
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; however, most of the endophyte/plant relationships are not well understood. Some endophytes may enhance host growth, nutrient acquisition and improve the plant's ability to tolerate abiotic stresses, such as drought and decrease biotic stresses by enhancing plant resistance to insects, pathogens and
herbivore
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
s. Although endophytic bacteria and fungi are frequently studied, endophytic archaea are increasingly being considered for their role in plant growth promotion as part of the core microbiome of a plant.
History
Endophytes were first described by the German botanist
Johann Heinrich Friedrich Link
Johann Heinrich Friedrich Link (2 February 1767 – 1 January 1851) was a German naturalist and botanist.
Biography
Link was born at Hildesheim as a son of the minister August Heinrich Link (1738–1783), who taught him love of nature throug ...
in 1809. They were thought to be plant parasitic fungi and they were later termed as "microzymas" by the French scientist Béchamp. There was a belief that plants were healthy under sterile conditions and it was not until 1887 that
Victor Galippe
The name Victor or Viktor may refer to:
* Victor (name), including a list of people with the given name, mononym, or surname
Arts and entertainment
Film
* ''Victor'' (1951 film), a French drama film
* ''Victor'' (1993 film), a French shor ...
discovered bacteria normally occurring inside plant tissues.
Though, most of the endophytic studies reports the mutualistic relationship of bacteria and fungus, Das et al., (2019) reported about endophytic virome and their probable function in plant defense mechanisms.
Transmission
Endophytes may be transmitted either vertically (directly from parent to offspring) or horizontally (among individuals). Vertically transmitted fungal endophytes are typically considered
clonal and transmit via
fungal 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 or ...
e penetrating the embryo within the host's
seeds, while reproduction of the fungi through asexual
conidia
A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an asexual, non-motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also called mitospores due to the ...
or sexual spores leads to horizontal transmission, where endophytes may spread between plants in a population or community.
Symbiosis

Most endophyte-plant relationships are still not well understood. However, recently it was shown that endophytes are transmitted from one generation to another via seeds, in a process called vertical transmission. Endophytes and plants often engage in mutualism, with endophytes primarily aiding in the health and survival of the host plant with issues such as pathogens and disease, water stress, heat stress, nutrient availability and poor soil quality, salinity, and herbivory.
In exchange the endophyte receives carbon for energy from the plant host. Plant-microbe interactions are not strictly
mutualistic, as endophytic fungi can potentially become
pathogens or
saprotrophs
Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi (f ...
, usually when the plant is stressed. Endophytes may become active and reproduce under specific environmental conditions or when their host plants are stressed or begin to
senesce, thereby limiting the amount of carbon provided to the endophyte.
Endophytes may benefit host plants by preventing other pathogenic or parasitic organisms from colonizing them. Endophytes can extensively colonize plant tissues and
competitively exclude other potential pathogens. Some fungal and bacterial endophytes have proven to increase plant growth and improve overall plant hardiness.
Studies have shown that endophytic fungi grow in a very intimate interaction with their host plant cells. Fungal
hyphae
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 or ...
have been seen growing either flattened or wedged against plant cells. This growth pattern indicates that fungal hyphae are substantially attached to the plant host's cell wall, but do not invade plant cells.
Endophytic fungal hyphae appear to grow at the same rate as their host leaves, within the intercellular spaces of the plant tissue.
The presence of certain fungal endophytes in host
meristems, leaves and reproductive structures has been shown to dramatically enhance the survival of their hosts. This enhanced survivability is largely attributed to endophytic production of
secondary metabolites which protect against herbivory as well as increased uptake of nutrients.
Studies have also shown that during experimental circumstances endophytes contribute significantly to plant growth and fitness under light-limited conditions, and plants appear to have increased reliance on their endophytic symbiont under these conditions.
There is evidence that plants and endophytes engage in communication with each other that can aid symbiosis. For example, plant chemical signals have been shown to activate gene expression in endophytes. One example of this plant-endosymbiont interaction occurs between
dicotyledonous plants in the
Convolvulaceae and
clavicipitaceous fungi. When the fungus is in the plant it synthesizes
ergoline alkaloids at a higher rate, compared to when it is grown apart from the plant. This supports the hypothesis that plant signaling is required in order to induce expression of endophytic secondary metabolites.
Effects on plant behavior
There are various behaviors that have been studied that resulted from endophyte symbiosis with plants. Through association with fungal endophytes, the root and shoot structures of ''Pseudotsuga menziesii'' (
Douglas-fir) saplings in low-nutrient conditions have been shown to be elongated, as well as undergo overall biomass increases.
The proposed mechanisms behind this include high inorganic phosphate solubilization ability by the fungi as well as organic phosphate mineralization, increased mycorrhizal associations through root colonization, and enhanced nitrogen and phosphorus uptake.
Specific endophyte species can also stimulate root growth by increasing the flux of
auxin
Auxins (plural of auxin ) are a class of plant hormones (or plant-growth regulators) with some morphogen-like characteristics. Auxins play a cardinal role in coordination of many growth and behavioral processes in plant life cycles and are essenti ...
to where the endophyte is.
Additionally, various reports on endophyte interactions have shown increased photosynthetic capacities of host plants as well as improved water relations.
Improvements in water use efficiency were observed in higher concentrations and a further increase was seen in water deficit conditions.
In addition, other various physiological pathways were activated upon endophytes interactions with host plants, enabling tighter water control and further water management, which are to be the main reasons behind improved water relations.
Specifically, evidence points to endophytes producing
ABA
ABA may refer to:
Businesses and organizations
Broadcasting
* Alabama Broadcasters Association, United States
* Asahi Broadcasting Aomori, Japanese television station
* Australian Broadcasting Authority
Education
* Académie des Beaux- ...
to affect stomatal conductance as well as microbial respiration and plants recycling .
However, the specific biochemical mechanisms behind these behavioral changes are still largely unknown and lower-level signal cascades have yet to be discovered. Furthermore, while the benefits of endophyte relations are well-studied, the costs of these relations are less well understood, such as the specific carbon costs, the system of endophyte governance, and the environmental conditions that facilitate a proper plant-endophyte relationship.
In an experiment investigating the interaction between ''
Miscanthus sinensis'' and the plant endophyte ''
Herbaspirillum frisingense'', a roughly 20% increase in fresh biomass was observed in ''M. sinensis'' following inoculation with ''H. frisingense''.
However, unique to this experiment was the mode by which this was thought to happen. Inoculation saw an upregulation in the genes relevant to
jasmonate
Jasmonate (JA) and its derivatives are lipid-based plant hormones that regulate a wide range of processes in plants, ranging from growth and photosynthesis to reproductive development. In particular, JAs are critical for plant defense against her ...
and
ethylene
Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds).
Ethylene i ...
production in the plant roots, although the mechanism to this is still unknown.
Specifically, ''H. frisingense'' was shown to upregulate ethylene receptors and repress ethylene response factors, overall leading to an increase in root growth.
Additionally, ''H. frisingense'' is known to produce
indoleacetic acid (IAA), and was also shown to manage IAA genes, indicating that there is an intricate balance maintained between ethylene and IAA by ''H. frisingense''.
Diversity
Endophytic species are very diverse; only a small minority of existing endophytes have been characterized. Many endophytes are in the phyla
Basidiomycota
Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basi ...
and
Ascomycota
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 ...
. Endophytic fungi may be from
Hypocreales
The Hypocreales are an order of fungi within the class Sordariomycetes. In 2008, it was estimated that it contained some 237 genera, and 2647 species in seven families. Since then, a considerable number of further taxa have been identified, in ...
and
Xylariales of the
Sordariomycetes (Pyrenomycetes) class or from the class of Loculoascomycetes. One group of fungal endophytes are the
arbuscular mycorrhizal fungi involving biotrophic
Glomeromycota
Glomeromycota (often referred to as glomeromycetes, as they include only one class, Glomeromycetes) are one of eight currently recognized divisions within the kingdom Fungi,
with approximately 230 described species. Members of the Glomeromycot ...
associated with various plant species. As often with other organisms associated with plants such as
mycorrhizal fungus, endophytes gain carbon from their association with the plant host. Bacterial endophytes are polyphyletic, belonging to broad range of taxa, including α-Proteobacteria, β-Proteobacteria, γ-Proteobacteria, Firmicutes, Actinobacteria.
One or more endophytic organisms are found in nearly every land plant.
It is suggested that areas of high plant diversity such as
tropical rainforests may also contain the highest diversity of endophytic organisms that possess novel and diverse chemical metabolites.
It has been estimated that there could be approximately 1 million endophytic fungi that exist in the world.
A diazotrophic bacterium isolated in lodgepole pines (''
Pinus contorta'') in British Columbia, Canada, is ''
Paenibacillus polymyxa'', which may help its host by fixing nitrogen.
Classification
Endophytes include a wide variety of microorganisms including fungi, bacteria and viruses. There are two different means of classifying endophytes.
Systemic and non-systemic
The first method divides endophytes into two categories: systemic (true) and nonsystemic (transient). These categories are based on the endophyte's genetics, biology, and mechanism of transmission from host to host.
Systemic endophytes are defined as organisms that live within plant tissues for the entirety of its life cycle and participate in a symbiotic relationship without causing disease or harm to the plant at any point. Additionally, systemic endophytes concentrations and diversity do not change in a host with changing environmental conditions.
Non-systemic or transient endophytes on the other hand vary in number and diversity within their plant hosts under changing environmental conditions. Non-systemic endophytes have also been shown to become
pathogenic
In biology, a pathogen ( el, πάθος, "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 ...
to their host plants under stressful or resource limited growing conditions.
An example of this would be ''
Colletotrichum fioriniae'', which is an endophyte of many
temperate broadleaved trees and shrubs, but can also be a pathogen on many fruits and some leaves.
Clavicipitaceous and non-clavicipitaceous
The second method divides fungal endophytes into four groups based on taxonomy and six other criteria: host range, host tissues colonized, ''in planta'' colonization, ''in planta'' biodiversity, mode of transmission and fitness benefits.
These four groups are divided into
clavicipitaceous endophytes (Class 1) and non-clavicipitaceous endophytes (Class 2, 3, and 4).
Class 1 endophytes are all phylogenetically related and proliferate within cool and warm season grasses. They typically colonize plant shoots where they form a systemic intercellular infection. Class 1 endophytes are mainly transmitted from host to host by vertical transmission, in which maternal plants pass fungi on to their offspring through seeds. Class 1 endophytes can further be divided into Types I, II and III. Among these three types of clavicipitaceous endophytes are different interactions with their plant hosts. These interaction range from
pathogenic to symbiotic and symptomatic to
asymptomatic
In medicine, any disease is classified asymptomatic if a patient tests as carrier for a disease or infection but experiences no symptoms. Whenever a medical condition fails to show noticeable symptoms after a diagnosis it might be considered asy ...
. Type III clavicipitaceous endophytes grow within their plant host without manifesting symptoms of disease or harming their host. Class 1 endophytes typically confer benefits on their plant host such as improving plant biomass, increasing drought tolerance and increasing the production of chemicals that are toxic and unappetizing to animals, thereby decreasing herbivory. These benefits can vary depending on the host and environmental conditions.
Non-clavicipitaceous endophytes represent a
polyphyletic group of organisms. Non-clavicipitaceous endophytes are typically
Ascomycota
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. The ecological roles of these fungi are diverse and still poorly understood. These endophyte plant interactions are widespread and have been found in nearly all land plants and ecosystems.
Many non-clavicipitaceous endophytes have the ability to switch between endophytic behavior and free-living lifestyles. Non-clavicipitaceous endophytes are divided into class 2, 3 and 4. Class 2 endophytes can grow in plant tissues both above and below ground. This class of non-clavicipitaceous endophytes has been the most extensively researched and has been shown to enhance fitness benefits of their plant host as a result of habitat-specific stresses such as pH, temperature and salinity.
Class 3 endophytes are restricted to growth in above ground plant tissues and form in localized areas of plant tissue. Class 4 endophytes are restricted to plant tissues below ground and can colonize much more of the plant tissue. These classes of non-clavicipitaceous endophytes have not been as extensively studied to date.
Applications
Endophytes may have potential future applications in agriculture.
Use of endophytes might potentially increase
crop yields. Turfgrass seed of ''
Festuca'' and ''
Lolium perenne'' infected with fungal
inoculants, ''
Acremonium coenophialum'' and ''
A. lolii'', is commercially available for use in growing lawns which might require less pesticide use -the grasses are poisonous to cattle and more resistant to some insect damage. As of 1999 this is only available in the afore-mentioned lawn grasses, which are sold as 'low maintenance'
cultivars. The fungi cause the grasses to contain toxic
alkaloids. The products provide high resistance to foliar lawn pests such as billbugs, chinch bugs, sod webworms, fall army-worms and Argentine stem weevils, but offer little protection to pests of grass roots such as grubs. The endophytes can survive most pesticides and are even resistant to some
fungicide
Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...
s, and are very suitable for use in
Integrated Pest Management.
Biofuel
A 2008 experiment with an isolate of a fungus called NRRL 50072 found that this strain can produce a small amount of fuel-like hydrocarbon compounds which was promoted as "myco-diesel". It was hoped that perhaps in the future this might provide a possible source of
biofuel
Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels, such as oil. According to the United States Energy Information Administration (E ...
. It was first misidentified as the endophyte ''
Gliocladium roseum'', but later research showed that it was in fact the
saprophyte ''
Ascocoryne sarcoides''.
A strain of endophytic fungi which appeared to be closely related to ''
Nigrograna mackinnonii'' which was isolated from a stem of the plant ''
Guazuma ulmifolia
''Guazuma ulmifolia'', commonly known as West Indian elm or bay cedar, is a medium-sized tree normally found in pastures and disturbed forests. This flowering plant from the family Malvaceae grows up to 30m in height and 30–40cm in diameter. I ...
'' collected in Ecuador was found to produce a variety of
volatile organic compounds including
terpenes and odd chain
polyenes. The polyenes isolated from the fungus have properties that are sought in
gasoline-surrogate biofuels.
Phytoremediation
Plants are potentially able to break down or sequester, or stimulate micro-organisms in the soil to break down or sequester, certain organic pollutants and inorganic pollutants such as
nickel in degraded ecosystems, which is known as
phytoremediation. In this endophytes may possibly assist plants in converting pollutants into less biologically harmful forms; in one of the few experiments performed a
plasmid
A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria; how ...
called TOM from a strain of a bacterium in the ''
Burkholderia'' genus known as G4 which can break down
trichloroethylene (TCE) was transferred to endophytes of
popular trees; although it did not help the plants remove more of this chemical than non-inoculated plants, the plants transpired less TCE into the air. In another experiment ''
Burkholderia'' bacteria with both the TOM plasmid as well as nickel resistance genes was inoculated into
yellow lupine; this increased the root mass of the plants, but the amounts of TCE transpired was not
statistically significant
In statistical hypothesis testing, a result has statistical significance when it is very unlikely to have occurred given the null hypothesis (simply by chance alone). More precisely, a study's defined significance level, denoted by \alpha, is the p ...
. Despite these failures, such techniques might lead to some future improvements.
Two strains of the endophytic fungi ''
Pestalotiopsis microspora'' isolated from stems of plants from the Ecuadorian rainforest were shown in laboratory experiments to be able to digest
polyurethane plastic as the fungus's sole carbon source in
anaerobic conditions, although many other non-endophytic fungi have demonstrated this ability, and most isolates of endophytic fungi in this experiment could perform this to some degree.
Drug discovery
Endophytes produce a wide variety of
secondary metabolites that might be useful as lead compounds in
drug discovery
In the fields of medicine, biotechnology and pharmacology, drug discovery is the process by which new candidate medications are discovered.
Historically, drugs were discovered by identifying the active ingredient from traditional remedies or by ...
. Endophyte
bioprospecting has already yielded compounds with
antibacterial,
antifungal
An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as crypto ...
,
antiviral,
antiparasitic,
cytotoxic
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa'').
Cell physiology
Treating cells ...
,
neuroprotective,
antioxidant
Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...
,
insulin
Insulin (, from Latin ''insula'', 'island') is a peptide hormone produced by beta cells of the pancreatic islets encoded in humans by the ''INS'' gene. It is considered to be the main anabolic hormone of the body. It regulates the metabolism o ...
-mimetic,
α-glucosidase inhibitory,
and
immunosuppressant properties. Manipulations of a plant's endosymbiots can affect plant development, growth and ultimately the quality and quantity of compounds harvested from the plant.
Studies have shown endophytic fungi are able to produce secondary metabolites previously thought to be manufactured by their plant hosts. The presence of these metabolites in plants could be attributable to endophyte production alone, or to combined endophyte and plant production following transfer of the corresponding genes from endophyte to plant or vice versa.
A well known example of the discovery of chemicals derived from endophytic fungi is from the fungus ''
Taxomyces andreanae'' isolated from the pacific yew ''
Taxus brevifolia''. ''T. andreanae'' produces
paclitaxel, also known as taxol. This drug is important for the treatment of cancer. Other endophytes since have been discovered that also produce paclitaxel in other host species, but to date there has been no successful industrial source of paclitaxel created.
Endophytes have been discovered with various anti-tumor properties. Endophytic fungi produce many secondary compounds such as
alkaloids,
triterpenes and
steroid
A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...
s which have been shown to have anti-tumor effects.
The alkaloid
beauvericin has been isolated from the fungus ''
Fusarium oxysporum'' and has shown
cytotoxicity
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa'').
Cell physiology
Treating cells ...
against the tumor cells
PC3,
PANC-1 PANC-1 is a human pancreatic cancer cell line isolated from a pancreatic carcinoma of Ductal cells, ductal cell origin.
PANC-1 was derived from the tissue of a 56-year-old male. The cells can metastasis, metastasize but have poor differentiation a ...
, and
A549.
Two fusarubin derivatives: anhydrofusarubin and methyl ether of fusarubin were isolated from endophytic fungus ''
Cladosporium sp.'' and have shown
cytotoxicity
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa'').
Cell physiology
Treating cells ...
against human
leukemia (K-562).
Three triterpenes were found in the endophyte Xylarialean sp., all three of these compounds displayed mild cytotoxic effects on tumor cells.
Some of the antimicrobial compounds produced by endophytic fungi are of interest in their effectiveness against pathogens which have developed resistances to antibiotics. Different fractions of ''
Cladosporium sp.'' including
secondary metabolite-methyl ether of fusarubin have shown antibacterial activity against ''
Staphylococcus aureus
''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive ...
'', ''
E. coli
''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...
'', ''
P. aeruginosa P. is an abbreviation or acronym that may refer to:
* Page (paper), where the abbreviation comes from Latin ''pagina''
* Paris Herbarium, at the ''Muséum national d'histoire naturelle''
* ''Pani'' (Polish), translating as Mrs.
* The ''Pacific Repo ...
'', and ''
Bacillus megaterium''.
Several isolates from the ascomycota ''
Pestalotiopsis'' sp. have been shown to have a broad range of antimicrobial effects,
even against
methicillin-resistant ''Staphylococcus aureus''. Also, compounds from the
marine fungus
Marine fungi are species of fungi that live in marine or estuarine environments. They are not a taxonomic group, but share a common habitat. Obligate marine fungi grow exclusively in the marine habitat while wholly or sporadically submerged in s ...
''
Nigrospora'' sp. have activity against strains of multi drug-resistant ''
Mycobacterium tuberculosis
''Mycobacterium tuberculosis'' (M. tb) is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, ''M. tuberculosis'' has an unusual, waxy coating on its c ...
''.
An endophytic fungus of the genus ''
Pseudomassaria
''Pseudomassaria'' is a genus of fungi in the family Hyponectriaceae
The Hyponectriaceae are a family of fungi, that was formerly in the order Xylariales
The Xylariales are an order (biology), order of fungi within the class (biology), class ...
'' has been found in the rainforest of the
Democratic Republic of the Congo. This fungus yields a metabolite that shows potential as an antidiabetic, also known as an insulin mimetic. This compound acts like insulin and has been shown to lower blood glucose levels in mouse model experiments.
Agriculture
Among the many promising applications of endophytic microbes are those intended to increase agricultural use of endophytes to produce crops that grow faster and are more resistant and hardier than crops lacking endophytes. ''
Epichloë'' endophytes are being widely used commercially in turf grasses to enhance the performance of the turf and its resistance to biotic and abiotic stresses. ''
Piriformospora indica
''Serendipita indica'' (synonym ''Piriformospora indica'') is a fungal species of the order Sebacinales. It is an endophytic root-colonising species, discovered from orchid plants in the Thar desert in Rajasthan, India by Prof. Ajit Verma and gro ...
'' is an interesting endophytic fungus of the order
Sebacinales, the fungus is capable of colonising roots and forming symbiotic relationship with many plants.
Endophytes appear to enhance the growth of their plant host symbionts. Endophytes also provide their hosts with an increased resilience to both abiotic and biotic stressors such as drought, poor soils and herbivory. The increased growth and resilience is likely caused by the endophytes ability to improve plant nutrition or secondary metabolite production, as in the case of ''Phoma eupatorii''s inhibition of the phytopathogen ''Phytophthora infestans''.
Endophytes accomplish this by increasing the uptake of valuable land limited nutrients from the soil such as phosphorus and making other plant nutrients available to plants such as
rock phosphate and atmospheric nitrogen which are normally trapped in forms that are inaccessible to plants.
Many endophytes protect plants from herbivory from both insects and animals by producing secondary metabolites that are either unappetizing or toxic to the herbivore. Increasingly there has been great importance placed on endophytes that protect valuable crops from invasive insects. One example of an endophyte-plant-insect interaction is located in the New Zealand grasslands, where endophytes, known as AR1 and AR37 are utilized to protect valuable ryegrass from the
Argentine stem weevil but remain palatable to another important food source, livestock.
There are several endophytes that have been discovered that exhibit insecticidal properties. One such endophyte comes from the ''Nodulisporium sp''. which was first harvested from the plant ''
Bontia daphnoides''. Indole
diterpenes, known as nodulisporic acids, have been harvested from this endophyte which have effective insecticidal properties against the blowfly larvae.
There are many obstacles to successfully implementing the use of endophytes in agriculture. Despite the many known benefits that endophytes may confer to their plant hosts,
conventional agricultural practices continue to take priority. Current agriculture relies heavily on fungicides and high levels of chemical fertilizers. The use of fungicides has a negative effect on endophytic fungi and fertilizers reduce a plant's dependence on its endophytic symbiont.
Despite this, the interest and use of bio-insecticides and using endophytes to aid in plant growth is increasing as organic and
sustainable agriculture is considered more important. As humans become more aware of the damage that synthetic insecticides cause to the environment and beneficial insects such as bees and butterflies biological insecticides may become more important to the agricultural industry.
See also
*
Biofertilizer
*
List of endophytes
*
Plant use of endophytic fungi in defense
*
Arbuscular mycorrhiza
*
Mycorrhiza
A mycorrhiza (from Greek μύκης ', "fungus", and ῥίζα ', "root"; pl. mycorrhizae, mycorrhiza or mycorrhizas) is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the plant ...
*
Rhizobia
Rhizobia are diazotrophic bacteria that fix nitrogen after becoming established inside the root nodules of legumes (Fabaceae). To express genes for nitrogen fixation, rhizobia require a plant host; they cannot independently fix nitrogen. In gene ...
References
{{Reflist, colwidth=30em
Microbial growth and nutrition
Fungus ecology
Bacteriology
Symbiosis