scholarly journals Pea Aphid as both Host and Vector for the Phytopathogenic Bacterium Pseudomonas syringae

2009 ◽  
Vol 75 (7) ◽  
pp. 2230-2235 ◽  
Author(s):  
John Stavrinides ◽  
Jodi K. McCloskey ◽  
Howard Ochman
Keyword(s):  
Pseudomonas Syringae ◽  
Pea Aphid ◽  
Epiphytic Bacteria ◽  
Agricultural Pests ◽  
Bacterial Sepsis ◽  
Phytopathogenic Bacterium ◽  
Mutagenesis Screen ◽  
Pea Aphids ◽  
Bacterial Transmission ◽  
Aphid Honeydew

ABSTRACT Aphids are widespread agricultural pests that are capable of disseminating plant viral diseases; however, despite coming into frequent contact with epiphytic bacteria, aphids are considered to have no role in bacterial transmission. Here, we demonstrate the ability of pea aphids to vector the phytopathogen Pseudomonas syringae pv. syringae B728a (PsyB728a). While feeding on plants colonized by epiphytic bacteria, aphids acquire the bacteria, which colonize the digestive tract, multiply, and are excreted in the aphid honeydew, resulting in inoculation of the phyllosphere with up to 107 phytopathogenic bacteria per cm2. Within days of ingesting bacteria, aphids succumb to bacterial sepsis, indicating that aphids serve as an alternative, nonplant host for PsyB728a. The related strain Pseudomonas syringae pv. tomato DC3000 is >1,000-fold less virulent than PsyB728a in the pea aphid, suggesting that PsyB728a possesses strain-specific pathogenicity factors that allow it to exploit aphids as hosts. To identify these factors, we performed a mutagenesis screen and recovered PsyB728a mutants that were hypovirulent, including one defective in a gene required for flagellum formation and motility. These interactions illustrate that aphids can also vector bacterial pathogens and that even seemingly host-restricted pathogens can have alternative host specificities and lifestyles.

scholarly journals Epiphytic strains of Pseudomonas syringae kill diverse aphid species.

2021 ◽  
Author(s):  
Melanie R. Smee ◽  
Imperio Real-Ramirez ◽  
Catalina Zuluaga Arias ◽  
Tory A. Hendry
Keyword(s):  
Biological Control ◽  
Pseudomonas Syringae ◽  
Plant Pathogens ◽  
Acyrthosiphon Pisum ◽  
Rhopalosiphum Padi ◽  
Aphid Species ◽  
Pea Aphid ◽  
Oral Exposure ◽  
Pest Species ◽  
Epiphytic Bacteria

Interactions between epiphytic bacteria and herbivorous insects are ubiquitous on plants, but little is known about their ecological implications. Aphids are devastating crop pests worldwide, and so understanding how epiphytic bacteria impact aphid populations is critically important. Recent evidence demonstrates that plant-associated bacteria, such as Pseudomonas syringae, can be highly virulent to one species of aphid, the pea aphid (Acyrthosiphon pisum). Yet currently we have no knowledge on how broad this phenomenon is across diverse aphid species that are of high agricultural concern. In controlled experiments using oral exposure in artificial diet, we challenged five aphid species of agricultural importance with three strains of P. syringae that vary in virulence to the pea aphid. These strains also vary in epiphytic ability and comprise two phytopathogens and one non-plant pathogenic strain. In general, differences in virulence to aphids remained relatively constant across strains regardless of the aphid species, except for the bird cherry-oat aphid (Rhopalosiphum padi) which is significantly less susceptible to two P. syringae strains. We demonstrate that lower infection incidence likely plays a role in the reduced susceptibility. Importantly, these data support previous results showing that interactions with epiphytic bacteria are important for aphids and may play a large, but underappreciated, role in insect population dynamics. Our study illustrates a potential role of epiphytic bacteria in the biological control of aphid pests broadly, but suggests the need for more research encompassing a greater diversity of pest species. Importance Sap-sucking aphids are insects of huge agricultural concern, not only because of direct damage caused by feeding, but also because of their ability to transmit various plant pathogens. Some bacteria that grow on leaf surfaces, such as Pseudomonas syringae, can infect and kill aphids, making them potentially useful in biological control of pest aphids. However, only one aphid species, the pea aphid (Acyrthosiphon pisum) has been tested for infection by P. syringae. Here we challenged five aphid species of agricultural importance with three strains of P. syringae that vary in virulence to the pea aphid. We found that four of these aphid species were susceptible to infection and death, suggesting that these bacteria could be broadly useful for biological control. However, one aphid species was much more resistant to infection, indicating that more testing on diverse aphid species is needed.

scholarly journals Insects as phyllosphere microbiome engineers: effects of aphids on a plant pathogen

2019 ◽  
Author(s):  
Melanie R. Smee ◽  
Imperio Real-Ramirez ◽  
Tory A. Hendry
Keyword(s):  
Pseudomonas Syringae ◽  
Acyrthosiphon Pisum ◽  
Waste Product ◽  
Insect Herbivores ◽  
Epiphytic Bacteria ◽  
Alternative Host ◽  
Associated Bacteria ◽  
Pea Aphids ◽  
Fitness Benefits ◽  
Diverse Plant

AbstractInsect herbivores are common in the phyllosphere, the above-ground parts of plants, and encounter diverse plant-associated bacteria there, yet how these organisms interact remains largely unknown. Strains of the bacterium Pseudomonas syringae grow well epiphytically and have been shown to grow within and kill hemipteran insects like the pea aphid, Acyrthosiphon pisum. Aphids are hypothesized to be an alternative host for these epiphytic bacteria but it is unclear if aphids provide fitness benefits to these bacterial pathogens. To determine if epiphytic bacteria could be adapted for infecting aphids, we characterized 21 strains of P. syringae for epiphytic ability and virulence to pea aphids and found that the two traits were positively correlated. For a subset of strains, we tested if the bacteria derived a fitness benefit from the presence of aphids. Some strains benefited significantly, with up to 18.9% higher population densities when aphids were present, and lower starting population density was predictive of higher benefit from aphid presence. However, further investigation found that honeydew, the sugary waste product of aphids, and not growth in aphids, increased P. syringae growth on leaves. This suggests that aphids may be important microbiome engineers in the phyllosphere, but evolutionarily dead-ends for epiphytic bacteria.

Honeydew sugars and osmoregulation in the pea aphid Acyrthosiphon pisum

1997 ◽  
Vol 200 (15) ◽  
pp. 2137-2143 ◽  
Author(s):  
T Wilkinson ◽  
D Ashford ◽  
J Pritchard ◽  
A Douglas
Keyword(s):  
Osmotic Pressure ◽  
Vicia Faba ◽  
Acyrthosiphon Pisum ◽  
Sucrose Concentration ◽  
Pea Aphid ◽  
Symbiotic Bacteria ◽  
Low Concentrations ◽  
Pea Aphids ◽  
High Concentrations ◽  
Aphid Honeydew

Pea aphids, Acyrthosiphon pisum, containing their symbiotic bacteria (untreated aphids) and experimentally deprived of their bacteria by treatment with the antibiotic rifampicin (antibiotic-treated aphids) were reared on the plant Vicia faba. The sugars in the honeydew produced by untreated aphids comprised predominantly the monosaccharides glucose and fructose, while the honeydew of antibiotic-treated aphids contained considerable amounts of oligosaccharides of up to 16 hexose units. The honeydew and haemolymph of the aphids were iso-osmotic, and their osmotic pressure was significantly lower in untreated aphids (0.91­0.95 MPa) than in antibiotic-treated aphids (1.01­1.05 MPa) (P<0.05). For insects reared on chemically defined diets containing 0.15­1.0 mol l-1 sucrose (osmotic pressure 1.1­4.0 MPa), the osmotic pressure of the aphid haemolymph did not vary with dietary osmotic pressure, but was regulated to approximately 1.0 MPa in untreated and 1.3 MPa in antibiotic-treated aphids. The sugars in the aphid honeydew varied with dietary sucrose concentration; with monosaccharides dominant at low concentrations and oligosaccharides dominant at high concentrations of dietary sucrose. The lowest dietary sucrose concentration at which honeydew oligosaccharides were detected was 0.2 mol l-1 for the antibiotic-treated aphids and 0.3 mol l-1 for untreated aphids. These data indicate that the aphid, and not its associated microbiota, mediates the synthesis of oligosaccharides when the osmotic pressure of the ingesta is high.

scholarly journals The Phytopathogen Dickeya dadantii (Erwinia chrysanthemi 3937) Is a Pathogen of the Pea Aphid

2006 ◽  
Vol 72 (3) ◽  
pp. 1956-1965 ◽  
Author(s):  
Anne-Marie Grenier ◽  
Gabrielle Duport ◽  
Sylvie Pagès ◽  
Guy Condemine ◽  
Yvan Rahbé
Keyword(s):  
Acyrthosiphon Pisum ◽  
Ecological Impact ◽  
Sitophilus Oryzae ◽  
Pea Aphid ◽  
Erwinia Chrysanthemi ◽  
Future Research ◽  
Close Relative ◽  
Bacterial Cells ◽  
Dickeya Dadantii ◽  
Phytopathogenic Bacterium

ABSTRACT Dickeya dadantii (Erwinia chrysanthemi) is a phytopathogenic bacterium causing soft rot diseases on many crops. The sequencing of its genome identified four genes encoding homologues of the Cyt family of insecticidal toxins from Bacillus thuringiensis, which are not present in the close relative Pectobacterium carotovorum subsp. atrosepticum. The pathogenicity of D. dadantii was tested on the pea aphid Acyrthosiphon pisum, and the bacterium was shown to be highly virulent for this insect, either by septic injury or by oral infection. The lethal inoculum dose was calculated to be as low as 10 ingested bacterial cells. A D. dadantii mutant with the four cytotoxin genes deleted showed a reduced per os virulence for A. pisum, highlighting the potential role of at least one of these genes in pathogenicity. Since only one bacterial pathogen of aphids has been previously described (Erwinia aphidicola), other species from the same bacterial group were tested. The pathogenic trait for aphids was shown to be widespread, albeit variable, within the phytopathogens, with no link to phylogenetic positioning in the Enterobacteriaceae. Previously characterized gut symbionts from thrips (Erwinia/Pantoea group) were also highly pathogenic to the aphid, whereas the potent entomopathogen Photorhabdus luminescens was not. D. dadantii is not a generalist insect pathogen, since it has low pathogenicity for three other insect species (Drosophila melanogaster, Sitophilus oryzae, and Spodoptera littoralis). D. dadantii was one of the most virulent aphid pathogens in our screening, and it was active on most aphid instars, except for the first one, probably due to anatomical filtering. The observed difference in virulence toward apterous and winged aphids may have an ecological impact, and this deserves specific attention in future research.

scholarly journals The algT Gene of Pseudomonas syringae pv. glycinea andNew Insights into the Transcriptional Organization of thealgT-muc Gene Cluster

2006 ◽  
Vol 188 (23) ◽  
pp. 8013-8021 ◽  
Author(s):  
Alexander Schenk ◽  
Michael Berger ◽  
Lisa M. Keith ◽  
Carol L. Bender ◽  
Georgi Muskhelishvili ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Pseudomonas Syringae ◽  
Azotobacter Vinelandii ◽  
Regulatory Gene ◽  
In Planta ◽  
Phytopathogenic Bacterium ◽  
Reverse Transcription Pcr ◽  
Alginate Production ◽  
Alginate Biosynthesis

ABSTRACT The phytopathogenic bacterium Pseudomonas syringae pv. glycinea infects soybean plants and causes bacterial blight. In addition to P. syringae, the human pathogen Pseudomonas aeruginosa and the soil bacterium Azotobacter vinelandii produce the exopolysaccharide alginate, a copolymer of d-mannuronic and l-guluronic acids. Alginate production in P. syringae has been associated with increased fitness and virulence in planta. Alginate biosynthesis is tightly controlled by proteins encoded by the algT-muc regulatory gene cluster in P. aeruginosa and A. vinelandii. These genes encode the alternative sigma factor AlgT (σ22), its anti-sigma factors MucA and MucB, MucC, a protein with a controversial function that is absent in P. syringae, and MucD, a periplasmic serine protease and homolog of HtrA in Escherichia coli. We compared an alginate-deficient algT mutant of P. syringae pv. glycinea with an alginate-producing derivative in which algT is intact. The alginate-producing derivative grew significantly slower in vitro growth but showed increased epiphytic fitness and better symptom development in planta. Evaluation of expression levels for algT, mucA, mucB, mucD, and algD, which encodes an alginate biosynthesis gene, showed that mucD transcription is not dependent on AlgT in P. syringae in vitro. Promoter mapping using primer extension experiments confirmed this finding. Results of reverse transcription-PCR demonstrated that algT, mucA, and mucB are cotranscribed as an operon in P. syringae. Northern blot analysis revealed that mucD was expressed as a 1.75-kb monocistronic mRNA in P. syringae.

scholarly journals Physical map of the chromosome of the phytopathogenic bacterium Pseudomonas syringae pv. phaseolicola

Microbiology ◽  
1998 ◽  
Vol 144 (2) ◽  
pp. 493-501 ◽  
Author(s):  
M. E. De Ita ◽  
R. Marsch-Moreno ◽  
P. Guzman ◽  
A. Alvarez-Morales
Keyword(s):  
Pseudomonas Syringae ◽  
Physical Map ◽  
Phytopathogenic Bacterium

SEASONAL ABUNDANCE OF THE PEA APHID, ACYRTHOSIPHON PISUM (HOMOPTERA: APHIDIDAE), IN MANITOBA FIELD PEAS

1986 ◽  
Vol 118 (6) ◽  
pp. 601-607 ◽  
Author(s):  
G.A. Maiteki ◽  
R.J. Lamb ◽  
S.T. Ali-Khan
Keyword(s):  
Pisum Sativum ◽  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Seasonal Abundance ◽  
Economic Threshold ◽  
Field Peas ◽  
Pea Aphids

AbstractPea aphids, Acyrthosiphon pisum (Harris), were sampled from 1980 to 1983 in field peas, Pisum sativum (L.), in Manitoba. Sweep and foliage samples were taken in commercial fields and plots. Aphids were found in late May or early June soon after the crop emerged, but populations were low throughout June. Populations increased in July, when the crop was flowering and producing pods, and peaked in the latter half of July or early August in 3 of the 4 years, when pods were maturing. Populations decreased rapidly after the peak, as the plants senesced. In 1980, a drought year, aphid densities were low and the populations peaked in the middle of August. From 1981 to 1983, densities exceeded the economic threshold in all commercial fields and all but one of the plots that were sampled.

scholarly journals Gene Expression Profiling Indicated Diverse Functions and Characteristics of Core Genes in Pea Aphid

Insects ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 186
Author(s):  
Ruizheng Tian ◽  
Yixiao Huang ◽  
Balachandar Balakrishnan ◽  
Maohua Chen
Keyword(s):  
Expression Profiling ◽  
Insect Pest ◽  
Transcriptome Profiling ◽  
Pea Aphid ◽  
Biological Processes ◽  
Specific Expression ◽  
The Core ◽  
Expression Of Genes ◽  
Pea Aphids ◽  
Core Genes

The pea aphid is a global insect pest, and variable phenotypes can be produced by pea aphids in the same genotype in response to changes in external environmental factors. However, detailed dynamic gene regulation networks and the core markers involved in different biological processes of pea aphids have not yet been reported. In this study, we obtained the published genomic and transcriptomic data, and performed transcriptome profiling of five pea aphid morphs (winged asexual female, wingless asexual female, wingless sexual female, winged male and wingless male) from each of three pea aphid genotypes, i.e., the transcriptomes from a total of 15 types of pea aphids were analyzed and the type-specific expression of genes in five different morphs was identified. The expression profiling was verified by quantitative real-time PCR (qPCR) analysis. Moreover, we determined the expression features and co-expression networks of highly variable genes. We also used the ARACNe method to obtain 263 core genes related to different biological pathways. Additionally, eight of the identified genes were aligned with transcription factor families, indicating that they act as transcription factors and regulate downstream genes. Furthermore, we found reliable markers using random forest methodology to distinguish different morphs of pea aphids. Our study provides a systematic and comprehensive approach for analyzing the core genes that may play important roles in a multitude of biological processes from the insect transcriptomes.

INFLUENCE OF STARVATION ON DEVELOPMENT AND REPRODUCTION IN APTEROUS VIRGINOPARAE OF THE PEA APHID, ACYRTHOSIPHON PISUM (HARRIS) (HOMOPTERA: APHIDIDAE)

1992 ◽  
Vol 124 (1) ◽  
pp. 87-95 ◽  
Author(s):  
K.L. Kouamé ◽  
M. Mackauer
Keyword(s):  
Vicia Faba ◽  
Acyrthosiphon Pisum ◽  
Reproductive Investment ◽  
Dry Weight ◽  
Pea Aphid ◽  
Nutrient Loss ◽  
Adult Weight ◽  
Pea Aphids ◽  
Wet Weight ◽  
Growth Development

AbstractThe influence of nutrient stress on growth, development, and reproduction in apterous virginoparae of the pea aphid, Acyrthosiphon pisum (Harris), was investigated in the laboratory. We tested the hypothesis that species with a high reproductive investment have low resistance to starvation. Aphids in two groups were starved daily from birth for 4 h and 6 h, respectively, and compared with feeding counterparts reared on leaves of broad beans, Vicia faba L. Aphid wet weight increased as an exponential function of age in all groups. Starved aphids had lower adult weight and required longer from birth to parturition than feeding aphids. These effects increased with the length of daily starvation. The number of offspring produced was correlated with adult dry weight. Aphids were unable to compensate, or to compensate completely, for water and nutrient loss resulting from starvation. It is suggested that pea aphids allocate resources first to maintenance and then to reproduction when deprived of food.

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