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Selection of Elms Tolerant to Dutch Elm Disease in South-West Romania. DIVERSITY 2022. [DOI: 10.3390/d14110980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Ophoiostoma novo- ulmi continues to be one of the most dangerous invasive fungi, destroying many autochthonous elm forests and cultures throughout the world. Searching for natural genotypes tolerant to Dutch Elm Disease (DED) is one of the main objectives of silviculturists all over the northern hemisphere in order to save the susceptible elms and to restore their ecosystem biodiversity. In this regard, the first trial was established between 1991 and 1994, in south-west Romania (Pădurea Verde, Timișoara), using three elm species (Ulmus minor, U. glabra, and U. laevis) with 38 provenances. A local strain of Ophiostoma novo-ulmi was used to artificially inoculate all elm variants and the DED evolution was observed. Furthermore, in 2018–2021 the trial was inventoried to understand the local genotype reaction to DED in the local environmental conditions after almost 30 years. The outcomes of the present study proved the continuous presence of the infections in the comparative culture and its proximity, but the identified pathogen had a new hybrid form (found for the first time in Romania) between O. novo-ulmi ssp. Americana x O. novo-ulmi ssp. novo-ulmi. Wych elm (U. glabra) was extremely sensitive to DED: only 12 trees (out of 69 found in 2018) survived in 2021, and only one tree could be selected according to the adopted health criteria (resistance and vigour). The field elm (U. minor) was sensitive to the pathogen, but there were still individuals that showed good health status and growth. In contrast, the European white elm (U. laevis) proved constant tolerance to DED: only 15% had been found dead or presented severe symptoms of dieback. Overall, the results of this study report the diverse reactions of the Romanian regional elm genotypes to DED over the last three decades, providing promising perspectives for improving the presence of elms in the forest ecosystems of the Carpathian basin.
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Martín JA, Domínguez J, Solla A, Brasier CM, Webber JF, Santini A, Martínez-Arias C, Bernier L, Gil L. Complexities underlying the breeding and deployment of Dutch elm disease resistant elms. NEW FORESTS 2021; 54:661-696. [PMID: 37361260 PMCID: PMC10287581 DOI: 10.1007/s11056-021-09865-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 07/03/2021] [Indexed: 06/28/2023]
Abstract
Dutch elm disease (DED) is a vascular wilt disease caused by the pathogens Ophiostoma ulmi and Ophiostoma novo-ulmi with multiple ecological phases including pathogenic (xylem), saprotrophic (bark) and vector (beetle flight and beetle feeding wound) phases. Due to the two DED pandemics during the twentieth century the use of elms in landscape and forest restoration has declined significantly. However new initiatives for elm breeding and restoration are now underway in Europe and North America. Here we discuss complexities in the DED 'system' that can lead to unintended consequences during elm breeding and some of the wider options for obtaining durability or 'field resistance' in released material, including (1) the phenotypic plasticity of disease levels in resistant cultivars infected by O. novo-ulmi; (2) shortcomings in test methods when selecting for resistance; (3) the implications of rapid evolutionary changes in current O. novo-ulmi populations for the choice of pathogen inoculum when screening; (4) the possibility of using active resistance to the pathogen in the beetle feeding wound, and low attractiveness of elm cultivars to feeding beetles, in addition to resistance in the xylem; (5) the risk that genes from susceptible and exotic elms be introgressed into resistant cultivars; (6) risks posed by unintentional changes in the host microbiome; and (7) the biosecurity risks posed by resistant elm deployment. In addition, attention needs to be paid to the disease pressures within which resistant elms will be released. In the future, biotechnology may further enhance our understanding of the various resistance processes in elms and our potential to deploy trees with highly durable resistance in elm restoration. Hopefully the different elm resistance processes will prove to be largely under durable, additive, multigenic control. Elm breeding programmes cannot afford to get into the host-pathogen arms races that characterise some agricultural host-pathogen systems.
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Affiliation(s)
- Juan A. Martín
- Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
- Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences (SLU), Alnarp, Sweden
| | - Jorge Domínguez
- Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
- Centro Nacional de Recursos Genéticos Forestales Puerta de Hierro. TRAGSA., Ctra. de la Coruña, Km 7.5, 28040 Madrid, Spain
| | - Alejandro Solla
- Faculty of Forestry, Institute for Dehesa Research (INDEHESA), University of Extremadura, Avenida Virgen del Puerto 2, 10600 Plasencia, Spain
| | | | | | - Alberto Santini
- Istituto per la Protezione Sostenibile delle Piante – C.N.R., Via Madonna del Piano, 10, 50019 Sesto Fiorentino, Italy
| | - Clara Martínez-Arias
- Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
| | - Louis Bernier
- Centre d’étude de la Forêt (CEF), Université Laval, Quebec City, QC G1V 0A6 Canada
| | - Luis Gil
- Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
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Brasier C, Franceschini S, Forster J, Kirk S. Enhanced Outcrossing, Directional Selection and Transgressive Segregation Drive Evolution of Novel Phenotypes in Hybrid Swarms of the Dutch Elm Disease Pathogen Ophiostoma novo-ulmi. J Fungi (Basel) 2021; 7:jof7060452. [PMID: 34204036 PMCID: PMC8228177 DOI: 10.3390/jof7060452] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/02/2021] [Accepted: 06/03/2021] [Indexed: 11/16/2022] Open
Abstract
In the 1970s, clones of the two subspecies of Ophiostoma novo-ulmi, subsp. americana (SSAM) and subsp. novo-ulmi (SSNU) began to overlap in Europe, resulting in hybrid swarms. By 1983-1986, hybrids with high, SSAM-like growth and pathogenic fitness comprised ~75% of popula-tions at Limburg, Netherlands and Orvieto, Italy. We resampled these populations in 2008 to examine trends in hybrid fitness traits. Since preliminary sampling in 1979-1980, MAT-1 locus frequency had increased from ~0% to ~32% at Orvieto and 5% to ~43% at Limburg, and vegeta-tive incompatibility type frequency had changed from near clonal to extremely diverse at both sites. This represents an enormous increase in outcrossing and recombination potential, due in part to selective acquisition (under virus pressure) of MAT-1 and vic loci from the resident O. ulmi and in part to SSAM × SSNU hybridisation. Overt virus infection in the 2008 samples was low (~4%), diagnostic SSAM and SSNU cu and col1 loci were recombinant, and no isolates exhib-ited a parental SSAM or SSNU colony pattern. At both sites, mean growth rate and mean patho-genicity to 3-5 m clonal elm were high SSAM-like, indicating sustained directional selection for these characters, though at Orvieto growth rate was slower. The once frequent SSNU-specific up-mut colony dimorphism was largely eliminated at both sites. Perithecia formed by Limburg isolates were mainly an extreme, long-necked SSNU-like form, consistent with transgressive segregation resulting from mismatch of SSAM and SSNU developmental loci. Orvieto isolates produced more parental-like perithecia, suggesting the extreme phenotypes may have been se-lected against. The novel phenotypes in the swarms are remodelling O. novo-ulmi in Europe. Locally adapted genotypes may emerge.
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Hybridization and introgression drive genome evolution of Dutch elm disease pathogens. Nat Ecol Evol 2020; 4:626-638. [PMID: 32123324 DOI: 10.1038/s41559-020-1133-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 01/29/2020] [Indexed: 11/08/2022]
Abstract
Hybridization and the resulting introgression can drive the success of invasive species via the rapid acquisition of adaptive traits. The Dutch elm disease pandemics in the past 100 years were caused by three fungal lineages with permeable reproductive barriers: Ophiostoma ulmi, Ophiostoma novo-ulmi subspecies novo-ulmi and Ophiostoma novo-ulmi subspecies americana. Using whole-genome sequences and growth phenotyping of a worldwide collection of isolates, we show that introgression has been the main driver of genomic diversity and that it impacted fitness-related traits. Introgressions contain genes involved in host-pathogen interactions and reproduction. Introgressed isolates have enhanced growth rate at high temperature and produce different necrosis sizes on an in vivo model for pathogenicity. In addition, lineages diverge in many pathogenicity-associated genes and exhibit differential mycelial growth in the presence of a proxy of a host defence compound, implying an important role of host trees in the molecular and functional differentiation of these pathogens.
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Hindal DF, MacDonald WL. Comparisons of Pathogenicity and Cultural Characteristics Among four Isolates of Ceratocystis Ulmi and Some Variants. Mycologia 2018. [DOI: 10.1080/00275514.1979.12021130] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- D. F. Hindal
- Division of Plant Sciences, West Virginia University, Morgantown, West Virginia 26506
| | - W. L. MacDonald
- Division of Plant Sciences, West Virginia University, Morgantown, West Virginia 26506
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Rare interspecific hybrids in natural populations of the Dutch elm disease pathogens Ophiostoma ulmi and O. novo-ulmi. ACTA ACUST UNITED AC 1998. [DOI: 10.1017/s0953756297004541] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Jeng R, Hintz WE, Bowden CG, Horgen PA, Hubbes M. A comparison of the nucleotide sequence of the cerato-ulmin gene and the rDNA ITS between aggressive and non-aggressive isolates of Ophiostoma ulmi sensu lato, the causal agent of Dutch elm disease. Curr Genet 1996; 29:168-73. [PMID: 8821664 DOI: 10.1007/bf02221581] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Little genetic information exists comparing aggressive and non-aggressive isolates of the causal agent of Dutch elm disease, Ophiostoma ulmi. Two genetic elements were compared between the subgroups. The ceratoulmin cu gene product has been associated with disease symptoms. Nucleotide-sequence analysis of cu and the internal transcribed spacer (ITS) region of the rDNA were made from three aggressive and three non-aggressive isolates of the pathogen. Our results suggested uniformity within, and unique differences between, subgroups. Differences were detected for cu in the promoter, coding, and transcription termination regions. Sequence data for the ITS clearly distinguish the subgroups.
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Affiliation(s)
- R Jeng
- Faculty of Forestry, University of Toronto, Ontario, Canada
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Brasier CM. Episodic selection as a force in fungal microevolution, with special reference to clonal speciation and hybrid introgression. ACTA ACUST UNITED AC 1995. [DOI: 10.1139/b95-381] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Episodic selection encompasses any sudden environmental disturbance likely to lead to a significant alteration in a species' population structure. Such disturbances include geographical transposition, a change in substrate availability, exposure to a new host or a new vector, climate change, and pollution stress. Today, such events may often be brought about by man. Their role in the promotion of fungal microevolution is discussed. In some circumstances, episodic selection may result in the emergence of a highly fitted clone from an originally heterogeneous population, and sustained disturbance may lead to clonal speciation. Clonal speciation accompanied by loss of sexual function, whether under episodic selection or under less intensive but analagous environmental conditions, could account for the origin of many of today's imperfect taxa (Deuteromycotina). Geographical transposition, a special form of episodic selection, can lead to hybridization between previously allopatric species. This may result in modifications to existing species via the acquisition of new loci or cytoplasmic elements, in the production of new taxa via secondary speciation, or in the emergence of hybrid swarms. Episodic selection will also favour survival of novel genotypes by providing new habitats for exploitation, so encouraging novel evolutionary development. Key words: episodic selection, fungal speciation, hybridization, introgression.
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Brasier C, Mehrotra M. Ophiostoma himal-ulmi sp. nov., a new species of Dutch elm disease fungus endemic to the Himalayas. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/s0953-7562(09)80887-3] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Charter NW, Buck KW, Brasier CM. De-novo generation of mitochondrial DNA plasmids following cytoplasmic transmission of a degenerative disease in Ophiostoma novo-ulmi. Curr Genet 1993; 24:505-14. [PMID: 8299172 DOI: 10.1007/bf00351714] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A mitochondrial DNA plasmid was detected in an isolate of Ophiostoma novo-ulmi with a degenerative disease. The DNA plasmid was shown to be derived from the mitochondrial DNA and to map to a region corresponding to the large ribosomal RNA coding region. The DNA plasmid was not transmitted into sexual (ascospore) progeny, irrespective of whether the diseased isolate acted as the female or male parent. Transmission of the disease to healthy, plasmid-free, "recipient" isolates by hyphal anastomosis was not accompanied by transfer of mitochondrial DNA or DNA plasmid from the diseased "donor" isolate, but resulted in de-novo generation of different plasmids, derived from the recipient's mitochondrial DNA.
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Affiliation(s)
- N W Charter
- Department of Biology, Imperial College of Science, Technology and Medicine, London, UK
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Ophiostoma novo-ulmi sp. nov., causative agent of current Dutch elm disease pandemics. Mycopathologia 1991. [DOI: 10.1007/bf00462219] [Citation(s) in RCA: 178] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Mitochondrial DNA restriction fragment length polymorphisms of aggressive and non-aggressive isolates of Ophiostoma ulmi. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/s0953-7562(09)80065-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Kile G, Brasier C. Inheritance and inter-relationship of fitness characters in progeny of an aggressive × non-aggressive cross of Ophiostoma ulmi. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/s0953-7562(10)80013-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Ophiostoma ULMI, Cause of Dutch Elm Disease. ACTA ACUST UNITED AC 1988. [DOI: 10.1016/b978-0-12-033706-4.50017-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Brasier C, Kirk S. Maternal inheritance of chloramphenicol tolerance in Ophiostoma ulmi. ACTA ACUST UNITED AC 1986. [DOI: 10.1016/s0007-1536(86)80224-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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A Preliminary investigation of the genetics of pathogenicity in hop wilt isolates of Verticillium albo-atrum. ACTA ACUST UNITED AC 1985. [DOI: 10.1016/s0007-1536(85)80201-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Inheritance of pathogenicity and cultural characters in Gaeumannomyces graminis var. tritici. ACTA ACUST UNITED AC 1981. [DOI: 10.1016/s0007-1536(81)80042-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Brasier C, Lea J, Rawlings M. The aggressive and non-aggressive strains of Ceratocystis ulmi have different temperature optima for growth. ACTA ACUST UNITED AC 1981. [DOI: 10.1016/s0007-1536(81)80141-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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