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Jones JT, Haegeman A, Danchin EGJ, Gaur HS, Helder J, Jones MGK, Kikuchi T, Manzanilla-López R, Palomares-Rius JE, Wesemael WML, Perry RN. Top 10 plant-parasitic nematodes in molecular plant pathology. MOLECULAR PLANT PATHOLOGY 2013; 14:946-61. [PMID: 23809086 PMCID: PMC6638764 DOI: 10.1111/mpp.12057] [Citation(s) in RCA: 877] [Impact Index Per Article: 73.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The aim of this review was to undertake a survey of researchers working with plant-parasitic nematodes in order to determine a 'top 10' list of these pathogens based on scientific and economic importance. Any such list will not be definitive as economic importance will vary depending on the region of the world in which a researcher is based. However, care was taken to include researchers from as many parts of the world as possible when carrying out the survey. The top 10 list emerging from the survey is composed of: (1) root-knot nematodes (Meloidogyne spp.); (2) cyst nematodes (Heterodera and Globodera spp.); (3) root lesion nematodes (Pratylenchus spp.); (4) the burrowing nematode Radopholus similis; (5) Ditylenchus dipsaci; (6) the pine wilt nematode Bursaphelenchus xylophilus; (7) the reniform nematode Rotylenchulus reniformis; (8) Xiphinema index (the only virus vector nematode to make the list); (9) Nacobbus aberrans; and (10) Aphelenchoides besseyi. The biology of each nematode (or nematode group) is reviewed briefly.
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Review |
12 |
877 |
2
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De Tender CA, Devriese LI, Haegeman A, Maes S, Ruttink T, Dawyndt P. Bacterial Community Profiling of Plastic Litter in the Belgian Part of the North Sea. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:9629-9638. [PMID: 26204244 DOI: 10.1021/acs.est.5b01093] [Citation(s) in RCA: 247] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Bacterial colonization of marine plastic litter (MPL) is known for over four decades. Still, only a few studies on the plastic colonization process and its influencing factors are reported. In this study, seafloor MPL was sampled at different locations across the Belgian part of the North Sea to study bacterial community structure using 16S metabarcoding. These marine plastic bacterial communities were compared with those of sediment and seawater, and resin pellets sampled on the beach, to investigate the origin and uniqueness of plastic bacterial communities. Plastics display great variation of bacterial community composition, while each showed significant differences from those of sediment and seawater, indicating that plastics represent a distinct environmental niche. Various environmental factors correlate with the diversity of MPL bacterial composition across plastics. In addition, intrinsic plastic-related factors such as pigment content may contribute to the differences in bacterial colonization. Furthermore, the differential abundance of known primary and secondary colonizers across the various plastics may indicate different stages of bacterial colonization, and may confound comparisons of free-floating plastics. Our studies provide insights in the factors that shape plastic bacterial colonization and shed light on the possible role of plastic as transport vehicle for bacteria through the aquatic environment.
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247 |
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De Tender C, Devriese LI, Haegeman A, Maes S, Vangeyte J, Cattrijsse A, Dawyndt P, Ruttink T. Temporal Dynamics of Bacterial and Fungal Colonization on Plastic Debris in the North Sea. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:7350-7360. [PMID: 28562015 DOI: 10.1021/acs.est.7b00697] [Citation(s) in RCA: 200] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Despite growing evidence that biofilm formation on plastic debris in the marine environment may be essential for its biodegradation, the underlying processes have yet to be fully understood. Thus, far, bacterial biofilm formation had only been studied after short-term exposure or on floating plastic, yet a prominent share of plastic litter accumulates on the seafloor. In this study, we explored the taxonomic composition of bacterial and fungal communities on polyethylene plastic sheets and dolly ropes during long-term exposure on the seafloor, both at a harbor and an offshore location in the Belgian part of the North Sea. We reconstructed the sequence of events during biofilm formation on plastic in the harbor environment and identified a core bacteriome and subsets of bacterial indicator species for early, intermediate, and late stages of biofilm formation. Additionally, by implementing ITS2 metabarcoding on plastic debris, we identified and characterized for the first time fungal genera on plastic debris. Surprisingly, none of the plastics exposed to offshore conditions displayed the typical signature of a late stage biofilm, suggesting that biofilm formation is severely hampered in the natural environment where most plastic debris accumulates.
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Haegeman A, Mantelin S, Jones JT, Gheysen G. Functional roles of effectors of plant-parasitic nematodes. Gene 2011; 492:19-31. [PMID: 22062000 DOI: 10.1016/j.gene.2011.10.040] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 10/12/2011] [Accepted: 10/20/2011] [Indexed: 11/17/2022]
Abstract
Plant pathogens have evolved a variety of different strategies that allow them to successfully infect their hosts. Plant-parasitic nematodes secrete numerous proteins into their hosts. These proteins, called effectors, have various functions in the plant cell. The most studied effectors to date are the plant cell wall degrading enzymes, which have an interesting evolutionary history since they are believed to have been acquired from bacteria or fungi by horizontal gene transfer. Extensive genome, transcriptome and proteome studies have shown that plant-parasitic nematodes secrete many additional effectors. The function of many of these is less clear although during the last decade, several research groups have determined the function of some of these effectors. Even though many effectors remain to be investigated, it has already become clear that they can have very diverse functions. Some are involved in suppression of plant defences, while others can specifically interact with plant signalling or hormone pathways to promote the formation of nematode feeding sites. In this review, the most recent progress in the understanding of the function of plant-parasitic nematode effectors is discussed.
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Review |
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Kyndt T, Denil S, Haegeman A, Trooskens G, Bauters L, Van Criekinge W, De Meyer T, Gheysen G. Transcriptional reprogramming by root knot and migratory nematode infection in rice. THE NEW PHYTOLOGIST 2012; 196:887-900. [PMID: 22985291 DOI: 10.1111/j.1469-8137.2012.04311.x] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 07/27/2012] [Indexed: 05/20/2023]
Abstract
Rice is one of the most important staple crops worldwide, but its yield is compromised by different pathogens, including plant-parasitic nematodes. In this study we have characterized specific and general responses of rice (Oryza sativa) roots challenged with two endoparasitic nematodes with very different modes of action. Local transcriptional changes in rice roots upon root knot (Meloidogyne graminicola) and root rot nematode (RRN, Hirschmanniella oryzae) infection were studied at two time points (3 and 7 d after infection, dai), using mRNA-seq. Our results confirm that root knot nematodes (RKNs), which feed as sedentary endoparasites, stimulate metabolic pathways in the root, and enhance nutrient transport towards the induced root gall. The migratory RRNs, on the other hand, induce programmed cell death and oxidative stress, and obstruct the normal metabolic activity of the root. While RRN infection causes up-regulation of biotic stress-related genes early in the infection, the sedentary RKNs suppress the local defense pathways (e.g. salicylic acid and ethylene pathways). Interestingly, hormone pathways mainly involved in plant development were strongly induced (gibberellin) or repressed (cytokinin) at 3 dai. These results uncover previously unrecognized nematode-induced expression profiles related to their specific infection strategy.
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Haegeman A, Jones JT, Danchin EGJ. Horizontal gene transfer in nematodes: a catalyst for plant parasitism? MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:879-87. [PMID: 21539433 DOI: 10.1094/mpmi-03-11-0055] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The origin of plant parasitism within the phylum Nematoda is intriguing. The ability to parasitize plants has originated independently at least three times during nematode evolution and, as more molecular data has emerged, it has become clear that multiple instances of horizontal gene transfer (HGT) from bacteria and fungi have played a crucial role in the nematode's adaptation to this new lifestyle. The first reported HGT cases in plant-parasitic nematodes were genes encoding plant cell wall-degrading enzymes. Other putative examples of HGT were subsequently described, including genes that may be involved in the modulation of the plant's defense system, the establishment of a nematode feeding site, and the synthesis or processing of nutrients. Although, in many cases, it is difficult to pinpoint the donor organism, candidate donors are usually soil dwelling and are either plant-pathogenic or plant-associated microorganisms, hence occupying the same ecological niche as the nematodes. The exact mechanisms of transfer are unknown, although close contacts with donor microorganisms, such as symbiotic or trophic interactions, are a possibility. The widespread occurrence of horizontally transferred genes in evolutionarily independent plant-parasitic nematode lineages suggests that HGT may be a prerequisite for successful plant parasitism in nematodes.
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Review |
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113 |
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Massart S, Chiumenti M, De Jonghe K, Glover R, Haegeman A, Koloniuk I, Komínek P, Kreuze J, Kutnjak D, Lotos L, Maclot F, Maliogka V, Maree HJ, Olivier T, Olmos A, Pooggin MM, Reynard JS, Ruiz-García AB, Safarova D, Schneeberger PHH, Sela N, Turco S, Vainio EJ, Varallyay E, Verdin E, Westenberg M, Brostaux Y, Candresse T. Virus Detection by High-Throughput Sequencing of Small RNAs: Large-Scale Performance Testing of Sequence Analysis Strategies. PHYTOPATHOLOGY 2019; 109:488-497. [PMID: 30070618 DOI: 10.1094/phyto-02-18-0067-r] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Recent developments in high-throughput sequencing (HTS), also called next-generation sequencing (NGS), technologies and bioinformatics have drastically changed research on viral pathogens and spurred growing interest in the field of virus diagnostics. However, the reliability of HTS-based virus detection protocols must be evaluated before adopting them for diagnostics. Many different bioinformatics algorithms aimed at detecting viruses in HTS data have been reported but little attention has been paid thus far to their sensitivity and reliability for diagnostic purposes. Therefore, we compared the ability of 21 plant virology laboratories, each employing a different bioinformatics pipeline, to detect 12 plant viruses through a double-blind large-scale performance test using 10 datasets of 21- to 24-nucleotide small RNA (sRNA) sequences from three different infected plants. The sensitivity of virus detection ranged between 35 and 100% among participants, with a marked negative effect when sequence depth decreased. The false-positive detection rate was very low and mainly related to the identification of host genome-integrated viral sequences or misinterpretation of the results. Reproducibility was high (91.6%). This work revealed the key influence of bioinformatics strategies for the sensitive detection of viruses in HTS sRNA datasets and, more specifically (i) the difficulty in detecting viral agents when they are novel or their sRNA abundance is low, (ii) the influence of key parameters at both assembly and annotation steps, (iii) the importance of completeness of reference sequence databases, and (iv) the significant level of scientific expertise needed when interpreting pipeline results. Overall, this work underlines key parameters and proposes recommendations for reliable sRNA-based detection of known and unknown viruses.
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Ji H, Gheysen G, Denil S, Lindsey K, Topping JF, Nahar K, Haegeman A, De Vos WH, Trooskens G, Van Criekinge W, De Meyer T, Kyndt T. Transcriptional analysis through RNA sequencing of giant cells induced by Meloidogyne graminicola in rice roots. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:3885-98. [PMID: 23881398 PMCID: PMC3745741 DOI: 10.1093/jxb/ert219] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
One of the reasons for the progressive yield decline observed in aerobic rice production is the rapid build-up of populations of the rice root knot nematode Meloidogyne graminicola. These nematodes induce specialized feeding cells inside root tissue, called giant cells. By injecting effectors in and sipping metabolites out of these cells, they reprogramme normal cell development and deprive the plant of its nutrients. In this research we have studied the transcriptome of giant cells in rice, after isolation of these cells by laser-capture microdissection. The expression profiles revealed a general induction of primary metabolism inside the giant cells. Although the roots were shielded from light induction, we detected a remarkable induction of genes involved in chloroplast biogenesis and tetrapyrrole synthesis. The presence of chloroplast-like structures inside these dark-grown cells was confirmed by confocal microscopy. On the other hand, genes involved in secondary metabolism and more specifically, the majority of defence-related genes were strongly suppressed in the giant cells. In addition, significant induction of transcripts involved in epigenetic processes was detected inside these cells 7 days after infection.
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Haegeman A, Bauters L, Kyndt T, Rahman MM, Gheysen G. Identification of candidate effector genes in the transcriptome of the rice root knot nematode Meloidogyne graminicola. MOLECULAR PLANT PATHOLOGY 2013; 14:379-90. [PMID: 23279209 PMCID: PMC6638898 DOI: 10.1111/mpp.12014] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Plant-parasitic nematodes secrete so-called effectors into their host plant which are able to suppress the plant's defence responses, alter plant signalling pathways and, in the case of root knot nematodes, induce the formation of giant cells. Putative effectors have been successfully identified by genomics, transcriptomics and proteomics approaches. In this study, we investigated the transcriptome of the rice root knot nematode Meloidogyne graminicola by 454 sequencing of second-stage juveniles as well as mRNA-seq of rice infected tissue. Over 350 000 reads derived from M. graminicola preparasitic juveniles were assembled, annotated and checked for homologues in different databases. From infected rice tissue, 1.4% of all reads generated were identified as being derived from the nematode. Using multiple strategies, several putative effector genes were identified, both pioneer genes and genes corresponding to already known effectors. To check whether these genes could be involved in the interaction with the plant, in situ hybridization was performed on a selection of genes to localize their expression in the nematode. Most were expressed in the gland cells or amphids of the nematode, confirming possible secretion of the proteins and hence a role in infection. Other putative effectors showed a different expression pattern, potentially linked with the excretory/secretory system. This transcriptome study is a good starting point to functionally investigate novel effectors derived from M. graminicola. This will lead to better insights into the interaction between these nematodes and the model plant rice. Moreover, the transcriptome can be used to identify possible target genes for RNA interference (RNAi)-based control strategies. Four genes proved to be interesting targets by showing up to 40% higher mortality relative to the control treatment when soaked in gene-specific small interfering RNAs (siRNAs).
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10
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Haegeman A, Joseph S, Gheysen G. Analysis of the transcriptome of the root lesion nematode Pratylenchus coffeae generated by 454 sequencing technology. Mol Biochem Parasitol 2011; 178:7-14. [PMID: 21513748 DOI: 10.1016/j.molbiopara.2011.04.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/30/2011] [Accepted: 04/04/2011] [Indexed: 10/18/2022]
Abstract
To study interactions between plants and plant-parasitic nematodes, several omics studies have nowadays become extremely useful. Since most data available so far is derived from sedentary nematodes, we decided to improve the knowledge on migratory nematodes by studying the transcriptome of the nematode Pratylenchus coffeae through generating expressed sequence tags (ESTs) on a 454 sequencing platform. In this manuscript we present the generation, assembly and annotation of over 325,000 reads from P. coffeae. After assembling these reads, 56,325 contigs and singletons with an average length of 353bp were selected for further analyses. Homology searches revealed that 25% of these sequences had significant matches to the Swiss-prot/trEMBL database and 29% had significant matches in nematode ESTs. Over 10,000 sequences were successfully annotated, corresponding to over 6000 unique Gene Ontology identifiers and 5000 KEGG orthologues. Different approaches led to the identification of different sequences putatively involved in the parasitism process. Several plant cell wall modifying enzymes were identified, including an arabinogalactan galactosidase, so far identified in cyst nematodes only. Additionally, some new putative cell wall modifying enzymes are present belonging to GHF5 and GHF16, although further functional studies are needed to determine the true role of these proteins. Furthermore, a homologue to a chorismate mutase was found, suggesting that this parasitism gene has a wider occurrence in plant-parasitic nematodes than previously assumed. Finally, the dataset was searched for orthologues against the Meloidogyne genomes and genes involved in the RNAi pathway. In conclusion, the generated transcriptome data of P. coffeae will be very useful in the future for several projects: (1) evolutionary studies of specific gene families, such as the plant cell wall modifying enzymes, (2) the identification and functional analysis of candidate effector genes, (3) the development of new control strategies, e.g. by finding new targets for RNAi and (4) the annotation of the upcoming genome sequence.
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Research Support, Non-U.S. Gov't |
14 |
55 |
11
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Joos L, Beirinckx S, Haegeman A, Debode J, Vandecasteele B, Baeyen S, Goormachtig S, Clement L, De Tender C. Daring to be differential: metabarcoding analysis of soil and plant-related microbial communities using amplicon sequence variants and operational taxonomical units. BMC Genomics 2020; 21:733. [PMID: 33092529 PMCID: PMC7579973 DOI: 10.1186/s12864-020-07126-4] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 10/08/2020] [Indexed: 12/22/2022] Open
Abstract
Background Microorganisms are not only indispensable to ecosystem functioning, they are also keystones for emerging technologies. In the last 15 years, the number of studies on environmental microbial communities has increased exponentially due to advances in sequencing technologies, but the large amount of data generated remains difficult to analyze and interpret. Recently, metabarcoding analysis has shifted from clustering reads using Operational Taxonomical Units (OTUs) to Amplicon Sequence Variants (ASVs). Differences between these methods can seriously affect the biological interpretation of metabarcoding data, especially in ecosystems with high microbial diversity, as the methods are benchmarked based on low diversity datasets. Results In this work we have thoroughly examined the differences in community diversity, structure, and complexity between the OTU and ASV methods. We have examined culture-based mock and simulated datasets as well as soil- and plant-associated bacterial and fungal environmental communities. Four key findings were revealed. First, analysis of microbial datasets at family level guaranteed both consistency and adequate coverage when using either method. Second, the performance of both methods used are related to community diversity and sample sequencing depth. Third, differences in the method used affected sample diversity and number of detected differentially abundant families upon treatment; this may lead researchers to draw different biological conclusions. Fourth, the observed differences can mostly be attributed to low abundant (relative abundance < 0.1%) families, thus extra care is recommended when studying rare species using metabarcoding. The ASV method used outperformed the adopted OTU method concerning community diversity, especially for fungus-related sequences, but only when the sequencing depth was sufficient to capture the community complexity. Conclusions Investigation of metabarcoding data should be done with care. Correct biological interpretation depends on several factors, including in-depth sequencing of the samples, choice of the most appropriate filtering strategy for the specific research goal, and use of family level for data clustering.
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Journal Article |
5 |
54 |
12
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Jacob J, Vanholme B, Haegeman A, Gheysen G. Four transthyretin-like genes of the migratory plant-parasitic nematode Radopholus similis: members of an extensive nematode-specific family. Gene 2007; 402:9-19. [PMID: 17765408 DOI: 10.1016/j.gene.2007.07.015] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2007] [Revised: 06/25/2007] [Accepted: 07/03/2007] [Indexed: 11/16/2022]
Abstract
Screening 1154 ESTs from the plant-parasitic nematode Radopholus similis resulted in seven tags coding for proteins holding a transthyretin-like domain (PF01060). The seven ESTs corresponded to four different genes which were cloned from a cDNA library (accession numbers AM691117, AM691118, AM691119, AM691120). Transthyretin-like genes belong to a large family, different from the transthyretin and the transthyretin-related genes with whom they share some sequence similarity at the protein level. This similarity has caused an inconsistent use of different names and abbreviations in the past. To avoid further confusion, we introduce a standardized nomenclature for this gene family, and chose to name this barely characterized gene family ttl (as for transthyretin-like). Further examination of the identified genes, named Rs-ttl-1 to -4, showed that they are expressed in both juveniles and adults, but not in young embryos. Whole mount in situ hybridization revealed a distinct spatial expression pattern for two of the genes: Rs-ttl-1 is expressed in the tissues surrounding the vulva, whereas Rs-ttl-2 is expressed in the ventral nerve cord. The deduced protein sequences contain a putative signal peptide for secretion, pointing to an extracellular function of the mature proteins. Database screens showed that the ttl family is restricted to nematodes. Moreover, a HMMER search revealed that ESTs derived from ttl genes are more abundant in parasitic nematode libraries, with a bias towards the parasitic stages. Despite their abundance in nematodes, including the extensively studied model organism Caenorhabditis elegans, the function of TTL proteins remains obscure. Our data suggest a role in the nervous system. Even without insight into their biological function, the nematode-specific nature of this gene family makes it a promising target for nematicides or RNAi mediated control strategies against parasitic nematodes.
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Research Support, Non-U.S. Gov't |
18 |
54 |
13
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De Mulder T, Goossens K, Peiren N, Vandaele L, Haegeman A, De Tender C, Ruttink T, de Wiele TV, De Campeneere S. Exploring the methanogen and bacterial communities of rumen environments: solid adherent, fluid and epimural. FEMS Microbiol Ecol 2017; 93:fiw251. [PMID: 28011597 DOI: 10.1093/femsec/fiw251] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2016] [Indexed: 11/13/2022] Open
Abstract
The rumen microbiome occupies a central role in animal health and productivity. A better understanding of the rumen ecosystem is essential to increase productivity or decrease methane production. Samples were collected from the three main rumen environments: the solid-adherent fraction, the liquid fraction and the epithelium. For the liquid and solid fraction, two alternative sample processing protocols were compared, resulting in a total of five sample types: crude solids (S), the eluted solid-adherent fraction (Ad), free-living species in the crude rumen liquid (CRL), strained liquid samples (Lq) and epimural scrapings (Ep). The bacterial and methanogen communities of these sample types were analysed using 16S metabarcoding and qPCR. The results indicate that the liquid and solid-adherent environments are distinguished mainly by the differential abundance of specific taxonomic groups. Cellulolytic bacteria that pioneer biofilm formation, together with secondary colonisers are prevalent in solid-adherent samples, while dominant species in the fluid samples are primarily identified as consumers of soluble nutrients. Also, methanogen species are found to have a preference for either a solid-adherent or free-living occurrence. The epimural environment is characterised by a different microbial profile. Ten bacterial families and two methanogen genera are almost exclusively found in this environment.
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Journal Article |
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43 |
14
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Debode J, De Tender C, Soltaninejad S, Van Malderghem C, Haegeman A, Van der Linden I, Cottyn B, Heyndrickx M, Maes M. Chitin Mixed in Potting Soil Alters Lettuce Growth, the Survival of Zoonotic Bacteria on the Leaves and Associated Rhizosphere Microbiology. Front Microbiol 2016; 7:565. [PMID: 27148242 PMCID: PMC4838818 DOI: 10.3389/fmicb.2016.00565] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Accepted: 04/04/2016] [Indexed: 11/13/2022] Open
Abstract
Chitin is a promising soil amendment for improving soil quality, plant growth, and plant resilience. The objectives of this study were twofold. First, to study the effect of chitin mixed in potting soil on lettuce growth and on the survival of two zoonotic bacterial pathogens, Escherichia coli O157:H7 and Salmonella enterica on the lettuce leaves. Second, to assess the related changes in the microbial lettuce rhizosphere, using phospholipid fatty acid (PLFA) analysis and amplicon sequencing of a bacterial 16S rRNA gene fragment and the fungal ITS2. As a result of chitin addition, lettuce fresh yield weight was significantly increased. S. enterica survival in the lettuce phyllosphere was significantly reduced. The E. coli O157:H7 survival was also lowered, but not significantly. Moreover, significant changes were observed in the bacterial and fungal community of the lettuce rhizosphere. PLFA analysis showed a significant increase in fungal and bacterial biomass. Amplicon sequencing showed no increase in fungal and bacterial biodiversity, but relative abundances of the bacterial phyla Acidobacteria, Verrucomicrobia, Actinobacteria, Bacteroidetes, and Proteobacteria and the fungal phyla Ascomycota, Basidiomycota, and Zygomycota were significantly changed. More specifically, a more than 10-fold increase was observed for operational taxonomic units belonging to the bacterial genera Cellvibrio, Pedobacter, Dyadobacter, and Streptomyces and to the fungal genera Lecanicillium and Mortierella. These genera include several species previously reported to be involved in biocontrol, plant growth promotion, the nitrogen cycle and chitin degradation. These results enhance the understanding of the response of the rhizosphere microbiome to chitin amendment. Moreover, this is the first study to investigate the use of soil amendments to control the survival of S. enterica on plant leaves.
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Naalden D, Haegeman A, de Almeida‐Engler J, Birhane Eshetu F, Bauters L, Gheysen G. The Meloidogyne graminicola effector Mg16820 is secreted in the apoplast and cytoplasm to suppress plant host defense responses. MOLECULAR PLANT PATHOLOGY 2018; 19:2416-2430. [PMID: 30011122 PMCID: PMC6638014 DOI: 10.1111/mpp.12719] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 06/19/2018] [Accepted: 06/19/2018] [Indexed: 05/06/2023]
Abstract
On invasion of roots, plant-parasitic nematodes secrete effectors to manipulate the cellular regulation of the host to promote parasitism. The root-knot nematode Meloidogyne graminicola is one of the most damaging nematodes of rice. Here, we identified a novel effector of this nematode, named Mg16820, expressed in the nematode subventral glands. We localized the Mg16820 effector in the apoplast during the migration phase of the second-stage juvenile in rice roots. In addition, during early development of the feeding site, Mg16820 was localized in giant cells, where it accumulated in the cytoplasm and the nucleus. Using transient expression in Nicotiana benthamiana leaves, we demonstrated that Mg16820 directed to the apoplast was able to suppress flg22-induced reactive oxygen species production. In addition, expression of Mg16820 in the cytoplasm resulted in the suppression of the R2/Avr2- and Mi-1.2-induced hypersensitive response. A potential target protein of Mg16820 identified with the yeast two-hybrid system was the dehydration stress-inducible protein 1 (DIP1). Bimolecular fluorescence complementation resulted in a strong signal in the nucleus. DIP1 has been described as an abscisic acid (ABA)-responsive gene and ABA is involved in the biotic and abiotic stress response. Our results demonstrate that Mg16820 is able to act in two cellular compartments as an immune suppressor and targets a protein involved in the stress response, therefore indicating an important role for this effector in parasitism.
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40 |
16
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Beirinckx S, Viaene T, Haegeman A, Debode J, Amery F, Vandenabeele S, Nelissen H, Inzé D, Tito R, Raes J, De Tender C, Goormachtig S. Tapping into the maize root microbiome to identify bacteria that promote growth under chilling conditions. MICROBIOME 2020; 8:54. [PMID: 32305066 PMCID: PMC7166315 DOI: 10.1186/s40168-020-00833-w] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 03/19/2020] [Indexed: 05/03/2023]
Abstract
BACKGROUND When maize (Zea mays L.) is grown in the Northern hemisphere, its development is heavily arrested by chilling temperatures, especially at the juvenile phase. As some endophytes are beneficial for plants under stress conditions, we analyzed the impact of chilling temperatures on the root microbiome and examined whether microbiome-based analysis might help to identify bacterial strains that could promote growth under these temperatures. RESULTS We investigated how the maize root microbiome composition changed by means of 16S rRNA gene amplicon sequencing when maize was grown at chilling temperatures in comparison to ambient temperatures by repeatedly cultivating maize in field soil. We identified 12 abundant and enriched bacterial families that colonize maize roots, consisting of bacteria recruited from the soil, whereas seed-derived endophytes were lowly represented. Chilling temperatures modified the root microbiome composition only slightly, but significantly. An enrichment of several chilling-responsive families was detected, of which the Comamonadaceae and the Pseudomonadaceae were the most abundant in the root endosphere of maize grown under chilling conditions, whereas only three were strongly depleted, among which the Streptomycetaceae. Additionally, a collection of bacterial strains isolated from maize roots was established and a selection was screened for growth-promoting effects on juvenile maize grown under chilling temperatures. Two promising strains that promoted maize growth under chilling conditions were identified that belonged to the root endophytic bacterial families, from which the relative abundance remained unchanged by variations in the growth temperature. CONCLUSIONS Our analyses indicate that chilling temperatures affect the bacterial community composition within the maize root endosphere. We further identified two bacterial strains that boost maize growth under chilling conditions. Their identity revealed that analyzing the chilling-responsive families did not help for their identification. As both strains belong to root endosphere enriched families, visualizing and comparing the bacterial diversity in these communities might still help to identify new PGPR strains. Additionally, a strain does not necessarely need to belong to a high abundant family in the root endosphere to provoke a growth-promoting effect in chilling conditions. Video abstract.
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Vandegehuchte MB, Kyndt T, Vanholme B, Haegeman A, Gheysen G, Janssen CR. Occurrence of DNA methylation in Daphnia magna and influence of multigeneration Cd exposure. ENVIRONMENT INTERNATIONAL 2009; 35:700-6. [PMID: 19249097 DOI: 10.1016/j.envint.2009.01.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Revised: 11/26/2008] [Accepted: 01/02/2009] [Indexed: 05/23/2023]
Abstract
Most of the research on the epigenetic phenomenon of DNA methylation has been performed with vertebrates and plants. Knowledge on DNA methylation in Daphnia magna, a key test organism in aquatic toxicology, is completely lacking. Through epigenetic inheritance, effects of transient chemical exposure could be transferred to non-exposed generations, which could have a major impact on ecological risk assessment procedures. In this study, we determined if CpG methylation occurs in D. magna and if this can be influenced by exposure to toxic substances. Homologs of human DNA methyltransferases DNMT1, DNMT2 and DNMT3A were found in the partially available D. magna genome. Using an optimized "Amplification of Intermethylated Sites (AIMS)" technique, two methylated fragments were discovered in D. magna DNA. No homology was found for these sequences. The methylation and the D. magna origin of the fragments were confirmed with Southern analysis. This optimized AIMS technique was then applied to DNA of D. magna which were exposed to 180 microg/L Cd for two generations. Exposure resulted in a significant decrease in reproduction. The same methylated fragments with the same band intensity were observed in DNA of both non-exposed and exposed daphnids. As such, it could not be demonstrated that Cd exposure altered DNA methylation. However, the presence of DNA methylation in D. magna shows that potentially epigenetic effects may occur in this species.
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De Tender C, Haegeman A, Vandecasteele B, Clement L, Cremelie P, Dawyndt P, Maes M, Debode J. Dynamics in the Strawberry Rhizosphere Microbiome in Response to Biochar and Botrytis cinerea Leaf Infection. Front Microbiol 2016; 7:2062. [PMID: 28066380 PMCID: PMC5177642 DOI: 10.3389/fmicb.2016.02062] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 12/07/2016] [Indexed: 01/18/2023] Open
Abstract
Adding biochar, the solid coproduct of biofuel production, to peat can enhance strawberry growth, and disease resistance against the airborne fungal pathogen Botrytis cinerea. Additionally, biochar can induce shifts in the strawberry rhizosphere microbiome. However, the moment that this biochar-mediated shift occurs in the rhizosphere is not known. Further, the effect of an above-ground infection on the strawberry rhizosphere microbiome is unknown. In the present study we established two experiments in which strawberry transplants (cv. Elsanta) were planted either in peat or in peat amended with 3% biochar. First, we established a time course experiment to measure the effect of biochar on the rhizosphere bacterial and fungal communities over time. In a second experiment, we inoculated the strawberry leaves with B. cinerea, and studied the impact of the infection on the rhizosphere bacterial community. The fungal rhizosphere community was stabilized after 1 week, except for the upcoming Auriculariales, whereas the bacterial community shifted till 6 weeks. An effect of the addition of biochar to the peat on the rhizosphere microbiome was solely measured for the bacterial community from week 6 of plant growth onwards. When scoring the plant development, biochar addition was associated with enhanced root formation, fruit production, and postharvest resistance of the fruits against B. cinerea. We hypothesize that the bacterial rhizosphere microbiome, but also biochar-mediated changes in chemical substrate composition could be involved in these events. Infection of the strawberry leaves with B. cinerea induced shifts in the bacterial rhizosphere community, with an increased bacterial richness. This disease-induced effect was not observed in the rhizospheres of the B. cinerea-infected plants grown in the biochar-amended peat. The results show that an above-ground infection has its effect on the strawberry rhizosphere microbiome, changing the bacterial interactions in the root-substrate interface. This infection effect on the bacterial rhizosphere microbiome seems to be comparable to, but less pronounced than the effect of biochar-addition to the peat. The biological meaning of these observations needs further research, but this study indicates that biochar and an above-ground pathogen attack help the plant to recruit rhizosphere microbes that may aid them in their plant growth and health.
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Załuga J, Stragier P, Baeyen S, Haegeman A, Van Vaerenbergh J, Maes M, De Vos P. Comparative genome analysis of pathogenic and non-pathogenic Clavibacter strains reveals adaptations to their lifestyle. BMC Genomics 2014; 15:392. [PMID: 24885539 PMCID: PMC4059874 DOI: 10.1186/1471-2164-15-392] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 05/09/2014] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The genus Clavibacter harbors economically important plant pathogens infecting agricultural crops such as potato and tomato. Although the vast majority of Clavibacter strains are pathogenic, there is an increasing number of non-pathogenic isolates reported. Non-pathogenic Clavibacter strains isolated from tomato seeds are particularly problematic because they affect the current detection and identification tests for Clavibacter michiganensis subsp. michiganensis (Cmm), which is regulated with a zero tolerance in tomato seed. Their misidentification as pathogenic Cmm hampers a clear judgment on the seed quality and health. RESULTS To get more insight in the genetic features linked to the lifestyle of these bacteria, a whole-genome sequence of the tomato seed-borne non-pathogenic Clavibacter LMG 26808 was determined. To gain a better understanding of the molecular determinants of pathogenicity, the genome sequence of LMG 26808 was compared with that of the pathogenic Cmm strain (NCPPB 382). The comparative analysis revealed that LMG 26808 does not contain plasmids pCM1 and pCM2 and also lacks the majority of important virulence factors described so far for pathogenic Cmm. This explains its apparent non-pathogenic nature in tomato plants. Moreover, the genome analysis of LMG 26808 detected sequences from a plasmid originating from a member of Enterobacteriaceae/Klebsiella relative. Genes received that way and coding for antibiotic resistance may provide a competitive advantage for survival of LMG 26808 in its ecological niche. Genetically, LMG 26808 was the most similar to the pathogenic Cmm NCPPB 382 but contained more mobile genetic elements. The genome of this non-pathogenic Clavibacter strain contained also a high number of transporters and regulatory genes. CONCLUSIONS The genome sequence of the non-pathogenic Clavibacter strain LMG 26808 and the comparative analyses with other pathogenic Clavibacter strains provided a better understanding of the genetic bases of virulence and adaptation mechanisms present in the genus Clavibacter.
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Kyndt T, Nahar K, Haegeman A, De Vleesschauwer D, Höfte M, Gheysen G. Comparing systemic defence-related gene expression changes upon migratory and sedentary nematode attack in rice. PLANT BIOLOGY (STUTTGART, GERMANY) 2012; 14 Suppl 1:73-82. [PMID: 22188265 DOI: 10.1111/j.1438-8677.2011.00524.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Complex defence signalling pathways, controlled by different hormones, are known to be involved in the reaction of plants to a wide range of biotic and abiotic stress factors. Here, we studied the differential expression of genes involved in stress and defence responses in systemic tissue of rice infected with the root knot nematode (RKN) Meloidogyne graminicola and the migratory root rot nematode Hirschmanniella oryzae, two agronomically important rice pathogens with very different lifestyles. qRT-PCR revealed that all investigated systemic tissues had significantly lower expression of isochorismate synthase, a key enzyme for salicylic acid production involved in basal defence and systemic acquired resistance. The systemic defence response upon migratory nematode infection was remarkably similar to fungal rice blast infection. Almost all investigated defence-related genes were up-regulated in rice shoots 3 days after root rot nematode attack, including the phenylpropanoid pathway, ethylene pathway and PR genes, but many of which were suppressed at 7 dpi. Systemic shoot tissue of RKN-infected plants showed similar attenuation of expression of almost all studied genes already at 3 dpi, with clear attenuation of the ethylene pathway and methyl jasmonate biosynthesis. These results provide an interesting starting point for further studies to elucidate how nematodes are able to suppress systemic plant defence mechanisms and the effect in multitrophic interactions.
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Haegeman A, Vanholme B, Gheysen G. Characterization of a putative endoxylanase in the migratory plant-parasitic nematode Radopholus similis. MOLECULAR PLANT PATHOLOGY 2009; 10:389-401. [PMID: 19400841 PMCID: PMC6640231 DOI: 10.1111/j.1364-3703.2009.00539.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Plant-parasitic nematodes have developed an arsenal of enzymes to degrade the rigid plant cell wall. In this article, we report the presence of a putative endoxylanase in the migratory endoparasitic nematode Radopholus similis. This enzyme is thought to facilitate the migration of the nematode, as it breaks down xylan, the major component of hemicellulose. The corresponding gene (Rs-xyl1) was cloned and the sequence revealed three small introns. Interestingly, the position of all three introns was conserved in a putative endoxylanase from Meloidogyne hapla, and the position of one intron was conserved in two endoxylanases from Meloidogyne incognita, which suggests a common ancestral gene. The spatial and temporal expression of the Rs-xyl1 gene was examined by in situ hybridization and semi-quantitative reverse transcriptase-polymerase chain reaction. The putative protein consists of a signal peptide, a catalytic domain and a carbohydrate-binding module (CBM). The catalytic domain showed similarity to both glycosyl hydrolase family 5 (GHF5) and GHF30 enzymes. Using Hidden Markov Model profiles and phylogenetic analysis, we were able to show that Rs-XYL1 and its closest homologues are not members of GHF5, as suggested previously, but rather form a subclass within GHF30. Silencing the putative endoxylanase by double-stranded RNA targeting of the CBM region resulted in an average decrease in infection of 60%, indicating that the gene is important for the nematode to complete its life cycle.
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Vanholme B, Haegeman A, Jacob J, Cannoot B, Gheysen G. Arabinogalactan endo-1,4-β-galactosidase: a putative plant cell wall-degrading enzyme of plant-parasitic nematodes. NEMATOLOGY 2009. [DOI: 10.1163/156854109x404599] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
Plant-parasitic nematodes secrete a plethora of enzymes to degrade
polysaccharides of the recalcitrant plant cell wall. Here we report on the
presence of a putative endo-1,4-β-galactosidase (EC 3.2.1.89) in cyst
nematodes of the genus Heterodera. This enzyme hydrolyses β-1,4-galactan in
the hairy regions of pectin and to our knowledge it is the first report of
this class of enzymes in animals. The gene was cloned from H. schachtii and
subjected to a detailed molecular characterisation. The deduced protein
contains a putative signal peptide for secretion, being in agreement with
the presumed extracellular function of the mature protein. It has a
molecular mass of 33.78 kDa and folds into an (α/β)8 barrel structure
typical for glycosyl hydrolases. The two glutamic acids that function as
electron donor and acceptor in the active site are conserved. Whole mount in
situ hybridisation revealed that the gene is expressed in the subventral
pharyngeal glands and the expression was correlated with the onset of
parasitism.
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Kutnjak D, Tamisier L, Adams I, Boonham N, Candresse T, Chiumenti M, De Jonghe K, Kreuze JF, Lefebvre M, Silva G, Malapi-Wight M, Margaria P, Mavrič Pleško I, McGreig S, Miozzi L, Remenant B, Reynard JS, Rollin J, Rott M, Schumpp O, Massart S, Haegeman A. A Primer on the Analysis of High-Throughput Sequencing Data for Detection of Plant Viruses. Microorganisms 2021; 9:841. [PMID: 33920047 PMCID: PMC8071028 DOI: 10.3390/microorganisms9040841] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 04/09/2021] [Accepted: 04/10/2021] [Indexed: 12/12/2022] Open
Abstract
High-throughput sequencing (HTS) technologies have become indispensable tools assisting plant virus diagnostics and research thanks to their ability to detect any plant virus in a sample without prior knowledge. As HTS technologies are heavily relying on bioinformatics analysis of the huge amount of generated sequences, it is of utmost importance that researchers can rely on efficient and reliable bioinformatic tools and can understand the principles, advantages, and disadvantages of the tools used. Here, we present a critical overview of the steps involved in HTS as employed for plant virus detection and virome characterization. We start from sample preparation and nucleic acid extraction as appropriate to the chosen HTS strategy, which is followed by basic data analysis requirements, an extensive overview of the in-depth data processing options, and taxonomic classification of viral sequences detected. By presenting the bioinformatic tools and a detailed overview of the consecutive steps that can be used to implement a well-structured HTS data analysis in an easy and accessible way, this paper is targeted at both beginners and expert scientists engaging in HTS plant virome projects.
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De Tender C, Mesuere B, Van der Jeugt F, Haegeman A, Ruttink T, Vandecasteele B, Dawyndt P, Debode J, Kuramae EE. Peat substrate amended with chitin modulates the N-cycle, siderophore and chitinase responses in the lettuce rhizobiome. Sci Rep 2019; 9:9890. [PMID: 31289280 PMCID: PMC6617458 DOI: 10.1038/s41598-019-46106-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 06/19/2019] [Indexed: 11/09/2022] Open
Abstract
Chitin is a valuable peat substrate amendment by increasing lettuce growth and reducing the survival of the zoonotic pathogen Salmonella enterica on lettuce leaves. The production of chitin-catabolic enzymes (chitinases) play a crucial role and are mediated through the microbial community. A higher abundance of plant-growth promoting microorganisms and genera involved in N and chitin metabolism are present in a chitin-enriched substrate. In this study, we hypothesize that chitin addition to peat substrate stimulates the microbial chitinase production. The degradation of chitin leads to nutrient release and the production of small chitin oligomers that are related to plant growth promotion and activation of the plant's defense response. First a shotgun metagenomics approach was used to decipher the potential rhizosphere microbial functions then the nutritional content of the peat substrate was measured. Our results show that chitin addition increases chitin-catabolic enzymes, bacterial ammonium oxidizing and siderophore genes. Lettuce growth promotion can be explained by a cascade degradation of chitin to N-acetylglucosamine and eventually ammonium. The occurrence of increased ammonium oxidizing bacteria, Nitrosospira, and amoA genes results in an elevated concentration of plant-available nitrate. In addition, the increase in chitinase and siderophore genes may have stimulated the plant's systemic resistance.
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