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Rangel LI, Leveau JHJ. Applied microbiology of the phyllosphere. Appl Microbiol Biotechnol 2024; 108:211. [PMID: 38358509 PMCID: PMC10869387 DOI: 10.1007/s00253-024-13042-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 02/16/2024]
Abstract
The phyllosphere, or plant leaf surface, represents a microbial ecosystem of considerable size, holding extraordinary biodiversity and enormous potential for the discovery of new products, tools, and applications in biotechnology, agriculture, medicine, and elsewhere. This mini-review highlights the applied microbiology of the phyllosphere as an original field of study concerning itself with the genes, gene products, natural compounds, and traits that underlie phyllosphere-specific adaptations and services that have commercial and economic value for current or future innovation. Examples include plant-growth-promoting and disease-suppressive phyllobacteria, probiotics and fermented foods that support human health, as well as microbials that remedy foliar contamination with airborne pollutants, residual pesticides, or plastics. Phyllosphere microbes promote plant biomass conversion into compost, renewable energy, animal feed, or fiber. They produce foodstuffs such as thickening agents and sugar substitutes, industrial-grade biosurfactants, novel antibiotics and cancer drugs, as well as enzymes used as food additives or freezing agents. Furthermore, new developments in DNA sequence-based profiling of leaf-associated microbial communities allow for surveillance approaches in the context of food safety and security, for example, to detect enteric human pathogens on leafy greens, predict plant disease outbreaks, and intercept plant pathogens and pests on internationally traded goods. KEY POINTS: • Applied phyllosphere microbiology concerns leaf-specific adaptations for economic value • Phyllobioprospecting searches the phyllosphere microbiome for product development • Phyllobiomonitoring tracks phyllosphere microbial profiles for early risk detection.
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Affiliation(s)
- Lorena I Rangel
- Cell & Molecular Sciences, The James Hutton Institute, Dundee, Scotland, UK.
- Department of Plant Pathology, University of California, Davis, CA, USA.
| | - Johan H J Leveau
- Department of Plant Pathology, University of California, Davis, CA, USA.
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2
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Leisner CP, Potnis N, Sanz-Saez A. Crosstalk and trade-offs: Plant responses to climate change-associated abiotic and biotic stresses. PLANT, CELL & ENVIRONMENT 2023; 46:2946-2963. [PMID: 36585762 DOI: 10.1111/pce.14532] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 12/07/2022] [Accepted: 12/28/2022] [Indexed: 06/17/2023]
Abstract
As sessile organisms, plants are constantly challenged by a dynamic growing environment. This includes fluctuations in temperature, water availability, light levels, and changes in atmospheric constituents such as carbon dioxide (CO2 ) and ozone (O3 ). In concert with changes in abiotic conditions, plants experience changes in biotic stress pressures, including plant pathogens and herbivores. Human-induced increases in atmospheric CO2 levels have led to alterations in plant growth environments that impact their productivity and nutritional quality. Additionally, it is predicted that climate change will alter the prevalence and virulence of plant pathogens, further challenging plant growth. A knowledge gap exists in the complex interplay between plant responses to biotic and abiotic stress conditions. Closing this gap is crucial for developing climate resilient crops in the future. Here, we briefly review the physiological responses of plants to elevated CO2 , temperature, tropospheric O3 , and drought conditions, as well as the interaction of these abiotic stress factors with plant pathogen pressure. Additionally, we describe the crosstalk and trade-offs involved in plant responses to both abiotic and biotic stress, and outline targets for future work to develop a more sustainable future food supply considering future climate change.
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Affiliation(s)
- Courtney P Leisner
- Department of Biological Sciences, Auburn University, Auburn, Alabama, USA
| | - Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
| | - Alvaro Sanz-Saez
- Department of Crop, Soil and Environmental Science, Auburn University, Auburn, Alabama, USA
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3
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de Sousa DM, Janssen L, Rosa RB, Belmok A, Yamada JK, Corrêa RFT, de Souza Andrade M, Inoue-Nagata AK, Ribeiro BM, de Carvalho Pontes N. Isolation, characterization, and evaluation of putative new bacteriophages for controlling bacterial spot on tomato in Brazil. Arch Virol 2023; 168:222. [PMID: 37548749 DOI: 10.1007/s00705-023-05846-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 07/07/2023] [Indexed: 08/08/2023]
Abstract
Bacterial spot is a highly damaging tomato disease caused by members of several species of the genus Xanthomonas. Bacteriophages have been studied for their potential use in the biological control of bacterial diseases. In the current study, bacteriophages were obtained from soil and tomato leaves in commercial fields in Brazil with the aim of obtaining biological control agents against bacterial spot. Phage isolation was carried out by co-cultivation with isolates of Xanthomonas euvesicatoria pv. perforans, which was prevalent in the collection areas. In a host range evaluation, none of the phage isolates was able to induce a lytic cycle in all of the bacterial isolates tested. In in vivo tests, treatment of susceptible bacterial isolates with the corresponding phage prior to application to tomato plants led to a reduction in the severity of the resulting disease. The level of disease control provided by phage application was equal to or greater than that achieved using copper hydroxide. Electron microscopy analysis showed that all of the phages had similar morphology, with head and tail structures similar to those of viruses belonging to the class Caudoviricetes. The presence of short, non-contractile tubular tails strongly suggested that these phages belong to the family Autographiviridae. This was confirmed by phylogenetic analysis, which further revealed that they all belong to the genus Pradovirus. The phages described here are closely related to each other and potentially belong to a new species within the genus. These phages will be evaluated in future studies against other tomato xanthomonad strains to assess their potential as biological control agents.
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Affiliation(s)
- Dayane Maria de Sousa
- Programa de Pós-Graduação em Olericultura, Instituto Federal Goiano (IF Goiano), Morrinhos, GO, Brazil
| | - Luis Janssen
- Laboratory of Baculovirus, Cell Biology Department, University of Brasília (UnB), Campus Universitário Darcy Ribeiro, Brasília, DF, Brazil
| | - Raphael Barboza Rosa
- Programa de Pós-Graduação em Olericultura, Instituto Federal Goiano (IF Goiano), Morrinhos, GO, Brazil
| | - Aline Belmok
- Laboratory of Baculovirus, Cell Biology Department, University of Brasília (UnB), Campus Universitário Darcy Ribeiro, Brasília, DF, Brazil
| | - Jaqueline Kiyomi Yamada
- Programa de Pós-Graduação em Olericultura, Instituto Federal Goiano (IF Goiano), Morrinhos, GO, Brazil
| | - Roberto Franco Teixeira Corrêa
- Laboratory of Baculovirus, Cell Biology Department, University of Brasília (UnB), Campus Universitário Darcy Ribeiro, Brasília, DF, Brazil
| | - Miguel de Souza Andrade
- Laboratory of Baculovirus, Cell Biology Department, University of Brasília (UnB), Campus Universitário Darcy Ribeiro, Brasília, DF, Brazil
| | | | - Bergmann Morais Ribeiro
- Laboratory of Baculovirus, Cell Biology Department, University of Brasília (UnB), Campus Universitário Darcy Ribeiro, Brasília, DF, Brazil
| | - Nadson de Carvalho Pontes
- Programa de Pós-Graduação em Olericultura, Instituto Federal Goiano (IF Goiano), Morrinhos, GO, Brazil.
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4
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Jones KR, Hughey MC, Belden LK. Colonization order of bacterial isolates on treefrog embryos impacts microbiome structure in tadpoles. Proc Biol Sci 2023; 290:20230308. [PMID: 36946107 PMCID: PMC10031419 DOI: 10.1098/rspb.2023.0308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Accepted: 03/06/2023] [Indexed: 03/23/2023] Open
Abstract
Priority effects, or impacts of colonization order, may have lasting influence on ecological community composition. The embryonic microbiome is subject to stochasticity in colonization order of bacteria. Stochasticity may be especially impactful for embryos developing in bacteria-rich environments, such as the embryos of many amphibians. To determine if priority effects experienced as embryos impacted bacterial community composition in newly hatched tadpoles, we selectively inoculated the embryos of laboratory-raised hourglass treefrogs, Dendropsophus ebraccatus, with bacteria initially isolated from the skin of wild D. ebraccatus adults over 2 days. First, embryos were inoculated with two bacteria in alternating sequences. Next, we evaluated the outcomes of priority effects in an in vitro co-culture assay absent of host factors. We then performed a second embryo experiment, inoculating embryos with one of three bacteria on the first day and a community of five target bacteria on the second. Through 16S rRNA gene amplicon sequencing, we observed relative abundance shifts in tadpole bacteria communities due to priority effects. Our results suggest that the initial bacterial source pools of embryos shape bacterial communities at later life stages; however, the magnitude of those changes is dependent on the host environment and the identity of bacterial colonists.
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Affiliation(s)
- Korin Rex Jones
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061-0131, USA
| | - Myra C. Hughey
- Department of Biology, Vassar College, Poughkeepsie, NY 12604, USA
| | - Lisa K. Belden
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061-0131, USA
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5
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Esmael A, Al-Hindi RR, Albiheyri RS, Alharbi MG, Filimban AAR, Alseghayer MS, Almaneea AM, Alhadlaq MA, Ayubu J, Teklemariam AD. Fresh Produce as a Potential Vector and Reservoir for Human Bacterial Pathogens: Revealing the Ambiguity of Interaction and Transmission. Microorganisms 2023; 11:microorganisms11030753. [PMID: 36985326 PMCID: PMC10056104 DOI: 10.3390/microorganisms11030753] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/08/2023] [Accepted: 03/10/2023] [Indexed: 03/17/2023] Open
Abstract
The consumer demand for fresh produce (vegetables and fruits) has considerably increased since the 1980s for more nutritious foods and healthier life practices, particularly in developed countries. Currently, several foodborne outbreaks have been linked to fresh produce. The global rise in fresh produce associated with human infections may be due to the use of wastewater or any contaminated water for the cultivation of fruits and vegetables, the firm attachment of the foodborne pathogens on the plant surface, and the internalization of these agents deep inside the tissue of the plant, poor disinfection practices and human consumption of raw fresh produce. Several investigations have been established related to the human microbial pathogens (HMPs) interaction, their internalization, and survival on/within plant tissue. Previous studies have displayed that HMPs are comprised of several cellular constituents to attach and adapt to the plant’s intracellular niches. In addition, there are several plant-associated factors, such as surface morphology, nutrient content, and plant–HMP interactions, that determine the internalization and subsequent transmission to humans. Based on documented findings, the internalized HMPs are not susceptible to sanitation or decontaminants applied on the surface of the fresh produce. Therefore, the contamination of fresh produce by HMPs could pose significant food safety hazards. This review provides a comprehensive overview of the interaction between fresh produce and HMPs and reveals the ambiguity of interaction and transmission of the agents to humans.
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Affiliation(s)
- Ahmed Esmael
- Botany and Microbiology Department, Faculty of Science, Benha University, Benha 13518, Egypt
- Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
- Correspondence: (A.E.); (R.R.A.)
| | - Rashad R. Al-Hindi
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Correspondence: (A.E.); (R.R.A.)
| | - Raed S. Albiheyri
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Mona G. Alharbi
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Amani A. R. Filimban
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Mazen S. Alseghayer
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Monitoring and Risk Assessment Department, Saudi Food and Drug Authority, Riyadh 13513, Saudi Arabia
| | - Abdulaziz M. Almaneea
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Monitoring and Risk Assessment Department, Saudi Food and Drug Authority, Riyadh 13513, Saudi Arabia
| | - Meshari Ahmed Alhadlaq
- Molecular Biology Section, Reference Laboratory for Microbiology Department, Research and Laboratories Sector, Saudi Food and Drug Authority, Riyadh 13513, Saudi Arabia
| | - Jumaa Ayubu
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Addisu D. Teklemariam
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
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6
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Karmakar K, Chakraborty S, Kumar JR, Nath U, Nataraja KN, Chakravortty D. Role of lactoyl-glutathione lyase of Salmonella in the colonization of plants under salinity stress. Res Microbiol 2023; 174:104045. [PMID: 36842715 DOI: 10.1016/j.resmic.2023.104045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 02/17/2023] [Accepted: 02/18/2023] [Indexed: 02/28/2023]
Abstract
Salmonella, a foodborne human pathogen, can colonize the members of the kingdom Plantae. However, the basis of the persistence of Salmonella in plants is largely unknown. Plants encounter various biotic and abiotic stress agents in soil. We conjectured that methylglyoxal (MG), one of the common metabolites that accumulate in plants during both biotic and abiotic stress, plays a role in regulating the plant-Salmonella interaction. The interaction of Salmonella Typhimurium with plants under salinity stress was investigated. It was observed that wild-type Salmonella Typhimurium can efficiently colonize the root, but mutant bacteria lacking MG detoxifying enzyme, lactoyl-glutathione lyase (Lgl), showed lower colonization in roots exclusively under salinity stress. This colonization defect is due to the poor viability of the mutated bacterial strains under these conditions. This is the first report to prove the role of MG-detoxification genes in the colonization of stressed plants and highlights the possible involvement of metabolic genes in the evolution of the plant-associated life of Salmonella.
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Affiliation(s)
- Kapudeep Karmakar
- Regional Research Station, Terai Zone, Uttar Banga Krishi Viswavidyalaya, Coochbehar-736165, India.
| | - Sangeeta Chakraborty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India.
| | - Jyothsna R Kumar
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India.
| | - Utpal Nath
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India.
| | - Karaba N Nataraja
- Department of Crop Physiology, University of Agricultural Science, Bangalore 560012, India.
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India; Adjunct Faculty, School of Biology, Indian Institute of Science and Educational Research, Thiruvananthapuram 695551, India.
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7
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Gu G, Murphy CM, Hamilton AM, Zheng J, Nou X, Rideout SL, Strawn LK. Effect of pesticide application on
Salmonella
survival on inoculated tomato leaves. J Food Saf 2023. [DOI: 10.1111/jfs.13043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Ganyu Gu
- School of Plant and Environmental Sciences Virginia Tech Blacksburg Virginia USA
- Environmental Microbial and Food Safety Laboratory United States Department of Agriculture‐Agricultural Research Service Beltsville Maryland USA
| | - Claire M. Murphy
- Department of Food Science and Technology Virginia Tech Blacksburg Virginia USA
| | - Alexis M. Hamilton
- Department of Food Science and Technology Virginia Tech Blacksburg Virginia USA
| | - Jie Zheng
- Center for Food Safety and Applied Nutrition US Food and Drug Administration College Park Maryland USA
| | - Xiangwu Nou
- Environmental Microbial and Food Safety Laboratory United States Department of Agriculture‐Agricultural Research Service Beltsville Maryland USA
| | - Steven L. Rideout
- School of Plant and Environmental Sciences Virginia Tech Blacksburg Virginia USA
| | - Laura K. Strawn
- Department of Food Science and Technology Virginia Tech Blacksburg Virginia USA
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8
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Lovelace AH, Chen HC, Lee S, Soufi Z, Bota P, Preston GM, Kvitko BH. RpoS contributes in a host-dependent manner to Salmonella colonization of the leaf apoplast during plant disease. Front Microbiol 2022; 13:999183. [PMID: 36425046 PMCID: PMC9679226 DOI: 10.3389/fmicb.2022.999183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 10/21/2022] [Indexed: 11/04/2023] Open
Abstract
Contaminated fresh produce has been routinely linked to outbreaks of Salmonellosis. Multiple studies have identified Salmonella enterica factors associated with successful colonization of diverse plant niches and tissues. It has also been well documented that S. enterica can benefit from the conditions generated during plant disease by host-compatible plant pathogens. In this study, we compared the capacity of two common S. enterica research strains, 14028s and LT2 (strain DM10000) to opportunistically colonize the leaf apoplast of two model plant hosts Arabidopsis thaliana and Nicotiana benthamiana during disease. While S. enterica 14028s benefited from co-colonization with plant-pathogenic Pseudomonas syringae in both plant hosts, S. enterica LT2 was unable to benefit from Pto co-colonization in N. benthamiana. Counterintuitively, LT2 grew more rapidly in ex planta N. benthamiana apoplastic wash fluid with a distinctly pronounced biphasic growth curve in comparison with 14028s. Using allelic exchange, we demonstrated that both the N. benthamiana infection-depedent colonization and apoplastic wash fluid growth phenotypes of LT2 were associated with mutations in the S. enterica rpoS stress-response sigma factor gene. Mutations of S. enterica rpoS have been previously shown to decrease tolerance to oxidative stress and alter metabolic regulation. We identified rpoS-dependent alterations in the utilization of L-malic acid, an abundant carbon source in N. benthamiana apoplastic wash fluid. We also present data consistent with higher relative basal reactive oxygen species (ROS) in N. benthamiana leaves than in A. thaliana leaves. The differences in basal ROS may explain the host-dependent disease co-colonization defect of the rpoS-mutated LT2 strain. Our results indicate that the conducive environment generated by pathogen modulation of the apoplast niche can vary from hosts to host even with a common disease-compatible pathogen.
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Affiliation(s)
- Amelia H. Lovelace
- The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom
| | - Hsiao-Chun Chen
- Department of Plant Pathology, University of Georgia, Athens, GA, United States
| | - Sangwook Lee
- Department of Microbiology, University of Georgia, Athens, GA, United States
| | - Ziad Soufi
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Pedro Bota
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Gail M. Preston
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Brian H. Kvitko
- Department of Plant Pathology, University of Georgia, Athens, GA, United States
- The Plant Center, University of Georgia, Athens, GA, United States
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9
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Xanthomonas
Infection Transforms the Apoplast into an Accessible and Habitable Niche for Salmonella enterica. Appl Environ Microbiol 2022; 88:e0133022. [PMID: 36314834 PMCID: PMC9680631 DOI: 10.1128/aem.01330-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial spot disease caused by
Xanthomonas
species devastates tomato production worldwide. Salmonellosis outbreaks from consumption of raw produce have been linked to the arrival of
Salmonella enterica
on crop plants in the field via contaminated irrigation water.
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10
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Manus MB. Ecological Processes and Human Behavior Provide a Framework for Studying the Skin Microbial Metacommunity. MICROBIAL ECOLOGY 2022; 84:689-702. [PMID: 34636925 DOI: 10.1007/s00248-021-01884-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 09/24/2021] [Indexed: 06/13/2023]
Abstract
Metacommunity theory dictates that a microbial community is supported both by local ecological processes and the dispersal of microbes between neighboring communities. Studies that apply this perspective to human-associated microbial communities are thus far limited to the gut microbiome. Yet, the skin serves as the primary barrier between the body and the external environment, suggesting frequent opportunities for microbial dispersal to the variable microbial communities that are housed across skin sites. This paper applies metacommunity theory to understand the dispersal of microbes to the skin from the physical and social environment, as well as between different skin sites on an individual's body. This includes highlighting the role of human behavior in driving microbial dispersal, as well as shaping physiological properties of skin that underscore local microbial community dynamics. By leveraging data from research on the skin microbiomes of amphibians and other animals, this paper provides recommendations for future research on the skin microbial metacommunity, including generating testable predictions about the ecological underpinnings of the skin microbiome.
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Affiliation(s)
- Melissa B Manus
- Department of Anthropology, Northwestern University, Evanston, IL, USA.
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11
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Salmonella enterica changes Macrosteles quadrilineatus feeding behaviors resulting in altered S. enterica distribution on leaves and increased populations. Sci Rep 2022; 12:8544. [PMID: 35595751 PMCID: PMC9122940 DOI: 10.1038/s41598-022-11750-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 04/28/2022] [Indexed: 11/08/2022] Open
Abstract
Hemipteran insects are ubiquitous inhabitants of the phyllosphere. Changes in microbial phyllosphere communities have recently been demonstrated following infestation by Macrosteles quadrilineatus (Aster Leafhopper). Although epiphytic Salmonella enterica populations naturally decline in the phyllosphere of plants, M. quadrilineatus infestation facilitated the growth of the bacterial pathogen populations. Here, we demonstrate that cellular damage by insect stylet penetration results in a localized beneficial niche on the leaf surface, leading to enhanced S. enterica populations. We measured S. enterica populations and colonization patterns on plants infested with Hemipterans with distinct feeding behaviors. M. quadrilineatus infestation resulted in higher solute leakage and significantly greater bacterial populations than plants absent of insects. Following immigration via contaminated irrigation water, the highest populations of S. enterica are naturally found on the tips of tomato leaflets. We discovered M. quadrilineatus feeding preference altered the natural distribution of S. enterica populations, and that the presence of S. enterica altered the distribution of probing attempts. These findings elucidate how cellular damage resulting from insect feeding drives changes in bacterial colonization of the phyllosphere.
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12
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Cowles KN, Block AK, Barak JD. Xanthomonas hortorum pv. gardneri TAL effector AvrHah1 is necessary and sufficient for increased persistence of Salmonella enterica on tomato leaves. Sci Rep 2022; 12:7313. [PMID: 35508535 PMCID: PMC9068798 DOI: 10.1038/s41598-022-11456-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 04/25/2022] [Indexed: 01/16/2023] Open
Abstract
Salmonella enterica is ubiquitous in the plant environment, persisting in the face of UV stress, plant defense responses, desiccation, and nutrient limitation. These fluctuating conditions of the leaf surface result in S. enterica population decline. Biomultipliers, such as the phytopathogenic bacterium Xanthomonas hortorum pv. gardneri (Xhg), alter the phyllosphere to the benefit of S. enterica. Specific Xhg-dependent changes to this niche that promote S. enterica persistence remain unclear, and this work focuses on identifying factors that lead to increased S. enterica survival on leaves. Here, we show that the Xhg transcription activator-like effector AvrHah1 is both necessary and sufficient for increased survival of S. enterica on tomato leaves. An Xhg avrHah1 mutant fails to influence S. enterica survival while addition of avrHah1 to X. vesicatoria provides a gain of function. Our results indicate that although Xhg stimulates a robust immune response from the plant, AvrHah1 is not required for these effects. In addition, we demonstrate that cellular leakage that occurs during disease is independent of AvrHah1. Investigation of the interaction between S. enterica, Xhg, and the plant host provides information regarding how an inhospitable environment changes during infection and can be transformed into a habitable niche.
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Affiliation(s)
- Kimberly N Cowles
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, USA
| | - Anna K Block
- Center for Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture-Agricultural Research Service, Gainesville, FL, USA
| | - Jeri D Barak
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, USA.
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13
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MacIntyre AM, Meline V, Gorman Z, Augustine SP, Dye CJ, Hamilton CD, Iyer-Pascuzzi AS, Kolomiets MV, McCulloh KA, Allen C. Trehalose increases tomato drought tolerance, induces defenses, and increases resistance to bacterial wilt disease. PLoS One 2022; 17:e0266254. [PMID: 35476629 PMCID: PMC9045674 DOI: 10.1371/journal.pone.0266254] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Accepted: 03/16/2022] [Indexed: 12/13/2022] Open
Abstract
Ralstonia solanacearum causes bacterial wilt disease, leading to severe crop losses. Xylem sap from R. solanacearum-infected tomato is enriched in the disaccharide trehalose. Water-stressed plants also accumulate trehalose, which increases drought tolerance via abscisic acid (ABA) signaling. Because R. solanacearum-infected plants suffer reduced water flow, we hypothesized that bacterial wilt physiologically mimics drought stress, which trehalose could mitigate. We found that R. solanacearum-infected plants differentially expressed drought-associated genes, including those involved in ABA and trehalose metabolism, and had more ABA in xylem sap. Consistent with this, treating tomato roots with ABA reduced both stomatal conductance and stem colonization by R. solanacearum. Treating roots with trehalose increased xylem sap ABA and reduced plant water use by lowering stomatal conductance and temporarily improving water use efficiency. Trehalose treatment also upregulated expression of salicylic acid (SA)-dependent tomato defense genes; increased xylem sap levels of SA and other antimicrobial compounds; and increased bacterial wilt resistance of SA-insensitive NahG tomato plants. Additionally, trehalose treatment increased xylem concentrations of jasmonic acid and related oxylipins. Finally, trehalose-treated plants were substantially more resistant to bacterial wilt disease. Together, these data show that exogenous trehalose reduced both water stress and bacterial wilt disease and triggered systemic disease resistance, possibly through a Damage Associated Molecular Pattern (DAMP) response pathway. This suite of responses revealed unexpected linkages between plant responses to biotic and abiotic stress and suggested that R. solanacearum-infected plants increase trehalose to improve water use efficiency and increase wilt disease resistance. The pathogen may degrade trehalose to counter these efforts. Together, these results suggest that treating tomatoes with exogenous trehalose could be a practical strategy for bacterial wilt management.
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Affiliation(s)
- April M. MacIntyre
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States of America
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Valerian Meline
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, United States of America
| | - Zachary Gorman
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, United States of America
| | - Steven P. Augustine
- Department of Botany, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Carolyn J. Dye
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Corri D. Hamilton
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Anjali S. Iyer-Pascuzzi
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, United States of America
| | - Michael V. Kolomiets
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, United States of America
| | - Katherine A. McCulloh
- Department of Botany, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Caitilyn Allen
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States of America
- * E-mail:
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14
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Debray R, Herbert RA, Jaffe AL, Crits-Christoph A, Power ME, Koskella B. Priority effects in microbiome assembly. Nat Rev Microbiol 2021; 20:109-121. [PMID: 34453137 DOI: 10.1038/s41579-021-00604-w] [Citation(s) in RCA: 145] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2021] [Indexed: 11/09/2022]
Abstract
Advances in next-generation sequencing have enabled the widespread measurement of microbiome composition across systems and over the course of microbiome assembly. Despite substantial progress in understanding the deterministic drivers of community composition, the role of historical contingency remains poorly understood. The establishment of new species in a community can depend on the order and/or timing of their arrival, a phenomenon known as a priority effect. Here, we review the mechanisms of priority effects and evidence for their importance in microbial communities inhabiting a range of environments, including the mammalian gut, the plant phyllosphere and rhizosphere, soil, freshwaters and oceans. We describe approaches for the direct testing and prediction of priority effects in complex microbial communities and illustrate these with re-analysis of publicly available plant and animal microbiome datasets. Finally, we discuss the shared principles that emerge across study systems, focusing on eco-evolutionary dynamics and the importance of scale. Overall, we argue that predicting when and how current community state impacts the success of newly arriving microbial taxa is crucial for the management of microbiomes to sustain ecological function and host health. We conclude by discussing outstanding conceptual and practical challenges that are faced when measuring priority effects in microbiomes.
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Affiliation(s)
- Reena Debray
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, USA.
| | - Robin A Herbert
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, USA. .,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Alexander L Jaffe
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, USA
| | | | - Mary E Power
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Britt Koskella
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, USA
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15
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Salmonella Genomics and Population Analyses Reveal High Inter- and Intraserovar Diversity in Freshwater. Appl Environ Microbiol 2021; 87:AEM.02594-20. [PMID: 33397693 DOI: 10.1128/aem.02594-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 12/21/2020] [Indexed: 01/04/2023] Open
Abstract
Freshwater can support the survival of the enteric pathogen Salmonella, though temporal Salmonella diversity in a large watershed has not been assessed. At 28 locations within the Susquehanna River basin, 10-liter samples were assessed in spring and summer over 2 years. Salmonella prevalence was 49%, and increased river discharge was the main driver of Salmonella presence. The amplicon-based sequencing tool, CRISPR-SeroSeq, was used to determine serovar population diversity and detected 25 different Salmonella serovars, including up to 10 serovars from a single water sample. On average, there were three serovars per sample, and 80% of Salmonella-positive samples contained more than one serovar. Serovars Give, Typhimurium, Thompson, and Infantis were identified throughout the watershed and over multiple collections. Seasonal differences were evident: serovar Give was abundant in the spring, whereas serovar Infantis was more frequently identified in the summer. Eight of the ten serovars most commonly associated with human illness were detected in this study. Crucially, six of these serovars often existed in the background, where they were masked by a more abundant serovar(s) in a sample. Serovars Enteritidis and Typhimurium, especially, were masked in 71 and 78% of samples where they were detected, respectively. Whole-genome sequencing-based phylogeny demonstrated that strains within the same serovar collected throughout the watershed were also very diverse. The Susquehanna River basin is the largest system where Salmonella prevalence and serovar diversity have been temporally and spatially investigated, and this study reveals an extraordinary level of inter- and intraserovar diversity.IMPORTANCE Salmonella is a leading cause of bacterial foodborne illness in the United States, and outbreaks linked to fresh produce are increasing. Understanding Salmonella ecology in freshwater is of importance, especially where irrigation practices or recreational use occur. As the third largest river in the United States east of the Mississippi, the Susquehanna River is the largest freshwater contributor to the Chesapeake Bay, and it is the largest river system where Salmonella diversity has been studied. Rainfall and subsequent high river discharge rates were the greatest indicators of Salmonella presence in the Susquehanna and its tributaries. Several Salmonella serovars were identified, including eight commonly associated with foodborne illness. Many clinically important serovars were present at a low frequency within individual samples and so could not be detected by conventional culture methods. The technologies employed here reveal an average of three serovars in a 10-liter sample of water and up to 10 serovars in a single sample.
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16
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Influence of Bacterial Competitors on Salmonella enterica and Enterohemorrhagic Escherichia coli Growth in Microbiological Media and Attachment to Vegetable Seeds. Foods 2021; 10:foods10020285. [PMID: 33572548 PMCID: PMC7912496 DOI: 10.3390/foods10020285] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/19/2021] [Accepted: 01/26/2021] [Indexed: 12/28/2022] Open
Abstract
Interests in using biological agents for control of human pathogens on vegetable seeds are rising. This study evaluated whether probiotic bacterium Lactobacillus rhamnosus GG, bacterial strains previously used as biocontrol agents in plant science, as well as a selected plant pathogen could compete with foodborne human pathogens, such as Salmonella enterica and enterohemorrhagic Escherichia coli (EHEC), for growth in microbiological media and attachment to vegetable seeds; and to determine whether the metabolites in cell-free supernatants of competitive bacterial spent cultures could inhibit the growth of the two pathogens. The results suggest that the co-presence of competitive bacteria, especially L. rhamnosus GG, significantly (p < 0.05) inhibited the growth of Salmonella and EHEC. Cell-free supernatants of L. rhamnosus GG cultures significantly reduced the pathogen populations in microbiological media. Although not as effective as L. rhamnosus GG in inhibiting the growth of Salmonella and EHEC, the biocontrol agents were more effective in competing for attachment to vegetable seeds. The study observed the inhibition of human bacterial pathogens by competitive bacteria or their metabolites and the competitive attachment to sprout seeds among all bacteria involved. The results will help strategize interventions to produce vegetable seeds and seed sprouts free of foodborne pathogens.
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17
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Arellano-Ayala K, Ascencio-Valle FJ, Gutiérrez-González P, Estrada-Girón Y, Torres-Vitela MR, Macías-Rodríguez ME. Hydrophobic and adhesive patterns of lactic acid bacteria and their antagonism against foodborne pathogens on tomato surface (Solanum lycopersicum L.). J Appl Microbiol 2020; 129:876-891. [PMID: 32320113 DOI: 10.1111/jam.14672] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 04/01/2020] [Accepted: 04/17/2020] [Indexed: 12/01/2022]
Abstract
AIMS To evaluate tomato epiphyte lactic acid bacteria (LAB) hydrophobicity and auto-aggregation as an indicator of bacteria adhesion to tomato. Likewise, use LAB adhesion and co-aggregation as mechanisms to antagonize pathogen attachment. METHODS AND RESULTS Fifty-four LAB were screened to evaluate their hydrophobic, auto- and co-aggregative properties against Salmonella Typhimurium, Saintpaul, Montevideo and Escherichia coli O157:H7. Subsequently, tomato adhesion of Enterococcus faecium Col1-1C, Weisella cibaria 11-E-2 and W. confusa Col 1-13 with high, medium and low hydrophobicity and high co-aggregation was investigated as well as their pathogen antagonism. Results indicate that bacteria hydrophobicity and auto-aggregation correspond to LAB adhesion to tomato. Enterococcus faecium Col1-1C interfered in most of the pathogen adhesion and micrographs revealed that such effect could be related to the inhibition of structures-type biofilm on E. coli O157:H7 and the aggregate formation on Salmonella. CONCLUSIONS Lactic acid bacteria hydrophobicity and auto-aggregation can estimate bacteria adhesion to tomato and adhesive and co-aggregative properties could serve as a tool to antagonize foodborne pathogens under specific conditions. SIGNIFICANCE AND IMPACT OF THE STUDY This study evidence the interference of Ent. faecium Col1-1C in E. coli O157:H7 biofilm formation and Salmonella colonization.
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Affiliation(s)
- K Arellano-Ayala
- Advanced Green Energy and Environment Institute (AGEE), Handong Global University, Pohang, Gyungbuk, South Korea.,Centro Universitario de Ciencias Exactas e Ingenierías, University of Guadalajara, Guadalajara, Jalisco, México
| | - F J Ascencio-Valle
- Center for Biological Research of the Northwest, CIBNOR, Instituto Politécnico Nacional #195, La Paz, BCS, Mexico
| | - P Gutiérrez-González
- Centro Universitario de Ciencias Exactas e Ingenierías, University of Guadalajara, Guadalajara, Jalisco, México
| | - Y Estrada-Girón
- Centro Universitario de Ciencias Exactas e Ingenierías, University of Guadalajara, Guadalajara, Jalisco, México
| | - M R Torres-Vitela
- Centro Universitario de Ciencias Exactas e Ingenierías, University of Guadalajara, Guadalajara, Jalisco, México
| | - M E Macías-Rodríguez
- Centro Universitario de Ciencias Exactas e Ingenierías, University of Guadalajara, Guadalajara, Jalisco, México
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18
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Ferelli AMC, Bolten S, Szczesny B, Micallef SA. Salmonella enterica Elicits and Is Restricted by Nitric Oxide and Reactive Oxygen Species on Tomato. Front Microbiol 2020; 11:391. [PMID: 32231649 PMCID: PMC7082413 DOI: 10.3389/fmicb.2020.00391] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 02/25/2020] [Indexed: 11/17/2022] Open
Abstract
The enteric pathogen Salmonella enterica can interact with parts of the plant immune system despite not being a phytopathogen. Previous transcriptomic profiling of S. enterica associating with tomato suggested that Salmonella was responding to oxidative and nitrosative stress in the plant niche. We aimed to investigate whether Salmonella was eliciting generation of reactive oxygen species (ROS) and nitric oxide (NO), two components of the microbe-associated molecular pattern (MAMP)-triggered immunity (MTI) of plants. We also sought to determine whether this interaction had any measurable effects on Salmonella colonization of plants. Biochemical, gene expression and on-plant challenge assays of tomato vegetative and fruit organs were conducted to assess the elicitation of ROS and NO in response to Salmonella Newport association. The counter bacterial response and the effect of NO and ROS on Salmonella colonization was also investigated. We detected H2O2 in leaves and fruit following challenge with live S. Newport (p < 0.05). Conversely, NO was detected on leaves but not on fruit in response to S. Newport (p < 0.05). We found no evidence of plant defense attenuation by live S. Newport. Bacterial gene expression of S. Newport associating with leaves and fruit were indicative of adaptation to biotic stress in the plant niche. The nitrosative stress response genes hmpA and yoaG were significantly up-regulated in S. Newport on leaves and fruit tissue compared to tissue scavenged of NO or ROS (p < 0.05). Chemical modulation of these molecules in the plant had a restrictive effect on bacterial populations. Significantly higher S. Newport titers were retrieved from H2O2 scavenged leaves and fruit surfaces compared to controls (p < 0.05). Similarly, S. Newport counts recovered from NO-scavenged leaves, but not fruit, were higher compared to control (p < 0.05), and significantly lower on leaves pre-elicited to produce endogenous NO. We present evidence of Salmonella elicitation of ROS and NO in tomato, which appear to have a restricting effect on the pathogen. Moreover, bacterial recognition of ROS and NO stress was detected. This work shows that tomato has mechanisms to restrict Salmonella populations and ROS and NO detoxification may play an important role in Salmonella adaptation to the plant niche.
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Affiliation(s)
- Angela Marie C Ferelli
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD, United States
| | - Samantha Bolten
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD, United States
| | - Brooke Szczesny
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD, United States
| | - Shirley A Micallef
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD, United States.,Centre for Food Safety and Security Systems, University of Maryland, College Park, MD, United States
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19
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Melotto M, Brandl MT, Jacob C, Jay-Russell MT, Micallef SA, Warburton ML, Van Deynze A. Breeding Crops for Enhanced Food Safety. FRONTIERS IN PLANT SCIENCE 2020; 11:428. [PMID: 32351531 PMCID: PMC7176021 DOI: 10.3389/fpls.2020.00428] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 03/24/2020] [Indexed: 05/12/2023]
Abstract
An increasing global population demands a continuous supply of nutritious and safe food. Edible products can be contaminated with biological (e.g., bacteria, virus, protozoa), chemical (e.g., heavy metals, mycotoxins), and physical hazards during production, storage, transport, processing, and/or meal preparation. The substantial impact of foodborne disease outbreaks on public health and the economy has led to multidisciplinary research aimed to understand the biology underlying the different contamination processes and how to mitigate food hazards. Here we review the knowledge, opportunities, and challenges of plant breeding as a tool to enhance the food safety of plant-based food products. First, we discuss the significant effect of plant genotypic and phenotypic variation in the contamination of plants by heavy metals, mycotoxin-producing fungi, and human pathogenic bacteria. In addition, we discuss the various factors (i.e., temperature, relative humidity, soil, microbiota, cultural practices, and plant developmental stage) that can influence the interaction between plant genetic diversity and contaminant. This exposes the necessity of a multidisciplinary approach to understand plant genotype × environment × microbe × management interactions. Moreover, we show that the numerous possibilities of crop/hazard combinations make the definition and identification of high-risk pairs, such as Salmonella-tomato and Escherichia coli-lettuce, imperative for breeding programs geared toward improving microbial safety of produce. Finally, we discuss research on developing effective assays and approaches for selecting desirable breeding germplasm. Overall, it is recognized that although breeding programs for some human pathogen/toxin systems are ongoing (e.g., Fusarium in wheat), it would be premature to start breeding when targets and testing systems are not well defined. Nevertheless, current research is paving the way toward this goal and this review highlights advances in the field and critical points for the success of this initiative that were discussed during the Breeding Crops for Enhanced Food Safety workshop held 5-6 June 2019 at University of California, Davis.
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Affiliation(s)
- Maeli Melotto
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
- *Correspondence: Maeli Melotto,
| | - Maria T. Brandl
- United States Department of Agriculture-Agricultural Research Service, Produce Safety and Microbiology Research, Albany, CA, United States
| | - Cristián Jacob
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Michele T. Jay-Russell
- Western Center for Food Safety, University of California, Davis, Davis, CA, United States
| | - Shirley A. Micallef
- Department of Plant Science and Landscape Architecture, Center for Food Safety and Security Systems, University of Maryland, College Park, MD, United States
| | - Marilyn L. Warburton
- United States Department of Agriculture-Agricultural Research Service, Corn Host Plant Research Resistance Unit Mississippi State, Starkville, MS, United States
| | - Allen Van Deynze
- Plant Breeding Center, Department of Plant Sciences, University of California, Davis, Davis, CA, United States
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20
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Transmission of human enteric pathogens from artificially-inoculated flowers to vegetable sprouts/seedlings developed via contaminated seeds. Food Control 2019. [DOI: 10.1016/j.foodcont.2018.12.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Bulgari D, Montagna M, Gobbi E, Faoro F. Green Technology: Bacteria-Based Approach Could Lead to Unsuspected Microbe⁻Plant⁻Animal Interactions. Microorganisms 2019; 7:microorganisms7020044. [PMID: 30736387 PMCID: PMC6406919 DOI: 10.3390/microorganisms7020044] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/23/2019] [Accepted: 02/02/2019] [Indexed: 12/16/2022] Open
Abstract
The recent and massive revival of green strategies to control plant diseases, mainly as a consequence of the Integrated Pest Management (IPM) rules issued in 2009 by the European Community and the increased consumer awareness of organic products, poses new challenges for human health and food security that need to be addressed in the near future. One of the most important green technologies is biocontrol. This approach is based on living organisms and how these biocontrol agents (BCAs) directly or indirectly interact as a community to control plant pathogens and pest. Although most BCAs have been isolated from plant microbiomes, they share some genomic features, virulence factors, and trans-kingdom infection abilities with human pathogenic microorganisms, thus, their potential impact on human health should be addressed. This evidence, in combination with the outbreaks of human infections associated with consumption of raw fruits and vegetables, opens new questions regarding the role of plants in the human pathogen infection cycle. Moreover, whether BCAs could alter the endophytic bacterial community, thereby leading to the development of new potential human pathogens, is still unclear. In this review, all these issues are debated, highlighting that the research on BCAs and their formulation should include these possible long-lasting consequences of their massive spread in the environment.
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Affiliation(s)
- Daniela Bulgari
- Department of Agricultural and Environmental Sciences-Production, Landscape, Agroenergy, University of Milan, Italy, via Celoria 2, 20133 Milan, Italy.
- Piattaforma di Microbiologia Agroalimentare ed Ambientale (Pi.Mi.A.A.), AgroFood Lab, Department ofMolecular and Translational Medicine, University of Brescia; 25121 Brescia, Italy.
| | - Matteo Montagna
- Department of Agricultural and Environmental Sciences-Production, Landscape, Agroenergy, University of Milan, Italy, via Celoria 2, 20133 Milan, Italy.
| | - Emanuela Gobbi
- Piattaforma di Microbiologia Agroalimentare ed Ambientale (Pi.Mi.A.A.), AgroFood Lab, Department ofMolecular and Translational Medicine, University of Brescia; 25121 Brescia, Italy.
| | - Franco Faoro
- Department of Agricultural and Environmental Sciences-Production, Landscape, Agroenergy, University of Milan, Italy, via Celoria 2, 20133 Milan, Italy.
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22
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Karmakar K, Nath U, Nataraja KN, Chakravortty D. Root mediated uptake of Salmonella is different from phyto-pathogen and associated with the colonization of edible organs. BMC PLANT BIOLOGY 2018; 18:344. [PMID: 30537948 PMCID: PMC6290541 DOI: 10.1186/s12870-018-1578-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 11/29/2018] [Indexed: 06/09/2023]
Abstract
BACKGROUND Pre-harvest contamination of fruits and vegetables by Salmonella in fields is one of the causes of food-borne outbreaks. Natural openings like stomata, hydathodes and fruit cracks are known to serve as entry points. While there are reports indicating that Salmonella colonize and enter root through lateral root emerging area, further investigations regarding how the accessibility of Salmonella to lateral root is different from phyto-pathogenic bacteria, the efficacy of lateral root to facilitate entry have remained unexplored. In this study we attempted to investigate the lateral root mediated entry of Salmonella, and to bridge this gap in knowledge. RESULTS Unlike phytopathogens, Salmonella cannot utilize cellulose as the sole carbon source. This negates the fact of active entry by degrading plant cellulose and pectin. Endophytic Salmonella colonization showed a high correlation with number of lateral roots. When given equal opportunity to colonize the plants with high or low lateral roots, Salmonella internalization was found higher in the plants with more lateral roots. However, the epiphytic colonization in both these plants remained unaltered. To understand the ecological significance, we induced lateral root production by increasing soil salinity which made the plants susceptible to Salmonella invasion and the plants showed higher Salmonella burden in the aerial organs. CONCLUSION Salmonella, being unable to degrade plant cell wall material relies heavily on natural openings. Therefore, its invasion is highly dependent on the number of lateral roots which provides an entry point because of the epidermis remodeling. Thus, when number of lateral root was enhanced by increasing the soil salinity, plants became susceptible to Salmonella invasion in roots and its transmission to aerial organs.
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Affiliation(s)
- Kapudeep Karmakar
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012 India
| | - Utpal Nath
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012 India
| | - Karaba N. Nataraja
- Department of Crop Physiology, University of Agricultural Science, GKVK, Bangalore, 560065 India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012 India
- Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore, 560012 India
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23
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Cowles KN, Groves RL, Barak JD. Leafhopper-Induced Activation of the Jasmonic Acid Response Benefits Salmonella enterica in a Flagellum-Dependent Manner. Front Microbiol 2018; 9:1987. [PMID: 30190716 PMCID: PMC6115507 DOI: 10.3389/fmicb.2018.01987] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 08/07/2018] [Indexed: 11/29/2022] Open
Abstract
Enteric human pathogens such as Salmonella enterica are typically studied in the context of their animal hosts, but it has become apparent that these bacteria spend a significant portion of their life cycle on plants. S. enterica survives the numerous stresses common to a plant niche, including defense responses, water and nutrient limitation, and exposure to UV irradiation leading to an increased potential for human disease. In fact, S. enterica is estimated to cause over one million cases of foodborne illness each year in the United States with 20% of those cases resulting from consumption of contaminated produce. Although S. enterica successfully persists in the plant environment, phytobacterial infection by Pectobacterium carotovorum or Xanthomonas spp. increases S. enterica survival and infrequently leads to growth on infected plants. The co-association of phytophagous insects, such as the Aster leafhopper, Macrosteles quadrilineatus, results in S. enterica populations that persist at higher levels for longer periods of time when compared to plants treated with S. enterica alone. We hypothesized that leafhoppers increase S. enterica persistence by altering the plant defense response to the benefit of the bacteria. Leafhopper infestation activated the jasmonic acid (JA) defense response while S. enterica colonization triggered the salicylic acid (SA) response. In tomato plants co-treated with S. enterica and leafhoppers, both JA- and SA-inducible genes were activated, suggesting that the presence of leafhoppers may affect the crosstalk that occurs between the two immune response pathways. To rule out the possibility that leafhoppers provide additional benefits to S. enterica, plants were treated with a chemical JA analog to activate the immune response in the absence of leafhoppers. Although bacterial populations continue to decline over time, analog treatment significantly increased bacterial persistence on the leaf surface. Bacterial mutant analysis determined that the bacterial flagellum, whether functional or not, was required for increased S. enterica survival after analog treatment. By investigating the interaction between this human pathogen, a common phytophagous insect, and their plant host, we hope to elucidate the mechanisms promoting S. enterica survival on plants and provide information to be used in the development of new food safety intervention strategies.
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Affiliation(s)
- Kimberly N Cowles
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States
| | - Russell L Groves
- Department of Entomology, University of Wisconsin-Madison, Madison, WI, United States
| | - Jeri D Barak
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, United States
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24
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Potnis N, Colee J, Jones JB, Barak JD. Plant pathogen-induced water-soaking promotes Salmonella enterica growth on tomato leaves. Appl Environ Microbiol 2015; 81:8126-34. [PMID: 26386057 PMCID: PMC4651078 DOI: 10.1128/aem.01926-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 09/14/2015] [Indexed: 11/20/2022] Open
Abstract
Plant pathogen infection is a critical factor for the persistence of Salmonella enterica on plants. We investigated the mechanisms responsible for the persistence of S. enterica on diseased tomato plants by using four diverse bacterial spot Xanthomonas species that differ in disease severities. Xanthomonas euvesicatoria and X. gardneri infection fostered S. enterica growth, while X. perforans infection did not induce growth but supported the persistence of S. enterica. X. vesicatoria-infected leaves harbored S. enterica populations similar to those on healthy leaves. Growth of S. enterica was associated with extensive water-soaking and necrosis in X. euvesicatoria- and X. gardneri-infected plants. The contribution of water-soaking to the growth of S. enterica was corroborated by an increased growth of populations on water-saturated leaves in the absence of a plant pathogen. S. enterica aggregates were observed with bacterial spot lesions caused by either X. euvesicatoria or X. vesicatoria; however, more S. enterica aggregates formed on X. euvesicatoria-infected leaves as a result of larger lesion sizes per leaf area and extensive water-soaking. Sparsely distributed lesions caused by X. vesicatoria infection do not support the overall growth of S. enterica or aggregates in areas without lesions or water-soaking; S. enterica was observed as single cells and not aggregates. Thus, pathogen-induced water-soaking and necrosis allow S. enterica to replicate and proliferate on tomato leaves. The finding that the pathogen-induced virulence phenotype affects the fate of S. enterica populations in diseased plants suggests that targeting of plant pathogen disease is important in controlling S. enterica populations on plants.
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Affiliation(s)
- Neha Potnis
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - James Colee
- Department of Statistics, University of Florida, Gainesville, Florida, USA
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - Jeri D Barak
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
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25
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Potnis N, Timilsina S, Strayer A, Shantharaj D, Barak JD, Paret ML, Vallad GE, Jones JB. Bacterial spot of tomato and pepper: diverse Xanthomonas species with a wide variety of virulence factors posing a worldwide challenge. MOLECULAR PLANT PATHOLOGY 2015; 16:907-20. [PMID: 25649754 PMCID: PMC6638463 DOI: 10.1111/mpp.12244] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
TAXONOMIC STATUS Bacteria; Phylum Proteobacteria; Class Gammaproteobacteria; Order Xanthomonadales; Family Xanthomonadaceae; Genus Xanthomonas; Species Xanthomonas euvesicatoria, Xanthomonas vesicatoria, Xanthomonas perforans and Xanthomonas gardneri. MICROBIOLOGICAL PROPERTIES Gram-negative, rod-shaped bacterium, aerobic, motile, single polar flagellum. HOST RANGE Causes bacterial spot disease on plants belonging to the Solanaceae family, primarily tomato (Solanum lycopersicum), pepper (Capsicum annuum) and chilli peppers (Capsicum frutescens). DISEASE SYMPTOMS Necrotic lesions on all above-ground plant parts. DISTRIBUTION Worldwide distribution of X. euvesicatoria and X. vesicatoria on tomato and pepper; X. perforans and X. gardneri increasingly being isolated from the USA, Canada, South America, Africa and Europe. A wide diversity within the bacterial spot disease complex, with an ability to cause disease at different temperatures, makes this pathogen group a worldwide threat to tomato and pepper production. Recent advances in genome analyses have revealed the evolution of the pathogen with a plethora of novel virulence factors. Current management strategies rely on the use of various chemical control strategies and sanitary measures to minimize pathogen spread through contaminated seed. Chemical control strategies have been a challenge because of resistance by the pathogen. Breeding programmes have been successful in developing commercial lines with hypersensitive and quantitative resistance. However, durability of resistance has been elusive. Recently, a transgenic approach has resulted in the development of tomato genotypes with significant levels of resistance and improved yield that hold promise. In this article, we discuss the current taxonomic status, distribution of the four species, knowledge of virulence factors, detection methods and strategies for disease control with possible directions for future research.
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Affiliation(s)
- Neha Potnis
- Department of Plant Pathology, Fifield Hall, University of Florida, Gainesville, FL, 32611, USA
| | - Sujan Timilsina
- Department of Plant Pathology, Fifield Hall, University of Florida, Gainesville, FL, 32611, USA
| | - Amanda Strayer
- Department of Plant Pathology, Fifield Hall, University of Florida, Gainesville, FL, 32611, USA
| | - Deepak Shantharaj
- Department of Plant Pathology, Fifield Hall, University of Florida, Gainesville, FL, 32611, USA
| | - Jeri D Barak
- Department of Plant Pathology, Russell Laboratories, University of Wisconsin, Madison, WI, 53706, USA
| | - Mathews L Paret
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, 33598, USA
| | - Gary E Vallad
- North Florida Research & Education Center, University of Florida, Quincy, FL, 32351-5677, USA
| | - Jeffrey B Jones
- Department of Plant Pathology, Fifield Hall, University of Florida, Gainesville, FL, 32611, USA
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26
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Markland SM, Ferelli AM, Craighead SA, Bais H, Kniel KE. Application of Bacillus subtilis to the roots of leafy greens, in the presence of Listeria innocua and Salmonella Newport, induces closure of stomata. Foodborne Pathog Dis 2015; 12:828-35. [PMID: 26270607 DOI: 10.1089/fpd.2015.1952] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Plant growth-promoting rhizobacterium Bacillus subtilis UD1022 has been shown to trigger an induced systemic response in Arabidopsis thaliana. This interaction causes plant stomata to close, protecting the plant from infection by plant pathogens and thereby increasing crop yield. The purpose of this study was to determine whether UD1022 applied to the roots of plants is able to induce stomata closure in leafy greens as well as influence the persistence of human pathogens (Listeria and Salmonella) on plants. UD1022 induced stomata closure in the presence of human pathogens on both lettuce and spinach 3 h post-inoculation (p<0.0001). Results were confirmed by root inoculation with heat-killed UD1022, which did not induce stomata closure. Presence of UD1022 on lettuce roots significantly reduced the persistence of Listeria on plants after 3 days post-inoculation (p=0.02) but had less of an effect on the persistence of Salmonella. The results of this study indicate that plant growth-promoting rhizobacterium B. subtilis UD1022 may be able to prevent contamination by some human pathogens. This is the first study to investigate the use of plant growth-promoting rhizobacteria to control the persistence of human pathogens on plants.
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Affiliation(s)
- Sarah M Markland
- 1 Department of Animal and Food Sciences, University of Delaware , Newark, Delaware
| | - Angela M Ferelli
- 1 Department of Animal and Food Sciences, University of Delaware , Newark, Delaware
| | - Shani A Craighead
- 1 Department of Animal and Food Sciences, University of Delaware , Newark, Delaware
| | - Harsh Bais
- 2 Department of Plant and Soil Sciences, University of Delaware , Newark, Delaware
- 3 Delaware Biotechnology Institute , Newark, Delaware
| | - Kalmia E Kniel
- 1 Department of Animal and Food Sciences, University of Delaware , Newark, Delaware
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27
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Jarvis KG, White JR, Grim CJ, Ewing L, Ottesen AR, Beaubrun JJG, Pettengill JB, Brown E, Hanes DE. Cilantro microbiome before and after nonselective pre-enrichment for Salmonella using 16S rRNA and metagenomic sequencing. BMC Microbiol 2015; 15:160. [PMID: 26264042 PMCID: PMC4534111 DOI: 10.1186/s12866-015-0497-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 07/28/2015] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Salmonella enterica is a common cause of foodborne gastroenteritis in the United States and is associated with outbreaks in fresh produce such as cilantro. Salmonella culture-based detection methods are complex and time consuming, and improvments to increase detection sensitivity will benefit consumers. In this study, we used 16S rRNA sequencing to determine the microbiome of cilantro. We also investigated changes to the microbial community prior to and after a 24-hour nonselective pre-enrichment culture step commonly used by laboratory analysts to resuscitate microorganisms in foods suspected of contamination with pathogens. Cilantro samples were processed for Salmonella detection according to the method in the United States Food and Drug Administration Bacteriological Analytical Manual. Genomic DNA was extracted from culture supernatants prior to and after a 24-hour nonselective pre-enrichment step and 454 pyrosequencing was performed on 16S rRNA amplicon libraries. A database of Enterobacteriaceae 16S rRNA sequences was created, and used to screen the libraries for Salmonella, as some samples were known to be culture positive. Additionally, culture positive cilantro samples were examined for the presence of Salmonella using shotgun metagenomics on the Illumina MiSeq. RESULTS Time zero uncultured samples had an abundance of Proteobacteria while the 24-hour enriched samples were composed mostly of Gram-positive Firmicutes. Shotgun metagenomic sequencing of Salmonella culture positive cilantro samples revealed variable degrees of Salmonella contamination among the sequenced samples. CONCLUSIONS Our cilantro study demonstrates the use of high-throughput sequencing to reveal the microbiome of cilantro, and how the microbiome changes during the culture-based protocols employed by food safety laboratories to detect foodborne pathogens. Finding that culturing the cilantro shifts the microbiome to a predominance of Firmicutes suggests that changing our culture-based methods will improve detection sensitivity for foodborne enteric pathogens.
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Affiliation(s)
- Karen G Jarvis
- U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, OARSA, Laurel, MD, USA.
| | - James R White
- Oak Ridge Institute for Science and Technology, Oak Ridge, TN, USA.
| | - Christopher J Grim
- U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, OARSA, Laurel, MD, USA.
- Oak Ridge Institute for Science and Technology, Oak Ridge, TN, USA.
| | - Laura Ewing
- U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, OARSA, Laurel, MD, USA.
| | - Andrea R Ottesen
- U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, ORS, College Park, MD, USA.
| | - Junia Jean-Gilles Beaubrun
- U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, OARSA, Laurel, MD, USA.
| | - James B Pettengill
- U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, ORS, College Park, MD, USA.
| | - Eric Brown
- U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, ORS, College Park, MD, USA.
| | - Darcy E Hanes
- U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, OARSA, Laurel, MD, USA.
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28
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Balbontín R, Vlamakis H, Kolter R. Mutualistic interaction between Salmonella enterica and Aspergillus niger and its effects on Zea mays colonization. Microb Biotechnol 2015; 7:589-600. [PMID: 25351041 PMCID: PMC4265077 DOI: 10.1111/1751-7915.12182] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/10/2014] [Accepted: 09/12/2014] [Indexed: 01/09/2023] Open
Abstract
Salmonella Typhimurium inhabits a variety of environments and is able to infect a broad range of hosts. Throughout its life cycle, some hosts can act as intermediates in the path to the infection of others. Aspergillus niger is a ubiquitous fungus that can often be found in soil or associated to plants and microbial consortia. Recently, S. Typhimurium was shown to establish biofilms on the hyphae of A. niger. In this work, we have found that this interaction is stable for weeks without a noticeable negative effect on either organism. Indeed, bacterial growth is promoted upon the establishment of the interaction. Moreover, bacterial biofilms protect the fungus from external insults such as the effects of the anti-fungal agent cycloheximide. Thus, the Salmonella-Aspergillus interaction can be defined as mutualistic. A tripartite gnotobiotic system involving the bacterium, the fungus and a plant revealed that co-colonization has a greater negative effect on plant growth than colonization by either organism in dividually. Strikingly, co-colonization also causes a reduction in plant invasion by S. Typhimurium. This work demonstrates that S. Typhimurium and A. niger establish a mutualistic interaction that alters bacterial colonization of plants and affects plant physiology.
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Affiliation(s)
- Roberto Balbontín
- Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, HIM building, Room #1042, Boston, MA, 02115, USA
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29
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Acquisition of Iron Is Required for Growth of Salmonella spp. in Tomato Fruit. Appl Environ Microbiol 2015; 81:3663-70. [PMID: 25795672 DOI: 10.1128/aem.04257-14] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 03/14/2015] [Indexed: 11/20/2022] Open
Abstract
Salmonella remains a leading cause of bacterial food-borne disease, sickening millions each year. Although outbreaks of salmonellosis have traditionally been associated with contaminated meat products, recent years have seen numerous disease cases caused by the consumption of produce. Tomatoes have been specifically implicated, due to the ability of Salmonella spp. to enter the tomato fruit and proliferate within, making the decontamination of the raw product impossible. To investigate the genetic means by which Salmonella is able to survive and proliferate within tomatoes, we conducted a screen for bacterial genes of Salmonella enterica serovar Montevideo specifically induced after inoculation into ripe tomato fruit. Among these genes, we found 17 members of the previously described anaerobic Fur (ferric uptake regulator) regulon. Fur is a transcriptional and posttranscriptional regulator known to sense iron, suggesting the importance of this mineral to Salmonella within tomatoes. To test whether iron acquisition is essential for Salmonella growth in tomatoes, we tested a ΔfepDGC mutant, which lacks the ability to import iron-associated siderophores. This mutant grew significantly more poorly within tomatoes than did the wild type, but the growth defect of the mutant was fully reversed by the addition of exogenous iron, demonstrating the need for bacterial iron scavenging. Further, dependence upon iron was not apparent for Salmonella growing in filtered tomato juice, implicating the cellular fraction of the fruit as an important mediator of iron acquisition by the bacteria.
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30
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Wiedemann A, Virlogeux-Payant I, Chaussé AM, Schikora A, Velge P. Interactions of Salmonella with animals and plants. Front Microbiol 2015; 5:791. [PMID: 25653644 PMCID: PMC4301013 DOI: 10.3389/fmicb.2014.00791] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 12/22/2014] [Indexed: 12/16/2022] Open
Abstract
Salmonella enterica species are Gram-negative bacteria, which are responsible for a wide range of food- and water-borne diseases in both humans and animals, thereby posing a major threat to public health. Recently, there has been an increasing number of reports, linking Salmonella contaminated raw vegetables and fruits with food poisoning. Many studies have shown that an essential feature of the pathogenicity of Salmonella is its capacity to cross a number of barriers requiring invasion of a large variety of cells and that the extent of internalization may be influenced by numerous factors. However, it is poorly understood how Salmonella successfully infects hosts as diversified as animals or plants. The aim of this review is to describe the different stages required for Salmonella interaction with its hosts: (i) attachment to host surfaces; (ii) entry processes; (iii) multiplication; (iv) suppression of host defense mechanisms; and to point out similarities and differences between animal and plant infections.
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Affiliation(s)
- Agnès Wiedemann
- Institut National de la Recherche Agronomique, UMR1282 Infectiologie et Santé Publique Nouzilly, France ; UMR1282 Infectiologie et Santé Publique, Université François Rabelais Tours, France
| | - Isabelle Virlogeux-Payant
- Institut National de la Recherche Agronomique, UMR1282 Infectiologie et Santé Publique Nouzilly, France ; UMR1282 Infectiologie et Santé Publique, Université François Rabelais Tours, France
| | - Anne-Marie Chaussé
- Institut National de la Recherche Agronomique, UMR1282 Infectiologie et Santé Publique Nouzilly, France ; UMR1282 Infectiologie et Santé Publique, Université François Rabelais Tours, France
| | - Adam Schikora
- Institute for Phytopathology, Research Center for BioSystems, Land Use and Nutrition (IFZ), Justus Liebig University Giessen Giessen, Germany
| | - Philippe Velge
- Institut National de la Recherche Agronomique, UMR1282 Infectiologie et Santé Publique Nouzilly, France ; UMR1282 Infectiologie et Santé Publique, Université François Rabelais Tours, France
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31
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De novo amino acid biosynthesis contributes to salmonella enterica growth in Alfalfa seedling exudates. Appl Environ Microbiol 2014; 81:861-73. [PMID: 25416761 DOI: 10.1128/aem.02985-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica is a member of the plant microbiome. Growth of S. enterica in sprouting-seed exudates is rapid; however, the active metabolic networks essential in this environment are unknown. To examine the metabolic requirements of S. enterica during growth in sprouting-seed exudates, we inoculated alfalfa seeds and identified 305 S. enterica proteins extracted 24 h postinoculation from planktonic cells. Over half the proteins had known metabolic functions, and they are involved in over one-quarter of the known metabolic reactions. Ion and metabolite transport accounted for the majority of detected reactions. Proteins involved in amino acid transport and metabolism were highly represented, suggesting that amino acid metabolic networks may be important for S. enterica growth in association with roots. Amino acid auxotroph growth phenotypes agreed with the proteomic data; auxotrophs in amino acid-biosynthetic pathways that were detected in our screen developed growth defects by 48 h. When the perceived sufficiency of each amino acid was expressed as a ratio of the calculated biomass requirement to the available concentration and compared to growth of each amino acid auxotroph, a correlation between nutrient availability and bacterial growth was found. Furthermore, glutamate transport acted as a fitness factor during S. enterica growth in association with roots. Collectively, these data suggest that S. enterica metabolism is robust in the germinating-alfalfa environment; that single-amino-acid metabolic pathways are important but not essential; and that targeting central metabolic networks, rather than dedicated pathways, may be necessary to achieve dramatic impacts on bacterial growth.
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32
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Soto-Arias JP, Groves RL, Barak JD. Transmission and retention of Salmonella enterica by phytophagous hemipteran insects. Appl Environ Microbiol 2014; 80:5447-56. [PMID: 24973069 PMCID: PMC4136094 DOI: 10.1128/aem.01444-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 06/19/2014] [Indexed: 11/20/2022] Open
Abstract
Several pest insects of human and livestock habitations are known as vectors of Salmonella enterica; however, the role of plant-feeding insects as vectors of S. enterica to agricultural crops remains unexamined. Using a hemipteran insect pest-lettuce system, we investigated the potential for transmission and retention of S. enterica. Specifically, Macrosteles quadrilineatus and Myzus persicae insects were fed S. enterica-inoculated lettuce leaf discs or artificial liquid diets confined in Parafilm sachets to allow physical contact or exclusively oral ingestion of the pathogen, respectively. After a 24-h acquisition access period, insects were moved onto two consecutive noninoculated leaf discs or liquid diets and allowed a 24-h inoculation access period on each of the two discs or sachets. Similar proportions of individuals from both species ingested S. enterica after a 24-h acquisition access period from inoculated leaf discs, but a significantly higher proportion of M. quadrilineatus retained the pathogen internally after a 48-h inoculation access period. S. enterica was also recovered from the honeydew of both species. After a 48-h inoculation access period, bacteria were recovered from a significantly higher proportion of honeydew samples from M. quadrilineatus than from M. persicae insects. The recovery of S. enterica from leaf discs and liquid diets postfeeding demonstrated that both species of insects were capable of transmitting the bacteria in ways that are not limited to mechanical transmission. Overall, these results suggest that phytophagous insects may serve as potential vectors of S. enterica in association with plants.
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Affiliation(s)
- José Pablo Soto-Arias
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Russell L Groves
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Jeri D Barak
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
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33
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Gautam D, Dobhal S, Payton ME, Fletcher J, Ma LM. Surface survival and internalization of salmonella through natural cracks on developing cantaloupe fruits, alone or in the presence of the melon wilt pathogen Erwinia tracheiphila. PLoS One 2014; 9:e105248. [PMID: 25147942 PMCID: PMC4141780 DOI: 10.1371/journal.pone.0105248] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 07/22/2014] [Indexed: 11/18/2022] Open
Abstract
Outbreaks of foodborne illness attributed to the consumption of Salmonella-tainted cantaloupe have occurred repeatedly, but understanding of the ecology of Salmonella on cantaloupe fruit surfaces is limited. We investigated the interactions between Salmonella enterica Poona, the plant pathogenic bacterium Erwinia tracheiphila, and cantaloupe fruit. Fruit surfaces were inoculated at the natural cracking stage by spreading S. enterica and E. tracheiphila, 20 µl at 107 cfu/ml, independently or together, over a 2×2 cm rind area containing a crack. Microbial and microscopic analyses were performed at 0, 9 and 24 days post inoculation (DPI). Even at 24 DPI (fruit maturity) S. enterica was detected on 14% and 40% of the fruit inoculated with S. enterica alone and the two-pathogen mixture, respectively. However, the population of S. enterica declined gradually after initial inoculation. E. tracheiphila, inoculated alone or together with Salmonella, caused watersoaked lesions on cantaloupe fruit; but we could not conclude in this study that S. enterica survival on the fruit surface was enhanced by the presence of those lesions. Of fruit inoculated with E. tracheiphila alone and sampled at 24 DPI, 61% had watersoaked lesions on the surface. In nearly half of those symptomatic fruits the watersoaking extended into the sub-rind mesocarp, and E. tracheiphila was recovered from that tissue in 50% of the symptomatic fruit. In this work, E. tracheiphila internalized through natural cracks on developing fruits. S. enterica was never detected in the fruit interior (ca. 2-3 mm below rind surface) under the limited conditions of our experiments, but the possibility that it, or other human pathogens that contaminate fresh produce, might also do so should be investigated under a wider range of conditions and produce types.
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Affiliation(s)
- Dhiraj Gautam
- National Institute for Microbial Forensics & Food and Agricultural Biosecurity, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Shefali Dobhal
- National Institute for Microbial Forensics & Food and Agricultural Biosecurity, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Mark E. Payton
- Department of Statistics, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Jacqueline Fletcher
- National Institute for Microbial Forensics & Food and Agricultural Biosecurity, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Li Maria Ma
- National Institute for Microbial Forensics & Food and Agricultural Biosecurity, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, United States of America
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34
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Lim JA, Lee DH, Heu S. The interaction of human enteric pathogens with plants. THE PLANT PATHOLOGY JOURNAL 2014; 30:109-16. [PMID: 25288993 PMCID: PMC4174842 DOI: 10.5423/ppj.rw.04.2014.0036] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 05/10/2014] [Accepted: 05/10/2014] [Indexed: 05/16/2023]
Abstract
There are an increasing number of outbreaks of human pathogens related to fresh produce. Thus, the growth of human pathogens on plants should be explored. Human pathogens can survive under the harsh environments in plants, and can adhere and actively invade plants. Plant-associated microbiota or insects contribute to the survival and transmission of enteric pathogens in plants. Human enteric pathogens also trigger plant innate immunity, but some pathogens-such as Salmonella-can overcome this defense mechanism.
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Affiliation(s)
- Jeong-A Lim
- Division of Microbial Safety, National Academy of Agricultural Science, Rural Development Administration, Suwon 441-707, Korea
| | - Dong Hwan Lee
- Division of Microbial Safety, National Academy of Agricultural Science, Rural Development Administration, Suwon 441-707, Korea
| | - Sunggi Heu
- Division of Microbial Safety, National Academy of Agricultural Science, Rural Development Administration, Suwon 441-707, Korea
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