Asexual Epichloë Fungi—Obligate Mutualists
27 Oct 2021-Vol. 1, Iss: 4, pp 1084-1100
TL;DR: Asexual Epichloe are obligate fungal mutualists that form symbiosis with many temperate grass species, providing several advantages to the host as discussed by the authors, such as protection against vertebrate and invertebrate herbivores, improved resistance to phytopathogens, increased adaptation to drought stress, nutrient deficiency, and heavy metal-containing soils.
Abstract: Asexual Epichloe are obligate fungal mutualists that form symbiosis with many temperate grass species, providing several advantages to the host. These advantages include protection against vertebrate and invertebrate herbivores (i.e., grazing livestock and invertebrate pests, respectively), improved resistance to phytopathogens, increased adaptation to drought stress, nutrient deficiency, and heavy metal-containing soils. Selected Epichloe strains are utilised in agriculture mainly for their pest resistance traits, which are moderated via the production of Epichloe-derived secondary metabolites. For pastoral agriculture, the use of these endophyte infected grasses requires the balancing of protection against insect pests with reduced impacts on animal health and welfare.
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TL;DR: Endophyte seed-transmission efficiency appears to be influenced primarily by plant defense responses which reduce endophyte colonization of host reproductive tissues.
Abstract: Asexual Epichloë are endophytic fungi that form mutualistic symbioses with cool-season grasses, conferring to their hosts protection against biotic and abiotic stresses. Symbioses are maintained between grass generations as hyphae are vertically transmitted from parent to progeny plants through seed. However, endophyte transmission to the seed is an imperfect process where not all seeds become infected. The mechanisms underpinning the varying efficiencies of seed transmission are poorly understood. Host gene expression in response to Epichloë sp. LpTG-3 strain AR37 was examined within inflorescence primordia and ovaries of high and low endophyte transmission genotypes within a single population of perennial ryegrass. A genome-wide association study was conducted to identify population-level single nucleotide polymorphisms (SNPs) and associated genes correlated with vertical transmission efficiency. For low transmitters of AR37, upregulation of perennial ryegrass receptor-like kinases and resistance genes, typically associated with phytopathogen detection, comprised the largest group of differentially expressed genes (DEGs) in both inflorescence primordia and ovaries. DEGs involved in signaling and plant defense responses, such as cell wall modification, secondary metabolism, and reactive oxygen activities were also abundant. Transmission-associated SNPs were associated with genes for which gene ontology analysis identified “response to fungus” as the most significantly enriched term. Moreover, endophyte biomass as measured by quantitative PCR of Epichloë non-ribosomal peptide synthetase genes, was significantly lower in reproductive tissues of low-transmission hosts compared to high-transmission hosts. Endophyte seed-transmission efficiency appears to be influenced primarily by plant defense responses which reduce endophyte colonization of host reproductive tissues.
2 citations
TL;DR: In this article , the authors reviewed the role of Epichloë fungal endophytes in maintaining pasture persistence and as a result the pastoral economy of New Zealand will be reviewed.
Abstract: Pastoral agriculture underpins the New Zealand economy. Its success in generating export income is due to a mild and moist temperate climate, productive soils, innovative farmers supported by an effective research and development system, and an energy efficient production system based on year-round grazing. However, pastoral agriculture is entirely reliant on introduced pasture and forage species and their ability to withstand both endemic and introduced pasture pests. Critical to this is the mutualistic relationship between ryegrass and Epichloë fungal endophytes which provide a range of secondary metabolites that deter herbivory by both ruminants and insect pests. The challenge has been to identify and commercialise Epichloë strains which while providing protection against insect pests, ensuring ryegrass persistence, do not cause animal health and welfare issues. The critical role that Epichloë fungal endophytes play in maintaining pasture persistence and as a result the pastoral economy of New Zealand will be reviewed.
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TL;DR: Historically, endophytic bacteria have been thought to be weakly virulent plant pathogens but have recently been discovered to have several beneficial effects on host plants, such as plant growth promotion and increased resistance against plant pathogens and parasites.
Abstract: Endophytic bacteria are ubiquitous in most plant species, residing latently or actively colonizing plant tissues locally as well as systemically Several definitions have been proposed for endophyt
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TL;DR: The International Association for Plant Taxonomy (IApt-Taxon) as mentioned in this paper provides a taxonomic overview of the plant taxonomy and its relationships with plant taxa and its taxa.
Abstract: © 2018, International Association for Plant Taxonomy. All rights reserved. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, or be translated into any other language, without written permission from the copyright holder. https://www.iapt-taxon.org/nomen/main.php
1,190 citations
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
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
TL;DR: All fungi invading plant foliage have an asymptomatic period in their life cycle that varies from an imperceptibly short period to a lifetime, and questions are how genetic diversity of the fungus and phenotypic plasticity in fungal life history traits are answered.
548 citations