908. |
| 26. | Rudolph, K. 1979. Bacterial brown spot disease of bush bean (Phaseolus vulgaris L.) in Germany, incited by Pseudomonas syringae van Hall s. s. pathovar phaseoli. Z. Pflanzenkr. Pflanzenschutz 86:75-85. |
| 27. | Saad, S. M., and D. J. Hagedorn. 1972. Relationship of isolate source to virulence of Pseudomonas syringae on Phaseolus vulgaris. Phytopathology 62:678-680. |
| 28. | Schaad, N. W., H. Azad, R. C. Peet, and N. J. Panopoulos. 1989. Identification of Pseudomonas syringae pv. phaseolicola by a DNA hybridization probe. Phytopathology 79:903-907. |
| 29. | Seemüller, E., and M. Arnold. 1978. Pathogenicity, syringomycin production and other characteristics of pseudomonad strains isolated from deciduous fruit trees, p. 703-710. In Proceedings of the 4th International Conference on Plant Pathogenic Bacteria. |
| 30. | Sokal, R. R., and P. H. A. Sneath. 1963. Principles of numerical taxonomy, p. 169-210. W. H. Freeman & Co., San Francisco, Calif. |
| 31. |
Sundin, G. W.,
D. H. Demezas, and C. L. Bender.
1994.
Genetic and plasmid diversity within natural populations of Pseudomonas syringae with various exposures to copper and streptomycin bactericides.
Appl. Environ. Microbiol.
60:4421-4431 |
| 32. |
Versalovic, J.,
T. Koeuth, and J. R. Lupski.
1991.
Distribution of repetitive DNA sequences in eubacteria and application to fingerprinting of bacterial genomes.
Nucleic Acids Res.
19:6823-6831 |
| 33. | Weingart, H., and B. Völksch. 1997. Genetic fingerprinting of Pseudomonas syringae pathovars using ERIC-, REP-, and IS50-PCR. J. Phytopathol. 145:339-345. |
| 34. | Young, J. M. 1991. Pathogenicity and identification of the lilac pathogen, Pseudomonas syringae pv. syringae van Hall 1902. Ann. Appl. Biol. 118:283-298. |
Applied and Environmental Microbiology, October 1998, p. 3818-3823, Vol. 64, No. 10
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
This article has been cited by other articles:
-
Goss, E. M., Kreitman, M., Bergelson, J.
(2005). Genetic Diversity, Recombination and Cryptic Clades in Pseudomonas viridiflava Infecting Natural Populations of Arabidopsis thaliana. Genetics
169: 21-35
[Abstract] [Full Text] -
Oguiza, J. A., Rico, A., Rivas, L. A., Sutra, L., Vivian, A., Murillo, J.
(2004). Pseudomonas syringae pv. phaseolicola can be separated into two genetic lineages distinguished by the possession of the phaseolotoxin biosynthetic cluster. Microbiology
150: 473-482
[Abstract] [Full Text] -
Oda, Y., Wanders, W., Huisman, L. A., Meijer, W. G., Gottschal, J. C., Forney, L. J.
(2002). Genotypic and Phenotypic Diversity within Species of Purple Nonsulfur Bacteria Isolated from Aquatic Sediments. Appl. Environ. Microbiol.
68: 3467-3477
[Abstract] [Full Text] -
Hirano, S. S., Upper, C. D.
(2000). Bacteria in the Leaf Ecosystem with Emphasis on Pseudomonas syringae---a Pathogen, Ice Nucleus, and Epiphyte. Microbiol. Mol. Biol. Rev.
64: 624-653
[Abstract] [Full Text]
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»