Interspecific hybridization and bioactive alkaloid variation increases diversity in endophytic<i>Epichloë</i>species of<i>Bromus laevipes</i>

Charlton, Nikki D.; Craven, Kelly D.; Afkhami, Michelle E.; Hall, Bradley A.; Ghimire, Sita R.; Young, Carolyn A.

doi:10.1111/1574-6941.12393

Cited by 57 publications

(71 citation statements)

References 64 publications

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“…Epichloë cabralii BlaTG-2 isolate NFe661, Epichloë sp. FaTG-2 G3 isolate NFe45115, and an isolate of Epichloë uncinata E167 have known per Ϫ chemotypes (18,19,29), yet each of these isolates appeared to contain at least one fulllength perA allele (Fig. 4).…”

Section: Resultsmentioning

confidence: 99%

“…The remaining three per Ϫ isolates, E. cabralii BlaTG-2 isolate NFe661, E. uncinata isolate e167, and Epichloë sp. FaTG-2 G3 isolate NFe45115, were hybrids (18,19,29). A 1-bp insertion causing a frameshift mutation was identified in E. cabralii BlaTG-2 NFe661 allele 1 (Fig.…”

Section: E Festucaementioning

confidence: 99%

“…poae; nt, not tested. Known peramine chemotypes are indicated as Per ϩ (peramine producer) or per Ϫ (peramine nonproducer) (5,6,18,19,29,43,44). Peramine production was predicted for isolates with unknown peramine chemotypes based on the presence of expected PCR products amplified from all perA domains and are indicated by ϩ or Ϫ.…”

Section: E Festucaementioning

confidence: 99%

“…This deletion is associated with the insertion of the miniature inverted-repeat transposable element (MITE) designated 3m (17). However, there are many other cases of peramine-negative (per Ϫ ) isolates for which the genetic basis is unknown (18,19).Peramine production is an important trait when considering Disparate independent genetic events disrupt the secondary metabolism gene perA in certain symbiotic Epichloë species. Appl Environ Microbiol…”

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Disparate Independent Genetic Events Disrupt the Secondary Metabolism Gene perA in Certain Symbiotic Epichloë Species

Berry

Takach

Schardl

et al. 2015

Appl Environ Microbiol

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Peramine is an insect-feeding deterrent produced by Epichloë species in symbiotic association with C 3 grasses. The perA gene responsible for peramine synthesis encodes a two-module nonribosomal peptide synthetase. Alleles of perA are found in most Epichloë species; however, peramine is not produced by many perA-containing Epichloë isolates. The genetic basis of these peramine-negative chemotypes is often unknown. Using PCR and DNA sequencing, we analyzed the perA genes from 72 Epichloë isolates and identified causative mutations of perA null alleles. We found nonfunctional perA-⌬R* alleles, which contain a transposon-associated deletion of the perA region encoding the C-terminal reductase domain, are widespread within the Epichloë genus and represent a prevalent mutation found in nonhybrid species. Disparate phylogenies of adjacent A2 and T2 domains indicated that the deletion of the reductase domain (R*) likely occurred once and early in the evolution of the genus, and subsequently there have been several recombinations between those domains. A number of novel point, deletion, and insertion mutations responsible for abolishing peramine production in full-length perA alleles were also identified. The regions encoding the first and second adenylation domains (A1 and A2, respectively) were common sites for such mutations. Using this information, a method was developed to predict peramine chemotypes by combining PCR product size polymorphism analysis with sequencing of the perA adenylation domains. Fungal secondary metabolites are a diverse group of important but often nonessential organic compounds with a wide range of properties that are likely to be advantageous for the producing organism or in some cases essential for pathogenicity or developmental stages (1-3). These low-molecular-weight compounds tend to only be produced under certain environmental or growth conditions. The biosynthetic pathways for production of any particular class of secondary metabolites are common to many fungi, but production of a specific secondary metabolite is often unique to a small phylogenetic group of species (4). Epichloë species are fungal endophytes of C 3 grasses that are known to produce several bioactive alkaloids that provide bioprotective properties to the host plant (5). These secondary metabolites include the indolediterpenes, ergot alkaloids, lolines, and peramine ( Fig. 1) (6, 7). The indole-diterpene lolitrem B and ergot alkaloid ergovaline have significant detrimental effects on the health and production of stock animals that graze infected pastures (7,8). The lolines are insecticidal (9), and peramine is a potent deterrent of feeding by insects, including the agriculturally important invertebrate pest Listronotus bonariensis (Argentine stem weevil) (10-12).Peramine synthesis is catalyzed by the two-module nonribosomal peptide synthetase (NRPS), peramine synthetase (PerA), encoded by the 8.3-kb gene perA (12). The first module of PerA contains an adenylation (A1) domain responsible for selection and activation of t...

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Section: Resultsmentioning

confidence: 99%

Section: E Festucaementioning

confidence: 99%

Section: E Festucaementioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Disparate Independent Genetic Events Disrupt the Secondary Metabolism Gene perA in Certain Symbiotic Epichloë Species

Berry

Takach

Schardl

et al. 2015

Appl Environ Microbiol

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Detection and Isolation of Epichloë Species, Fungal Endophytes of Grasses

2015

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Epichloë species (including former Neotyphodium species) are endophytic fungi that significantly affect fitness of cool‐season grass hosts, potentially by increasing nutrient uptake and resistance to drought, parasitism and herbivory. Epichloë species are obligately biotrophic, living in the intercellular spaces of their plant hosts, and spreading systemically throughout host aerial tissues. The reproduction of Epichloë species is versatile; some strains have both sexual and asexual modes of reproduction, but others are restricted to one or the other mode. The reproduction mode determines the dissemination mechanism, and the asexual species most important to agriculture are strictly seed‐borne, cause no signs or symptoms, and are undetectable except by specialized microscopic, molecular or antigenic procedures. These procedures can be used to identify endophytes in a variety of plant tissues. Similar protocols can be modified to detect less common symbionts, such as the penicillate “p‐endophytes,” when they occur by themselves or together with Epichloë species. © 2015 by John Wiley & Sons, Inc.

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Using niche breadth theory to explain generalization in mutualisms

Batstone

Carscadden

Afkhami

et al. 2018

Ecology

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For a mutualism to remain evolutionarily stable, theory predicts that mutualists should limit their associations to high-quality partners. However, most mutualists either simultaneously or sequentially associate with multiple partners that confer the same type of reward. By viewing mutualisms through the lens of niche breadth evolution, we outline how the environment shapes partner availability and relative quality, and ultimately a focal mutualist's partner breadth. We argue that mutualists that associate with multiple partners may have a selective advantage compared to specialists for many reasons, including sampling, complementarity, and portfolio effects, as well as the possibility that broad partner breadth increases breadth along other niche axes. Furthermore, selection for narrow partner breadth is unlikely to be strong when the environment erodes variation in partner quality, reduces the costs of interacting with low-quality partners, spatially structures partner communities, or decreases the strength of mutualism. Thus, we should not be surprised that most mutualists have broad partner breadth, even if it allows for ineffective partners to persist.

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Interspecific hybridization and bioactive alkaloid variation increases diversity in endophyticEpichloëspecies ofBromus laevipes

Cited by 57 publications

References 64 publications

Disparate Independent Genetic Events Disrupt the Secondary Metabolism Gene perA in Certain Symbiotic Epichloë Species

Disparate Independent Genetic Events Disrupt the Secondary Metabolism Gene perA in Certain Symbiotic Epichloë Species

Detection and Isolation of Epichloë Species, Fungal Endophytes of Grasses

Using niche breadth theory to explain generalization in mutualisms

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