Exploring Pseudomonas syringae Ecology via Direct Microscopic Observations of the Leaf Surface

2003 ◽  
pp. 29-40
Author(s):  
J.-M. Monier ◽  
S. E. Lindow
Keyword(s):  
Pseudomonas Syringae ◽  
Leaf Surface

scholarly journals First Report of Pseudomonas syringae pv. aptata Causing Bacterial Leaf Spot on Sugar Beet in Serbia

Plant Disease ◽  
2015 ◽  
Vol 99 (2) ◽  
pp. 281-281 ◽  
Author(s):  
V. Stojšin ◽  
J. Balaž ◽  
D. Budakov ◽  
Slaviša Stanković ◽  
I. Nikolić ◽  
...  
Keyword(s):  
Sugar Beet ◽  
Pseudomonas Syringae ◽  
Leaf Spot ◽  
Leaf Surface ◽  
Negative Control ◽  
Gyrb Gene ◽  
Bacterial Suspension ◽  
Bacterial Strains ◽  
Gene Sequences ◽  
Bacterial Leaf Spot

A severe bacterial leaf spot was observed during June and July 2013 on commercial cultivars of sugar beet (Beta vulgaris var. saccharifera) in the Vojvodina Province of Serbia. Serbia is a major sugar beet production area in southeastern Europe, with 62,895 ha and 3 million tons of sugar beet yield in 2013. A foliar leaf spot observed in 25 commercial sugar beet fields surveyed ranged from 0.1 to 40% severity. Symptoms were characterized as circular or irregular, 5- to 20-mm diameter, white to light brown necrotic spots, each with a dark margin. Diseased leaves were rinsed in sterilized, distilled water (SDW) and dried at room temperature, and leaf sections taken from the margin of necrotic tissue were macerated in SDW. Isolations from 48 symptomatic leaves onto nutrient agar with 5% (w/v) sucrose (NAS) produced bacterial colonies that were whitish, circular, dome-shaped, and Levan-positive. Representative isolates (n = 105) were Gram negative; aerobic; positive for catalase, fluorescence on King's medium B, and tobacco hypersensitivity; and negative for oxidase, potato rot, and arginine dehydrolase. These reactions corresponded to LOPAT group Ia, which includes Pseudomonas syringae pathovars (2). Repetitive extragenic palindromic sequence (rep)-PCR was used for genetic fingerprinting the isolates using the REP, ERIC, and BOX primers. Twenty-five different profiles were obtained among the strains. From each profile group, one representative strain was sequenced for the gyrB gene (1). Four heterogenic groups were observed, and representative gyrB gene sequences of each group were deposited in the NCBI GenBank (Accession Nos. KJ950024 to KJ950027). The sequences were compared with those of pathotype strain P. syringae pv. aptata CFBP 1617 deposited in the PAMDB database; one strain was 100% homologous, and the other three were 99% homologous. To fulfill identification of the Serbian sugar beet isolates, gltA and rpoD partial gene sequences were determined (1), and the sequences were deposited as Accession Nos. KM386838 to KM386841 for gltA and KM386830 to KM38683033 for rpoD. The sequences were 100% homologous with those of pathotype strain CFBP 1617. Pathogenicity of each of four representative bacterial strains was tested on 3-week-old plants of the sugar beet cultivars Marinela, Serenada, and Jasmina (KWS, Belgrade, Serbia) and Lara (NS Seme, Novi Sad, Serbia) by atomizing a bacterial suspension of ~106 CFU/ml of the appropriate isolate onto the abaxial leaf surface of three plants per cultivar until water-soaking of the leaf surface was observed. Three plants of each cultivar atomized similarly with P. syringae pv. aptata CFBP 2473 and SDW served as positive and negative control treatments, respectively. Inoculated plants were kept in a clear plastic box at 80 to 100% RH and 17 ± 1°C and examined for symptom development over 3 weeks. For all test isolates and the control strain, inoculated leaves first developed water-soaked lesions 7 days after inoculation (DAI). By 10 to 14 DAI, lesions were necrotic and infection had spread to the petioles. By 21 DAI, wilting was observed on more than 50% of inoculated plants. Negative control plants were symptomless. Bacteria re-isolated onto NAS from inoculated leaves had the same colony morphology, LOPAT results, and gyrB partial gene sequences as described for the test strains. No bacteria were re-isolated from negative control plants. Based on these tests, the pathogen causing leaf spot on sugar beet in Serbia was identified as P. syringae pv. aptata. References: (1) P. Ferrente and M. Scortichini. Plant Pathol. 59:954, 2010. (2) R. A. Lelliott et al. J. Appl. Bacteriol. 29:470, 1966.

scholarly journals Disruption of N-Αcyl Homoserine Lactone-Mediated Cell Signaling and Iron Acquisition in Epiphytic Bacteria by Leaf Surface Compounds

2006 ◽  
Vol 72 (12) ◽  
pp. 7678-7686 ◽  
Author(s):  
Katerina Karamanoli ◽  
Steven E. Lindow
Keyword(s):  
Plant Species ◽  
Pseudomonas Syringae ◽  
Plant Extracts ◽  
Leaf Surface ◽  
Culture Media ◽  
Iron Acquisition ◽  
Homoserine Lactone ◽  
Signaling Systems ◽  
Surface Compounds ◽  
Reporter Strains

ABSTRACT Since N-acyl homoserine lactones (AHLs) are key mediators of cell density-dependent regulation of traits involved in virulence and epiphytic fitness in gram-negative bacteria such as Pseudomonas syringae, a variety of plant species were examined to determine their production of leaf surface compounds that could interact with these signaling systems. Leaf washings of 17 of 52 plant species tested stimulated or inhibited AHL-dependent traits in at least one of the bacterial reporter strains used. The active compounds from most plants could be distinguished from known AHLs due to different patterns of mobility during C8 and C18 reverse-phase thin-layer chromatography (TLC) and normal-phase TLC compared to the patterns for authentic bacterial AHLs. All plant extracts were also tested to determine their abilities to sequester iron and trigger bacterial siderophore synthesis on a medium containing abundant iron. Leaf washings from 16 of the 52 plant species, as well as tannic acid solutions, stimulated pyoverdine synthesis in P. syringae in a high-iron medium. These preparations also inhibited the growth of a P. syringae mutant unable to produce pyoverdine siderophores but not the growth of the wild-type bacterium. The stimulation of siderophore production and the growth inhibition by plant extracts and purified tannins were both reversed by addition of ferric chloride to culture media, indicating that iron was made unavailable by the compounds released onto the leaf surface.

scholarly journals Bacterial Leaf Spot Diseases of Leafy Crucifers in Oklahoma Caused by Pathovars of Xanthomonas campestris

Plant Disease ◽  
2000 ◽  
Vol 84 (9) ◽  
pp. 1008-1014 ◽  
Author(s):  
Youfu Zhao ◽  
John P. Damicone ◽  
David H. Demezas ◽  
Carol L. Bender
Keyword(s):  
Pseudomonas Syringae ◽  
Leaf Spot ◽  
Xanthomonas Campestris ◽  
Leaf Surface ◽  
Black Rot ◽  
Local Strains ◽  
Leaf Spots ◽  
Abaxial Leaf Surface ◽  
Polymerase Chain ◽  
Reference Strains

Fields of kale, spinach mustard, and turnip were severely damaged by bacterial leaf spots during 1994 to 1996. Symptoms included circular to angular necrotic lesions with yellow halos and water-soaking on the abaxial leaf surface. Yellow, mucoid strains isolated from leaf spots were identified as Xanthomonas campestris using Biolog. Four strains caused black lesions on stems of cabbage seedlings in an excised cotyledon assay, leaf spots and sunken dark lesions on petioles of spray-inoculated crucifers, and leaf spots on spray-inoculated tomato. These strains were classified as X. campestris pv. armoraciae. Most other strains from leafy crucifers and all strains from a cabbage field caused black rot in the cotyledon assay and in spray-inoculations. Many of these strains also caused leaf spots on collard and kale but not stem and petiole lesions. The strains causing black rot were classified as X. campestris pv. campestris. Cluster analysis of Biolog profiles yielded a small group that contained local strains of both pathovars, and a large group comprised of reference and local strains of each pathovar, and some local, nonpathogenic strains. Five fingerprint groups were identified by rep-polymerase chain reaction using the BOXA1R primer. Local and reference strains of each pathovar occurred in two of the groups. Two pathovars of X. campestris are involved in the leaf spot diseases. Both pathovars were recovered within several fields, and also were recovered along with Pseudomonas syringae pv. maculicola. This is the first report of Xanthomonas leaf spot caused by X. campestris pv. armoraciae in Oklahoma.

scholarly journals Persistent after-effects of heavy rain on concentrations of ice nuclei and rainfall suggest a biological cause

2015 ◽  
Vol 15 (5) ◽  
pp. 2313-2326 ◽  
Author(s):  
E. K. Bigg ◽  
S. Soubeyrand ◽  
C. E. Morris
Keyword(s):  
Pseudomonas Syringae ◽  
Leaf Surface ◽  
Daily Rainfall ◽  
Heavy Rain ◽  
Historical Record ◽  
Past Century ◽  
Long Term Effects ◽  
Power Stations ◽  
Ice Nuclei ◽  
Rainfall Frequency

Abstract. Rainfall is one of the most important aspects of climate, but the extent to which atmospheric ice nuclei (IN) influence its formation, quantity, frequency, and location is not clear. Microorganisms and other biological particles are released following rainfall and have been shown to serve as efficient IN, in turn impacting cloud and precipitation formation. Here we investigated potential long-term effects of IN on rainfall frequency and quantity. Differences in IN concentrations and rainfall after and before days of large rainfall accumulation (i.e., key days) were calculated for measurements made over the past century in southeastern and southwestern Australia. Cumulative differences in IN concentrations and daily rainfall quantity and frequency as a function of days from a key day demonstrated statistically significant increasing logarithmic trends (R2 > 0.97). Based on observations that cumulative effects of rainfall persisted for about 20 days, we calculated cumulative differences for the entire sequence of key days at each site to create a historical record of how the differences changed with time. Comparison of pre-1960 and post-1960 sequences most commonly showed smaller rainfall totals in the post-1960 sequences, particularly in regions downwind from coal-fired power stations. This led us to explore the hypothesis that the increased leaf surface populations of IN-active bacteria due to rain led to a sustained but slowly diminishing increase in atmospheric concentrations of IN that could potentially initiate or augment rainfall. This hypothesis is supported by previous research showing that leaf surface populations of the ice-nucleating bacterium Pseudomonas syringae increased by orders of magnitude after heavy rain and that microorganisms become airborne during and after rain in a forest ecosystem. At the sites studied in this work, aerosols that could have initiated rain from sources unrelated to previous rainfall events (such as power stations) would automatically have reduced the influences on rainfall of those whose concentrations were related to previous rain, thereby leading to inhibition of feedback. The analytical methods described here provide means to map and delimit regions where rainfall feedback mediated by microorganisms is suspected to occur or has occurred historically, thereby providing rational means to establish experimental set-ups for verification.

scholarly journals Attachment of Pseudomonas syringae onto Leaf Surface of Italian Ryegrass.

1996 ◽  
Vol 11 (2) ◽  
pp. 33-40 ◽  
Author(s):  
HISAO MORISAKI ◽  
MARIE ARAI ◽  
SHINICHI TAKASHIMA
Keyword(s):  
Pseudomonas Syringae ◽  
Leaf Surface ◽  
Italian Ryegrass

scholarly journals Genome-wide identification of Pseudomonas syringae genes required for fitness during colonization of the leaf surface and apoplast

2019 ◽  
Vol 116 (38) ◽  
pp. 18900-18910 ◽  
Author(s):  
Tyler C. Helmann ◽  
Adam M. Deutschbauer ◽  
Steven E. Lindow
Keyword(s):  
Pseudomonas Syringae ◽  
Leaf Surface ◽  
Functional Categories ◽  
In Planta ◽  
Genome Wide ◽  
Leaf Surfaces ◽  
Microbe Interactions ◽  
Bacterial Genes ◽  
Broad Understanding

The foliar plant pathogen Pseudomonas syringae can establish large epiphytic populations on leaf surfaces before apoplastic colonization. However, the bacterial genes that contribute to these lifestyles have not been completely defined. The fitness contributions of 4,296 genes in P. syringae pv. syringae B728a were determined by genome-wide fitness profiling with a randomly barcoded transposon mutant library that was grown on the leaf surface and in the apoplast of the susceptible plant Phaseolus vulgaris. Genes within the functional categories of amino acid and polysaccharide (including alginate) biosynthesis contributed most to fitness both on the leaf surface (epiphytic) and in the leaf interior (apoplast), while genes involved in type III secretion system and syringomycin synthesis were primarily important in the apoplast. Numerous other genes that had not been previously associated with in planta growth were also required for maximum epiphytic or apoplastic fitness. Fourteen hypothetical proteins and uncategorized glycosyltransferases were also required for maximum competitive fitness in and on leaves. For most genes, no relationship was seen between fitness in planta and either the magnitude of their expression in planta or degree of induction in planta compared to in vitro conditions measured in other studies. A lack of association of gene expression and fitness has important implications for the interpretation of transcriptional information and our broad understanding of plant–microbe interactions.

Scanning electron microscopy of colonization of pear leaves by Pseudomonas syringae pv. syringae

1987 ◽  
Vol 65 (12) ◽  
pp. 2517-2522 ◽  
Author(s):  
E. Lucienne Mansvelt ◽  
Martin J. Hattingh
Keyword(s):  
Electron Microscopy ◽  
Pseudomonas Syringae ◽  
Electron Microscope Study ◽  
Leaf Surface ◽  
Leaf Tissue ◽  
Scanning Electron Microscope Study ◽  
Leaf Spots ◽  
Favorable Conditions ◽  
Cuticular Layer ◽  
Scanning Electron

A scanning electron microscope study was undertaken to determine how Pseudomonas syringae pv. syringae van Hall colonizes the surface of pear leaves and enters leaf tissue. Bacteria multiplied on the leaf surface, particularly on trichomes and in depressions of the cuticular layer. Masses of bacteria were associated with leaf spots, which appeared 9 days after inoculation under favorable conditions. The pathogen entered leaf tissue through the open base of trichomes and through microscopic fissures in depressions of the cuticular layer. The resident phase of P. syringae pv. syringae probably survives on trichomes of pear leaves.

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