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Davies KG, Mohan S, Phani V, Srivastava A. Exploring the mechanisms of host-specificity of a hyperparasitic bacterium ( Pasteuria spp.) with potential to control tropical root-knot nematodes ( Meloidogyne spp.): insights from Caenorhabditis elegans. Front Cell Infect Microbiol 2023; 13:1296293. [PMID: 38173791 PMCID: PMC10761439 DOI: 10.3389/fcimb.2023.1296293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 11/22/2023] [Indexed: 01/05/2024] Open
Abstract
Plant-parasitic nematodes are important economic pests of a range of tropical crops. Strategies for managing these pests have relied on a range of approaches, including crop rotation, the utilization of genetic resistance, cultural techniques, and since the 1950's the use of nematicides. Although nematicides have been hugely successful in controlling nematodes, their toxicity to humans, domestic animals, beneficial organisms, and the environment has raised concerns regarding their use. Alternatives are therefore being sought. The Pasteuria group of bacteria that form endospores has generated much interest among companies wanting to develop microbial biocontrol products. A major challenge in developing these bacteria as biocontrol agents is their host-specificity; one population of the bacterium can attach to and infect one population of plant-parasitic nematode but not another of the same species. Here we will review the mechanism by which infection is initiated with the adhesion of endospores to the nematode cuticle. To understand the genetics of the molecular processes between Pasteuria endospores and the nematode cuticle, the review focuses on the nature of the bacterial adhesins and how they interact with the nematode cuticle receptors by exploiting new insights gained from studies of bacterial infections of Carnorhabditis elegans. A new Velcro-like multiple adhesin model is proposed in which the cuticle surface coat, which has an important role in endospore adhesion, is a complex extracellular matrix containing glycans originating in seam cells. The genes associated with these seam cells appear to have a dual role by retaining some characteristics of stem cells.
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Affiliation(s)
- Keith G. Davies
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
| | - Sharad Mohan
- Division of Nematology, Indian Agricultural Research Institute, New Delhi, India
| | - Victor Phani
- Department of Agricultural Entomology, College of Agriculture, Uttar Banga Krishi Viswavidyalaya, Dakshin Dinajpur, West Bengal, India
| | - Arohi Srivastava
- Dr. D. Y Patil Biotechnology & Bioinformatics Institute, Dr. D. Y. Patil Vidyapeeth, Pune, India
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Perrine-Walker F, Le K. Propidium iodide enabled live imaging of Pasteuria sp.-Pratylenchus zeae infection studies under fluorescence microscopy. PROTOPLASMA 2021; 258:279-287. [PMID: 33070241 DOI: 10.1007/s00709-020-01567-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 10/07/2020] [Indexed: 05/28/2023]
Abstract
Live imaging allows observations of cell structures and processes in real time, to monitor dynamic changes within living organisms compared to fixed organisms. Fluorescence microscopy was used to monitor the dynamic infection process of the nematode parasitic bacterium Pasteuria sp. and the sugarcane root-lesion nematode, Pratylenchus zeae. Under fluorescence microscopy, green-autofluorescent globules were observed in live control and Pasteuria sp.-infected nematodes. Only nematodes killed by Pasteuria sp. or heat treated displayed a diffuse pattern of autofluorescence. Propidium iodide (PI), used as a cell membrane integrity indicator, confirmed that the nematode's cuticle acts as an impermeable barrier. PI stained cells/DNA of heat-treated control and Pasteuria sp.-infected P. zeae. PI as a counterstain facilitated the location of Pasteuria endospores on the cuticle surface of P. zeae. No PI staining was observed in sporangia and in endospores within the nematode body. However, PI specifically stained endospores on the cuticle surface and within the cuticle carcass showing, in mature propagules, a ring-like pattern. Live imaging, combined with fluorescence microscopy and fluorescent dyes such as PI, appears useful in live studies on plant nematode interactions with nematophagous bacteria.
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Affiliation(s)
- Francine Perrine-Walker
- School of Life and Environmental Sciences, Life Earth and Environmental Sciences Building (F22), The University of Sydney, Sydney, NSW, 2006, Australia.
- Institute of Agriculture, Biomedical Building (C81), The University of Sydney, 1 Central Avenue, Australian Technology Park, Eveleigh, NSW, 2015, Australia.
| | - Khoa Le
- School of Life and Environmental Sciences, Life Earth and Environmental Sciences Building (F22), The University of Sydney, Sydney, NSW, 2006, Australia
- Institute of Agriculture, Biomedical Building (C81), The University of Sydney, 1 Central Avenue, Australian Technology Park, Eveleigh, NSW, 2015, Australia
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Gamalero E, Glick BR. The Use of Plant Growth-Promoting Bacteria to Prevent Nematode Damage to Plants. BIOLOGY 2020; 9:biology9110381. [PMID: 33171782 PMCID: PMC7695023 DOI: 10.3390/biology9110381] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 10/31/2020] [Accepted: 11/04/2020] [Indexed: 01/17/2023]
Abstract
Simple Summary It has been estimated that 100 g of bulk soil can host about 2000–4000 nematodes and this amount is increased 5-fold in the rhizosphere. A certain number of these nematodes are pathogenic for plants and cause yield and economic losses. Application of chemical nematicides is the most common method used to reduce nematode populations, but these chemicals can have a negative impact on both the environment and human health. Therefore, other more environmentally friendly methods of suppression of plant-parasitic nematodes have been proposed. Among them, the use of plant beneficial soil bacteria, behaving as biocontrol agents against nematodes, represent a potential alternative to chemicals. Abstract Plant-parasitic nematodes have been estimated to annually cause around US $173 billion in damage to plant crops worldwide. Moreover, with global climate change, it has been suggested that the damage to crops from nematodes is likely to increase in the future. Currently, a variety of potentially dangerous and toxic chemical agents are used to limit the damage to crops by plant-parasitic nematodes. As an alternative to chemicals and a more environmentally friendly means of decreasing nematode damage to plants, researchers have begun to examine the possible use of various soil bacteria, including plant growth-promoting bacteria (PGPB). Here, the current literature on some of the major mechanisms employed by these soil bacteria is examined. It is expected that within the next 5–10 years, as scientists continue to elaborate the mechanisms used by these bacteria, biocontrol soil bacteria will gradually replace the use of chemicals as nematicides.
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Affiliation(s)
- Elisa Gamalero
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale, Viale T. Michel 11, 15121 Alessandria, Italy
- Correspondence: ; Tel.: +39-0131-360238
| | - Bernard R. Glick
- Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada;
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Dyrdahl-Young R, Hu W, DiGennaro P. Temporal expression patterns of Pasteuria spp. sporulation genes. J Nematol 2019; 51:e2019-39. [PMID: 34179813 PMCID: PMC6916136 DOI: 10.21307/jofnem-2019-039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Indexed: 11/11/2022] Open
Abstract
Endospore-forming bacterium in the genus Pasteuria spp. infect multiple agriculturally significant plant parasitic nematodes and has potential as a potent biological control. Success as a biological control requires not only spore attachment to the cuticle, but sporulation and reproduction within the nematode host. Tracking and identifying Pasteuria spp. development is then critical to demonstrating efficacy as a biocontrol. Microscopic observations suggest Pasteuria spp. follows the model bacterium, Bacillus subtilis, sporulation. Here, we identified B. subtilis homologs of sporulation regulators in Pasteuria spp. and characterized the temporal expression of these genes throughout the bacterium's ∼30-d lifecycle in Meloidogyne arenaria as a means of tracking sporulation development. Detectable levels of transcripts of Spo0F were present as early as 5 d after the nematodes were exposes to Pasteuria spp. and were relatively constant throughout the 30-d lifecycle. Transcripts to Sigma-F were significantly higher in the middle of the lifecycle, while the transcripts of Sigma-G were detectable between 15 and 25 d, nearing the end of the lifecycle. These three markers can be used to track the process of sporulation in the nematode and augment microscopic observations. Tracking sporulation of Pasteuria spp. is important to fully realize its potential as a biological control method as it can more readily identify successful parasitism, define host ranges, and inform in vitro growth progress.
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Affiliation(s)
| | - Weiming Hu
- Department of Entomology and Nematology, University of Florida, Gainesville, FL32611
| | - Peter DiGennaro
- Department of Entomology and Nematology, University of Florida, Gainesville, FL32611
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Liu C, Gibson AK, Timper P, Morran LT, Tubbs RS. Rapid change in host specificity in a field population of the biological control organism Pasteuria penetrans. Evol Appl 2019; 12:744-756. [PMID: 30976307 PMCID: PMC6439493 DOI: 10.1111/eva.12750] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 11/21/2018] [Accepted: 11/28/2018] [Indexed: 12/29/2022] Open
Abstract
In biological control, populations of both the biological control agent and the pest have the potential to evolve and even to coevolve. This feature marks the most powerful and unpredictable aspect of biological control strategies. In particular, evolutionary change in host specificity of the biological control agent could increase or decrease its efficacy. Here, we tested for change in host specificity in a field population of the biological control organism Pasteuria penetrans. Pasteuria penetrans is an obligate parasite of the plant parasitic nematodes Meloidogyne spp., which are major agricultural pests. From 2013 through 2016, we collected yearly samples of P. penetrans from eight plots in a field infested with M. arenaria. Plots were planted either with peanut (Arachis hypogaea) or with a rotation of peanut and soybean (Glycine max). To detect temporal change in host specificity, we tested P. penetrans samples annually for their ability to attach to (and thereby infect) four clonal lines of M. arenaria. After controlling for temporal variation in parasite abundance, we found that P. penetrans from each of the eight plots showed temporal variation in their attachment specificity to the clonal host lines. The trajectories of change in host specificity were largely unique to each plot. This result suggests that local forces, at the level of individual plots, drive change in specificity. We hypothesize that coevolution with local M. arenaria hosts may be one such force. Lastly, we observed an overall reduction in attachment rate with samples from rotation plots relative to samples from peanut plots. This result may reflect lower abundance of P. penetrans under crop rotation, potentially due to suppressed density of host nematodes. As a whole, the results show local change in specificity on a yearly basis, consistent with evolution of a biological control organism in its ability to infect and suppress its target pest.
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Affiliation(s)
- Chang Liu
- Department of Plant PathologyUniversity of GeorgiaTiftonGeorgia
| | | | | | | | - R. Scott Tubbs
- Crop and Soil Sciences, College of Agricultural and Environmental SciencesUniversity of GeorgiaTiftonGeorgia
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Phani V, Somvanshi VS, Shukla RN, Davies KG, Rao U. A transcriptomic snapshot of early molecular communication between Pasteuria penetrans and Meloidogyne incognita. BMC Genomics 2018; 19:850. [PMID: 30486772 PMCID: PMC6263062 DOI: 10.1186/s12864-018-5230-8] [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: 10/10/2018] [Accepted: 11/07/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Southern root-knot nematode Meloidogyne incognita (Kofoid and White, 1919), Chitwood, 1949 is a key pest of agricultural crops. Pasteuria penetrans is a hyperparasitic bacterium capable of suppressing the nematode reproduction, and represents a typical coevolved pathogen-hyperparasite system. Attachment of Pasteuria endospores to the cuticle of second-stage nematode juveniles is the first and pivotal step in the bacterial infection. RNA-Seq was used to understand the early transcriptional response of the root-knot nematode at 8 h post Pasteuria endospore attachment. RESULTS A total of 52,485 transcripts were assembled from the high quality (HQ) reads, out of which 582 transcripts were found differentially expressed in the Pasteuria endospore encumbered J2 s, of which 229 were up-regulated and 353 were down-regulated. Pasteuria infection caused a suppression of the protein synthesis machinery of the nematode. Several of the differentially expressed transcripts were putatively involved in nematode innate immunity, signaling, stress responses, endospore attachment process and post-attachment behavioral modification of the juveniles. The expression profiles of fifteen selected transcripts were validated to be true by the qRT PCR. RNAi based silencing of transcripts coding for fructose bisphosphate aldolase and glucosyl transferase caused a reduction in endospore attachment as compared to the controls, whereas, silencing of aspartic protease and ubiquitin coding transcripts resulted in higher incidence of endospore attachment on the nematode cuticle. CONCLUSIONS Here we provide evidence of an early transcriptional response by the nematode upon infection by Pasteuria prior to root invasion. We found that adhesion of Pasteuria endospores to the cuticle induced a down-regulated protein response in the nematode. In addition, we show that fructose bisphosphate aldolase, glucosyl transferase, aspartic protease and ubiquitin coding transcripts are involved in modulating the endospore attachment on the nematode cuticle. Our results add new and significant information to the existing knowledge on early molecular interaction between M. incognita and P. penetrans.
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Affiliation(s)
- Victor Phani
- Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Vishal S Somvanshi
- Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Rohit N Shukla
- Bionivid Technology Private Limited, 209, 4th Cross, Kasturi Nagar, Bangalore, India
| | - Keith G Davies
- Department of Biological and Environmental Sciences, University of Hertfordshire, Hatfield, UK. .,Division of Biotechnology and Plant Health, Norwegian Institute of Bioeconomy Research, Postboks 115 NO-1431, Ås, Norway.
| | - Uma Rao
- Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, India.
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