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Macaya-Sanz D, Witzell J, Collada C, Gil L, Martín JA. Core endophytic mycobiome in Ulmus minor and its relation to Dutch elm disease resistance. FRONTIERS IN PLANT SCIENCE 2023; 14:1125942. [PMID: 36925756 PMCID: PMC10011445 DOI: 10.3389/fpls.2023.1125942] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 02/13/2023] [Indexed: 06/18/2023]
Abstract
The core microbiota of plants exerts key effects on plant performance and resilience to stress. The aim of this study was to identify the core endophytic mycobiome in U. minor stems and disentangle associations between its composition and the resistance to Dutch elm disease (DED). We also defined its spatial variation within the tree and among distant tree populations. Stem samples were taken i) from different heights of the crown of a 168-year-old elm tree, ii) from adult elm trees growing in a common garden and representing a gradient of resistance to DED, and iii) from trees growing in two distant natural populations, one of them with varying degrees of vitality. Endophyte composition was profiled by high throughput sequencing of the first internal transcribed spacer region (ITS1) of the ribosomal DNA. Three families of yeasts (Buckleyzymaceae, Trichomeriaceae and Bulleraceae) were associated to DED-resistant hosts. A small proportion (10%) of endophytic OTUs was almost ubiquitous throughout the crown while tree colonization by most fungal taxa followed stochastic patterns. A clear distinction in endophyte composition was found between geographical locations. By combining all surveys, we found evidence of a U. minor core mycobiome, pervasive within the tree and ubiquitous across locations, genotypes and health status.
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Affiliation(s)
- David Macaya-Sanz
- Departamento de Ecología y Genética Forestal, Instituto de Ciencias Forestales (ICIFOR-INIA), CSIC, Madrid, Spain
| | - Johanna Witzell
- Department of Forestry and Wood Technology, Linnaeus University, Växjö, Sweden
| | - Carmen Collada
- Departamento de Sistemas y Recursos Naturales, Escuela Técnica Superior de Ingeniería (ETSI) Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, Madrid, Spain
| | - Luis Gil
- Departamento de Sistemas y Recursos Naturales, Escuela Técnica Superior de Ingeniería (ETSI) Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, Madrid, Spain
| | - Juan A. Martín
- Departamento de Sistemas y Recursos Naturales, Escuela Técnica Superior de Ingeniería (ETSI) Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, Madrid, Spain
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Sobrino-Plata J, Martínez-Arias C, Ormeño-Moncalvillo S, Fernández I, Collada C, Gil L, Pieterse CMJ, Martín JA. No priming, just fighting-endophytic yeast attenuates the defense response and the stress induced by Dutch elm disease in Ulmus minor Mill. TREE PHYSIOLOGY 2022; 42:2086-2099. [PMID: 35708521 DOI: 10.1093/treephys/tpac062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 06/06/2022] [Indexed: 06/15/2023]
Abstract
One century after the first report of Dutch elm disease (DED), there is still no practical solution for this problem threatening European and American elms (Ulmus spp.). The long breeding cycles needed to select resistant genotypes and the lack of efficient treatments keep disease incidence at high levels. In this work, the expression of defense-related genes to the causal agent of DED, Ophiostoma novo-ulmi Brasier, was analyzed in in vitro clonal plantlets from two DED-resistant and two DED-susceptible Ulmus minor Mill. trees. In addition, the effect of the inoculation of an endophytic pink-pigmented yeast (Cystobasidium sp.) on the plant's defense system was tested both individually and in combination with O. novo-ulmi. The multifactorial nature of the resistance to DED was confirmed, as no common molecular response was found in the two resistant genotypes. However, the in vitro experimental system allowed discrimination of the susceptible from the resistant genotypes, showing higher levels of oxidative damage and phenolic compounds in the susceptible genotypes after pathogen inoculation. Inoculation of the endophyte before O. novo-ulmi attenuated the plant molecular response induced by the pathogen and moderated oxidative stress levels. Niche competition, endophyte-pathogen antagonism and molecular crosstalk between the host and the endophyte are discussed as possible mechanisms of stress reduction. In sum, our results confirm the complex and heterogeneous nature of DED resistance mechanisms and highlight the possibility of using certain endophytic yeasts as biological tools to improve tree resilience against biotic stress.
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Affiliation(s)
- J Sobrino-Plata
- Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, Jose Antonio Novais 10, 28040 Madrid, Spain
- Departamento de Genética, Fisiología y Microbiología, Facultad de CC. Biológicas, Universidad Complutense de Madrid, Jose Antonio Novais 12, 28040 Madrid, Spain
| | - C Martínez-Arias
- Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, Jose Antonio Novais 10, 28040 Madrid, Spain
| | - S Ormeño-Moncalvillo
- Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, Jose Antonio Novais 10, 28040 Madrid, Spain
| | - I Fernández
- Plant-Microbe Interactions, Department of Biology, Science4Life, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
- Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC), Cordel de Merinas 40-52, 37008 Salamanca, Spain
| | - C Collada
- Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, Jose Antonio Novais 10, 28040 Madrid, Spain
| | - L Gil
- Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, Jose Antonio Novais 10, 28040 Madrid, Spain
| | - C M J Pieterse
- Plant-Microbe Interactions, Department of Biology, Science4Life, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - J A Martín
- Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, Jose Antonio Novais 10, 28040 Madrid, Spain
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Martínez-Arias C, Sobrino-Plata J, Gil L, Rodríguez-Calcerrada J, Martín JA. Priming of Plant Defenses against Ophiostoma novo-ulmi by Elm ( Ulmus minor Mill.) Fungal Endophytes. J Fungi (Basel) 2021; 7:687. [PMID: 34575725 PMCID: PMC8469682 DOI: 10.3390/jof7090687] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/18/2021] [Accepted: 08/21/2021] [Indexed: 11/28/2022] Open
Abstract
Some fungal endophytes of forest trees are recognized as beneficial symbionts against stresses. In previous works, two elm endophytes from the classes Cystobasidiomycetes and Eurotiomycetes promoted host resistance to abiotic stress, and another elm endophyte from Dothideomycetes enhanced host resistance to Dutch elm disease (DED). Here, we hypothesize that the combined effect of these endophytes activate the plant immune and/or antioxidant system, leading to a defense priming and/or increased oxidative protection when exposed to the DED pathogen Ophiostoma novo-ulmi. To test this hypothesis, the short-term defense gene activation and antioxidant response were evaluated in DED-susceptible (MDV1) and DED-resistant (VAD2 and MDV2.3) Ulmus minor genotypes inoculated with O. novo-ulmi, as well as two weeks earlier with a mixture of the above-mentioned endophytes. Endophyte inoculation induced a generalized transient defense activation mediated primarily by salicylic acid (SA). Subsequent pathogen inoculation resulted in a primed defense response of variable intensity among genotypes. Genotypes MDV1 and VAD2 displayed a defense priming driven by SA, jasmonic acid (JA), and ethylene (ET), causing a reduced pathogen spread in MDV1. Meanwhile, the genotype MDV2.3 showed lower defense priming but a stronger and earlier antioxidant response. The defense priming stimulated by elm fungal endophytes broadens our current knowledge of the ecological functions of endophytic fungi in forest trees and opens new prospects for their use in the biocontrol of plant diseases.
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Affiliation(s)
- Clara Martínez-Arias
- Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid, 28040 Madrid, Spain; (J.S.-P.); (L.G.); (J.R.-C.); (J.A.M.)
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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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