scholarly journals Biological Control of Bacterial Speck of Tomato Under Field Conditions at Several Locations in North America

2002 ◽  
Vol 92 (12) ◽  
pp. 1284-1292 ◽  
Author(s):  
M. Wilson ◽  
H. L. Campbell ◽  
P. Ji ◽  
J. B. Jones ◽  
D. A. Cuppels
Keyword(s):  
Biological Control ◽  
Disease Severity ◽  
Pseudomonas Syringae ◽  
Field Experiments ◽  
Effective Strain ◽  
Field Conditions ◽  
Tomato Dc3000 ◽  
Bacterial Speck ◽  
Disease Reduction ◽  
Bacterial Speck Disease

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.

Bacteriophytochromes from Pseudomonas syringae pv. tomato DC3000 modulate the early stages of plant colonization during bacterial speck disease

2020 ◽  
Vol 156 (3) ◽  
pp. 695-712 ◽  
Author(s):  
Laura Moyano ◽  
Analía Carrau ◽  
Silvana Petrocelli ◽  
Ivana Kraiselburd ◽  
Wolfgang Gärtner ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Colonization ◽  
Tomato Dc3000 ◽  
Bacterial Speck ◽  
Early Stages ◽  
Bacterial Speck Disease

scholarly journals Assessment of the Importance of Similarity in Carbon Source Utilization Profiles between the Biological Control Agent and the Pathogen in Biological Control of Bacterial Speck of Tomato

2002 ◽  
Vol 68 (9) ◽  
pp. 4383-4389 ◽  
Author(s):  
Pingsheng Ji ◽  
Mark Wilson
Keyword(s):  
Biological Control ◽  
Carbon Source ◽  
Disease Severity ◽  
Pseudomonas Syringae ◽  
Biological Control Agent ◽  
Carbon Sources ◽  
Control Agent ◽  
Carbon Source Utilization ◽  
Bacterial Speck

ABSTRACT Bacterial speck of tomato, caused by Pseudomonas syringae pv. tomato, was used to determine whether similarity in carbon source utilization between a preemptive biological control agent and the pathogen was significant in determining the ability of the bacterium to suppress disease. Similarity in carbon source utilization was quantified as the ratio of the number of tomato carbon sources utilized in vitro by the biological control agent to the number of tomato carbon sources utilized in vitro by the target pathogen (the niche overlap index [NOI]). Suppression of the disease was quantified as the percent reduction in disease severity compared to the pathogen-only control when nonpathogenic bacteria were applied to foliage 48 h prior to the pathogen. In the collection of 36 nonpathogenic bacterial strains, there was a significant (P < 0.01), but weak (r2 = 0.25), correlation between reduction in disease severity and similarity in carbon source utilization, suggesting that similarity in carbon source use was significant in determining ability to suppress disease. The relationship was investigated further using catabolic mutants of P. syringae strain TLP2, an effective biological control agent of speck. Catabolic mutants exhibited lower levels of similarity (NOI = 0.07 to 0.90) than did wild-type TLP2 (NOI = 0.93). With these catabolic mutants there was a significant (P < 0.01), and stronger (r2 = 0.42), correlation between reduction in disease severity and similarity in carbon source utilization. This suggests that similarity in carbon source utilization was a more important component of biological control ability for the catabolic mutants than for the nonpathogenic bacteria. Together, these studies indicate that suppression of bacterial speck of tomato was correlated with nutritional similarity between the pathogenic and nonpathogenic bacteria and suggest that preemptive utilization of carbon sources was probably involved in the biological control of the disease by both the naturally occurring nonpathogenic bacteria and the catabolic mutants.

scholarly journals Pseudomonas syringae pv. tomato DC3000 Type III Effector HopAA1-1 Functions Redundantly with Chlorosis-Promoting Factor PSPTO4723 to Produce Bacterial Speck Lesions in Host Tomato

2009 ◽  
Vol 22 (11) ◽  
pp. 1341-1355 ◽  
Author(s):  
Kathy R. Munkvold ◽  
Alistair B. Russell ◽  
Brian H. Kvitko ◽  
Alan Collmer
Keyword(s):  
Pseudomonas Syringae ◽  
Type Iii Secretion ◽  
Plant Cells ◽  
Secretion System ◽  
Effector Proteins ◽  
Gtpase Activating Protein ◽  
Tomato Dc3000 ◽  
Bacterial Speck ◽  
Type Iii ◽  
Bacterial Speck Disease

The ability of Pseudomonas syringae pv. tomato DC3000 to cause bacterial speck disease in tomato is dependent on the injection, via the type III secretion system, of approximately 28 Avr/Hop effector proteins. HopAA1-1 is encoded in the conserved effector locus (CEL) of the P. syringae Hrp pathogenicity island. Transiently expressed HopAA1-1 acts inside Saccharomyces cerevisiae and plant cells to elicit cell death. hopAA1 homologs were cloned and sequenced from the CEL of seven P. syringae strains representing diverse pathovars. Analysis of the sequences revealed that HopAA1-1 carries a potential GTPase-activating protein (GAP) domain, GALRA, which is polymorphic (FEN instead of LRA) in HopAA1-2, a paralogous DC3000 effector. Deleting hopAA1-1 from DC3000 reduces the formation of necrotic speck lesions in dip-inoculated tomato leaves if effector-gene cluster IX or just PSPTO4723 within this region has been deleted. A HopAA1-1 mutant in which the putative catalytic arginine in the GAP-like domain has been replaced with alanine retains its ability to kill yeast and promote the formation of speck lesions by the ΔhopAA1-1ΔIX mutant, but a HopAA1-1 mutant carrying the FEN polymorphism loses both of these abilities. Unexpectedly, PSPTO4723 does not appear to encode an effector and its deletion also reduces disease-associated chlorosis.

Biological Control of Kudzu (Pueraria lobata) with the Plant PathogenPseudomonas syringaepv.phaseolicola

Weed Science ◽  
1996 ◽  
Vol 44 (3) ◽  
pp. 645-649 ◽  
Author(s):  
Nina K. Zidack ◽  
Paul A. Backman
Keyword(s):  
Biological Control ◽  
Disease Severity ◽  
Pseudomonas Syringae ◽  
Field Experiments ◽  
Leaf Age ◽  
Early Spring ◽  
Pueraria Lobata ◽  
In Planta ◽  
Young Leaves ◽  
Organosilicone Surfactant

Pseudomonas syringaepv.phaseolicolaformulated with an organosilicone surfactant was tested as a potential bioherbicide for kudzu. Greenhouse studies were performed to determine the effect of kudzu plant age and leaf age on disease severity and growth of the bacteriumin planta.Eight-week-old plants were more diseased 4 wk after spraying and had a higher potential for regrowth 7 wk after spraying than 12-wk-old plants. Young leaves developed water-soaked lesions earlier than older leaves and supported higher populations of bacteria. Data from field experiments at two separate locations indicated that single applications in late spring were as effective as multiple applications in early spring and were enhanced by repeat application. Three months after the beginning of the experiment, extensive regrowth occurred for all bioherbicide treatments and no differences were noted between treatments and the nontreated control.

scholarly journals Field Control of Bacterial Spot and Bacterial Speck of Tomato Using a Plant Activator

Plant Disease ◽  
2001 ◽  
Vol 85 (5) ◽  
pp. 481-488 ◽  
Author(s):  
F. J. Louws ◽  
M. Wilson ◽  
H. L. Campbell ◽  
D. A. Cuppels ◽  
J. B. Jones ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Systemic Acquired Resistance ◽  
Field Experiments ◽  
Production Systems ◽  
Acquired Resistance ◽  
Dry Weight ◽  
Bacterial Spot ◽  
Population Densities ◽  
Bacterial Speck ◽  
Plant Activator

Acibenzolar-S-methyl (CGA 245704 or Actigard 50WG) is a plant activator that induces systemic acquired resistance (SAR) in many different crops to a number of pathogens. Acibenzolar-S-methyl was evaluated for management of bacterial spot (Xanthomonas axonopodis pv. vesicatoria) and bacterial speck (Pseudomonas syringae pv. tomato) of tomato in 15 and 7 field experiments, respectively. Experiments were conducted over a 4-year period in Florida, Alabama, North Carolina, Ohio, and Ontario using local production systems. Applied at 35 g a.i. ha-1, acibenzolar-S-methyl reduced foliar disease severity in 14 of the 15 bacterial spot and all 7 bacterial speck experiments. Disease control was similar or superior to that obtained using a standard copper bactericide program. Acibenzolar-S-methyl also reduced bacterial fruit spot and speck incidence. Tomato yield was not affected by using the plant activator in the field when complemented with fungicides to manage foliar fungal diseases, but tomato transplant dry weight was negatively impacted. X. axonopodis pv. vesicatoria population densities on greenhouse-grown tomato transplants were reduced by acibenzolar-S-methyl treatment. Bacterial speck and spot population densities on leaves of field-grown plants were not dramatically affected. Acibenzolar-S-methyl can be integrated as a viable alternative to copper-based bactericides for field management of bacterial spot and speck, particularly where copper-resistant populations predominate.

scholarly journals Protection of Tomato Seedlings against Infection by Pseudomonas syringae pv. Tomato by Using the Plant Growth-Promoting Bacterium Azospirillum brasilense

2002 ◽  
Vol 68 (6) ◽  
pp. 2637-2643 ◽  
Author(s):  
Yoav Bashan ◽  
Luz E. de-Bashan
Keyword(s):  
Plant Growth ◽  
Pseudomonas Syringae ◽  
Azospirillum Brasilense ◽  
Dry Weight ◽  
Tomato Plants ◽  
Bacterial Speck ◽  
Plant Growth Promoting ◽  
Bacterial Speck Disease ◽  
Growth Promoting ◽  
Mist Chamber

ABSTRACT Pseudomonas syringae pv. tomato, the causal agent of bacterial speck of tomato, and the plant growth-promoting bacterium Azospirillum brasilense were inoculated onto tomato plants, either alone, as a mixed culture, or consecutively. The population dynamics in the rhizosphere and foliage, the development of bacterial speck disease, and their effects on plant growth were monitored. When inoculated onto separate plants, the A. brasilense population in the rhizosphere of tomato plants was 2 orders of magnitude greater than the population of P. syringae pv. tomato (107 versus 105 CFU/g [dry weight] of root). Under mist chamber conditions, the leaf population of P. syringae pv. tomato was 1 order of magnitude greater than that of A. brasilense (107 versus 106 CFU/g [dry weight] of leaf). Inoculation of seeds with a mixed culture of the two bacterial strains resulted in a reduction of the pathogen population in the rhizosphere, an increase in the A. brasilense population, the prevention of bacterial speck disease development, and improved plant growth. Inoculation of leaves with the mixed bacterial culture under mist conditions significantly reduced the P. syringae pv. tomato population and significantly decreased disease severity. Challenge with P. syringae pv. tomato after A. brasilense was established in the leaves further reduced both the population of P. syringae pv. tomato and disease severity and significantly enhanced plant development. Both bacteria maintained a large population in the rhizosphere for 45 days when each was inoculated separately onto tomato seeds (105 to 106 CFU/g [dry weight] of root). However, P. syringae pv. tomato did not survive in the rhizosphere in the presence of A. brasilense. Foliar inoculation of A. brasilense after P. syringae pv. tomato was established on the leaves did not alleviate bacterial speck disease, and A. brasilense did not survive well in the phyllosphere under these conditions, even in a mist chamber. Several applications of a low concentration of buffered malic acid significantly enhanced the leaf population of A. brasilense (>108 CFU/g [dry weight] of leaf), decreased the population of P. syringae pv. tomato to almost undetectable levels, almost eliminated disease development, and improved plant growth to the level of uninoculated healthy control plants. Based on our results, we propose that A. brasilense be used in prevention programs to combat the foliar bacterial speck disease caused by P. syringae pv. tomato.

Chemical profile, nutraceutical and anti-phytobacterial properties of the essential oil from Dalea foliolosa (Fabaceae)

2017 ◽  
pp. 724 ◽  
Author(s):  
Nemesio Villa- Ruano ◽  
Yesenia Pacheco- Hernández ◽  
Efraín-Rubio- Rosas ◽  
José A. Zárate- Reyes ◽  
Edmundo Lozoya- Gloria ◽  
...  
Keyword(s):  
Biological Control ◽  
Antioxidant Activity ◽  
Essential Oil ◽  
Pseudomonas Syringae ◽  
Caryophyllene Oxide ◽  
Annual Plant ◽  
Dpph Radical ◽  
Chemical Profile ◽  
Tomato Dc3000 ◽  
Oxygenated Monoterpene

The present work describes the chemical composition of the leaf essential oils from the annual plant Dalea foliolosa, which was collected in three consecutive years (2014-2016). The amount of monoterpenes (69.5-84.6%) was higher to that of sesquiterpenes (10.3-22.9%) and aliphatic hydrocarbons (1-2.1%). Cryptone (22.3-30.6%) was the most abundant oxygenated monoterpene, followed by linalool (10.4-17.6%), caryophyllene oxide (4.6-15.3%), ascaridole (4.5-7.4%) and β-citronellol (3.8-5.6%). The hydrodistillated extract showed antioxidant activity against DPPH radical (IC50, 45-156 µg mL-1), strong anti-α-glucosidase activity (IC50, 14-47 µg mL-1) and inhibited the growth of Pseudomonas syringae pv. tabaci TBR2004 (MIC, 44-105 µg mL-1) and P. syringae pv. tomato DC3000 (MIC, 35-155 µg mL-1). The possible use of the essential oil as a novel additive for anti-hyperglycemic supplements and for the biological control of the analyzed Pseudomonas syringae varieties, may be contemplated.

Resistance of standing milkvetch (Astragalus adsurgens) varieties to Embellisia astragali

2012 ◽  
Vol 63 (4) ◽  
pp. 351 ◽  
Author(s):  
B. H. Yu ◽  
Z. B. Nan ◽  
Y. Z. Li ◽  
H. L. Lin
Keyword(s):  
Disease Severity ◽  
Field Experiments ◽  
Agronomic Traits ◽  
Disease Incidence ◽  
Dry Weight ◽  
Severity Index ◽  
Field Conditions ◽  
Disease Severity Index ◽  
Greenhouse Experiments ◽  
Astragalus Adsurgens

Yellow stunt and root rot caused by Embellisia astragali are major factors contributing to declining yields of standing milkvetch (Astragalus adsurgens). The resistance of ten varieties of standing milkvetch to E. astragali was evaluated under laboratory, greenhouse, and field conditions. Seed germination/emergence, shoot and root length, plant dry weight, disease incidence, mortality, and disease severity index were monitored. The results show that Shanxi and Zhongsha No. 1 varieties had the best agronomic traits and lowest levels of disease in all experiments, while the varieties Neimeng and Ningxia had the highest susceptibility to disease. Germination/emergence differed significantly (P < 0.05) between varieties after inoculation, and compared with the control, germination/emergence of inoculated treatments of nine varieties decreased on average by 1.5% in laboratory experiments and by 4.1% in greenhouse experiments at 15 days after inoculation. Inoculation reduced shoot length by an average of 24.4% and 41.5% (P < 0.05) in laboratory and greenhouse experiments, respectively, in six of ten varieties. All varieties showed significantly (P < 0.05) lower plant dry weight following inoculation, with reductions ranging from 0.3 to 0.6 mg in the laboratory and from 82.6 to 149.4 mg in the greenhouse. Resistance to the pathogen was evaluated on the basis of disease incidence, a disease severity index (DSI), and mortality; varieties showing different resistance were grouped using cluster analysis. There were significant correlations between the results of laboratory and greenhouse experiments (r = 0.79; P < 0.01) and between greenhouse and field experiments (r = 0.83; P < 0.01) across all varieties. Multiple regression analysis between laboratory/greenhouse and field experiments on DSI suggested that screening in the laboratory/greenhouse could be an alternative method of rapidly estimating DSI under field conditions.

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