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Realini FM, Escobedo VM, Ueno AC, Bastías DA, Schardl CL, Biganzoli F, Gundel PE. Anti-herbivory defences delivered by Epichloë fungal endophytes: a quantitative review of alkaloid concentration variation among hosts and plant parts. Ann Bot 2024; 133:509-520. [PMID: 38320313 PMCID: PMC11037487 DOI: 10.1093/aob/mcae014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 02/01/2024] [Indexed: 02/08/2024]
Abstract
BACKGROUND AND AIMS In the subfamily Poöideae (Poaceae), certain grass species possess anti-herbivore alkaloids synthesized by fungal endophytes that belong to the genus Epichloë (Clavicipitaceae). The protective role of these symbiotic endophytes can vary, depending on alkaloid concentrations within specific plant-endophyte associations and plant parts. METHODS We conducted a literature review to identify articles containing alkaloid concentration data for various plant parts in six important pasture species, Lolium arundinaceum, Lolium perenne, Lolium pratense, Lolium multiflorum|Lolium rigidum and Festuca rubra, associated with their common endophytes. We considered the alkaloids lolines (1-aminopyrrolizidines), peramine (pyrrolopyrazines), ergovaline (ergot alkaloids) and lolitrem B (indole-diterpenes). While all these alkaloids have shown bioactivity against insect herbivores, ergovaline and lolitrem B are harmful for mammals. KEY RESULTS Loline alkaloid levels were higher in the perennial grasses L. pratense and L. arundinaceum compared to the annual species L. multiflorum and L. rigidum, and higher in reproductive tissues than in vegetative structures. This is probably due to the greater biomass accumulation in perennial species that can result in higher endophyte mycelial biomass. Peramine concentrations were higher in L. perenne than in L. arundinaceum and not affected by plant part. This can be attributed to the high within-plant mobility of peramine. Ergovaline and lolitrem B, both hydrophobic compounds, were associated with plant parts where fungal mycelium is usually present, and their concentrations were higher in plant reproductive tissues. Only loline alkaloid data were sufficient for below-ground tissue analyses and concentrations were lower than in above-ground parts. CONCLUSIONS Our study provides a comprehensive synthesis of fungal alkaloid variation across host grasses and plant parts, essential for understanding the endophyte-conferred defence extent. The patterns can be understood by considering endophyte growth within the plant and alkaloid mobility. Our study identifies research gaps, including the limited documentation of alkaloid presence in roots and the need to investigate the influence of different environmental conditions.
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Affiliation(s)
- Florencia M Realini
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Departamento de Ecología, Genética y Evolución, Laboratorio de Citogenética y Evolución (LaCyE), Ciudad Autónoma de Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Ecología, Genética y Evolución (IEGEBA), Ciudad Autónoma de Buenos Aires, Argentina
| | - Víctor M Escobedo
- Instituto de Investigación Interdisciplinaria (I3), Universidad de Talca, Campus Talca, Chile
- Centro de Ecología Integrativa, Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile
| | - Andrea C Ueno
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
- Instituto de Investigación Interdisciplinaria (I3), Universidad de Talca, Campus Talca, Chile
- Centro de Ecología Integrativa, Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile
| | - Daniel A Bastías
- AgResearch Limited, Grasslands Research Centre, Palmerston North 4442, New Zealand
| | | | - Fernando Biganzoli
- Departamento de Métodos Cuantitativos y Sistemas de Información, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Pedro E Gundel
- IFEVA, Facultad de Agronomía, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
- Centro de Ecología Integrativa, Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile
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Zhang W, Gundel PE, Jáuregui R, Card SD, Mace WJ, Johnson RD, Bastías DA. The growth promotion in endophyte symbiotic plants does not penalise the resistance to herbivores and bacterial microbiota. Plant Cell Environ 2024. [PMID: 38616528 DOI: 10.1111/pce.14912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 03/19/2024] [Accepted: 03/29/2024] [Indexed: 04/16/2024]
Abstract
A trade-off between growth and defence against biotic stresses is common in plants. Fungal endophytes of the genus Epichloë may relieve this trade-off in their host grasses since they can simultaneously induce plant growth and produce antiherbivore alkaloids that circumvent the need for host defence. The Epichloë ability to decouple the growth-defence trade-off was evaluated by subjecting ryegrass with and without Epichloë endophytes to an exogenous treatment with gibberellin (GA) followed by a challenge with Rhopalosiphum padi aphids. In agreement with the endophyte-mediated trade-off decoupling hypothesis, the GA-derived promotion of plant growth increased the susceptibility to aphids in endophyte-free plants but did not affect the insect resistance in endophyte-symbiotic plants. In line with the unaltered insect resistance, the GA treatment did not reduce the concentration of Epichloë-derived alkaloids. The Epichloë mycelial biomass was transiently increased by the GA treatment but at the expense of hyphal integrity. The response of the phyllosphere bacterial microbiota to both GA treatment and Epichloë was also evaluated. Only Epichloë, and not the GA treatment, altered the composition of the phyllosphere microbiota and the abundance of certain bacterial taxa. Our findings clearly demonstrate that Epichloë does indeed relieve the plant growth-defence trade-off.
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Affiliation(s)
- Wei Zhang
- AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | - Pedro E Gundel
- Centro de Ecología Integrativa, Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile
| | - Ruy Jáuregui
- Animal Health Laboratory, Biosecurity New Zealand, Ministry for Primary Industries, Upper Hutt, New Zealand
| | - Stuart D Card
- AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | - Wade J Mace
- AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | - Richard D Johnson
- AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | - Daniel A Bastías
- AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
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Bastías DA, Ueno AC, Gundel PE. Global Change Factors Influence Plant-Epichloë Associations. J Fungi (Basel) 2023; 9:jof9040446. [PMID: 37108902 PMCID: PMC10145611 DOI: 10.3390/jof9040446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 03/10/2023] [Accepted: 03/17/2023] [Indexed: 04/08/2023] Open
Abstract
There is an increasing interest in determining the influence of global change on plant–microorganism interactions. We review the results of experiments that evaluated the effects of the global change factors carbon dioxide, ozone, temperature, drought, flooding, and salinity on plant symbioses with beneficial Epichloë endophytes. The factors affected the performance of both plants and endophytes as well as the frequency of plants symbiotic with the fungus. Elevated carbon dioxide levels and low temperatures differentially influenced the growth of plants and endophytes, which could compromise the symbioses. Furthermore, we summarise the plant stage in which the effects of the factors were quantified (vegetative, reproductive, or progeny). The factors ozone and drought were studied at all plant stages, but flooding and carbon dioxide were studied in just a few of them. While only studied in response to ozone and drought, evidence showed that the effects of these factors on symbiotic plants persisted trans-generationally. We also identified the putative mechanisms that would explain the effects of the factors on plant–endophyte associations. These mechanisms included the increased contents of reactive oxygen species and defence-related phytohormones, reduced photosynthesis, and altered levels of plant primary metabolites. Finally, we describe the counteracting mechanisms by which endophytes would mitigate the detrimental effects of the factors on plants. In presence of the factors, endophytes increased the contents of antioxidants, reduced the levels of defence-related phytohormones, and enhanced the plant uptake of nutrients and photosynthesis levels. Knowledge gaps regarding the effects of global change on plant–endophyte associations were identified and discussed.
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Affiliation(s)
- Daniel A. Bastías
- AgResearch Limited, Grasslands Research Centre, Palmerston North 4442, New Zealand
| | - Andrea C. Ueno
- Centro de Ecología Integrativa, Instituto de Ciencias Biológicas, Universidad de Talca, Talca 3480094, Chile
- Instituto de Investigación Interdisciplinaria (I3), Universidad de Talca, Campus Talca, Talca 3480094, Chile
| | - Pedro E. Gundel
- Centro de Ecología Integrativa, Instituto de Ciencias Biológicas, Universidad de Talca, Talca 3480094, Chile
- Facultad de Agronomía, IFEVA, CONICET, Universidad de Buenos Aires, Buenos Aires C1417DSE, Argentina
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Affiliation(s)
| | - Pedro E Gundel
- IFEVA, CONICET, Universidad de Buenos Aires, Facultad de Agronomía, Buenos Aires, Argentina
- Centro de Ecología Integrativa, Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile
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Bastías DA, Balestrini R, Pollmann S, Gundel PE. Environmental interference of plant-microbe interactions. Plant Cell Environ 2022; 45:3387-3398. [PMID: 36180415 PMCID: PMC9828629 DOI: 10.1111/pce.14455] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 09/23/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
Environmental stresses can compromise the interactions of plants with beneficial microbes. In the present review, experimental results showing that stresses negatively affect the abundance and/or functionality of plant beneficial microbes are summarized. It is proposed that the environmental interference of these plant-microbe interactions is explained by the stress-mediated induction of plant signalling pathways associated with defence hormones and reactive oxygen species. These plant responses are recognized to regulate beneficial microbes within plants. The direct negative effect of stresses on microbes may also contribute to the environmental regulation of these plant mutualisms. It is also posited that, in stress situations, beneficial microbes harbour mechanisms that contribute to maintain the mutualistic associations. Beneficial microbes produce effector proteins and increase the antioxidant levels in plants that counteract the detrimental effects of plant stress responses on them. In addition, they deliver specific stress-protective mechanisms that assist to their plant hosts to mitigate the negative effects of stresses. Our study contributes to understanding how environmental stresses affect plant-microbe interactions and highlights why beneficial microbes can still deliver benefits to plants in stressful environments.
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Affiliation(s)
- Daniel A. Bastías
- AgResearch LimitedGrasslands Research CentrePalmerston NorthNew Zealand
| | | | - Stephan Pollmann
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)–Instituto Nacional de Investigación y Tecnología Agraria y Alimentación (INIA/CSIC)Campus de MontegancedoMadridSpain
- Departamento de Biotecnología‐Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de BiosistemasUniversidad Politécnica de Madrid (UPM)MadridSpain
| | - Pedro E. Gundel
- IFEVA, CONICET, Universidad de Buenos AiresFacultad de AgronomíaBuenos AiresArgentina
- Centro de Ecología Integrativa, Instituto de Ciencias BiológicasUniversidad de TalcaTalcaChile
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Bastías DA, Applegate ER, Johnson LJ, Card SD. Factors controlling the effects of mutualistic bacteria on plants associated with fungi. Ecol Lett 2022; 25:1879-1888. [PMID: 35810320 PMCID: PMC9544109 DOI: 10.1111/ele.14073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 05/31/2022] [Accepted: 06/21/2022] [Indexed: 11/29/2022]
Abstract
Plants interacting with mutualistic fungi (MF) or antagonistic fungi (AF) can form associations with bacteria. We assessed whether the performance gain conferred by mutualistic bacteria to fungal-associated plants is affected by the interaction between symbiont traits, type of bacterial-protective traits against AF and abiotic/biotic stresses. Results showed that (A) performance gain conferred by bacteria to MF-associated plants was greater when symbionts promoted distinct rather than similar plant functions, (B) bacterial-based alleviation of the AF's negative effect on plants was independent of the type of protective trait, (C) bacteria promoted a greater performance of symbiotic plants in presence of biotic, but not abiotic, stress compared to stress-free situations. The plant performance gain was not affected by any fungal-bacterial trait combination but optimised when bacteria conferred resistance traits in biotic stress situations. The effects of bacteria on fungal-associated plants were controlled by the interaction between the symbionts' functional traits and the relationship between bacterial traits and abiotic/biotic stresses.
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Affiliation(s)
- Daniel A Bastías
- Grasslands Research Centre, AgResearch Limited, Palmerston North, New Zealand
| | - Emma R Applegate
- Grasslands Research Centre, AgResearch Limited, Palmerston North, New Zealand
| | - Linda J Johnson
- Grasslands Research Centre, AgResearch Limited, Palmerston North, New Zealand
| | - Stuart D Card
- Grasslands Research Centre, AgResearch Limited, Palmerston North, New Zealand
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Bastías DA, Gundel PE, Johnson RD, Gianoli E. How and when fungal endophytes can eliminate the plant growth-defence trade-off: mechanistic perspectives. New Phytol 2022; 235:388-390. [PMID: 35548876 PMCID: PMC9321058 DOI: 10.1111/nph.18161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 04/08/2022] [Indexed: 06/15/2023]
Affiliation(s)
- Daniel A. Bastías
- AgResearch LimitedGrasslands Research CentrePalmerston North4442New Zealand
| | - Pedro E. Gundel
- Facultad de AgronomíaIFEVAUniversidad de Buenos Aires, CONICETBuenos AiresC1417DSEArgentina
- Laboratorio de Biología VegetalInstituto de Ciencias BiológicasUniversidad de TalcaCampus LircayTalca3480094Chile
| | - Richard D. Johnson
- AgResearch LimitedGrasslands Research CentrePalmerston North4442New Zealand
| | - Ernesto Gianoli
- Departamento de BiologíaUniversidad de La SerenaCasilla 554La Serena1700000Chile
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Bastías DA, Bustos LB, Jáuregui R, Barrera A, Acuña-Rodríguez IS, Molina-Montenegro MA, Gundel PE. Epichloë Fungal Endophytes Influence Seed-Associated Bacterial Communities. Front Microbiol 2022; 12:795354. [PMID: 35058911 PMCID: PMC8764391 DOI: 10.3389/fmicb.2021.795354] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 11/24/2021] [Indexed: 11/30/2022] Open
Abstract
Seeds commonly harbour diverse bacterial communities that can enhance the fitness of future plants. The bacterial microbiota associated with mother plant’s foliar tissues is one of the main sources of bacteria for seeds. Therefore, any ecological factor influencing the mother plant’s microbiota may also affect the diversity of the seed’s bacterial community. Grasses form associations with beneficial vertically transmitted fungal endophytes of genus Epichloë. The interaction of plants with Epichloë endophytes and insect herbivores can influence the plant foliar microbiota. However, it is unknown whether these interactions (alone or in concert) can affect the assembly of bacterial communities in the produced seed. We subjected Lolium multiflorum plants with and without its common endophyte Epichloë occultans (E+, E-, respectively) to an herbivory treatment with Rhopalosiphum padi aphids and assessed the diversity and composition of the bacterial communities in the produced seed. The presence of Epichloë endophytes influenced the seed bacterial microbiota by increasing the diversity and affecting the composition of the communities. The relative abundances of the bacterial taxa were more similarly distributed in communities associated with E+ than E- seeds with the latter being dominated by just a few bacterial groups. Contrary to our expectations, seed bacterial communities were not affected by the aphid herbivory experienced by mother plants. We speculate that the enhanced seed/seedling performance documented for Epichloë-host associations may be explained, at least in part, by the Epichloë-mediated increment in the seed-bacterial diversity, and that this phenomenon may be applicable to other plant-endophyte associations.
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Affiliation(s)
- Daniel A Bastías
- AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | - Ludmila Bubica Bustos
- IFEVA, CONICET, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Ruy Jáuregui
- AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | - Andrea Barrera
- Laboratorio de Ecología Integrativa, Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile
| | - Ian S Acuña-Rodríguez
- Laboratorio de Ecología Integrativa, Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile
| | - Marco A Molina-Montenegro
- Laboratorio de Ecología Integrativa, Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile.,Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Universidad Católica del Norte, Coquimbo, Chile.,Centro de Investigación de Estudios Avanzados del Maule, Universidad Católica del Maule, Talca, Chile
| | - Pedro E Gundel
- IFEVA, CONICET, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina.,Laboratorio de Ecología Integrativa, Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile
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Kou MZ, Bastías DA, Christensen MJ, Zhong R, Nan ZB, Zhang XX. The Plant Salicylic Acid Signalling Pathway Regulates the Infection of a Biotrophic Pathogen in Grasses Associated with an Epichloë Endophyte. J Fungi (Basel) 2021; 7:jof7080633. [PMID: 34436172 PMCID: PMC8399569 DOI: 10.3390/jof7080633] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/28/2021] [Accepted: 07/31/2021] [Indexed: 12/13/2022] Open
Abstract
The study of the contribution of the plant defence hormones, salicylic acid (SA) and jasmonic acid (JA), in the resistance against pathogens of plants associated with Epichloë fungal endophytes has been scanty. We hypothesised that Epichloë spp., capable of inducing host plant SA-dependent defences, would increase the levels of plant resistance against biotrophic pathogens. Plants of Achnatherum inebrians, with and without the fungal endophyte Epichloë gansuensis, were inoculated with the biotrophic fungal pathogen Blumeria graminis. We measured the status of plant defences (associated with SA and JA signalling pathways) and the levels of resistance to the pathogen. Plants associated with the endophyte showed less disease symptoms caused by the biotrophic pathogen than plants without the endophyte. In agreement with our hypothesis, the Epichloë endophyte increased the plant production of SA and enhanced the expression levels of plant genes of synthesis and response to the SA hormone. The elevated expression of SA-related genes coding for putative plant enzymes with anti-fungal activities promoted by the endophyte may explain the enhanced resistance to the pathogen. The present study highlights that interaction between the plant immune system and Epichloë fungal endophytes can contribute significantly to the resistance of endophyte-symbiotic plants against pathogens.
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Affiliation(s)
- Ming-Zhu Kou
- State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China; (M.-Z.K.); (R.Z.); (Z.-B.N.)
| | - Daniel A. Bastías
- Resilient Agriculture Innovation Centre of Excellence, AgResearch Limited, Grasslands Research Centre, Palmerston North 4442, New Zealand; (D.A.B.); (M.J.C.)
| | - Michael J. Christensen
- Resilient Agriculture Innovation Centre of Excellence, AgResearch Limited, Grasslands Research Centre, Palmerston North 4442, New Zealand; (D.A.B.); (M.J.C.)
| | - Rui Zhong
- State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China; (M.-Z.K.); (R.Z.); (Z.-B.N.)
| | - Zhi-Biao Nan
- State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China; (M.-Z.K.); (R.Z.); (Z.-B.N.)
| | - Xing-Xu Zhang
- State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China; (M.-Z.K.); (R.Z.); (Z.-B.N.)
- Correspondence:
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Bastías DA, Gianoli E, Gundel PE. Fungal endophytes can eliminate the plant growth-defence trade-off. New Phytol 2021; 230:2105-2113. [PMID: 33690884 DOI: 10.1111/nph.17335] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 03/08/2021] [Indexed: 05/27/2023]
Abstract
A trade-off between growth and defence functions is commonly observed in plants. We propose that the association of plants with Epichloë fungal endophytes may eliminate this trade-off. This would be a consequence of the double role of these endophytes in host plants: the stimulation of plant growth hormones (e.g. gibberellins) and the fungal production of antiherbivore alkaloids. We put forward a model that integrates this dual effect of endophytes on plant growth and defence and test its predictions by means of meta-analysis of published literature. Our results support the notion that the enhanced plant resistance promoted by endophytes does not compromise plant growth. The limits and ecological benefits of this endophyte-mediated lack of plant growth-defence trade-off are discussed.
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Affiliation(s)
- Daniel A Bastías
- Resilient Agriculture Innovation Centre of Excellence, AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | - Ernesto Gianoli
- Departamento de Biología, Universidad de La Serena, Casilla 554, La Serena, Chile
- Departamento de Botánica, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Pedro E Gundel
- Facultad de Agronomía, IFEVA, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
- Laboratorio de Biología Vegetal, Instituto de Ciencias Biológicas, Universidad de Talca, Campus Lircay, Talca, Chile
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Bastías DA, Johnson LJ, Card SD. Symbiotic bacteria of plant-associated fungi: friends or foes? Curr Opin Plant Biol 2020; 56:1-8. [PMID: 31786411 DOI: 10.1016/j.pbi.2019.10.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 10/21/2019] [Accepted: 10/30/2019] [Indexed: 06/10/2023]
Abstract
Many bacteria form symbiotic associations with plant-associated fungi. The effects of these symbionts on host fitness usually depend on symbiont or host genotypes and environmental conditions. However, bacterial endosymbionts, that is those living within fungal cells, may positively regulate host performance as their survival is often heavily dependent on host fitness. Contrary to this, bacteria that establish ectosymbiotic associations with fungi, that is those located on the hyphal surface or in close vicinity to fungal mycelia, may not have an apparent net effect on fungal performance due to the low level of fitness dependency on their host. Our analysis supports the hypothesis that endosymbiotic bacteria of fungi are beneficial symbionts, and that effects of ectosymbiotic bacteria on fungal performance depends on the bacterial type involved in the interaction (e.g. helper versus pathogen of fungi). Ecological scenarios, where the presence of beneficial bacterial endosymbionts of fungi could be compromised, are also discussed.
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Affiliation(s)
- Daniel A Bastías
- Forage Science, AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand.
| | - Linda J Johnson
- Forage Science, AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | - Stuart D Card
- Forage Science, AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
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Bastías DA, Martínez-Ghersa MA, Newman JA, Card SD, Mace WJ, Gundel PE. Sipha maydis sensitivity to defences of Lolium multiflorum and its endophytic fungus Epichloë occultans. PeerJ 2019; 7:e8257. [PMID: 31976166 PMCID: PMC6966988 DOI: 10.7717/peerj.8257] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 11/20/2019] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Plants possess a sophisticated immune system to defend from herbivores. These defence responses are regulated by plant hormones including salicylic acid (SA) and jasmonic acid (JA). Sometimes, plant defences can be complemented by the presence of symbiotic microorganisms. A remarkable example of this are grasses establishing symbiotic associations with Epichloë fungal endophytes. We studied the level of resistance provided by the grass' defence hormones, and that provided by Epichloë fungal endophytes, against an introduced herbivore aphid. These fungi protect their hosts against herbivores by producing bioactive alkaloids. We hypothesized that either the presence of fungal endophytes or the induction of the plant salicylic acid (SA) defence pathway would enhance the level of resistance of the grass to the aphid. METHODS Lolium multiflorum plants, with and without the fungal endophyte Epichloë occultans, were subjected to an exogenous application of SA followed by a challenge with the aphid, Sipha maydis. RESULTS Our results indicate that neither the presence of E. occultans nor the induction of the plant's SA pathway regulate S. maydis populations. However, endophyte-symbiotic plants may have been more tolerant to the aphid feeding because these plants produced more aboveground biomass. We suggest that this insect insensitivity could be explained by a combination between the ineffectiveness of the specific alkaloids produced by E. occultans in controlling S. maydis aphids and the capacity of this herbivore to deal with hormone-dependent defences of L. multiflorum.
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Affiliation(s)
- Daniel A. Bastías
- IFEVA, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, Buenos Aires, Argentina
- Forage Science, AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | | | - Jonathan A. Newman
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Stuart D. Card
- Forage Science, AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | - Wade J. Mace
- Forage Science, AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | - Pedro E. Gundel
- IFEVA, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, Buenos Aires, Argentina
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Bastías DA, Alejandra Martínez-Ghersa M, Newman JA, Card SD, Mace WJ, Gundel PE. The plant hormone salicylic acid interacts with the mechanism of anti-herbivory conferred by fungal endophytes in grasses. Plant Cell Environ 2018; 41:395-405. [PMID: 29194664 DOI: 10.1111/pce.13102] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 11/06/2017] [Accepted: 11/13/2017] [Indexed: 06/07/2023]
Abstract
The plant hormone salicylic acid (SA) is recognized as an effective defence against biotrophic pathogens, but its role as regulator of beneficial plant symbionts has received little attention. We studied the relationship between the SA hormone and leaf fungal endophytes on herbivore defences in symbiotic grasses. We hypothesize that the SA exposure suppresses the endophyte reducing the fungal-produced alkaloids. Because of the role that alkaloids play in anti-herbivore defences, any reduction in their production should make host plants more susceptible to herbivores. Lolium multiflorum plants symbiotic and nonsymbiotic with the endophyte Epichloë occultans were exposed to SA followed by a challenge with the aphid Rhopalosiphum padi. We measured the level of plant resistance to aphids, and the defences conferred by endophytes and host plants. Symbiotic plants had lower concentrations of SA than did the nonsymbiotic counterparts. Consistent with our prediction, the hormonal treatment reduced the concentration of loline alkaloids (i.e., N-formyllolines and N-acetylnorlolines) and consequently decreased the endophyte-conferred resistance against aphids. Our study highlights the importance of the interaction between the plant immune system and endophytes for the stability of the defensive mutualism. Our results indicate that the SA plays a critical role in regulating the endophyte-conferred resistance against herbivores.
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Affiliation(s)
- Daniel A Bastías
- IFEVA, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, Av. San Martín 4453, Buenos Aires, C1417DSE, Argentina
| | - M Alejandra Martínez-Ghersa
- IFEVA, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, Av. San Martín 4453, Buenos Aires, C1417DSE, Argentina
| | - Jonathan A Newman
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Stuart D Card
- Forage Science, AgResearch Limited, Grasslands Research Centre, Private Bag 11008, Palmerston North, 4442, New Zealand
| | - Wade J Mace
- Forage Science, AgResearch Limited, Grasslands Research Centre, Private Bag 11008, Palmerston North, 4442, New Zealand
| | - Pedro E Gundel
- IFEVA, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, Av. San Martín 4453, Buenos Aires, C1417DSE, Argentina
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Bozinovic F, Bastías DA, Boher F, Clavijo-Baquet S, Estay SA, Angilletta MJ. The Mean and Variance of Environmental Temperature Interact to Determine Physiological Tolerance and Fitness. Physiol Biochem Zool 2011; 84:543-52. [DOI: 10.1086/662551] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Folguera G, Bastías DA, Caers J, Rojas JM, Piulachs MD, Bellés X, Bozinovic F. An experimental test of the role of environmental temperature variability on ectotherm molecular, physiological and life-history traits: Implications for global warming. Comp Biochem Physiol A Mol Integr Physiol 2011; 159:242-6. [DOI: 10.1016/j.cbpa.2011.03.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2011] [Revised: 03/08/2011] [Accepted: 03/08/2011] [Indexed: 11/28/2022]
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