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 EFFICACY OF BIOCHEMICAL PREPARATIONS AND EXTRACT FROM Hypericum perforatum AGAINST BACTERIAL DISEASES

2019 ◽  
Vol 18 (3) ◽  
Author(s):  
Małgorzata Schollenberger ◽  
Sylwia Pudło ◽  
Elżbieta Paduch-Cichal ◽  
Ewa Mirzwa-Mróz
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Pseudomonas Syringae ◽  
Pathogenic Bacteria ◽  
Hypericum Perforatum ◽  
Agar Plate ◽  
Nutrient Agar ◽  
Bacterial Strains ◽  
Bacterial Diseases ◽  
Nutrient Agar Medium

The biotechnical preparations: Biosept Active (based on a grapefruit extract) and BioZell (based on thyme oil) as well as Hypericum perforatum extract, streptomycin solution and fungicide Champion 50WP (active ingredient substance – e.i. 50% copper hydroxide) were investigated for antimicrobial effects against plant pathogenic bacteria: Agrobacterium tumefaciens, Pseudomonas syringae pv. syringae and Xanthomonas ar- boricola pv. corylina. The screening was carried out in vitro on three media: Nutrient Agar (NA Difco), Pseudomonas Agar F (Merck) – analogue of King B and 523. In the experiments, the agar plate method was applied. There were no statistically significant differences in the effect of streptomycin and Champion 50WP on the growth inhibition of three bacteria strains for medium 523 and Nutrient Agar and of P. syringae pv. syringae and X. arboricola pv. corylina for medium King B. It was determined that the antibacterial activity of Biosept Active and BioZell biopreparations and H. perforatum extract against Agrobacterium tumefaciens (strain C58), Pseudomonas syringae pv. syringae (strain 760) and Xanthomonas arboricola pv. corylina (strain RIPF-x13) were dependent on the strain of pathogen as well as the growth medium used. According to the research results obtained, the Biosept Active preparation and H. perforatum extract demonstrated high bacteriostatic activity against three bacterial strains grown on the Nutrient Agar medium.

Effects of cyst components and low temperature exposure of Heterodera glycines eggs on juvenile hatching in vitro

Nematology ◽  
2011 ◽  
Vol 13 (7) ◽  
pp. 837-844 ◽  
Author(s):  
Edward P. Masler ◽  
Stephen T. Rogers
Keyword(s):  
Low Temperature ◽  
Heterodera Glycines ◽  
Temperature Treatment ◽  
Early Embryo ◽  
Residual Effects ◽  
Low Temperature Treatment ◽  
Affected Relative ◽  
Temperature Exposure ◽  
Low Temperature Exposure

AbstractThe effects of low temperature treatment of Heterodera glycines eggs and the interaction of this treatment with egg condition and cyst influences were examined in vitro. Exposure of eggs to 5°C for 1 week followed by a return to normal culture temperature resulted in a 25-33% reduction in hatch after 2 weeks at 28°C but there was no effect on the timing of hatch. Hatch from encysted eggs was 40% lower than from free eggs at 2 weeks, and hatch from low temperature-encysted eggs was more than 60% lower during the same period. Encystment also altered the timing of hatch relative to free eggs from the same cohort. Hatch from free eggs in the presence of cyst contents was accelerated relative to free eggs without cyst contents, but the total cumulative percent hatch was not increased. Reduction in hatch as a result of low temperature treatment was significant only if the treatment was applied prior to the first juvenile stage (J1). J1 were not affected relative to the hatch of second-stage juveniles (J2). However, the effect of low temperature on earlier stages was not detected until development ceased at early J1 and later J1. Also, low temperature treatment affected the apparent locomotion of some newly hatched J2; 16-fold more J2 from treated eggs were retained on 30 μm pore sieves than those from control eggs. The depression of hatch by low temperature egg treatment was apparently the result of the residual effects on early embryo stages, leading to arrest of development prior to J2.

The 73-kb pIAA plasmid increases competitive fitness of Pseudomonas syringae subspecies savastanoi in oleander

1993 ◽  
Vol 39 (7) ◽  
pp. 659-664 ◽  
Author(s):  
Sara E. Silverstone ◽  
David G. Gilchrist ◽  
Richard M. Bostock ◽  
Tsune Kosuge
Keyword(s):  
Population Density ◽  
Pseudomonas Syringae ◽  
Indoleacetic Acid ◽  
Leaf Tissue ◽  
Insertion Mutant ◽  
Wild Type ◽  
In Planta ◽  
Bacterial Strains ◽  
Growth And Survival ◽  
Iaa Production

Pseudomonas syringae subsp. savastanoi causes tumors on olive and oleander by producing the plant growth regulators indoleacetic acid (IAA) and cytokinins following infection of the plant. The contribution of IAA production to the ability of P. syringae subsp. savastanoi to grow and survive in oleander leaf tissue was studied. Bacterial strains differing only with respect to IAA production were characterized. Growth and survival of wild-type and two mutant strains of P. syringae subsp. savastanoi in oleander leaf tissue were monitored by weekly colony counts and IAA plate assays. Growth rate of the three strains in culture and in planta did not differ significantly. However, the wild-type strain reached a higher population density and maintained its maximum density at least 9 weeks longer than either mutant population. An insertion mutant containing the IAA plasmid (pIAA), but incapable of IAA production, did not maintain a higher population density than a strain cured of the IAA plasmid. The pIAA-cured strain maintained a higher population density when coinoculated with an IAA-producing strain than when inoculated alone. These results suggest that IAA production may contribute to the fitness of P. syringae subsp. savastanoi in oleander tissue and that the iaa operon alone may be responsible for the competitive advantage of cells harboring pIAA.Key words: indoleacetic acid, bacterial ecology.

scholarly journals Immunogold Labeling of Hrp Pili of Pseudomonas syringae pv. tomato Assembled in Minimal Medium and In Planta

2001 ◽  
Vol 14 (2) ◽  
pp. 234-241 ◽  
Author(s):  
Wenqi Hu ◽  
Jing Yuan ◽  
Qiao-Ling Jin ◽  
Patrick Hart ◽  
Sheng Yang He
Keyword(s):  
Arabidopsis Thaliana ◽  
Pseudomonas Syringae ◽  
Minimal Medium ◽  
Leaf Tissue ◽  
Hypersensitive Reaction ◽  
Immunogold Labeling ◽  
Structural Protein ◽  
In Planta ◽  
Hrp Genes

Hypersensitive reaction and pathogenicity (hrp) genes are required for Pseudomonas syringae pv. tomato (Pst) DC3000 to cause disease in susceptible tomato and Arabidopsis thaliana plants and to elicit the hypersensitive response in resistant plants. The hrp genes encode a type III protein secretion system known as the Hrp system, which in Pst DC3000 secretes HrpA, HrpZ, HrpW, and AvrPto and assembles a surface appendage, named the Hrp pilus, in hrp-gene-inducing minimal medium. HrpA has been suggested to be the Hrp pilus structural protein on the basis of copurification and mutational analyses. In this study, we show that an antibody against HrpA efficiently labeled Hrp pili, whereas antibodies against HrpW and HrpZ did not. Immunogold labeling of bacteria-infected Arabidopsis thaliana leaf tissue with an Hrp pilus antibody revealed a characteristic lineup of gold particles around bacteria and/or at the bacterium-plant contact site. These results confirm that HrpA is the major structural protein of the Hrp pilus and provide evidence that Hrp pili are assembled in vitro and in planta.

scholarly journals Ice-nucleation-active (INA) Bacteria: A Detriment to Strawberry Flower Survival during Low-temperature Exposure

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 428B-428
Author(s):  
Michele R. Warmund ◽  
James T. English
Keyword(s):  
Low Temperature ◽  
Pseudomonas Syringae ◽  
Ice Nucleation ◽  
Ice Crystals ◽  
Colony Forming Units ◽  
Ina Bacteria ◽  
Temperature Exposure ◽  
Low Temperature Exposure ◽  
Ice Crystallization

Experiments were conducted to determine the temperatures at which different densities of INA bacteria incite ice crystallization on `Totem' strawberry flowers and to determine if there is a relationship between densities of INA bacteria on strawberry flowers and floral injury. Primary flowers were inoculated with Pseudomonas syringae at 106 cells/ml buffer, incubated at 25°C day/10°C night and 100% RH for 48 h, and exposed to –2.0°C. No ice nucleation occurred on these inoculated flowers and all of the flowers survived. However, when inoculated flowers were subjected to lower temperatures, ice nucleation occurred at –2.2°C and few of the flowers survived. In contrast, ice crystals formed on the surface of most non-inoculated flowers at –2.8°C and 21% of the flowers survived exposure to –3.5°C. When INA bacterial densities were ≈105 colony forming units/g dry wt, floral injury occurred at a warmer temperature than to flowers that had lower bacterial densities.

Bacteria occurring in onion (Allium cepa L.) foliage in Puerto Rico.

1969 ◽  
pp. 199-219
Author(s):  
Juan Calle-Bellido ◽  
Lydia I. Rivera-Vargas ◽  
Myrna Alameda ◽  
Irma Cabrera
Keyword(s):  
Puerto Rico ◽  
Pseudomonas Syringae ◽  
Allium Cepa ◽  
Leaf Tissue ◽  
Field Conditions ◽  
Bacterial Strains ◽  
Burkholderia Glumae ◽  
Pathogenic Potential ◽  
Allium Cepa L ◽  
Leaf Tissues

Bacteria associated with foliar symptoms of onion (Allium cepa L.) were examined in the southern region of Puerto Rico from January through April 2004. Different symptoms were observed in onion foliage of cultivars 'Mercedes' and 'Excalibur' at Juana Díaz and Santa Isabel, Puerto Rico. Ellipsoidal sunken lesions with soft rot and disruption of tissue were the most common symptoms observed in onion foliage in field conditions. From a total of 39 bacterial strains isolated from diverse symptoms in onion foliage, 38% were isolated from soft rotting lesions. Ninety-two percent of the bacteria isolated from onion foliage was Gram negative. Pantoea spp. with 25%, was the most frequently isolated genus, followed by Pasteurella spp. and Serratia rubidae with 10% each. Fifty- six percent of the strains held plant pathogenic potential; these strains belong to the genera Acidovorax sp., Burkholderia sp., Clavibacter sp., Curtobacterium sp., Enterobacter sp., Pantoea spp., Pseudomonas spp., and Xanthomonas spp. Pathogenicity tests showed that seven out of eight tested bacterial strains evaluated under field conditions caused symptoms in onion foliage for both cultivars. Acidovorax avenae subsp. citrulli, Burkholderia glumae, Pantoea agglomerans, P. dispersa, Pseudomonas sp., Xanthomonas sp., and Xanthomonas-Wke sp. were pathogenic to leaf tissues. Clavibacter michiganensis was not pathogenic to leaf tissues. Other bacteria identified as associated with onion leaf tissue were Curtobacterium flaccumfaciens, Cytophaga sp., Enterobacter cloacae, Flavimonas oryzihabitans, Mannheimia haemolytica, Pantoea stewartii, Pasteurella anatis, P. bettyae, P. langaaensis, Photobacterium damselae, Pseudomonas syringae pv. aptata, Rhizobium radiobacter, Serratia rubidae, Sphingobacterium spiritivorum, Sphingomonas sanguinis, and an unknown strain. This paper is the first survey of bacteria associated with onion foliage in Puerto Rico. The role of non- phytopathogenic bacteria associated with the life cycle of onion under field conditions remains unknown.

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 557 PB 374 EFFICACIES OF CRYOPROTECTANTS APPLIED TO STRAWBERRY PLANTS INOCULATED WITH ICE-NUCLEATION-ACTIVE BACTERIA

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 511d-511
Author(s):  
Michele R. Warmund ◽  
James T. English
Keyword(s):  
Low Temperature ◽  
Pseudomonas Syringae ◽  
Ice Nucleation ◽  
Freezing Injury ◽  
Fragaria Ananassa ◽  
Full Bloom ◽  
Ina Bacteria ◽  
Active Bacteria ◽  
Temperature Exposure ◽  
Low Temperature Exposure

Cryoprotectants were applied at labeled rates to primary flowers of `Honeoye' strawberry (Fragaria × ananassa Duch.) plants at full bloom to determine their effects on the floral organs. Frostgard at 50 ml/liter or KDL at 22 ml/liter injured pistils and resulted in misshapened fruit. Floral buds that were closed when cryoprotectants were applied were uninjured. In other experiments, efficacies of cryoprotectants were determined after floral tissues of `Honeoye' strawberry plants were inoculated or not inoculated with the ice-nucleation-active (INA) bacteria, Pseudomonas syringae van Hall and subjected to sub-freezing temperatures. None of the products protected primary or secondary flowers against freezing injury regardless of the occurrence of INA bacteria. INA bacteria were not recovered from primary flowers of treated plants that were killed by low temperature exposure, indicating that non-bacterial nuclei may incite freezing in these tissues.

scholarly journals Resident Bacteria on Leaves Enhance Survival of Immigrant Cells of Salmonella enterica

2013 ◽  
Vol 103 (4) ◽  
pp. 341-351 ◽  
Author(s):  
Cesar Poza-Carrion ◽  
Trevor Suslow ◽  
Steven Lindow
Keyword(s):  
Pseudomonas Syringae ◽  
Salmonella Enterica ◽  
Bacterial Species ◽  
Bacterial Strains ◽  
Isolated Cells ◽  
Leaf Surfaces ◽  
Viable Population ◽  
Population Sizes ◽  
Cellular Aggregates

Although Salmonella enterica apparently has comparatively low epiphytic fitness on plants, external factors that would influence its ability to survive on plants after contamination would be of significance in the epidemiology of human diseases caused by this human pathogen. Viable population sizes of S. enterica applied to plants preinoculated with Pseudomonas syringae or either of two Erwinia herbicola strains was ≥10-fold higher than that on control plants that were not precolonized by such indigenous bacteria when assessed 24 to 72 h after the imposition of desiccation stress. The protective effect of P. fluorescens, which exhibited antibiosis toward S. enterica in vitro, was only ≈50% that conferred by other bacterial strains. Although S. enterica could produce small cellular aggregates after incubation on wet leaves for several days, and the cells in such aggregates were less susceptible to death upon acute dehydration than solitary cells (as determined by propidium iodide staining), most Salmonella cells were found as isolated cells when it was applied to leaves previously colonized by other bacterial species. The proportion of solitary cells of S. enterica coincident with aggregates of cells of preexisting epiphytic species that subsequently were judged as nonviable by viability staining on dry leaves was as much as 10-fold less than those that had landed on uncolonized portions of the leaf. Thus, survival of immigrant cells of S. enterica on plants appears to be strongly context dependent, and the presence of common epiphytic bacteria on plants can protect such immigrants from at least one key stress (i.e., desiccation) encountered on leaf surfaces.

scholarly journals Antimicrobial Activity Screening of Rhizosphere Soil Bacteria from Tomato and Genome-Based Analysis of their Antimicrobial Biosynthetic Potential

2020 ◽  
Author(s):  
Lu Zhou ◽  
Chunxu Song ◽  
Zhibo Li ◽  
Oscar P. Kuipers
Keyword(s):  
Antimicrobial Activity ◽  
Plant Growth ◽  
Disease Control ◽  
Pseudomonas Syringae ◽  
Rhizosphere Soil ◽  
Gene Clusters ◽  
Bacterial Strains ◽  
Vast Number ◽  
Tomato Disease

Abstract Background: Tomato plant growth is frequently hampered by a high susceptibility to pests and diseases. Traditional chemical control causes a serious impact on both the environment and human health. Therefore, seeking environment-friendly and cost-effective green methods in agricultural production becomes crucial nowadays. Plant Growth Promoting Rhizobacteria (PGPR) can promote plant growth through biological activity. Their use is considered to be a promising sustainable approach for crop growth. Moreover, a vast number of biosynthetic gene clusters (BGCs) for secondary metabolite production are being revealed in PGPR, which helps to find potential anti-microbial activities for tomato disease control.Results: We isolated 351 bacterial strains (181 of which are Bacillus sp.) from healthy tomato, rhizosphere soil, and tomato tissues. In vitro antagonistic assays revealed that 34 Bacillus strains have antimicrobial activity against Erwinia carotovora, Pseudomonas syringae; Rhizoctonia solani; Botrytis cinerea; Verticillium dahliae and Phytophthora infestans. The genomes of 10 Bacillus and Paenibacillus strains with good antagonistic activity were sequenced. Via genome mining approaches, we identified 120 BGCs encoding NRPs, PKs-NRPs, PKs, terpenes and bacteriocins, including known compounds such as fengycin, surfactin, bacillibactin, subtilin, etc. In addition, several novel BGCs were identified. We discovered that the NRPs and PKs-NRPs BGCs in Bacillus species are encoding highly conserved known compounds as well as various novel variants.Conclusions: This study highlights the great number of varieties of BGCs in Bacillus strains. These findings pave the road for future usage of Bacillus strains as biocontrol agents for tomato disease control and are a resource arsenal for novel antimicrobial discovery.

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