''Epichloë'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

ascomycete Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The def ...

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

forming an

endophytic An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; ...

symbiosis Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biological interaction, between two organisms of different species. The two organisms, termed symbionts, can fo ...

with

grasses Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivated in ...

. Grass choke disease is a symptom in grasses induced by some ''Epichloë'' species, which form

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

-bearing mats (

stromata The ''Stromata'' (), a mistake for ''Stromateis'' (Στρωματεῖς, "Patchwork," i.e., ''Miscellanies''), attributed to Clement of Alexandria (c. 150 – c. 215), is the third of a trilogy of works regarding the Christian life. The oldest ...

) on

tiller A tiller or till is a lever used to steer a vehicle. The mechanism is primarily used in watercraft, where it is attached to an outboard motor, rudder post, rudder post or stock to provide leverage in the form of torque for the helmsman to turn ...

s and suppress the development of their

host plant In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include a ...

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

. For most of their life cycle however, ''Epichloë'' grow in the intercellular space of stems, leaves, inflorescences, and seeds of the grass plant without incurring symptoms of disease. In fact, they provide several benefits to their host, including the production of different herbivore-deterring

alkaloids Alkaloids are a broad class of naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large variety of organisms i ...

, increased stress resistance, and growth promotion. Within the family

Clavicipitaceae The Clavicipitaceae are a family (biology), family of fungi within the order Hypocreales. A 2008 estimate placed 43 genus, genera in the family, but a study in 2020 has increased this number to 50. Phylogeny Molecular phylogeny, phylogenetic ana ...

, ''Epichloë'' is embedded in a group of endophytic and

plant pathogen Plant diseases are diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like orga ...

ic fungi, whose common ancestor probably derived from an animal pathogen. The genus includes both species with a sexually reproducing (

teleomorph In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota: *Teleomorph: the sexual reproductive stage (morph), typically a fruiting body. *Anamorph: an ase ...

ic) stage and

asexual Asexual or Asexuals may refer to: *Asexual reproduction **Asexual reproduction in starfish *Asexuality, the lack of sexual attraction to anyone or lack of interest in or desire for sexual activity. **Gray asexuality, the spectrum between asexualit ...

anamorph In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota: *Teleomorph: the sexual reproductive stage (morph), typically a fruiting body. *Anamorph: an ase ...

ic species. The latter were previously placed in the

form genus Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships. Form classification, generally restricted to palaeontology, reflects uncertainty; the goal of sc ...

'' Neotyphodium'' but included in ''Epichloë'' after

molecular phylogenetics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

had shown asexual and sexual species to be intermingled in a single

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

Hybrid speciation Hybrid speciation is a form of speciation where hybridization between two different species leads to a new species, reproductively isolated from the parent species. Previously, reproductive isolation between two species and their parents was tho ...

has played an important role in the evolution of the genus. ''Epichloë'' species are ecologically significant through their effects on host plants. Their presence has been shown to alter the composition of

plant communities A plant community is a collection or Association (ecology), association of plant species within a designated geographical unit, which forms a relatively uniform patch, distinguishable from neighboring patches of different vegetation types. The comp ...

and

food web A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Position in the food web, or trophic level, is used in ecology to broadly classify organisms as autotrophs or he ...

s. Grass varieties, especially of

tall fescue ''Lolium arundinaceum'', commonly known as tall fescue, is a cool-season, perennial C3 grass species native to Europe and introduced to North America and other parts of the world. It naturally occurs in grasslands and coastal marshes.Texas Park ...

and

ryegrass ''Lolium'' is a genus of tufted grasses in the bluegrass subfamily (Pooideae). It is often called ryegrass, but this term is sometimes used to refer to grasses in other genera. They are characterized by bunch-like growth habits. ''Lolium'' ...

, with symbiotic ''Epichloë'' endophyte strains, are commercialised and used for

pasture Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing. Types of pasture Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, c ...

and

turf Sod is the upper layer of turf that is harvested for transplanting. Turf consists of a variable thickness of a soil medium that supports a community of turfgrasses. In British and Australian English, sod is more commonly known as ''turf'', ...

Taxonomy

Elias Fries Elias Magnus Fries (15 August 1794 – 8 February 1878) was a Swedish mycologist and botanist. He is sometimes called the "Linnaeus of Mycology". In his works he described and assigned botanical names to hundreds of fungus and lichen sp ...

, in 1849, first defined ''Epichloë'' as a

subgenus In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

of ''

Cordyceps ''Cordyceps'' is a genus of ascomycete fungi (sac fungi) that includes over 260 species worldwide, many of which are parasitic. Diverse variants of cordyceps have had more than 1,500 years of use in Chinese medicine. Most ''Cordyceps'' specie ...

''. As

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

, he designated '' Cordyceps typhina'', originally described by

Christiaan Hendrik Persoon Christiaan Hendrik Persoon (31 December 1761 – 16 November 1836) was a Cape Colony mycologist who is recognized as one of the founders of mycology, mycological Taxonomy (biology), taxonomy. Early life Persoon was born in Cape Colony at ...

. The brothers

Charles Charles is a masculine given name predominantly found in English language, English and French language, French speaking countries. It is from the French form ''Charles'' of the Proto-Germanic, Proto-Germanic name (in runic alphabet) or ''* ...

and

Louis René Tulasne Louis René Étienne Tulasne, a.k.a. Edmond Tulasne (12 September 1815 – 22 December 1885) was a French botanist and mycologist born in Azay-le-Rideau. He originally studied law at Poitiers, but his interest later turned to botany. As a yo ...

then raised the subgenus to genus rank in 1865. ''Epichloë typhina'' would remain the only species in the genus until the discovery of fungal grass endophytes causing livestock intoxications in the 1970s and 1980s, which stimulated the description of new species. Several species from Africa and Asia that develop stromata on grasses were split off as a separate genus '' Parepichloe'' in 1998. Many ''Epichloë'' species have forms that reproduce sexually, and several purely asexual species are closely related to them. These

anamorphs In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota: *Teleomorph: the sexual reproductive stage (morph), typically a fruiting body. *Anamorph: an asex ...

were long classified separately: Morgan-Jones and Gams (1982) collected them in a section (''Albo-lanosa'') of genus ''

Acremonium ''Acremonium'' is a genus of fungi in the family Hypocreaceae. It used to be known as ''Cephalosporium''. Description ''Acremonium'' species are usually slow-growing and are initially compact and moist. Their hyphae are fine and hyaline, and p ...

''. In a

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

study in 1996, Glenn and colleagues found the genus to be

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

and proposed a new genus '' Neotyphodium'' for the anamorphic species related to ''Epichloë''. A number of species continued to be described in both genera until Leuchtmann and colleagues (2014) included most of the

''Neotyphodium'' in ''Epichloë''. Phylogenetic studies had shown both genera to be intermingled, and the

nomenclatural code Nomenclature codes or codes of nomenclature are the various rulebooks that govern the naming of living organisms. Standardizing the scientific names of biological organisms allows researchers to discuss findings (including the discovery of new s ...

required since 2011 that one single name be used for all stages of development of a fungal species. Only '' Neotyphodium starrii'', of unclear status, and '' N. chilense'', which is unrelated, were excluded from ''Epichloë''. File:Epichloë tubB phylogeny.jpg, center, 750px, alt=Phylogeny of the fungal genus Epichloë from aligned tubB gene sequences., Phylogeny of the genus *Epichloë*. Clicking on a species in the phylogeny will load the appropriate wikipedia article. desc bottom-left rect 844 337 1195 377 Epichloë amarillans rect 605 689 977 728 Epichloë aotearoae rect 931 534 1412 578 Epichloë baconii rect 606 636 1022 682 Epichloë brachyelytri rect 495 234 1206 277 Epichloë bromicola rect 496 282 796 332 Epichloë elymi rect 902 384 1454 475

Epichloë festucae ''Epichloë'' is a genus of ascomycete fungi forming an endophytic symbiosis with grasses. Grass choke disease is a symptom in grasses induced by some ''Epichloë'' species, which form spore-bearing mats (stromata) on tillers and suppress the de ...

rect 432 84 1105 180 Epichloë gansuensis rect 433 184 942 233 Epichloë glyceriae rect 902 485 1170 528 Epichloë mollis rect 433 32 985 75 Epichloë sibirica rect 932 586 1560 632 Epichloë stromatolonga rect 841 938 1581 1032 Epichloë sylvatica rect 771 736 1720 931

Epichloë typhina ''Epichloë typhina'' is a haploid sexual species in the fungal genus ''Epichloë''. It was Species description, originally described as a ''Sphaeria'' species. Today, however, it is classified in ''Epichloë''. A systemic grass symbiont first d ...

rect 924 1037 1716 1131

Species

As of 2024, there are 44 accepted species in the genus, with 1

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

and 5

varieties Variety may refer to: Arts and entertainment Entertainment formats * Variety (radio) * Variety show, in theater and television Films * ''Variety'' (1925 film), a German silent film directed by Ewald Andre Dupont * ''Variety'' (1935 film), ...

described. 20 species, 1 subspecies and 4 varieties are haploid. 24 species and 1 variety are hybrids (

allopolyploids Polyploidy is a condition in which the cells of an organism have more than two paired sets of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two complete sets of chromosomes, one from ...

). Several taxa are only known as anamorphic (asexual) forms, most of which have previously been classified in ''Neotyphodium''.

Life cycle and growth

''Epichloë'' species are specialized to form and maintain systemic, constitutive (long-term)

symbioses Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term

The best-studied of these symbionts are associated with the

grass Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family (biology), family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and spe ...

es and

sedges The Cyperaceae () are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large; botanists have described some 5,500 known species in about 90 generathe largest being the "true sedges" (genu ...

, in which they infect the leaves and other aerial tissues by growing between the plant cells (

growth) or on the surface above or beneath the cuticle (

epiphytic An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

growth). An individual infected plant will generally bear only a single genetic individual clavicipitaceous symbiont, so the plant-fungus system constitutes a genetic unit called a symbiotum (pl. symbiota). Symptoms and signs of the fungal infection, if manifested at all, only occur on a specific tissue or site of the host

, where the fungal stroma or sclerotium emerges. The stroma (pl. stromata) is a mycelial cushion that gives rise first to asexual spores (

conidia A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an asexual, non- motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also ...

), then to the sexual fruiting bodies (

ascocarp An ascocarp, or ascoma (: ascomata), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascoc ...

s; perithecia).

Sclerotia A sclerotium (; : sclerotia () is a compact mass of hardened fungal mycelium containing food reserves. One role of sclerotia is to survive environmental extremes. In some higher fungi such as ergot, sclerotia become detached and remain dormant u ...

are hard resting structures that later (after incubation on the ground) germinate to form stipate stromata. Depending on the fungus species, the host tissues on which stromata or sclerotia are produced may be young inflorescences and surrounding leaves, individual florets, nodes, or small segments of the leaves. Young stromata are hyaline (colorless), and as they mature they turn dark gray, black, or yellow-orange. Mature stromata eject meiotically derived spores (

ascospore In fungi, an ascospore is the sexual spore formed inside an ascus—the sac-like cell that defines the division Ascomycota, the largest and most diverse Division (botany), division of fungi. After two parental cell nucleus, nuclei fuse, the ascu ...

s), which are ejected into the atmosphere and initiate new plant infections (

horizontal transmission Horizontal transmission is the transmission of organisms between biotic and/or abiotic members of an ecosystem that are not in a parent-progeny relationship. Because the evolutionary fate of the agent is not tied to reproductive success of the host ...

). In some cases no stroma or sclerotium is produced, but the fungus infects seeds produced by the infected plant, and is thereby transmitted vertically to the next host generation. Most ''Epichloë'' species, and all asexual species, can vertically transmit. The taxonomic dichotomy is especially interesting in this group of symbionts, because vegetative propagation of fungal

mycelium Mycelium (: mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Its normal form is that of branched, slender, entangled, anastomosing, hyaline threads. Fungal colonies composed of mycelium are fo ...

occurs by vertical transmission, i.e., fungal growth into newly developing host tillers (=individual grass plants). Importantly, many ''Epichloë'' species infect new grass plants solely by growing into the seeds of their grass hosts, and infecting the growing seedling. Manifestation of the sexual state — which only occurs in ''Epichloë'' species — causes "choke disease", a condition in which grass

s are engulfed by rapid fungal outgrowth forming a stroma. The fungal stroma suppresses host seed production and culminates in the ejection of meiospores (

s) that mediate horizontal (contagious) transmission of the fungus to new plants. So, the two transmission modes exclude each other, although in many grass-''Epichloë'' symbiota the fungus actually displays both transmission modes simultaneously, by choking some tillers and transmitting in seeds produced by unchoked tillers. While being

obligate symbiont Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term

laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratories are found in a variety of settings such as schools ...

culture media A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Differen ...

such as

potato dextrose agar Potato dextrose agar (BAM Media M127
from the ...

or a minimal salts broth supplemented with thiamine, sugars or sugar alcohols, and organic nitrogen or ammonium. ''Epichloë'' species are commonly spread by

flies Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwin ...

of the genus ''

Botanophila ''Botanophila'' is a genus of flies of the family Anthomyiidae. Species List of species according to Catalogue of Life The Catalogue of Life (CoL) is an online database that provides an index of known species of animals, plants, fungi, an ...

''. The flies lay their eggs in the growing fungal tissues and the larvae feed on them. Stromata Botanophila Flies

Evolution

The epichloae display a number of central features that suggest a very strong and ancient association with their grass hosts. The symbiosis appears to have existed already during the early grass

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

that has spawned today's pooid grasses. This is suggested by

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

studies indicating a preponderance of codivergence of ''Epichloë'' species with the grass hosts they inhabit. Growth of the fungal symbiont is very tightly regulated within its grass host, indicated by a largely unbranched

mycelial Mycelium (: mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Its normal form is that of branched, slender, entangled, anastomosing, hyaline threads. Fungal colonies composed of mycelium are fou ...

morphology and remarkable synchrony of grass leaf and

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...

l extension of the fungus; the latter seems to occur via a mechanism that involves stretch-induced or ''intercalary'' elongation of the endophyte's hyphae, a process so far not found in any other fungal species, indicating specialized adaptation of the fungus to the dynamic growth environment inside its host. A complex

NADPH oxidase NADPH oxidase (nicotinamide adenine dinucleotide phosphate oxidase) is a membrane-bound enzyme complex that faces the extracellular space. It can be found in the plasma membrane as well as in the membranes of phagosomes used by neutrophil white ...

enzyme-based

ROS Ros or ROS or RoS may refer to: Organizations * Raggruppamento Operativo Speciale, the Anti-organized Crime Branch of the Italian Carabinieri * Registers of Scotland, a Scottish authority responsible for compiling and maintaining records * Repart ...

-generating system in ''Epichloë'' species is indispensable for maintenance of this growth synchrony. Thus, it has been demonstrated that deletion of genes encoding these enzymes in ''Epichloë festucae'' causes severely disordered fungal growth in grass tissues and even death of the grass plant. Molecular phylogenetic evidence demonstrates that asexual ''Epichloë'' species are derived either from sexual ''Epichloë'' species, or more commonly, are hybrids of two or more progenitor ''Epichloë'' species.

Bioactive compounds

Many ''Epichloë'' endophytes produce a diverse range of

natural product A natural product is a natural compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life. Natural products can also be prepared by chemical s ...

compounds with biological activities against a broad range of herbivores. The purpose of these compounds is as a

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacteria, bacterium, or plant, as well as the effect o ...

or feeding deterrence against insect and mammalian

herbivores A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

Ergoline Ergoline is a core structure in many alkaloids and their synthetic derivatives. Ergoline alkaloids were first characterized in ergot. Some of these are implicated in the condition of ergotism, which can take a convulsive form or a gangrenous for ...

alkaloids (which are ergot alkaloids, named after the

ergot Ergot ( ) or ergot fungi refers to a group of fungi of the genus ''Claviceps''. The most prominent member of this group is '' Claviceps purpurea'' ("rye ergot fungus"). This fungus grows on rye and related plants, and produces alkaloids that c ...

fungus, ''Claviceps purpurea'', a close relative of the epichloae) are characterized by a ring system derived from 4-

prenyl Prenylation (also known as isoprenylation or lipidation) is the addition of hydrophobic molecules to a protein or a biomolecule. It is usually assumed that prenyl groups (3-methylbut-2-en-1-yl) facilitate attachment to cell membranes, similar to ...

tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α-carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromat ...

. Among the most abundant ergot alkaloids in epichloë-symbiotic grasses is ergovaline, comprising an ergoline

moiety Moiety may refer to: __NOTOC__ Anthropology * Moiety (kinship), either of two groups into which a society is divided ** A division of society in the Iroquois societal structure in North America ** An Australian Aboriginal kinship group ** Native Ha ...

attached to a bicyclic

tripeptide A tripeptide is a peptide derived from three amino acids joined by two or sometimes three peptide bonds. As for proteins, the function of peptides is determined by the constituent amino acids and their sequence. In terms of scientific investigati ...

containing the amino acids L-

proline Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group but is rather a secondary amine. The secondary amine nitrogen is in the p ...

, L-

alanine Alanine (symbol Ala or A), or α-alanine, is an α-amino acid that is used in the biosynthesis of proteins. It contains an amine group and a carboxylic acid group, both attached to the central carbon atom which also carries a methyl group sid ...

, and L-

valine Valine (symbol Val or V) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated −NH3+ form under biological conditions), an α- carboxylic acid group (which is in the deproton ...

. Key genes and enzymes for ergot alkaloid

biosynthesis Biosynthesis, i.e., chemical synthesis occurring in biological contexts, is a term most often referring to multi-step, enzyme-Catalysis, catalyzed processes where chemical substances absorbed as nutrients (or previously converted through biosynthe ...

have been identified in epichloae and include ''dmaW'', encoding dimethylallyl-tryptophan synthase and ''lpsA'', a non-ribosomal peptide synthetase. Another group of epichloë alkaloids are the

indole Indole is an organic compound with the formula . Indole is classified as an aromatic heterocycle. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indoles are derivatives of indole ...

diterpenoid Diterpenes are a class of terpenes composed of four isoprene units, often with the molecular formula C20H32. They are biosynthesized by plants, animals and fungi via the HMG-CoA reductase pathway, with geranylgeranyl pyrophosphate being a primar ...

s, such as lolitrem B, which are produced from the activity of several enzymes, including

prenyltransferase Prenyltransferases (PTs) are a class of enzymes that transfer allylic prenyl groups to acceptor molecules. Prenyl transferases commonly refer to isoprenyl diphosphate syntheses (IPPSs). Prenyltransferases are a functional category and include seve ...

s and various

monooxygenase Monooxygenases are enzymes that incorporate one hydroxyl group (−OH) into substrates in many metabolic pathways. In this reaction, the two atoms of dioxygen are reduced to one hydroxyl group and one H2O molecule by the concomitant oxidation of ...

s. Both the ergoline and indole-diterpenoid alkaloids have

biological activity In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter. When a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or ...

against mammalian herbivores, and also activity against some insects. is a pyrrolopyrazine alkaloid thought to be biosynthesized from the

guanidinium Guanidine is the compound with the formula HNC(NH2)2. It is a colourless solid that dissolves in polar solvents. It is a strong base that is used in the production of plastics and explosives. It is found in urine predominantly in patients experie ...

-group-containing amino acid L-

arginine Arginine is the amino acid with the formula (H2N)(HN)CN(H)(CH2)3CH(NH2)CO2H. The molecule features a guanidinium, guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO2−) a ...

, and pyrrolidine-5-

carboxylate In organic chemistry, a carboxylate is the conjugate base of a carboxylic acid, (or ). It is an anion, an ion with negative charge. Carboxylate salts are salts that have the general formula , where M is a metal and ''n'' is 1, 2,... ...

, a precursor of L-

, and is an insect-feeding deterrent. One gene required for peramine synthesis – ' – was found by Tanaka ''et al.'', 2005. The loline alkaloids are 1-aminopyrrolizidines with an oxygen atom linking bridgehead carbons 2 and 7, and are biosynthesized from the amino acids L-proline and L-

homoserine Homoserine (also called isothreonine) is an α-amino acid with the chemical formula HO2CCH(NH2)CH2CH2OH. L-Homoserine is not one of the common amino acids encoded by DNA. It differs from the proteinogenic amino acid serine by insertion of an addit ...

. The lolines have

insecticidal Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. The major use of insecticides is in agriculture, but they are also used in home and garden settings, in ...

and insect-deterrent activities comparable to

nicotine Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...

. Loline accumulation is strongly induced in young growing tissues or by damage to the plant-fungus symbiotum. Many, but not all, epichloae produce up to three classes of these alkaloids in various combinations and amounts. Recently it has been shown that ''Epichloë uncinata'' infection and loline content afford ''

× Festulolium × ''Festulolium'' is a nothogenus of flowering plants in the grass family Poaceae. Naturally occurring hybrids, they are the result of crosses between species of two questionably distinct grass genera, ''Festuca'' (the fescues) and ''Lolium'' ( ...

'' grasses protection from black beetle ('' Heteronychus arator''). Many species in ''Epichloë'' produce biologically active alkaloids, such as

ergot alkaloid Ergoline is a core structure in many alkaloids and their synthetic derivatives. Ergoline alkaloids were first characterized in ergot. Some of these are implicated in the condition of ergotism, which can take a convulsive form or a gangrenous for ...

s, indole-diterpenoids (e.g., lolitrem B), loline alkaloids, and the unusual

alkaloid, peramine.

Ecology

Effects on the grass plant

It has been proposed that vertically transmitted

symbiont Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biological interaction, between two organisms of different species. The two organisms, termed symbionts, can fo ...

s should evolve to be

mutualists Mutualism describes the ecological interaction between two or more species where each species has a net benefit. Mutualism is a common type of ecological interaction. Prominent examples are: * the nutrient exchange between vascular plants and ...

since their reproductive fitness is intimately tied to that of their hosts. In fact, some positive effects of epichloae on their host plants include increased growth, drought tolerance, and

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

and

pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...

resistance. Resistance against herbivores has been attributed to

alkaloid Alkaloids are a broad class of natural product, naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large varie ...

s produced by the symbiotic epichloae. Although grass-epichloë symbioses have been widely recognized to be mutualistic in many wild and cultivated grasses, the interactions can be highly variable and sometimes antagonistic, especially under nutrient-poor conditions in the soil.

Ecosystem dynamics

Due to the relatively large number of grass species harboring epichloae and the variety of environments in which they occur, the mechanisms underlying beneficial or antagonistic outcomes of epichloë-grass symbioses are difficult to delineate in natural and also agricultural environments. Some studies suggest a relationship between grazing by herbivores and increased epichloë infestation of the grasses on which they feed, whereas others indicate a complex interplay between plant species and fungal symbionts in response to herbivory or environmental conditions. The strong anti-herbivore activities of several bioactive compounds produced by the epichloae and relatively modest direct effects of the epichloae on plant growth and physiology suggest that these compounds play a major role in the persistence of the symbiosis.

References

{{DEFAULTSORT:Epichloe Hypocreales genera Taxa named by Elias Magnus Fries Taxa described in 1945