Epichloë Fungal Endophytes—From a Biological Curiosity in Wild Grasses to an Essential Component of Resilient High Performing Ryegrass and Fescue Pastures
27 Nov 2020-Journal of Fungi (Multidisciplinary Digital Publishing Institute)-Vol. 6, Iss: 4, pp 322
TL;DR: The supply chain from science, through seed companies and retailers to the end-user farmer needs to be well resourced providing convincing information on the efficacy and ensuring effective quality control to result in a strong uptake of these Epichloë endophyte technologies in pastoral agriculture.
Abstract: The relationship between Epichloe endophytes found in a wide range of temperate grasses spans the continuum from antagonistic to mutualistic. The diversity of asexual mutualistic types can be characterised by the types of alkaloids they produce in planta. Some of these are responsible for detrimental health and welfare issues of ruminants when consumed, while others protect the host plant from insect pests and pathogens. In many temperate regions they are an essential component of high producing resilient tall fescue and ryegrass swards. This obligate mutualism between fungus and host is a seed-borne technology that has resulted in several commercial products being used with high uptake rates by end-user farmers, particularly in New Zealand and to a lesser extent Australia and USA. However, this has not happened by chance. It has been reliant on multi-disciplinary research teams undertaking excellent science to understand the taxonomic relationships of these endophytes, their life cycle, symbiosis regulation at both the cellular and molecular level, and the impact of secondary metabolites, including an understanding of their mammalian toxicity and bioactivity against insects and pathogens. Additionally, agronomic trials and seed biology studies of these microbes have all contributed to the delivery of robust and efficacious products. The supply chain from science, through seed companies and retailers to the end-user farmer needs to be well resourced providing convincing information on the efficacy and ensuring effective quality control to result in a strong uptake of these Epichloe endophyte technologies in pastoral agriculture.
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14 Apr 2008
22 citations
24 Sep 2021
TL;DR: A review of the current literature on antimicrobial properties exhibited by this genus of endophyte and discuss the reasons why this trait has historically remained a research curiosity rather than a trait of commercial significance can be found in this paper.
Abstract: Epichloe is a genus of filamentous fungal endophytes that has co-evolved with cool-season grasses with which they form long-term, symbiotic associations. The most agriculturally important associations for pasture persistence for grazing livestock are those between asexual vertically transmitted Epichloe strains and the pasture species, perennial ryegrass, and tall fescue. The fungus confers additional traits to their host grasses including invertebrate pest deterrence and drought tolerance. Selected strains of these mutualistic endophytes have been developed into highly efficacious biocontrol products and are widely utilized within the Americas, Australia, and New Zealand for pasture persistence. Less publicized is the antagonism Epichloe endophytes display towards multiple species of saprophytic and pathogenic microbes. This opinion piece will review the current literature on antimicrobial properties exhibited by this genus of endophyte and discuss the reasons why this trait has historically remained a research curiosity rather than a trait of commercial significance.
14 citations
TL;DR: In this article , the authors discuss and prioritise promising breeding strategies and direct and indirect breeding targets, and their time-perspective for future realisation in integrated insect pest protection of oilseed rape.
Abstract: In the past, breeding for incorporation of insect pest resistance or tolerance into cultivars for use in integrated pest management schemes in oilseed rape/canola (Brassica napus) production has hardly ever been approached. This has been largely due to the broad availability of insecticides and the complexity of dealing with high-throughput phenotyping of insect performance and plant damage parameters. However, recent changes in the political framework in many countries demand future sustainable crop protection which makes breeding approaches for crop protection as a measure for pest insect control attractive again. At the same time, new camera-based tracking technologies, new knowledge-based genomic technologies and new scientific insights into the ecology of insect-Brassica interactions are becoming available. Here we discuss and prioritise promising breeding strategies and direct and indirect breeding targets, and their time-perspective for future realisation in integrated insect pest protection of oilseed rape. In conclusion, researchers and oilseed rape breeders can nowadays benefit from an array of new technologies which in combination will accelerate the development of improved oilseed rape cultivars with multiple insect pest resistances/tolerances in the near future.
8 citations
01 Jan 2021
TL;DR: This review examines the current state of knowledge on the effects of Epichloë on the interactions of insects and drought in temperate grasses and identified endophyte strains that retain insect-active alkaloids while minimising the production of mammalian active toxins.
Abstract: Fungal Epichloe endophytes form symbiotic associations with many temperate grasses, such as Lolium and Festuca, giving their host grasses an ecological advantage. The importance of specific Epichloe endophytes in providing varying levels of protection against invertebrate pests has been well documented. Similarly, but with fewer studies, the benefits of Epichloe to host grasses in drought events has been shown. Endophyte-infected grasses show an improved persistence against herbivore insect attack as well as resilience under drought. However, there are relatively few studies that investigate the interaction between drought and insect pressure, and yet it is these combined pressures that can prove detrimental for a ryegrass or fescue crop. This review examines the current state of knowledge on the effects of Epichloe on the interactions of insects and drought in temperate grasses.
8 citations
TL;DR: The results suggested that E. bromicola significantly inhibited the growth of C. lunata, B. sorokiniana and C. sp.
7 citations
References
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2,578 citations
"Epichloë Fungal Endophytes—From a B..." refers background in this paper
...This change resulted from a requirement that a single genus name is to be used for all stages of the development of a fungal species [17]....
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TL;DR: How life history traits—such as fungal reproduction and pattern of infections and genotypic variation and ecological factors—in the ecology and evolution of endophytes and host plants is discussed are discussed.
Abstract: ▪ Abstract Endophytic fungi living asymptomatically within plant tissues have been found in virtually all plant species. Endophytes are considered plant mutualists: They receive nutrition and protection from the host plant while the host plant may benefit from enhanced competitive abilities and increased resistance to herbivores, pathogens, and various abiotic stresses. Limited evidence also indicates that endophytes may influence population dynamics, plant community diversity, and ecosystem function. However, most of the empirical evidence for this mutualism and its ecological consequences has been based on a few agronomic grass endophytes. More recent studies suggest that endophyte-host plant interactions are variable and range from antagonistic to mutualistic. A more comprehensive view of the ecology and evolution of endophytes and host plants is needed. This article discusses how life history traits—such as fungal reproduction and pattern of infections and genotypic variation and ecological factors—in...
1,022 citations
"Epichloë Fungal Endophytes—From a B..." refers background in this paper
...The reduced rate is thought to be due to the endophyte not necessarily being beneficial for the host plants in all environments [127,128] and/or an imperfect spread to all tillers of the plant resulting in the lack of transmission through seed [129], or reduced viability of the endophyte in seed [130,131]....
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TL;DR: Longitudinal studies suggest that the prevalence of seed‐transmitted endophytes can increase rapidly over time, and estimates of infection frequency have revealed variable levels of infection with especially high prevalence in the subfamily Pooideae.
Abstract: Over the past 20 yr much has been learned about a unique symbiotic interaction between fungal endophytes and grasses. The fungi (Clavicipitaceae, Ascomycota) grow intercellularly and systemically in aboveground plant parts. Vertically transmitted asexual endophytes forming asymptomatic infections of cool‐season grasses have been repeatedly derived from sexual species that abort host inflorescences. The phylogenetic distribution of seed‐transmitted endophytes is strongly suggestive of cocladogenesis with their hosts. Molecular evidence indicates that many seed‐transmitted endophytes are interspecific hybrids. Superinfection may result in hyphal fusion and parasexual recombination. Most endophytes produce one or more alkaloid classes that likely play some role in defending the host plant against pests. Hybridization may have led to the proliferation of alkaloid‐production genes among asexual endophytes, favoring hybrids. The ergot alkaloid ergovaline, lolitrems, and lolines are produced by only a ...
981 citations
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TL;DR: The endophytes gain shelter, nutrition, and dissemination via host propagules, and can contribute an array of host fitness enhancements including protection against insect and vertebrate herbivores and root nematodes, enhancements of drought tolerance and nutrient status, and improved growth particularly of the root.
Abstract: Grasses (family Poaceae) and fungi of the family Clavicipitaceae have a long history of symbiosis ranging in a continuum from mutualisms to antagonisms. This continuum is particularly evident among symbioses involving the fungal genus Epichloe (asexual forms = Neotyphodium spp.). In the more mutualistic symbiota, the epichloe endophytes are vertically transmitted via host seeds, and in the more antagonistic symbiota they spread contagiously and suppress host seed set. The endophytes gain shelter, nutrition, and dissemination via host propagules, and can contribute an array of host fitness enhancements including protection against insect and vertebrate herbivores and root nematodes, enhancements of drought tolerance and nutrient status, and improved growth particularly of the root. In some systems, such as the tall fescue N. coenophialum symbioses, the plant may depend on the endophyte under many natural conditions. Recent advances in endophyte molecular biology promise to shed light on the mechanisms of the symbioses and host benefits.
800 citations
TL;DR: Understanding mechanisms of abiotic stress tolerance in endophyte-infected grasses is essential for continued improvement and persistence of grasses for a range of applications, e.g., forage for semi-arid areas or cover plants for soil renovation.
Abstract: Cool-season grasses infected with Neotyphodium spp. endophytes have an extraordinary impact on the ecology and economy of pasture and turf. A range of adaptations of endophyte-infected grasses to biotic and abiotic stresses has been identified but mechanisms of these adaptations are not clearly understood. In this review, we present recent research progress on endophyte-related mechanisms affecting abiotic (drought, mineral) and selected aspects of biotic stress tolerance in cool-season grasses. Endophytes induce mechanisms of drought avoidance (morphological adaptations), drought tolerance (physiological and biochemical adaptations), and drought recovery in infected grasses. Mineral nutrition (nitrogen, phosphorus, calcium) affects production of ergot alkaloids, thus understanding mechanisms involved in mineral economy of endophyte-infected grasses will help in developing management practices to reduce forage toxicity to livestock. Previous research resolved the role of endophyte in nitrogen (N) economy of tall fescue. We identified two endophyte-related mechanisms in tall fescue operating in response to phosphorus (P) deficiency. The mechanisms are altered root morphology (reduced root diameters and longer root hairs) and chemical modification of the rhizosphere resulting from exudation of phenolic-like compounds. These mechanisms were shown to benefit endophyte-infected plants grown under P deficiency. We also report a mechanism of aluminum (Al) sequestration on root surfaces in endophyte-infected tall fescue, which appears to be related to exudation of phenolic-like compounds with Al-chelating activity. Understanding mechanisms of abiotic stress tolerance in endophyte-infected grasses is essential for continued improvement and persistence of grasses for a range of applications, e.g., forage for semi-arid areas or cover plants for soil renovation.
741 citations