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Journal ArticleDOI

Ryegrass Host Genetic Control of Concentrations of Endophyte-Derived Alkaloids

01 Jan 2002-Crop Science (Crop Science Society of America)-Vol. 42, Iss: 1, pp 51-57
TL;DR: Host plant selection may enable development of pastures with controlled low levels of toxic but ecologically beneficial endophyte metabolites, and little interaction between loci, and no directional dominance were indicated.
Abstract: Endophytic fungi in pasture grasses produce alkaloids which affect invertebrate and vertebrate herbivores. While the competence to produce an alkaloid is a property of the fungus, the host plant may moderate fungal activity. Host genetic influence on endophyte activity was studied in perennial ryegrass (Lolium perenne L.) infected with a common strain of Neotyphodium lolii (Latch, Christensen & Samuels) Glenn, Bacon & Hanlin. Progeny seedling families of a partial diallel cross and their 12 parent clones were compared in a glasshouse experiment. Peramine and ergovaline concentrations were determined by high pressure liquid chromatography (HPLC), and intensity of endophyte infection was determined by enzyme-linked immunosorbent assay (ELISA). Concentrations of peramine and ergovaline and the amount of endophyte mycelium in plants varied between families, consistently across two glasshouse cells and (for the HPLC data) two harvests. There was no indication of any maternal effects. Host genetic control was evident in significant general combining ability effects and smaller specific combining ability effects. Parent-progeny correlation coefficients were high, and narrow-sense heritability was estimated as 0.70, 0.72, and 0.58 respectively for ergovaline, peramine, and ELISA. Further analysis indicated little interaction between loci, and no directional dominance. The three traits were correlated, indicating that 41 and 65% of the genetically controlled variation in ergovaline and peramine concentrations, respectively, was a function of mycelial mass. However, there were departures from these relationships. Host plant selection may enable development of pastures with controlled low levels of toxic but ecologically beneficial endophyte metabolites.
Citations
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Journal ArticleDOI
TL;DR: This review weaves together the different strands of multidisciplinary research aimed at ultimately exploiting epichloae endophytes for increased pasture performance.
Abstract: Epichloae endophytes of family Clavicipitaceae (comprising genera Epichloe and Neotyphodium) are fungal symbionts of Pooideae grasses. The associations formed, range from mutually beneficial to antagonistic and the nature of this relationship is dependent upon the importance of vertical (via host seeds) versus horizontal (ascospore mediated) transmission of the fungus. These endophytes can enhance their hosts’ survival through protection from abiotic and biotic stresses and can thus be utilized in an agricultural context. Animal-safe grass-endophyte associations that confer bio-protective properties for increased pasture persistence and productivity have been developed and commercialized. One of the crucial drivers underpinning the selection of epichloae strains for commercial development is endophyte derived bioactivity. The potential of next generation endophytes is determined by testing a number of attributes such as agronomic fitness, animal and food safety as well as compatibility with host plants of interest. Strategic research supports these activities by focusing on elucidating mechanisms of compatibility between host and fungal symbiont, as well as investigating other molecular drivers of symbiosis such as siderophore mediated iron-uptake, fungal signalling, fungal growth in host plants and fungal secondary metabolism. This review weaves together the different strands of multidisciplinary research aimed at ultimately exploiting epichloae endophytes for increased pasture performance.

238 citations


Cites background from "Ryegrass Host Genetic Control of Co..."

  • ...The genetics of the novel host may result in a fungal alkaloid output that differs from that observed in the native host (Easton et al. 2002)....

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Journal ArticleDOI
TL;DR: This work proposes a mutualism-parasitism continuum for the symbiosis between asexual endophytes and grasses, which is similar to the associations between plants and mycorrhizal fungi.

212 citations

Journal ArticleDOI
TL;DR: The results stress the need for wider quantification of fungal endophytes in the grassland-foliar endophyte context, and have implications for how introducing new cultivars, novelendophytes or increasing N inputs affect the role of endophyts in grassland ecosystems.
Abstract: Summary • The relationship between cool-season grasses and fungal endophytes is widely regarded as mutualistic, but there is growing uncertainty about whether changes in resource supply and environment benefit both organisms to a similar extent. • Here, we infected two perennial ryegrass (Lolium perenne) cultivars (AberDove, Fennema) that differ in carbohydrate content with three strains of Neotyphodium lolii (AR1, AR37, common strain) that differ intrinsically in alkaloid profile. We grew endophyte-free and infected plants under high and low nitrogen (N) supply and used quantitative PCR (qPCR) to estimate endophyte concentrations in harvested leaf tissues. • Endophyte concentration was reduced by 40% under high N supply, and by 50% in the higher sugar cultivar. These two effects were additive (together resulting in 75% reduction). Alkaloid production was also reduced under both increased N supply and high sugar cultivar, and for three of the four alkaloids quantified, concentrations were linearly related to endophyte concentration. • The results stress the need for wider quantification of fungal endophytes in the grassland–foliar endophyte context, and have implications for how introducing new cultivars, novel endophytes or increasing N inputs affect the role of endophytes in grassland ecosystems.

207 citations


Cites background from "Ryegrass Host Genetic Control of Co..."

  • ...Differences in infection rates and alkaloid concentrations between cultivars (indeed, between individual genotypes) are known to exist (Easton et al., 2002; Faeth et al., 2006), suggesting strong host × endophyte specificities (Cheplick & Cho, 2003; Saikkonen et al....

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Journal ArticleDOI
TL;DR: It is proposed that endophyte-grass symbiosis provides an excellent model to study microbially mediated multirophic interactions from molecular mechanisms to ecology, and joint approaches of (bio)chemists, molecular biologists, plant physiologists, evolutionary biologists, and ecologists are urgently needed.
Abstract: Defensive mutualism is widely accepted as providing the best framework for understanding how seed-transmitted, alkaloid producing fungal endophytes of grasses are maintained in many host populations. Here, we first briefly review current knowledge of bioactive alkaloids produced by systemic grass-endophytes. New findings suggest that chemotypic diversity of the endophyte-grass symbiotum is far more complex, involving multifaceted signaling and chemical cross-talk between endophyte and host cells (e.g., reactive oxygen species and antioxidants) or between plants, herbivores, and their natural enemies (e.g., volatile organic compounds, and salicylic acid and jasmonic acid pathways). Accumulating evidence also suggests that the tight relationship between the systemic endophyte and the host grass can lead to the loss of grass traits when the lost functions, such as plant defense to herbivores, are compensated for by an interactive endophytic fungal partner. Furthermore, chemotypic diversity of a symbiotum appears to depend on the endophyte and the host plant life histories, as well as on fungal and plant genotypes, abiotic and biotic environmental conditions, and their interactions. Thus, joint approaches of (bio)chemists, molecular biologists, plant physiologists, evolutionary biologists, and ecologists are urgently needed to fully understand the endophyte-grass symbiosis, its coevolutionary history, and ecological importance. We propose that endophyte-grass symbiosis provides an excellent model to study microbially mediated multirophic interactions from molecular mechanisms to ecology.

168 citations


Cites background from "Ryegrass Host Genetic Control of Co..."

  • ...Endophytes also may alter amount of available nutrients, sugars, and water, which also affect herbivore fitness (Agee and Hill 1994; Easton et al. 2002; Latch 1994; Leuchtmann et al. 2000; Liu et al. 2011; Rasmussen et al. 2007, 2012; Vázquez de Aldana et al. 2009)....

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Journal ArticleDOI
TL;DR: Two schemes for implementing genomic selection in ryegrass breeding are described, which allow two rounds of selection for key agronomic traits within a time period previously required for a single round, and incorporate recent advances in DNA sequencing technology to minimize costs.
Abstract: Genomic selection (GS) is a powerful method for exploitation of DNA sequence polymorphisms in breeding improvement, through the prediction of breeding values based on all markers distributed genome-wide. Forage grasses and legumes provide important targets for GS implementation, as many key traits are difficult or expensive to assess, and are measured late in the breeding cycle. Generic attributes of forage breeding programmes are described, along with status of genomic resources for a representative species group (ryegrasses). Two schemes for implementing GS in ryegrass breeding are described. The first requires relatively little modification of current schemes, but could lead to significant reductions in operating cost. The second scheme would allow two rounds of selection for key agronomic traits within a time period previously required for a single round, potentially leading to doubling of genetic gain rate, but requires a purpose-designed reference population. In both schemes, the limited extent of linkage disequilibrium (LD), which is the major challenge for GS implementation in ryegrass breeding, is addressed. The strategies also incorporate recent advances in DNA sequencing technology to minimize costs.

110 citations

References
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Journal ArticleDOI
01 Nov 1954-Genetics
TL;DR: The purpose of this article is to study more general genetic systems using new methods and more generations and an investigation of gene correlation in the parents together with some consideration of linkage and parental heterozygosity.
Abstract: HE investigation of the properties of groups of homozygous lines by means T of diallel crosses as proposed by HULL (1945) has subsequently been discussed in growing detail in a series of papers by JINKS and HAYMAN (1953 and later). With certain assumptions, the genetic variation present can be described in terms of the biometrical concepts of MATHER (1949) and accurate estimates obtained of the additive, dominance and environmental components. The distribution of genes in the parents is also revealed. The important result of these papers is that the diallel table of results can be tested (by the uniformity of Wr-V,) for conformity to the biometrical model before applying the model to the description of the genetic variation present. The genetic systems controlling many characters do not fit this simple model and it is the purpose of this article to study more general genetic systems using new methods and more generations. This paper concerns parental, F, and F, data and contains an investigation of gene correlation in the parents together with some consideration of linkage and parental heterozygosity. Data from diallel crosses in maize and cotton will be discussed by kind permission of those who conducted the experiments. Reference to HAYMAN (1954b) is by section number prefixed by H.

1,126 citations


"Ryegrass Host Genetic Control of Co..." refers background or methods in this paper

  • ...endophyte mycelium as indicated by ELISA, and this Extending the diallel analysis (Hayman, 1954), the reresult was consistent over harvests (in the case of the gression of array covariance (Wr) on variance (Vr) was alkaloids) and glasshouses (Table 1)....

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  • ...68 Extended diallel analysis (Hayman, 1954) indicated that 53 30....

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  • ...included in further analysis of the diallel to test hypotheses A perennial ryegrass plant grown from seed accessed from of gene action (Hayman, 1954)....

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Journal ArticleDOI
01 Apr 1956-Heredity
TL;DR: This paper is an attempt to give a generalised treatment of the major problems which occur with the use of Diallel crosses, to integrate wherever possible the already existing techniques, and to show the relationship of the diallel crossing method to Fisher's method of covariances between relatives as expressed in terms of additive and non-additive genetic variances.
Abstract: IN problems of quantitative inheritance it has been customary to make genetic analysis of populations using covariances between relatives, the method outlined in the classical paper by Fisher (1918). Associated with this approach is the notion of partitioning the total genotypic variance into additive and non-additive genetic components. The importance of this treatment of quantitative inheritance to the genetical theory of natural selection has been made clear by Fisher (1930), and the practical applications of these concepts to plant and animal improvement have been increasingly realised. In recent years techniques involving \"diallel crosses\" have been used in problems which concern quantitative inheritance. The methods used and problems attacked by this technique have been diverse. Sprague and Tatum (1942), Henderson (1948, 1952), and Griffing (i) have defined and applied the notions of general and specific combining ability to plant and animal experimental material using a variety of diallel crossing methods, but without an exact generalised genetic interpretation of the combining ability effects and variances. Hull (1946, 1952), Griffing (1950), Jinks (i4) and Hayman (I9Ma, i954b), again using diallel crossing systems, have given procedures for estimating other genetic parameters in terms of restricted gene models. The present paper is an attempt to give, in terms of population genetics, a generalised treatment of the major problems which occur with the use of diallel crosses, to integrate wherever possible the already existing techniques, and to show the relationship of the diallel crossing method to Fisher's method of covariances between relatives as expressed in terms of additive and non-additive genetic variances. We shall use the term \"diallel crosses\" to describe a procedure in which a set of p inbred lines are chosen and crosses among these lines are made. There are a maximum of p2 possible crosses, which can be represented by a p xp matrix with elements x such that x,, represents the jth inbred, x (i +j) represents the F1 between the i' z and jth inbreds, and x represents its reciprocal. Thus, the p2 combinations can be divided conveniently into three groups: (i) the p inbreds themselves; (2) one group OfP(P—') F1's; () a group of

484 citations


"Ryegrass Host Genetic Control of Co..." refers background in this paper

  • ...Finally, data were studied to determine genetic control of host plant effects analyzed by the diallel analysis (Griffing, 1956), with both and their relation with intensity of mycelial infection....

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Journal ArticleDOI
TL;DR: Five endophytic fungi isolated from Lolium perenne, including Acremonium loliae and a Gliocladium-like sp.
Abstract: SUMMARY The endophytic fungi Acremonium loliae and a Gliocladium-like sp. were isolated from Lolium perenne; A. coenophialum and a Phialophora-like sp. from Festuca arundinacea; and Epichloe typhina from F. rubra. All five fungi infected endophyte-free seedlings of the host grasses and F. arundinacea after artificial inoculation. All fungi except A. coenophialum were able to infect L. perenne. The inoculation technique involved placing endophyte mycelium into the coleoptile tissue of sterile seedlings growing on water agar in Petri dishes. Infection of mature plants with endophytes was not achieved. The presence of some endophytes in grasses can be beneficial to plant growth and persistence but deleterious to the health of animals which graze them. The desirability of infecting cultivars of grasses with endophytes is discussed.

321 citations


"Ryegrass Host Genetic Control of Co..." refers background or methods in this paper

  • ...isolated from host tissue and in January 1993 was inoculated Heritability coefficients (narrow sense, h) were calculated (Latch and Christensen, 1985) into endophyte-free seedlings from the analysis of variance tables, assuming no epistasis, of the New Zealand cultivar Grasslands Nui (Armstrong, as additive genetic variance ( A) divided by the sum of addi1977)....

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  • ...However, presence of endophyte in ryenatural hosts and inserted into different host populagrass pastures adversely affects the health and perfortions (Latch and Christensen, 1985), and maintain the mance of grazing livestock (Fletcher and Easton, 1997)....

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Journal ArticleDOI
TL;DR: The assignment of structure (1) to the major neurotoxin, lolitrem B, is based on its spectroscopic properties, particularly a detailed structure of its high-field 1H and 13C n.m.r. spectra, as well as chemical evidence.
Abstract: The lolitrems, tremorgenic neurotoxins from perennial ryegrass, are implicated in ryegrass staggers disorder in livestock; the assignment of structure (1) to the major neurotoxin, lolitrem B, is based on its spectroscopic properties, particularly a detailed structure of its high-field 1H and 13C n.m.r. spectra, as well as chemical evidence.

214 citations


"Ryegrass Host Genetic Control of Co..." refers background in this paper

  • ...Lolitrem B (1994) found 10-fold variation in ergovaline concentra(Gallagher et al., 1984), an indole-diterpenoid, is a neurotion of 19 perennial ryegrass genotypes (from one poputoxic tremorgen, primarily responsible for ryegrass staglation) infected with the same endophyte....

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Journal ArticleDOI
TL;DR: The benefits in yield and protection from damage by Argentine stem weevil from A. loliae-infected ryegrasses are discussed in relation to the known risk of ill-health in animals grazing infected pastures.
Abstract: Clones of Lolium perenne L. ‘Grasslands Nui’ perennial ryegrass, either infected with or free from Acremonium loliae Latch, Christensen & Samuels, and clones of ‘Grasslands Ruanui’ perennial ryegrass, either infected with or free from a Gliocladium-like endophyte, were grown at 20°C for 8 weeks in a controlled-environment room. Nui plants infected with A. loliae yielded 38% more total dry matter than uninfected plants. Infected plants showed significant increases in total leaf area, tiller numbers, and growth of leaves, pseudo stems, and roots, but the shoot: root ratio was unaffected. Infection of Ruanui with the Gliocladium-like sp. had no significant effect on yield even though total leaf area was reduced by 19%. The benefits in yield and protection from damage by Argentine stem weevil from A. loliae-infected ryegrasses are discussed in relation to the known risk of ill-health in animals grazing infected pastures.

202 citations


Additional excerpts

  • ...directly enhance host plant growth (Latch et al., 1985)....

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