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Goettelmann F, Chen Y, Knorst V, Yates S, Copetti D, Studer B, Kölliker R. High-resolution bulked segregant analysis enables candidate gene identification for bacterial wilt resistance in Italian ryegrass (Lolium multiflorum Lam.). THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 118:1516-1527. [PMID: 38412295 DOI: 10.1111/tpj.16693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 02/13/2024] [Accepted: 02/16/2024] [Indexed: 02/29/2024]
Abstract
Bacterial wilt, caused by Xanthomonas translucens pv. graminis (Xtg), is a serious disease of economically important forage grasses, including Italian ryegrass (Lolium multiflorum Lam.). A major QTL for resistance to Xtg was previously identified, but the precise location as well as the genetic factors underlying the resistance are yet to be determined. To this end, we applied a bulked segregant analysis (BSA) approach, using whole-genome deep sequencing of pools of the most resistant and most susceptible individuals of a large (n = 7484) biparental F2 population segregating for resistance to Xtg. Using chromosome-level genome assemblies as references, we were able to define a ~300 kb region highly associated with resistance on pseudo-chromosome 4. Further investigation of this region revealed multiple genes with a known role in disease resistance, including genes encoding for Pik2-like disease resistance proteins, cysteine-rich kinases, and RGA4- and RGA5-like disease resistance proteins. Investigation of allele frequencies in the pools and comparative genome analysis in the grandparents of the F2 population revealed that some of these genes contain variants with allele frequencies that correspond to the expected heterozygosity in the resistant grandparent. This study emphasizes the efficacy of combining BSA studies in very large populations with whole genome deep sequencing and high-quality genome assemblies to pinpoint regions associated with a binary trait of interest and accurately define a small set of candidate genes. Furthermore, markers identified in this region hold significant potential for marker-assisted breeding strategies to breed resistance to Xtg in Italian ryegrass cultivars more efficiently.
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Affiliation(s)
- Florian Goettelmann
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Yutang Chen
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Verena Knorst
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Steven Yates
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Dario Copetti
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
- Arizona Genomics Institute, The University of Arizona, Tucson, AZ, USA
| | - Bruno Studer
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Roland Kölliker
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
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Goettelmann F, Koebnik R, Roman-Reyna V, Studer B, Kölliker R. High genomic plasticity and unique features of Xanthomonas translucens pv. graminis revealed through comparative analysis of complete genome sequences. BMC Genomics 2023; 24:741. [PMID: 38053038 DOI: 10.1186/s12864-023-09855-8] [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: 07/05/2023] [Accepted: 11/28/2023] [Indexed: 12/07/2023] Open
Abstract
BACKGROUND Xanthomonas translucens pv. graminis (Xtg) is a major bacterial pathogen of economically important forage grasses, causing severe yield losses. So far, genomic resources for this pathovar consisted mostly of draft genome sequences, and only one complete genome sequence was available, preventing comprehensive comparative genomic analyses. Such comparative analyses are essential in understanding the mechanisms involved in the virulence of pathogens and to identify virulence factors involved in pathogenicity. RESULTS In this study, we produced high-quality, complete genome sequences of four strains of Xtg, complementing the recently obtained complete genome sequence of the Xtg pathotype strain. These genomic resources allowed for a comprehensive comparative analysis, which revealed a high genomic plasticity with many chromosomal rearrangements, although the strains were highly related. A high number of transposases were exclusively found in Xtg and corresponded to 413 to 457 insertion/excision transposable elements per strain. These mobile genetic elements are likely to be involved in the observed genomic plasticity and may play an important role in the adaptation of Xtg. The pathovar was found to lack a type IV secretion system, and it possessed the smallest set of type III effectors in the species. However, three XopE and XopX family effectors were found, while in the other pathovars of the species two or less were present. Additional genes that were specific to the pathovar were identified, including a unique set of minor pilins of the type IV pilus, 17 TonB-dependent receptors (TBDRs), and 11 plant cell wall degradative enzymes. CONCLUSION These results suggest a high adaptability of Xtg, conferred by the abundance of mobile genetic elements, which could play a crucial role in pathogen adaptation. The large amount of such elements in Xtg compared to other pathovars of the species could, at least partially, explain its high virulence and broad host range. Conserved features that were specific to Xtg were identified, and further investigation will help to determine genes that are essential to pathogenicity and host adaptation of Xtg.
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Affiliation(s)
- Florian Goettelmann
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Ralf Koebnik
- Plant Health Institute of Montpellier, University of Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | - Veronica Roman-Reyna
- Department of Plant Pathology and Environmental Microbiology, The Pennsylvania State University, University Park, PA, USA
| | - Bruno Studer
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Roland Kölliker
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland.
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Fernando K, Reddy P, Spangenberg GC, Rochfort SJ, Guthridge KM. Metabolic Potential of Epichloë Endophytes for Host Grass Fungal Disease Resistance. Microorganisms 2021; 10:64. [PMID: 35056512 PMCID: PMC8781568 DOI: 10.3390/microorganisms10010064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/22/2021] [Accepted: 12/24/2021] [Indexed: 12/27/2022] Open
Abstract
Asexual species of the genus Epichloë (Clavicipitaceae, Ascomycota) form endosymbiotic associations with Pooidae grasses. This association is important both ecologically and to the pasture and turf industries, as the endophytic fungi confer a multitude of benefits to their host plant that improve competitive ability and performance such as growth promotion, abiotic stress tolerance, pest deterrence and increased host disease resistance. Biotic stress tolerance conferred by the production of bioprotective metabolites has a critical role in an industry context. While the known antimammalian and insecticidal toxins are well characterized due to their impact on livestock welfare, antimicrobial metabolites are less studied. Both pasture and turf grasses are challenged by many phytopathogenic diseases that result in significant economic losses and impact livestock health. Further investigations of Epichloë endophytes as natural biocontrol agents can be conducted on strains that are safe for animals. With the additional benefits of possessing host disease resistance, these strains would increase their commercial importance. Field reports have indicated that pasture grasses associated with Epichloë endophytes are superior in resisting fungal pathogens. However, only a few antifungal compounds have been identified and chemically characterized, and these from sexual (pathogenic) Epichloë species, rather than those utilized to enhance performance in turf and pasture industries. This review provides insight into the various strategies reported in identifying antifungal activity from Epichloë endophytes and, where described, the associated antifungal metabolites responsible for the activity.
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Affiliation(s)
- Krishni Fernando
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (K.F.); (P.R.); (G.C.S.); (S.J.R.)
- School of Applied Systems Biology, La Trobe University, Bundoora, VIC 3083, Australia
| | - Priyanka Reddy
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (K.F.); (P.R.); (G.C.S.); (S.J.R.)
| | - German C. Spangenberg
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (K.F.); (P.R.); (G.C.S.); (S.J.R.)
- School of Applied Systems Biology, La Trobe University, Bundoora, VIC 3083, Australia
| | - Simone J. Rochfort
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (K.F.); (P.R.); (G.C.S.); (S.J.R.)
- School of Applied Systems Biology, La Trobe University, Bundoora, VIC 3083, Australia
| | - Kathryn M. Guthridge
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (K.F.); (P.R.); (G.C.S.); (S.J.R.)
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Te Molder D, Poncheewin W, Schaap PJ, Koehorst JJ. Machine learning approaches to predict the Plant-associated phenotype of Xanthomonas strains. BMC Genomics 2021; 22:848. [PMID: 34814827 PMCID: PMC8612006 DOI: 10.1186/s12864-021-08093-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 10/15/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The genus Xanthomonas has long been considered to consist predominantly of plant pathogens, but over the last decade there has been an increasing number of reports on non-pathogenic and endophytic members. As Xanthomonas species are prevalent pathogens on a wide variety of important crops around the world, there is a need to distinguish between these plant-associated phenotypes. To date a large number of Xanthomonas genomes have been sequenced, which enables the application of machine learning (ML) approaches on the genome content to predict this phenotype. Until now such approaches to the pathogenomics of Xanthomonas strains have been hampered by the fragmentation of information regarding pathogenicity of individual strains over many studies. Unification of this information into a single resource was therefore considered to be an essential step. RESULTS Mining of 39 papers considering both plant-associated phenotypes, allowed for a phenotypic classification of 578 Xanthomonas strains. For 65 plant-pathogenic and 53 non-pathogenic strains the corresponding genomes were available and de novo annotated for the presence of Pfam protein domains used as features to train and compare three ML classification algorithms; CART, Lasso and Random Forest. CONCLUSION The literature resource in combination with recursive feature extraction used in the ML classification algorithms provided further insights into the virulence enabling factors, but also highlighted domains linked to traits not present in pathogenic strains.
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Affiliation(s)
- Dennie Te Molder
- Laboratory of Systems and Synthetic Biology, Wageningen University, Wageningen, the Netherlands
| | - Wasin Poncheewin
- Laboratory of Systems and Synthetic Biology, Wageningen University, Wageningen, the Netherlands
| | - Peter J Schaap
- Laboratory of Systems and Synthetic Biology, Wageningen University, Wageningen, the Netherlands
- UNLOCK, Wageningen University, Wageningen, the Netherlands
| | - Jasper J Koehorst
- Laboratory of Systems and Synthetic Biology, Wageningen University, Wageningen, the Netherlands.
- UNLOCK, Wageningen University, Wageningen, the Netherlands.
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Fernando K, Reddy P, Vassiliadis S, Spangenberg GC, Rochfort SJ, Guthridge KM. The Known Antimammalian and Insecticidal Alkaloids Are Not Responsible for the Antifungal Activity of Epichloë Endophytes. PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10112486. [PMID: 34834850 PMCID: PMC8624124 DOI: 10.3390/plants10112486] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/12/2021] [Accepted: 11/13/2021] [Indexed: 06/13/2023]
Abstract
Asexual Epichloë sp. endophytes in association with pasture grasses produce agronomically important alkaloids (e.g., lolitrem B, epoxy-janthitrems, ergovaline, peramine, and lolines) that exhibit toxicity to grazing mammals and/or insect pests. Novel strains are primarily characterised for the presence of these compounds to ensure they are beneficial in an agronomical setting. Previous work identified endophyte strains that exhibit enhanced antifungal activity, which have the potential to improve pasture and turf quality as well as animal welfare through phytopathogen disease control. The contribution of endophyte-derived alkaloids to improving pasture and turf grass disease resistance has not been closely examined. To assess antifungal bioactivity, nine Epichloë related compounds, namely peramine hemisulfate, n-formylloline-d3, n-acetylloline hydrochloride, lolitrem B, janthitrem A, paxilline, terpendole E, terpendole C, and ergovaline, and four Claviceps purpurea ergot alkaloids, namely ergotamine, ergocornine, ergocryptine, and ergotaminine, were tested at concentrations higher than observed in planta in glasshouse and field settings using in vitro agar well diffusion assays against three common pasture and turf phytopathogens, namely Ceratobasidium sp., Drechslera sp., and Fusarium sp. Visual characterisation of bioactivity using pathogen growth area, mycelial density, and direction of growth indicated no inhibition of pathogen growth. This was confirmed by statistical analysis. The compounds responsible for antifungal bioactivity of Epichloë endophytes hence remain unknown and require further investigation.
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Affiliation(s)
- Krishni Fernando
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (K.F.); (P.R.); (S.V.); (G.C.S.); (S.J.R.)
- School of Applied Systems Biology, La Trobe University, Bundoora, VIC 3083, Australia
| | - Priyanka Reddy
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (K.F.); (P.R.); (S.V.); (G.C.S.); (S.J.R.)
| | - Simone Vassiliadis
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (K.F.); (P.R.); (S.V.); (G.C.S.); (S.J.R.)
| | - German C. Spangenberg
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (K.F.); (P.R.); (S.V.); (G.C.S.); (S.J.R.)
- School of Applied Systems Biology, La Trobe University, Bundoora, VIC 3083, Australia
| | - Simone J. Rochfort
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (K.F.); (P.R.); (S.V.); (G.C.S.); (S.J.R.)
- School of Applied Systems Biology, La Trobe University, Bundoora, VIC 3083, Australia
| | - Kathryn M. Guthridge
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (K.F.); (P.R.); (S.V.); (G.C.S.); (S.J.R.)
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Fernando K, Reddy P, Hettiarachchige IK, Spangenberg GC, Rochfort SJ, Guthridge KM. Novel Antifungal Activity of Lolium-Associated Epichloë Endophytes. Microorganisms 2020; 8:microorganisms8060955. [PMID: 32599897 PMCID: PMC7355949 DOI: 10.3390/microorganisms8060955] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/19/2020] [Accepted: 06/19/2020] [Indexed: 01/22/2023] Open
Abstract
Asexual Epichloë spp. fungal endophytes have been extensively studied for their functional secondary metabolite production. Historically, research mostly focused on understanding toxicity of endophyte-derived compounds on grazing livestock. However, endophyte-derived compounds also provide protection against invertebrate pests, disease, and other environmental stresses, which is important for ensuring yield and persistence of pastures. A preliminary screen of 30 strains using an in vitro dual culture bioassay identified 18 endophyte strains with antifungal activity. The novel strains NEA12, NEA21, and NEA23 were selected for further investigation as they are also known to produce alkaloids associated with protection against insect pests. Antifungal activity of selected endophyte strains was confirmed against three grass pathogens, Ceratobasidium sp., Dreschlera sp., and Fusarium sp., using independent isolates in an in vitro bioassay. NEA21 and NEA23 showed potent activity against Ceratobasidium sp. and NEA12 showed moderate inhibition against all three pathogens. Crude extracts from liquid cultures of NEA12 and NEA23 also inhibited growth of the phytopathogens Ceratobasidium sp. and Fusarium sp. and provided evidence that the compounds of interest are stable, constitutively expressed, and secreted. Comparative analysis of the in vitro and in planta metabolome of NEA12 and NEA23 using LCMS profile data revealed individual metabolites unique to each strain that are present in vitro and in planta. These compounds are the best candidates for the differential bioactivity observed for each strain. Novel endophyte strains show promise for endophyte-mediated control of phytopathogens impacting Lolium spp. pasture production and animal welfare.
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Affiliation(s)
- Krishni Fernando
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, 3083 Victoria, Australia; (K.F.); (P.R.); (I.K.H.); (G.C.S.); (S.J.R.)
- School of Applied Systems Biology, La Trobe University, Bundoora, 3083 Victoria, Australia
| | - Priyanka Reddy
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, 3083 Victoria, Australia; (K.F.); (P.R.); (I.K.H.); (G.C.S.); (S.J.R.)
| | - Inoka K. Hettiarachchige
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, 3083 Victoria, Australia; (K.F.); (P.R.); (I.K.H.); (G.C.S.); (S.J.R.)
| | - German C. Spangenberg
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, 3083 Victoria, Australia; (K.F.); (P.R.); (I.K.H.); (G.C.S.); (S.J.R.)
- School of Applied Systems Biology, La Trobe University, Bundoora, 3083 Victoria, Australia
| | - Simone J. Rochfort
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, 3083 Victoria, Australia; (K.F.); (P.R.); (I.K.H.); (G.C.S.); (S.J.R.)
- School of Applied Systems Biology, La Trobe University, Bundoora, 3083 Victoria, Australia
| | - Kathryn M. Guthridge
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, 3083 Victoria, Australia; (K.F.); (P.R.); (I.K.H.); (G.C.S.); (S.J.R.)
- Correspondence: ; Tel.: +61390327062
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Khojasteh M, Shah SMA, Haq F, Xu X, Taghavi SM, Osdaghi E, Chen G. Transcription Activator-Like Effectors Diversity in Iranian Strains of Xanthomonas translucens. PHYTOPATHOLOGY 2020; 110:758-767. [PMID: 31868568 DOI: 10.1094/phyto-11-19-0428-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Bacterial leaf streak caused by different pathovars of Xanthomonas translucens is the most important seedborne bacterial disease of small grain cereals. However, variations in the virulence-associated genomic areas of the pathogen remain uninvestigated. In this study, the diversity of transcription activator-like effectors (TALE) was investigated using the Southern blotting of BamHI-digested genomic DNAs in the Iranian strains of X. translucens. All 65 X. translucens strains were assigned into 13 genotypes, where 57 X. translucens pv. undulosa strains were placed in genotypes 1 to 8, and seven X. translucens pv. translucens strains were placed in genotypes 9 to 12. Interestingly, we did not find any TALE genes in the strain XtKm7 (genotype 13), which showed to be pathogenic only on barley. Virulence and aggressiveness of these strains in greenhouse conditions were in agreement with the TALE-based clustering of the strains in the pathovar level, though variations were observed in the aggressiveness of X. translucens pv. undulosa strains. In general, strains containing higher numbers of putative TALE genes were more virulent on wheat and barley than strains containing fewer. This is the first TALE-based genetic diversity analysis on X. translucens strains and provides novel insights into the virulence repertories and genomic characteristics of the pathogen. Further investigations using TALE mutagenesis and complementation analysis are warranted to precisely elucidate the role of each detected X. translucens TALE in bacterial virulence and aggressiveness either on wheat or barley.
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Affiliation(s)
- Moein Khojasteh
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China
- Department of Plant Protection, College of Agriculture, Shiraz University, Shiraz 71441-65186, Iran
| | - Syed Mashab Ali Shah
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Fazal Haq
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xiameng Xu
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - S Mohsen Taghavi
- Department of Plant Protection, College of Agriculture, Shiraz University, Shiraz 71441-65186, Iran
| | - Ebrahim Osdaghi
- Department of Plant Protection, College of Agriculture, Shiraz University, Shiraz 71441-65186, Iran
| | - Gongyou Chen
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China
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Curland RD, Gao L, Hirsch CD, Ishimaru CA. Localized Genetic and Phenotypic Diversity of Xanthomonas translucens Associated With Bacterial Leaf Streak on Wheat and Barley in Minnesota. PHYTOPATHOLOGY 2020; 110:257-266. [PMID: 31448998 DOI: 10.1094/phyto-04-19-0134-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Bacterial leaf streak (BLS) of wheat and barley has been a disease of increasing concern in the Upper Midwest over the past decade. In this study, intra- and interfield genetic and pathogenic diversity of bacteria causing BLS in Minnesota was evaluated. In 2015, 89 strains were isolated from 100 leaf samples collected from two wheat and two barley fields naturally infected with BLS. Virulence assays and multilocus sequence alignments of four housekeeping genes supported pathovar identifications. All wheat strains were pathogenic on wheat and barley and belonged to the same lineage as the Xanthomonas translucens pv. undulosa-type strain. All barley strains were pathogenic on barley but not on wheat. Three lineages of barley strains were detected. The frequency and number of sequence types of each pathovar varied within and between fields. A significant population variance was detected between populations of X. translucens pv. undulosa collected from different wheat fields. Population stratification of X. translucens pv. translucens was not detected. Significant differences in virulence were detected among three dominant sequence types of X. translucens pv. undulosa but not those of X. translucens pv. translucens. Field trials with wheat and barley plants inoculated with strains of known sequence type and virulence did not detect significant race structures within either pathovar. Knowledge of virulence, sequence types, and population structures of X. translucens on wheat and barley can support studies on plant-bacterial interactions and breeding for BLS disease resistance.
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Affiliation(s)
- Rebecca D Curland
- Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108
| | - Liangliang Gao
- Department of Plant Pathology, Kansas State University, Manhattan, KS 66506
| | - Cory D Hirsch
- Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108
| | - Carol A Ishimaru
- Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108
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Hersemann L, Wibberg D, Blom J, Goesmann A, Widmer F, Vorhölter FJ, Kölliker R. Comparative genomics of host adaptive traits in Xanthomonas translucens pv. graminis. BMC Genomics 2017; 18:35. [PMID: 28056815 PMCID: PMC5217246 DOI: 10.1186/s12864-016-3422-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Accepted: 12/14/2016] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Xanthomonas translucens pathovars differ in their individual host ranges among Poaceae. As the causal agent of bacterial wilt in Italian ryegrass (Lolium multiflorum Lam.), X. translucens pv. graminis (Xtg) is one of the most important bacterial pathogens in temperate grassland regions. The genomes of six Xtg strains from Switzerland, Norway, and New Zealand were sequenced in order to gain insight into conserved genomic traits from organisms covering a wide geographical range. Subsequent comparative analysis with previously published genome data of seven non-graminis X. translucens strains including the pathovars arrhenatheri, poae, phlei, cerealis, undulosa, and translucens was conducted to identify candidate genes linked to the host adaptation of Xtg to Italian ryegrass. RESULTS Phylogenetic analysis revealed a tight clustering of Xtg strains, which were found to share a large core genome. Conserved genomic traits included a non-canonical type III secretion system (T3SS) and a type IV pilus (T4P), which both revealed distinct primary structures of the pilins when compared to the non-graminis X. translucens strains. Xtg-specific traits that had no homologues in the other X. translucens strains were further found to comprise several hypothetical proteins, a TonB-dependent receptor, transporters, and effector proteins as well as toxin-antitoxin systems and DNA methyltransferases. While a nearly complete flagellar gene cluster was identified in one of the sequenced Xtg strains, phenotypic analysis pointed to swimming-deficiency as a common trait of the pathovar graminis. CONCLUSION Our study suggests that host adaptation of X. translucens pv. graminis may be conferred by a combination of pathovar-specific effector proteins, regulatory mechanisms, and adapted nutrient acquisition. Sequence deviations of pathogen-associated molecular patterns (PAMPs), as observed for the pilins of the T4P and T3SS, are moreover likely to impede perception by the plant defense machinery and thus facilitate successful host colonization of Italian ryegrass.
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Affiliation(s)
| | - Daniel Wibberg
- Center for Biotechnology, Bielefeld University, 33615, Bielefeld, Germany
| | - Jochen Blom
- Bioinformatics and Systems Biology, Justus Liebig University Giessen, 35392, Giessen, Germany
| | - Alexander Goesmann
- Bioinformatics and Systems Biology, Justus Liebig University Giessen, 35392, Giessen, Germany
| | - Franco Widmer
- Molecular Ecology, Agroscope, 8046, Zurich, Switzerland
| | - Frank-Jörg Vorhölter
- Center for Biotechnology, Bielefeld University, 33615, Bielefeld, Germany
- MVZ Dr. Eberhard & Partner Dortmund, 44137, Dortmund, Germany
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Wichmann F, Vorhölter FJ, Hersemann L, Widmer F, Blom J, Niehaus K, Reinhard S, Conradin C, Kölliker R. The noncanonical type III secretion system of Xanthomonas translucens pv. graminis is essential for forage grass infection. MOLECULAR PLANT PATHOLOGY 2013; 14:576-88. [PMID: 23578314 PMCID: PMC6638798 DOI: 10.1111/mpp.12030] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Xanthomonas translucens pv. graminis (Xtg) is a gammaproteobacterium that causes bacterial wilt on a wide range of forage grasses. To gain insight into the host-pathogen interaction and to identify the virulence factors of Xtg, we compared a draft genome sequence of one isolate (Xtg29) with other Xanthomonas spp. with sequenced genomes. The type III secretion system (T3SS) encoding a protein transport system for type III effector (T3E) proteins represents one of the most important virulence factors of Xanthomonas spp. In contrast with other Xanthomonas spp. assigned to clade 1 on the basis of phylogenetic analyses, we identified an hrp (hypersensitive response and pathogenicity) gene cluster encoding T3SS components and a representative set of 35 genes encoding putative T3Es in the genome of Xtg29. The T3SS was shown to be divergent from the hrp gene clusters of other sequenced Xanthomonas spp. Xtg mutants deficient in T3SS regulating and structural genes were constructed to clarify the role of the T3SS in forage grass colonization. Italian ryegrass infection with these mutants led to significantly reduced symptoms (P < 0.05) relative to plants infected with the wild-type strain. This showed that the T3SS is required for symptom evocation. In planta multiplication of the T3SS mutants was not impaired significantly relative to the wild-type, indicating that the T3SS is not required for survival until 14 days post-infection. This study represents the first major step to understanding the bacterial colonization strategies deployed by Xtg and may assist in the identification of resistance (R) genes in forage grasses.
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Affiliation(s)
- Fabienne Wichmann
- Agroscope Reckenholz-Tänikon Research Station ART, Reckenholzstrasse 191, 8046 Zurich, Switzerland
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Genetic Diversity and Pathogenicity of Xanthomonas axonopodis Strains Inducing Citrus Canker Disease in Iran and South Korea. Indian J Microbiol 2012; 51:194-9. [PMID: 22654164 DOI: 10.1007/s12088-011-0103-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Accepted: 03/03/2010] [Indexed: 10/18/2022] Open
Abstract
For the first time in 1989 citrus bacterial canker disease has seen on Citrusaurantiifolia in southern Iran. A total of 43 strains from affected citrus trees, ten strains from South Korea and representative from all known five pathotypes of Xanthomonas axonopodis pathogenic on citrus trees were used in this study. Isolated strains from Iran were indistinguishable by phenotypic, FAMEs, and SDS-PAGE analyses but showed different host range. First group were pathogenic on all tested citrus seedlings including C. aurantiifolia, C. limettioides, C. limon, C. jambhiri, Poncirus trifoliata X C. paradisi, C. aurantium, C. paradise, C. medica, P. trifoliate, C. grandis, C. sinensis, C. reticulate and C. sinensis X P. trifoliate. Pathogenicity of the second group were limited to C. aurantiifolia, C. limettioides, C. limon, C. jambhiri, P. trifoliata X C. paradis, and C. aurantium. Among the strains studied by AFLP fingerprinting six clusters were found. These clusters were: (1) strains of pathotype C; (2) strains of pathotypes B and D; (3) strains of pathotype A together with the main group of the Iranian strains; (4) strains isolated from Korea; (5) strains of pathotype E; and (6) seven strains from Iran which made a completely separate cluster. Strains from pathotypes B and D could not be differentiated by AFLP. The tested Iranian strains belongs to the two different groups and strains from Korea grouped as a subcluster from main cluster of Iranian strains belong to the pathotype A.
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Adhikari TB, Gurung S, Hansen JM, Bonman JM. Pathogenic and genetic diversity of Xanthomonas translucens pv. undulosa in North Dakota. PHYTOPATHOLOGY 2012; 102:390-402. [PMID: 22204654 DOI: 10.1094/phyto-07-11-0201] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa, has become more prevalent recently in North Dakota and neighboring states. From five locations in North Dakota, 226 strains of X. translucens pv. undulosa were collected and evaluated for pathogenicity and then selected strains were inoculated on a set of 12 wheat cultivars and other cereal hosts. The genetic diversity of all strains was determined using repetitive sequence-based polymerase chain reaction (rep-PCR) and insertion sequence-based (IS)-PCR. Bacterial strains were pathogenic on wheat and barley but symptom severity was greatest on wheat. Strains varied greatly in aggressiveness, and wheat cultivars also showed differential responses to several strains. The 16S ribosomal DNA sequences of the strains were identical, and distinct from those of the other Xanthomonas pathovars. Combined rep-PCR and IS-PCR data produced 213 haplotypes. Similar haplotypes were detected in more than one location. Although diversity was greatest (≈92%) among individuals within a location, statistically significant (P ≤ 0.001 or 0.05) genetic differentiation among locations was estimated, indicating geographic differentiation between pathogen populations. The results of this study provide information on the pathogen diversity in North Dakota, which will be useful to better identify and characterize resistant germplasm.
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Affiliation(s)
- Tika B Adhikari
- Department of Plant Pathology, North Dakota State University, Department 7660, P.O. Box 6050, Fargo 58108, ND, USA.
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Mukhopadhyay K, Haque I, Bandopadhyay R, Covert S, Porter D. AFLP based assessment of genetic relationships among shiitake (Lentinula ssp.) mushrooms. Mol Biol Rep 2012; 39:6059-65. [PMID: 22215213 DOI: 10.1007/s11033-011-1420-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 12/19/2011] [Indexed: 11/25/2022]
Abstract
Despite the economical importance of shiitake (Lentinula ssp.) mushrooms, until the present date little information exists on cultivated and wild species in correlation with geographic origin applying molecular techniques. Use of a high resolution molecular tool like AFLP for assessing genetic similarity and geographical diversity would be an important step towards understanding of different Lentinula species. Thirteen wild and 17 cultivated accessions of 3 Lentinula species were analysed with 64 EcoRI-MseI primer combinations and finally 32 reproducible and polymorphic primer combinations were considered for the analysis. A total of 816 informative AFLP markers were generated and scored as binary data. These data were analysed using various method packages for cluster analysis, genetic diversity and genetic differentiation. Percentage polymorphism was high (62.99%) among the species studied. Different clustering analysis segregated the wild and the cultivated species into two major branches, with the wild samples being further grouped according to their geographic location. Overall polymorphisms among cultivated strains in the USA were higher than that of the cultivated strains in Japan (58.9%).
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Affiliation(s)
- Kunal Mukhopadhyay
- Department of Biotechnology, Birla Institute of Technology, Mesra, Ranchi, 835215, Jharkhand, India.
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Munhoz CF, Weiss B, Hanai LR, Zucchi MI, Fungaro MHP, Oliveira ALM, Monteiro-Vitorello CB, Vieira MLC. Genetic diversity and a PCR-based method for Xanthomonas axonopodis detection in passion fruit. PHYTOPATHOLOGY 2011; 101:416-424. [PMID: 21077774 DOI: 10.1094/phyto-06-10-0169] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Xanthomonas axonopodis pv. passiflorae causes bacterial spot in passion fruit. It attacks the purple and yellow passion fruit as well as the sweet passion fruit. The diversity of 87 isolates of pv. passiflorae collected from across 22 fruit orchards in Brazil was evaluated using molecular profiles and statistical procedures, including an unweighted pair-group method with arithmetical averages-based dendrogram, analysis of molecular variance (AMOVA), and an assigning test that provides information on genetic structure at the population level. Isolates from another eight pathovars were included in the molecular analyses and all were shown to have a distinct repetitive sequence-based polymerase chain reaction profile. Amplified fragment length polymorphism technique revealed considerable diversity among isolates of pv. passiflorae, and AMOVA showed that most of the variance (49.4%) was due to differences between localities. Cluster analysis revealed that most genotypic clusters were homogeneous and that variance was associated primarily with geographic origin. The disease adversely affects fruit production and may kill infected plants. A method for rapid diagnosis of the pathogen, even before the disease symptoms become evident, has value for producers. Here, a set of primers (Xapas) was designed by exploiting a single-nucleotide polymorphism between the sequences of the intergenic 16S-23S rRNA spacer region of the pathovars. Xapas was shown to effectively detect all pv. passiflorae isolates and is recommended for disease diagnosis in passion fruit orchards.
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Affiliation(s)
- C F Munhoz
- Universidade de São Paulo, Escola Superior de Agricultura Luiz de Queiroz, Departamento de Genética, P.O. Box 83, 13400-970 Piracicaba, Brazil
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Wichmann F, Asp T, Widmer F, Kölliker R. Transcriptional responses of Italian ryegrass during interaction with Xanthomonas translucens pv. graminis reveal novel candidate genes for bacterial wilt resistance. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2011; 122:567-579. [PMID: 20976589 DOI: 10.1007/s00122-010-1470-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Accepted: 10/11/2010] [Indexed: 05/30/2023]
Abstract
Xanthomonas translucens pv. graminis (Xtg) causes bacterial wilt, a severe disease of forage grasses such as Italian ryegrass (Lolium multiflorum Lam.). In order to gain a more detailed understanding of the genetic control of resistance mechanisms and to provide prerequisites for marker assisted selection, the partial transcriptomes of two Italian ryegrass genotypes, one resistant and one susceptible to bacterial wilt were compared at four time points after Xtg infection. A cDNA microarray developed from a perennial ryegrass (Lolium perenne) expressed sequence tag set consisting of 9,990 unique genes was used for transcriptome analysis in Italian ryegrass. An average of 4,487 (45%) of the perennial ryegrass sequences spotted on the cDNA microarray were detected by cross-hybridisation to Italian ryegrass. Transcriptome analyses of the resistant versus the susceptible genotype revealed substantial gene expression differences (>1,200) indicating that great gene expression differences between different Italian ryegrass genotypes exist which potentially contribute to the observed phenotypic divergence in Xtg resistance between the two genotypes. In the resistant genotype, several genes differentially expressed after Xtg inoculation were identified which revealed similarities to transcriptional changes triggered by pathogen-associated molecular patterns in other plant-pathogen interactions. These genes represent candidate genes of particular interest for the development of tools for marker assisted resistance breeding.
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Affiliation(s)
- Fabienne Wichmann
- Agroscope Reckenholz-Tänikon Research Station ART, Reckenholzstrasse 191, Zurich, Switzerland
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Mayer L, da Silva WP, Moura AB, Vendruscolo CT. Aflp analysis of xanthomonas axonopodis and x. Arboricola strains used in xanthan production studies reveal high levels of polymorphism. Braz J Microbiol 2010; 41:741-8. [PMID: 24031551 PMCID: PMC3768658 DOI: 10.1590/s1517-83822010000300026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 10/17/2009] [Accepted: 03/29/2010] [Indexed: 11/21/2022] Open
Abstract
Amplified fragment length polymorphism (AFLP) was used to analyze the genetic diversity of 14 strains of Xanthomonas arboricola pv. pruni and seven strains of X. axonopodis pv. phaseoli, which are used in xanthan production studies. Relationships identified by the AFLP profiles were assessed for xanthan production capacity, geographical location and host plant. Strains were isolated from 10 different geographic regions in South and Southeast States in Brazil. Data were analyzed for genetic similarity using the Dice coefficient and subjected to UPGMA cluster analysis. A total of 128 AFLP fragments were generated from four primer combinations: EcoRI+C/MseI+0, EcoRI+A/MseI+0, EcoRI+G/MseI+T and EcoRI+G/MseI+A. Of these, 96.1% were polymorphic. X. axonopodis pv. phaseoli (SD = 0.27) was shown to be more polymorphic than X. arboricola pv. pruni (SD = 0.58). All 14 pathovar pruni strains were included in a single main group (SD = 0.58), while the pathovar phaseoli strains were divided into three separate groups, with one group containing five strains (SD = 0.38) and two isolated groups (SD = 0.31 and 0.27) composed of only one strain each. Species were distinguished by three and eight specific AFLP markers present in the pathovar phaseoli and the pathovar pruni, respectively. For the unique strain without xanthan production capacity (X. axonopodis pv. phaseoli str. 48), nine specific AFLP bands were found. There was no evidence that geographic area or host plant influenced genetic heterogeneity. Correlations between AFLP patterns and xanthan production capacity were found in some strains, but were not consistent enough to establish a relationship.
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Affiliation(s)
- Laurí Mayer
- Departamento de Ciência e Tecnologia Agroindustrial, Faculdade de Agronomia Eliseu Maciel, Universidade Federal de Pelotas , Pelotas, RS, , Brasil
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Bonin A, Ehrich D, Manel S. Statistical analysis of amplified fragment length polymorphism data: a toolbox for molecular ecologists and evolutionists. Mol Ecol 2007; 16:3737-58. [PMID: 17850542 DOI: 10.1111/j.1365-294x.2007.03435.x] [Citation(s) in RCA: 300] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Recently, the amplified fragment length polymorphism (AFLP) technique has gained a lot of popularity, and is now frequently applied to a wide variety of organisms. Technical specificities of the AFLP procedure have been well documented over the years, but there is on the contrary little or scattered information about the statistical analysis of AFLPs. In this review, we describe the various methods available to handle AFLP data, focusing on four research topics at the population or individual level of analysis: (i) assessment of genetic diversity; (ii) identification of population structure; (iii) identification of hybrid individuals; and (iv) detection of markers associated with phenotypes. Two kinds of analysis methods can be distinguished, depending on whether they are based on the direct study of band presences or absences in AFLP profiles ('band-based' methods), or on allelic frequencies estimated at each locus from these profiles ('allele frequency-based' methods). We investigate the characteristics and limitations of these statistical tools; finally, we appeal for a wider adoption of methodologies borrowed from other research fields, like for example those especially designed to deal with binary data.
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Affiliation(s)
- A Bonin
- Diversity Arrays Technology P/L, Yarralumla, ACT 2600, Australia
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Hu J, Zhang Y, Qian W, He C. Avirulence gene and insertion element-based RFLP as well as RAPD markers reveal high levels of genomic polymorphism in the rice pathogen Xanthomonas oryzae pv. oryzae. Syst Appl Microbiol 2007; 30:587-600. [PMID: 17959329 DOI: 10.1016/j.syapm.2007.08.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Accepted: 08/23/2007] [Indexed: 10/22/2022]
Abstract
Genetic polymorphism within the genomes of bacterial pathogens determines their evolutionary potential during long-term interaction with their hosts. To investigate the level of genetic variation in Xanthomonas oryzae pv. oryzae (Xoo), the causative agent of rice bacterial blight disease, three DNA marker systems, including (i) restriction fragment length polymorphism (RFLP) of the avrBs3/PthA family genes (avrXa27), (ii) RFLP of insertion (IS) elements and (iii) random amplified polymorphic DNA (RAPD) markers, were used to detect polymorphism among 32 Xoo strains that differed in their virulence patterns. All these strains contained multiple avrXa27 homologs that were variable in copy number and genomic location. RFLP of six IS elements revealed that these mobile sequences were abundant in Xoo genomes, with 150 of the total of 165 discernable markers being variable. Thirty-eight decamer primers of RAPD amplified a total of 691 bands, with 100% of them being variable. In addition, analysis of molecular variance (AMOVA) of data from RFLP analysis of IS elements and from RAPD analysis showed that most of the genetic variation residues were within Xoo populations, rather than between populations. Although all three DNA marker systems supported that substantial variation was maintained in Xoo genomes, Mantel tests did not identify significant correlation between the similarity coefficients calculated from them. The results of the present study indicated that Xoo genomes contain a high level of genetic polymorphism, which greatly facilitates the evolution of this important pathogen during interaction with its host rice plant.
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Affiliation(s)
- Jun Hu
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, PR China
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Abstract
Environmental microbiology is undergoing a dramatic revolution due to the increasing accumulation of biological information and contextual environmental parameters. This will not only enable a better identification of diversity patterns, but will also shed more light on the associated environmental conditions, spatial locations, and seasonal fluctuations, which could explain such patterns. Complex ecological questions may now be addressed using multivariate statistical analyses, which represent a vast potential of techniques that are still underexploited. Here, well-established exploratory and hypothesis-driven approaches are reviewed, so as to foster their addition to the microbial ecologist toolbox. Because such tools aim at reducing data set complexity, at identifying major patterns and putative causal factors, they will certainly find many applications in microbial ecology.
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Affiliation(s)
- Alban Ramette
- Microbial habitat group, Max Planck Institute for Marine Microbiology, Bremen, Germany.
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Studer B, Boller B, Herrmann D, Bauer E, Posselt UK, Widmer F, Kölliker R. Genetic mapping reveals a single major QTL for bacterial wilt resistance in Italian ryegrass (Lolium multiflorum Lam.). TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2006; 113:661-71. [PMID: 16799808 DOI: 10.1007/s00122-006-0330-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Accepted: 05/27/2006] [Indexed: 05/10/2023]
Abstract
Bacterial wilt caused by Xanthomonas translucens pv. graminis (Xtg) is a major disease of economically important forage crops such as ryegrasses and fescues. Targeted breeding based on seedling inoculation has resulted in cultivars with considerable levels of resistance. However, the mechanisms of inheritance of resistance are poorly understood and further breeding progress is difficult to obtain. This study aimed to assess the relevance of the seedling screening in the glasshouse for adult plant resistance in the field and to investigate genetic control of resistance to bacterial wilt in Italian ryegrass (Lolium multiflorum Lam.). A mapping population consisting of 306 F1 individuals was established and resistance to bacterial wilt was assessed in glasshouse and field experiments. Highly correlated data (r = 0.67-0.77, P < 0.01) between trial locations demonstrated the suitability of glasshouse screens for phenotypic selection. Analysis of quantitative trait loci (QTL) based on a high density genetic linkage map consisting of 368 amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers revealed a single major QTL on linkage group (LG) 4 explaining 67% of the total phenotypic variance (Vp). In addition, a minor QTL was observed on LG 5. Field experiments confirmed the major QTL on LG 4 to explain 43% (in 2004) to 84% (in 2005) of Vp and also revealed additional minor QTLs on LG 1, LG 4 and LG 6. The identified QTLs and the closely linked markers represent important targets for marker-assisted selection of Italian ryegrass.
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Affiliation(s)
- Bruno Studer
- Agroscope Reckenholz-Tänikon Research Station ART, Reckenholzstr. 191, 8046 Zurich, Switzerland
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