scholarly journals Description of the Bacterium Causing Blight of Leek as Pseudomonas syringae pv. porri (pv. nov.)

1998 ◽  
Vol 88 (8) ◽  
pp. 844-850 ◽  
Author(s):  
R. Samson ◽  
H. Shafik ◽  
A. Benjama ◽  
L. Gardan
Keyword(s):  
Pseudomonas Syringae ◽  
Host Plants ◽  
Numerical Taxonomy ◽  
Taxonomic Status ◽  
Hypersensitive Reaction ◽  
Ice Nucleation ◽  
Allium Porrum ◽  
Bacterial Strains ◽  
Routine Identification ◽  
Ice Nucleation Activity

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.

scholarly journals Effects of atmospheric conditions on ice nucleation activity of <i>Pseudomonas</i>

2012 ◽  
Vol 12 (22) ◽  
pp. 10667-10677 ◽  
Author(s):  
E. Attard ◽  
H. Yang ◽  
A.-M. Delort ◽  
P. Amato ◽  
U. Pöschl ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Pseudomonas Syringae ◽  
Ice Nucleation ◽  
Acidic Ph ◽  
Bacterial Cells ◽  
Atmospheric Conditions ◽  
Ice Nucleation Protein ◽  
Ice Melt ◽  
Nucleation Activity ◽  
Ice Nucleation Activity

Abstract. Although ice nuclei from bacterial origin are known to be efficient at the highest temperatures known for ice catalysts, quantitative data are still needed to assess their role in cloud processes. Here we studied the effects of three typical cloud conditions (i) acidic pH (ii) NO2 and O3 exposure and (iii) UV-A exposure on the ice nucleation activity (INA) of four Pseudomonas strains. Three of the Pseudomonas syringae strains were isolated from cloud water and the phyllosphere and Pseudomonas fluorescens strain CGina-01 was isolated from Antarctic glacier ice melt. Among the three conditions tested, acidic pH caused the most significant effects on INA likely due to denaturation of the ice nucleation protein complex. Exposure to NO2 and O3 gases had no significant or only weak effects on the INA of two P. syringae strains whereas the INA of P. fluorescens CGina-01 was significantly affected. The INA of the third P. syringae strain showed variable responses to NO2 and O3 exposure. These differences in the INA of different Pseudomonas suggest that the response to atmospheric conditions could be strain-specific. After UV-A exposure, a substantial loss of viability of all four strains was observed whereas their INA decreased only slightly. This corroborates the notion that under certain conditions dead bacterial cells can maintain their INA. Overall, the negative effects of the three environmental factors on INA were more significant at the warmer temperatures. Our results suggest that in clouds where temperatures are near 0 °C, the importance of bacterial ice nucleation in precipitation processes could be reduced by some environmental factors.

scholarly journals Measurement of Ice Nucleation-Active Bacteria on Plants and in Precipitation by Quantitative PCR

2013 ◽  
Vol 80 (4) ◽  
pp. 1256-1267 ◽  
Author(s):  
Thomas C. J. Hill ◽  
Bruce F. Moffett ◽  
Paul J. DeMott ◽  
Dimitrios G. Georgakopoulos ◽  
William L. Stump ◽  
...  
Keyword(s):  
Quantitative Pcr ◽  
Pseudomonas Syringae ◽  
Xanthomonas Campestris ◽  
Ice Nucleation ◽  
Content Type ◽  
Biological Source ◽  
Ina Bacteria ◽  
A Minor ◽  
Ice Nucleation Activity ◽  
Effective Contribution

ABSTRACTIce nucleation-active (INA) bacteria may function as high-temperature ice-nucleating particles (INP) in clouds, but their effective contribution to atmospheric processes, i.e., their potential to trigger glaciation and precipitation, remains uncertain. We know little about their abundance on natural vegetation, factors that trigger their release, or persistence of their ice nucleation activity once airborne. To facilitate these investigations, we developed two quantitative PCR (qPCR) tests of theinagene to directly count INA bacteria in environmental samples. Each of two primer pairs amplified most alleles of theinagene and, taken together, they should amplify all known alleles. To aid primer design, we collected many new INA isolates. Alignment of their partialinasequences revealed new and deeply branching clades, including sequences fromPseudomonas syringaepv.atropurpurea,Ps. viridiflava,Pantoea agglomerans,Xanthomonas campestris, and possiblyPs. putida,Ps. auricularis, andPs. poae. qPCR of leaf washings recorded ∼108inagenes g−1fresh weight of foliage on cereals and 105to 107g−1on broadleaf crops. Much lower populations were found on most naturally occurring vegetation. In fresh snow,inagenes from various INA bacteria were detected in about half the samples but at abundances that could have accounted for only a minor proportion of INP at −10°C (assuming oneinagene per INA bacterium). Despite this, an apparent biological source contributed an average of ∼85% of INP active at −10°C in snow samples. In contrast, a thunderstorm hail sample contained 0.3 INA bacteria per INP active at −10°C, suggesting a significant contribution to this sample.

scholarly journals 993 THEORY AND APPLICATION OF GENETIC ENGINEERING FOR STRESS RESISTANCE AND AVOIDANCE

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 571d-571
Author(s):  
Steven E. Lindow
Keyword(s):  
Population Size ◽  
Pseudomonas Syringae ◽  
Stress Resistance ◽  
Field Studies ◽  
Ice Nucleation ◽  
Site Directed Mutagenesis ◽  
Ice Formation ◽  
Bacterial Strains ◽  
Solanum Commersonii ◽  
Frost Injury

Genes determining the ability of the bacterium Pseudomonas syringae to catalyze ice formation have been cloned and characterized. Ice nucleation active (Ice+) strains of this species are common on plants and the supercooling ability of frost sensitive plants is inversely proportional to the logarithm of the population size of Ice+ bacteria at temperatures above -5C. Recombinant Ice- derivatives off. syringae were produced by site-directed mutagenesis using deletion containing ice genes cloned form this species. The Ice- strains colonized potatoes well in field studies, reduced the population size of Ice+ bacterial strains by about 50-fold, and reduced the incidence of frost injury an average of 82% in several radiative frosts of temperatures in the range of -3 to -5 C. The ice gene has also been introduced into Solanum commersonii to determine its effect on increasing the tolerance of ice formation in this frost tolerant species. Transgenic plants exhibit a much higher threshold ice nucleation temperature than the parental plants.

scholarly journals Updated Taxonomy of Pectobacterium Genus in the CIRM-CFBP Bacterial Collection: When Newly Described Species Reveal “Old” Endemic Population

2020 ◽  
Vol 8 (9) ◽  
pp. 1441 ◽  
Author(s):  
Perrine Portier ◽  
Jacques Pédron ◽  
Géraldine Taghouti ◽  
Cécile Dutrieux ◽  
Marie-Anne Barny
Keyword(s):  
Host Plants ◽  
Plant Pathogens ◽  
Genomic Analysis ◽  
Taxonomic Status ◽  
Bacterial Strains ◽  
Freshwater Environment ◽  
New Host ◽  
Two New Species ◽  
Endemic Population ◽  
Prevalent Species

Bacterial collections are invaluable tools for microbiologists. However, their practical use is compromised by imprecise taxonomical assignation of bacterial strains. This is particularly true for soft rotting plant pathogens of the Pectobacterium genus. We analysed the taxonomic status of 265 Pectobacterium strains deposited at CIRM-CFBP collection from 1944 to 2020. This collection gathered Pectobacterium strains isolated in 27 countries from 32 plant species representing 17 botanical families or from nonhost environments. The MLSA approach completed by genomic analysis of 15 strains was performed to update the taxonomic status of these 265 strains. The results showed that the CIRM-CFBP Pectobacterium collection harboured at least one strain of each species, with the exception of P. polonicum. Yet, seven strains could not be assigned to any of the described species and may represent at least two new species. Surprisingly, P. versatile, recently described in 2019, is the most prevalent species among CIRM-CFBP strains. An analysis of P. versatile strains revealed that this species is pandemic and isolated from various host plants and environments. At the opposite, other species gathered strains isolated from only one botanical family or exclusively from a freshwater environment. Our work also revealed new host plants for several Pectobacterium spp.

scholarly journals 031 Effects on the Supercooling Capacity of Capsicum annum L. by Epiphytic Bacteria Population

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 393C-393
Author(s):  
A. Rascon-Chu ◽  
A.A. Gardea ◽  
V. Guerrero-P ◽  
J. Martinez-T ◽  
C. Rivera ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Uv Light ◽  
Leaf Tissue ◽  
Epiphytic Bacteria ◽  
Vegetable Crops ◽  
Bacterial Strains ◽  
Temperature Exposure ◽  
Low Temperature Exposure ◽  
Ice Nucleation Activity

The effect of epiphytic bacteria population with different ice nucleation activity (INA) on the extent of supercooling of in vitro and leaf tissue disks of greenhouse-grown Capsicum annuum L. plants was determined. Bacterial strains were isolated on PDA and King's B medium from foliar samples of weeds from commercial apple orchards in Cuauhtemoc, Chihuahua, Mexico. Bacteria were screened by colony morphology, fluorescence under UV light, while growin on King's B medium plates and screened for ice-nucleating capability at -5 °C in suspensions of 108 cfu/mL. Ice nucleating (Ice+) and non-ice-nucleating (Ice-) active strains with fluorescent capacity were isolated from symptomless leaf samples. Four bacterial strains were used with different ina as epiphytic population models. Two Pseudomonas syringae strains, Pss29A and PD, from Oregon State Univ., with high Ice+ capability; P. fluorescens A-506, in its Blight Ban™ commercial lyophilized presentation; and UC001, a native fluorescent strain from CIAD-Cuauhtemoc; both Ice-strains. Freezing tests were carried out under controlled conditions. The high Ice+ strains Pss29A and PD increased the temperature of supercooling 2 and 1 °C compared to control samples. The non-inoculated tissue showed damage over 50% at -3 °C and below. Inoculated tissue with Ice+ strains (P. syringae 29A and PD), showed damage superior to 50% at -1 and -2 °C, respectively. Conversely, at none of the temperatures assayed, Ice-strains surpassed 50% damage. These results are of interest for further development of passive strategies towards minimizing damage due to low-temperature exposure of tropical vegetable crops.

scholarly journals First Report of Bacterial Leaf Spot of Italian Dandelion (Cichorium intybus) Caused by a Pseudomonas syringae Pathovar in California

Plant Disease ◽  
2006 ◽  
Vol 90 (2) ◽  
pp. 245-245 ◽  
Author(s):  
S. T. Koike ◽  
C. T. Bull
Keyword(s):  
Pseudomonas Syringae ◽  
Leaf Spot ◽  
Late Summer ◽  
Hypersensitive Reaction ◽  
Cichorium Intybus ◽  
Nutrient Broth ◽  
Bacterial Strains ◽  
Bacterial Leaf Spot ◽  
First Report ◽  
Leaf Spots

Italian dandelion (Cichorium intybus) is a leafy, nonhead forming chicory plant that is eaten as a fresh vegetable in salads. During the late summer (August through October) of 2002, in the Salinas Valley (Monterey County) in California, a previously unreported disease was found in commercial Italian dandelion fields. Early symptoms were angular, vein delimited, dark, water-soaked leaf spots that measured 2 to 7 mm in diameter. As disease developed, spots retained angular edges but exhibited various irregular shapes. Spots commonly formed along the edges of the leaves; in some cases these spots developed into lesions that measured between 10 and 30 mm long. Spots were visible from adaxial and abaxial sides and were dull black in color. A cream-colored pseudomonad was consistently isolated from leaf spots that were macerated and streaked onto sucrose peptone agar. Fungi were not recovered from any of the spots. Recovered strains were blue-green fluorescent when streaked onto King's medium B agar. Bacterial strains were levan positive, oxidase negative, and arginine dihydrolase negative. Strains did not rot potato slices but induced a hypersensitive reaction on tobacco (Nicotiana tabacum cv. Turk). These data indicated that the bacteria belonged to LOPAT group 1 of Pseudomonas syringae (1). Pathogenicity of six strains was tested by growing inoculum in nutrient broth shake cultures for 48 h, diluting to 106 CFU/ml, and spraying onto 12 6-week-old plants of Italian dandelion cv. Catalogna Special. Untreated control plants were sprayed with sterile nutrient broth. After 10 to 12 days in a greenhouse (24 to 26°C), leaf spots similar to those observed in the field developed on all inoculated plants. Strains were reisolated from the spots and identified as P. syringae. Control plants remained symptomless. These inoculation experiments were done twice and the results were the same. Amplification of repetitive bacterial sequences (repetitive sequence-based polymerase chain reaction [rep-PCR]) demonstrated that all Italian dandelion strains had the same rep-PCR fingerprint, which differed from fingerprints of P. syringae pv. tagetis and P. syringae pv. tabaci. Additionally, toxin specific primers did not amplify tagetitoxin or tabtoxin biosynthesis genes from Italian dandelion strains. To our knowledge, this is the first report of bacterial leaf spot of commercially grown Italian dandelion in California caused by a P. syringae pathovar. Because fields were irrigated with overhead sprinklers, the disease was severe in several fields and as much as 30% of those plantings were not harvested. Reference: (1) R. A. Lelliott et al. J. Appl. Bacteriol. 29:470, 1966.

scholarly journals First Report of Pseudomonas syringae pv. actinidiae, the Causal Agent of Bacterial Canker of Kiwifruit in France

Plant Disease ◽  
2011 ◽  
Vol 95 (10) ◽  
pp. 1311-1311 ◽  
Author(s):  
J. L. Vanneste ◽  
F. Poliakoff ◽  
C. Audusseau ◽  
D. A. Cornish ◽  
S. Paillard ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Housekeeping Gene ◽  
Hypersensitive Reaction ◽  
Ice Nucleation ◽  
Bacterial Canker ◽  
First Report ◽  
Leaf Spots ◽  
Commercial Species ◽  
Total Dna ◽  
Dna Fragment

In June 2010, young plants of kiwifruit growing in the French regions of Rhone-Alpes (Actinidia deliciosa ‘Summer’) and Aquitaine (A. chinensis ‘Jintao’) showed small, angular, necrotic leaf spots and cankers on some canes that was sometimes associated with production of a red exudate. Most of the affected canes died, and in a few cases after a few months, the entire plant died. Symptoms were consistent with Pseudomonas syringae pv. actinidiae, a bacterium that affects several species of Actinidia (A. deliciosa and A. chinensis, the two most important commercial species of kiwifruit). A recent outbreak of this disease is devastating the Italian kiwifruit industry. Bacterial colonies were isolated on King's medium B (KB) from leaf spots and infected canes. Three isolates from Aquitaine and 10 from Rhone-Alpes were retained for further characterization. The 13 isolates were gram negative, induced a hypersensitive reaction when infiltrated in tobacco plants, did not have a cytochrome c oxidase, an arginine dehydrolase or urease activity, did not hydrolyze esculin, starch, or gelatine, and did not induce ice nucleation. When plated on KB, these strains did not show strong fluorescence usually associated with strains of P. syringae. Complete lack of fluorescence reported for the pathotype strain ICMP 9817 has not been observed for those strains. They showed the same weak fluorescence as the strains of P. syringae pv. actinidiae recently isolated from Italy. Those characteristics match those of strains of P. syringae pv. actinidiae (3). Using total DNA of the 13 strains, the pathotype strain, and primers PsaF1/R2 (2), a 280-bp fragment was amplified by PCR, supporting the strains as being P. syringae pv. actinidiae. The amplicon from 6 of the 13 strains was sequenced and found to be 100% similar to the corresponding DNA fragment of the pathotype strain ICMP 9617 (GenBank AY342165). Partial sequences of 1,381 bp of the 16S rDNA gene of four of the six isolates, three strains isolated from Rhone-Alpes and one strain isolated from Aquitaine, were obtained by amplification with primers 27f and 1492r (1). Except for the sequence of strain 181, which was isolated from Aquitaine and had a 1 bp difference (GenBank JF323026), the other sequences were 100% identical to each other (GenBank JF323027 to JF323029). These four sequences were 99% identical to the 16SrDNA sequences of ICMP 9617, the pathotype strain of P. syringae pv. actinidiae (GenBank AB001431). These four strains and the pathotype strain were sprayed (1 × 109 CFU/ml) on leaves of four 6- to 8-week-old seedlings of A. chinensis each. After 4 days, small, necrotic, angular spots were found on all plants inoculated with those four strains and the pathotype strain. No symptoms were found on plants treated with water only. From those leaf spots, bacteria that had all the characteristics of P. syringae pv. actinidiae (as previously described) were isolated. Recently, two different haplotypes for the housekeeping gene cts were described for P. syringae pv. actinidiae (4), the strains isolated from France belong to the haplotype I. This is the same haplotype to which strains isolated from the recent Italian outbreak also belong. To our knowledge, this is the first report of bacterial canker of kiwifruit in France. References: (1) V. Gurtler and V. A. Stanisich. Microbiology 142:3 1996. (2) J. Rees-George et al. Plant Pathol. 59:453, 2010. (3) Y. Takikawa et al. Ann. Phytopathol. Soc. Jpn. 55:437, 1989. (4) J. L. Vanneste et al. N.Z. Plant Prot. 63:7, 2010.

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