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1.
Neotyphodium sp. Lp1, an endophytic fungus from perennial ryegrass (Lolium perenne), produces the mycotoxin ergovaline in infected grasses, whereas a mutant in which a particular peptide synthetase gene is knocked out does not. We examined the impact of this knockout on other constituents of the ergot alkaloid pathway. Two simple lysergic acid amides, ergine and a previously undescribed amide, were eliminated by the knockout. Lysergic acid accumulated in the knockout endophyte, but quantities were only 13% of the total lysergic acid derivatives accumulated in the wild type. Concentrations of several clavines were not substantially affected. However, a novel clavine accumulated to higher concentrations in perennial ryegrass containing the knockout strain. The results indicate that production of simple lysergic acid amides requires the activity or products of the ergovaline-associated peptide synthetase and that the regulation of ergot alkaloid production is modified in response to the relatively late block in the pathway.  相似文献   

2.
Tall fescue (Schedonorus arundinaceous (Schreb.)) is often infected with a common toxic fungal endophyte (Neotyphodium coenophialum) capable of producing alkaloids that affect grazing animal health, insect herbivory, plant production, and litter decomposition. The strength of these endophyte-associated effects is thought to depend on the abiotic and biotic conditions of a specific site. Prior work from Georgia, USA, has demonstrated that fungal endophyte infection can increase soil carbon pools of tall fescue pastures; however, for endophyte infection to contribute substantially to regional carbon sequestration, this result would have to hold true across the broad range of environmental conditions that support tall fescue growth. In this study, we evaluated whether endophyte infection consistently alters various soil parameters, including carbon storage, of tall fescue stands located throughout the southeastern United States. Soil samples were collected from nine sites with established paired high- and low- endophyte-infected tall fescue stands. These samples were analyzed for basic soil parameters, soil organic carbon (SOC), soil total nitrogen (TN), particulate and non-particulate organic matter-C and -N (POM, n-POM), C and N mineralization rates, and microbial biomass and community composition. Averaged across all sites, endophyte-infected tall fescue stands had 6% greater SOC and 5% greater TN pools in surface soil than adjacent endophyte-free stands. The lack of a significant interaction between site and endophyte infection status indicated that this result was relatively consistent across sites, despite differences in stand age, climate, and other environmental conditions. While POM C and POM N tended to be higher in endophyte-infected than endophyte-free stands, this result was not significant. However, greater pools of n-POM C and N were observed in endophyte-infected vs. endophyte-free stands when averaged across all the sites, suggesting increased retention of recalcitrant substrates occurred in response to fungal endophyte infection. Total microbial biomass, measured via phospholipid fatty acid (PLFA) analysis, was greater in endophyte-infected than endophyte-free soils when averaged across sites, reflecting the trends observed with SOC and TN. Microbial community composition shifted somewhat in response to fungal endophyte infection: significantly higher fungal to bacterial ratios were observed in endophyte-free compared to endophyte-infected stands. However, ordinations of the PLFA data demonstrated only slight separation of endophyte-infected and endophyte-free microbial communities at some sites and no clear separation at others. Enhanced SOC, TN, recalcitrant n-POM C and N pools, and altered microbial biomass and communities suggest that this aboveground fungal endophyte symbiosis has widespread effects on soil biology and biochemistry, and that high prevalence of the aboveground endophyte increases C sequestration capacity of tall fescue stands throughout the southeastern USA.  相似文献   

3.
ABSTRACT

An experiment was conducted to evaluate the effect of endophyte Neotyphodium coenophialum (Morgan-Jones and Gams) Glenn, Bacon, and Hanlin on the mineral content of tall fescue (Lolium arundinaceum Schreb., SJ Darbyshire) ecotypes (Fukaura, Koiwai, and Showa) grown on two Andisols (Black Andisol and Red Andisol) with different fertilities. Black Andisol, with a naturally low content of phosphorus, was high in other nutrients, while Red Andisol, with a naturally high content of phosphorus, was low in other nutrients. Shoot dry weight was significantly higher in endophyte-infected (E+) than endophyte-free (E?) plants grown in Black Andisol. On the other hand, in Red Andisol, only Fukaura showed higher shoot dry matter production in E+ plants as compared to E- plants. In general, greater concentrations of phosphorus and manganese were found in endophyte-infected (E+) plants than non-infected (E?) plants. Accumulation of all nutrients in E+ plants was remarkably higher than in E? plants. Excluding the plant ecotype effect, the nutrient concentration and accumulation pattern for plants in the two soils was different in E+ and E? plants. Plants growing in Black Andisol had greater concentrations of phosphorus (P), copper (Cu), and zinc (Zn) in E+ plants than those of E? plants whereas for plants in Red Andisol the reverse was true. Significantly higher concentration of manganese (Mn) was found in E+ plants irrespective of soils. Regardless of endophyte and ecotypes, plants grown in Black Andisol showed significantly higher values for both nutrient concentration and accumulation than those in Red Andisol. Apart from the plant ecotype Showa, all other ecotypes had the greatest accumulation and concentration of phosphorus in E+ plants. In two types of soil and among the three plant ecotypes, endophyte infection had different effects on nutrients acquisition. Giving emphasis on nutrient accumulation, endophyte played an overall negative role on plants grown in Red Andisol. There may be a metabolic cost of harboring endophytes offset its benefit in Red Andisol. Since the same species of endophyte infected all three ecotypes, our results show that the host/endophyte interaction depends on plant ecotype as well as the ability of the soil to supply nutrients.  相似文献   

4.
Experimental cultivars of the pasture grass tall fescue are infected with unique strains of the fungal endophyte Neotyphodium coenophialum, which produce low concentrations of ergot alkaloids. A rat model was evaluated as a tool for rapid, initial screening of experimental cultivars considered to be nontoxic. Rats were fed diets that included seed from experimental cultivars of tall fescue with introduced strains of N. coenophialum and a toxic control diet containing seed of the cultivar Kentucky 31 (KY31), with its endemic strain of N. coenophialum. Rats were preconditioned to a nontoxic diet and then fed treatment diets for 13 days with 5 days at thermoneutrality (21 degrees C) followed by 8 days under heat stress (31 degrees C). For most of the 13-day treatment period, rats fed KY31 exhibited depressed daily intake compared to those fed diets of cultivars with introduced endophytes (P < 0.05). In addition, rats fed KY31 exhibited significantly less weight than rats on other diets after heat treatment was imposed. For all initial trials and repeated trials, total intake and total gain calculated at the end of each trial were the most consistent indicators of toxicity.  相似文献   

5.
Neotyphodium coenophialum, (Morgan‐Jones & Gams) Glenn, Bacon & Hanlin, infected tall fescue (Festuca arundinacea Schreb.) plants perform better than non‐infected isolines on phosphorus (P)‐deficient soils. Our objective was to characterize growth and P uptake dynamics of tall fescue in response to endophyte infection and P source at low P availability in soil. Two tall fescue genotypes (DN2 and DN4) infected with their naturally occurring N. coenophialum strains (E+), and in noninfected (E‐) forms were grown in Lily soil (fine loamy siliceous, mesic Typic Hapludult) in a greenhouse for 20 weeks. Three soil P treatments were imposed: no P supplied (control) and P supplied as commercial fertilizer (PF) or as phosphate rock (PR) at the level of 25 mg P kg‐1 soil. Interaction of tall fescue genotype and endophyte status had a significant influence on mineral element uptake suggesting high specificity of endophyte‐tall fescue associations. Endophyte infection did not affect root dry matter (DM) when no P was supplied but shoot DM was reduced by 20%. More biomass was produced and greater P uptake rate occurred in PR than PF treatment. Root DM was greater in E+ DN4 than E‐DN4 when supplied with either PF or PR. In contrast, endophyte infection did not affect root DM of DN2, regardless of P source. Relative growth rate (RGR) of E+ plants grown with PR was 16% greater than that of E‐plants. Endophyte infection did not improve growth or P uptake in PF treatment. When PR was supplied, P uptake rate was 24% greater in E+ DN2 than E‐ DN2, but endophyte infection did not benefit DN4. Phosphorus‐use efficiency was 6% less in E+ DN2 but 16% greater in E+ DN4 compared to E‐ plants, regardless of P source. Root exudates of E+ DN2, but not E+ DN4 solubilized more P from PR than those of E‐ plants. The correlation between root RGR and P uptake rate was relatively high for E‐ plants (r=0.76), but low for E+ plants (r=0.27) grown with PR. Results suggest that P uptake by E+ tall fescue might rely on mechanisms other than an increase in root biomass (surface area). Endophyte infection modified tall fescue responses to P source. This phenomenon was associated with modes of P acquisition which included enhanced activity of root exudates in releasing P from PR in E+ plants (DN2), and increased root biomass (DN4). The dominant means of P acquisition may be determined by a specific association of endophyte and tall fescue genomes. Endophyte‐tall fescue association plasticity contributes to widespread success of symbiotic in marginal resource conditions.  相似文献   

6.
Ergot alkaloids are known toxic secondary metabolites of the fungus Claviceps purpurea occurring in various grains, especially rye products. The liver is responsible for converting the ergot alkaloids into metabolites; however, the toxic impact of these end products of metabolism is still unknown. The aim of this study was to analyze the metabolism of ergot alkaloids in colon and liver cell lines (HT-29, HepG2), as well as in human primary renal cells (RPTEC). It was shown that cells in vitro are able to metabolize ergot alkaloids, forming a variety of metabolic compounds. Significant differences between the used cell types could be identified, and a suitable model system was established using HT-29 cells, performing an intensive metabolism to hydroxylated metabolites. The formed substances were analyzed by coupling of high-performance liquid chromatography with fluorescence detection and Fourier transformation mass spectrometry (HPLC-FLD-FTMS) as a powerful tool to identify known and unknown metabolites.  相似文献   

7.
Liquid chromatographic determination of ergot alkaloids in wheat   总被引：1，自引：0，他引：1  
A method is described for the determination of individual ergot alkaloids in wheat. The sample is extracted with ethyl acetate-4% ammonium hydroxide (100 + 10), and the extract is cleaned up by liquid-liquid partition. The ergot alkaloids are resolved by liquid chromatography (LC), using a porous cross-linked polystyrene-divinylbenzene resin column and a mobile phase consisting of acetonitrile-0.05 M dibasic ammonium phosphate (55 + 45) buffered at pH 10.0. The ergot alkaloids ergonovine, ergonovinine, ergotamine, ergotaminine, alpha-ergocryptine, alpha-ergocryptinine, ergocristine, and ergocristinine are separated by LC and detected with a fluorescence detector. Recovery of ergot alkaloids added to wheat at levels of 16-760 ng/g averaged 85.6% with a coefficient of variation of 11.1%.  相似文献   

8.
Neotyphodium coenophialum-infected tall fescue contains ergopeptines. Except for interactions with biogenic amine receptors (e.g., dopamine type-2 receptor, D2R), little is known about how ergopeptines affect animal metabolism. The effect of ergopeptines on bovine nucleoside transporters (NT) was evaluated using Madin-Darby bovine kidney (MDBK) cells. Equilibrative NT1 (ENT1)-like activity accounted for 94% of total NT activity. Inhibitory competition (IC(50)) experiments found that this activity was inhibited by both bromocriptine (a synthetic model ergopeptine and D2R agonist) and ergovaline (a predominant ergopeptine of tall fescue). Kinetic inhibition analysis indicated that bromocriptine inhibited ENT1-like activity through a competitive and noncompetitive mechanism. Domperidone (a D2R antagonist) inhibited ENT1 activity more in the presence than in the absence of bromocriptine and displayed an IC(50) value lower than that of bromocriptine or ergovaline, suggesting that inhibition was not through D2R-mediated events. These novel mechanistic findings imply that cattle consuming endophyte-infected tall fescue have reduced ENT1 activity and, thus, impaired nucleoside metabolism.  相似文献   

9.
Roots of endophyte‐infected (E+) tall fescue (Festuca arundinacea Schreb.) exude more phenolic‐like reductants than roots of endophyte‐free (E‐) plants when mineral stressed. Phenolic compounds are efficient chelators of aluminum (Al) and may influence Al tolerance in many plant species. The objective of our study was to determine if enhanced release of phenolic compounds by roots of E+ plants contributes to Al tolerance in tall fescue. Two cloned genotypes (DN2 and DN11) of tall fescue infected with their naturally occurring fungal endophyte Neotyphodium coenophialum (Morgan‐Jones and Gams) Glenn, Bacon and Hanlin and their noninfected isolines were grown in nutrient solutions at 0 μM Al (Al‐) and at 640 μM Al (Al+) under controlled environment conditions. Root and shoot dry matter (DM) of endophyte‐infected tall fescue was greater in E+ than E‐ plants by 57% and 40%, respectively, when plants were grown without Al. Endophyte infection did not affect root and shoot DM of tall fescue grown with Al but relative (to Al‐treatment) reduction in root and shoot DM was greater in E+ than E‐ plants. In response to Al stress, more Al (47%) and P (49%) could be desorbed from root surfaces of E+ than E‐ plants. Aluminum concentrations in roots of E+ plants were 35% greater and P concentrations were 10% less than those determined in roots of E‐plants. No differences in mineral concentrations were observed in shoots, regardless of endophyte status, or Al level in nutrient solution. Roots of E+ plants increased pH of both Al‐ and Al+ nutrient solutions to a greater extent than roots of E‐ plants in a 48 h interval. Our results show that more Al can be sequestered on root surfaces and in root tissues of endophyte‐infected tall fescue than in plants devoid of endophyte. Aluminum sequestration was greater on root surfaces and in root tissues of E+ than E‐ plants of a given tall fescue genotype. Our results suggest that increased exudation of phenolic‐like compounds from roots of endophyte‐infected tall fescue may be directly involved in Al tolerance and serves as a mechanism for widespread adaptability and success of endophyte‐tall fescue associations.  相似文献   

10.
Infection with Neotyphodium spp. endophytes increases resistance to drought stress and soil mineral imbalances in tall fescue (Festuca arundinacea Schreb. = Lolium arundinaceum (Schreb.) S. J. Darbysh.) and meadow fescue (Festuca pratensis Huds. = Lolium pratense (Huds.) Darbysh.). We hypothesized that resistance of these grasses to salinity stress may also be attributed to endophyte infection. Two tall fescue genotypes, Fa75 and Fa83, and one meadow fescue genotype, Fp60, infected (E+) with their endophytic fungi, Neotyphodium coenophialum (Glenn, Bacon and Hanlin) and N. uncinatum (Glenn, Bacon and Hanlin), respectively, and their noninfected counterparts (E–) were cultured in nutrient solution at three salinity levels of 0, 85, and 170 mM NaCl. Except for genotype Fa75, E+ plants exhibited higher leaf survival rates than E– clones at a high salinity level (170 mM). Root dry matter was higher in E+ than in E– plants, but shoot dry matter was not affected by endophyte infection. This resulted in a lower shoot‐to‐root ratio in E+ plants (1.63) compared with E– plants (2.40). Sodium (Na+) and chloride (Cl–) concentrations were greater in roots of E– than in E+ clones. In shoots, Na+ and Cl– concentrations were not affected by the endophyte. In contrast, E+ plants accumulated more potassium (K+), which resulted in a greater K+ : Na+ ratio in shoots of E+ than in those of E– plants. Our results show that endophyte infection reduced Na+ and Cl– concentrations in tall fescue and meadow fescue roots but increased K+ concentrations in the shoots. Based on these results, we conclude that endophyte‐infected grasses may thrive better in salinity‐stress environments.  相似文献   

11.
The effect of infection by vesicular-arbuscular mycorrhiza on the predictive value of soil analysis for available P was tested in a glasshouse experiment. Leeks (Allium porrum) were grown on ten Rothamsted soils with a wide range of initial NaHCO3-soluble P, each of which also received 5 levels of added P. Soils were partially sterilized with 1 Mrad of γ-radiation, or left untreated; plants on sterilized soil were infected with yellow-vacuolate endophyte (Glomus mosseae) or left non-mycorrhizal. The NaHCO3-soluble P in the soils was measured 5 days after phosphate addition. Yields from all P levels on all soils were plotted against soil NaHCO3-soluble P content and separate smooth response curves were obtained for non-infected and artificially-infected plants. Infection increased yield only on soils with less than 100 mg P kg?1. In contrast, naturally-infected plants gave no clearly defined response curve to P, and on three soils the yields were consistently low. These soils gave very low natural infections and had low spore densities probably due to the cropping history of the sites. Artificially-infected plants had much higher shoot P concentrations than did uninfected plants of similar dry weight, over a large range of soil phosphate levels; this effect was also noted with the endophyte G. fasciculatus. Naturally-infected plants showed a poor relationship between shoot P concentration and yield.  相似文献   

12.
We investigated the role of gibberellins-producing endophyte Penicillium janthinellum LK5 associated with Solanum lycopersicum (host), abscisic acid (ABA)-deficient tomato mutant Sitiens and its wild-type Rheinlands Ruhm (Rhe) plants under cadmium (Cd) stress. A 100-μM Cd application to host, Sitiens and Rhe reduced the shoot growth, chlorophyll content and stomatal conductance. However, these parameters were significantly (P?<?0.0011) higher (1.0- to 2.6-folds) in host, Sitiens and Rhe under endophytic association than in non-endophyte infected plants (control) under Cd stress. Furthermore, endophytic association minimized the Cd-induced membrane injury and oxidative stress to host, Sitiens and Rhe plants by reducing electrolytes and lipid peroxidation while increasing the content of reduced glutathione and catalase activities as compared to non-endophyte-infected plants. Stress-responsive ABA content significantly increased (～2-folds) in Sitiens and Rhe under endophyte association, while in host plants it was decreased under Cd stress. Salicylic acid content was ～?1.7-fold higher in host, Sitiens and Rhe plants under Cd stress and endophyte association than in the control. Besides gibberellins production, the endophyte has the potential to solubilize phosphates (12.73?±?0.24 mg/l) since higher P was observed in the roots of Sitiens, Rhe and host plants. Similarly, nutrients like sulfur and calcium were more efficiently assimilated in roots of endophyte-associated plants than control under Cd stress. Conversely, Cd accumulation was significantly decreased (P?<?0.001) in the roots of endophyte-inoculated host, Sitiens and Rhe than control. In conclusion, endophyte symbiosis can counteract heavy metal stress which can exert negative effects on plant growth.  相似文献   

13.
Using HPLC-ESI-MS, several saturated and 1,2-dehydropyrrolizidine alkaloids were detected, mainly as their N-oxides, in fresh pollen collected from flowers of the pyrrolizidine alkaloid-producing plants Echium vulgare, E. plantagineum, Senecio jacobaea, S. ovatus, and Eupatorium cannabinum, and/or pollen loads from bees (bee pollen) that foraged on those plants. A major alkaloidal metabolite in S. ovatus was tentatively identified, using its mass spectrometric data and biogenic considerations, as the previously unreported, saturated alkaloid, 2-hydroxysarracine. Heating had very little effect on the 1,2-dehydropyrrolizidine alkaloids and their N-oxides from a variety of sources. Considered in conjunction with international concerns about the adverse effects of these alkaloids, the results strongly indicate a need for monitoring pollen supplies intended for human consumption, at least until conditions for processing and/or selection are clearly defined such as to significantly reduce the hepatotoxic (and potentially carcinogenic and genotoxic) pyrrolizidine alkaloid content of bee pollen.  相似文献   

14.
Locoweeds are defined as Astragalus and Oxytropis species that induce locoism due to the toxic alkaloid swainsonine. Swainsonine was detected in all parts of Astragalus lentiginosus and Astragalus mollissimus , with greater concentrations found in the aboveground parts. Undifilum oxytropis , a fungal endophyte responsible for the synthesis of swainsonine, was detected in all plant parts of A. lentiginosus and A. mollissimus. The amount of endophyte within a plant part does not always correspond to the concentration of swainsonine in the same part. Plants of A. mollissimus and A. lentiginosus can be divided into two chemotypes: those that contain swainsonine (>0.1%; chemotype 1) and those that contain little or no detectable swainsonine (<0.01%; chemotype 2). Chemotype 1 plants in both species had quantitatively higher amounts of endophyte compared to chemotype 2 plants. Swainsonine and endophyte amounts were not uniformly distributed within stalks of the same plant. For that reason, repeated sampling of stalks from the same plant during one growing season may provide misleading results. Sequence variants of U. oxytropis exist within populations of A. mollissimus, A. lentiginosus, and Oxytropis sericea and do not correlate with chemotype. These findings suggest several possible reasons for differential concentrations of swainsonine that will be tested in future work.  相似文献   

15.
Fusarium toxins, Alternaria toxins, and ergot alkaloids represent common groups of mycotoxins that can be found in cereals grown under temperate climatic conditions. Because most of them are chemically and thermally stable, these toxic fungal secondary metabolites might be transferred from grains into the final products. To get information on the commensurate contamination of various cereal-based products collected from the Czech retail market in 2010, the occurrence of "traditional" mycotoxins such as groups of A and B trichothecenes and zearalenone, less routinely determined Alternaria toxins (alternariol, alternariol monomethyl ether and altenuene), ergot alkaloids (ergosine, ergocryptine, ergocristine, and ergocornine) and "emerging" mycotoxins (enniatins A, A1, B, and B1 and beauvericin) were monitored. In a total 116 samples derived from white flour and mixed flour, breakfast cereals, snacks, and flour, only trichothecenes A and B and enniatins were found. Deoxynivalenol was detected in 75% of samples with concentrations ranging from 13 to 594 μg/kg, but its masked form, deoxynivalenol-3-β-d-glucoside, has an even higher incidence of 80% of samples, and concentrations ranging between 5 and 72 μg/kg were detected. Nivalenol was found only in three samples at levels of 30 μg/kg. For enniatins, all of the samples investigated were contaminated with at least one of four target enniatins. Enniatin A was detected in 97% of samples (concentration range of 20-2532 μg/kg) followed by enniatin B with an incidence in 91% of the samples (concentration range of 13-941 μg/kg) and enniatin B1 with an incidence of 80% in the samples tested (concentration range of 8-785 μg/kg). Enniatin A1 was found only in 44% of samples at levels ranging between 8 and 851 μg/kg.  相似文献   

16.
An improved extraction and cleanup procedure for quantitative analysis of ergovaline in Neotyphodium-infected grass tissues by high-performance liquid chromatography was developed, utilizing aqueous 2-propanol-lactic acid as extraction solvent. Losses of sample material and time requirements were significantly reduced, handling procedures simplified, and ergovaline and internal standard ergotamine recovered with similar efficiency from extracts. Analyses can be carried out on very small amounts (2-5 mg of dry weight) of samples and another endophyte-alkaloid, peramine, determined in the same extracts. Calibration curves with 2-propanol-lactic acid were linear over the range 0.004-0.938 microM ergovaline (= 2-500 ng/mL) in extracts, corresponding to 0.04-10 microg/g in samples. The distribution of ergovaline in the plant was extremely heterogeneous, indicating low in-planta mobility and strong regulation of accumulation by the internal plant environment. In contrast, peramine was much more uniformly distributed. These results clearly demonstrate very large differences in the tissue specificities of ergovaline and peramine.  相似文献   

17.
A greenhouse hydroponic experiment was conducted to study the effects of cadmium (Cd) on growth parameters of endophyte‐infected (EI) and endophyte‐free (EF) perennial ryegrass. The results showed that Cd stress (0.18 mM Cd) affected all measured plant parameters, regardless of whether they were endophyte‐infected or endophyte‐free. Endophyte infection enhanced tillering ability and reduced leaf elongation under conditions of Cd stress. Endophyte infection tended to reduce leaf and leaf‐sheath biomass of control plants (0 Cd), but tended to alleviate the detrimental effects of Cd regarding shoot biomass. As far as net–photosynthetic rate and maximal photochemical efficiency of photosystem II (Fv/Fm ratio) were concerned, no difference was observed between EI and EF leaves. Like other grasses, perennial ryegrass can accumulate Cd, and Cd concentrations in different organs were in the following order: root > sheath > leaf. Endophyte‐infected ryegrass accumulated more Cd than EF ryegrass, especially in the shoots.  相似文献   

18.
Following scientific risk assessments, several countries have imposed strict regulations on herbal medicines containing 1,2-dehydro-pyrrolizidine alkaloids. Using published data on the plants used in honey production, pyrrolizidine alkaloid-containing plants are shown in this review to represent a significant source of honey worldwide. This observation, honey consumption data, reported levels of pyrrolizidine alkaloids in honeys, and consideration of tolerable exposure levels determined for pyrrolizidine alkaloids in herbal medicines, leads to the conclusion that some honey is a potential threat to health, especially for infants and fetuses, and further investigation is warranted.  相似文献   

19.
Worldwide occurrence of mycotoxins in foods and feeds--an update   总被引：24，自引：0，他引：24  
In a review presented at the first FAO/WHO/UNEP Conference on Mycotoxins in 1977, the occurrence of aflatoxins, zearalenone, ochratoxin A, citrinin, trichothecenes, patulin, penicillic acid, and the ergot alkaloids was indicated to be significant in naturally contaminated foods and feeds. The information presented on aflatoxin contamination greatly exceeded that for all other mycotoxins combined. This study reviews the worldwide levels and occurrence of mycotoxins in various commodities since 1976. Comparatively few countries have lowered the acceptable levels for aflatoxins in susceptible commodities. However, intensified efforts are needed to establish control of aflatoxin levels in the global food supply, particularly in peanuts, tree nuts, corn, and animal feeds. Extensive deoxynivalenol (DON) contamination of grains, especially wheat, was demonstrated. Co-contamination of grains by Fusarium toxins, especially DON and nivalenol, with zearalenone to a lesser extent, was reported. However, more information on co-occurrence of Fusarium toxins in cereals should be developed. When contamination of feeds by ochratoxin A was significant, this toxin occurred in swine kidney and smoked meats in high levels. On the basis of occurrence and/or toxicity, patulin and penicillic acid contamination of foods does not appear to be of real concern. More recent developments suggest, however, that expanded monitoring studies of Alternaria toxins, moniliformin, citrinin, cyclopiazonic acid, penitrem A, and ergot alkaloids are indicated.  相似文献   

20.
Locoism is a toxic syndrome of livestock caused by the ingestion of a subset of legumes known as locoweeds endemic to arid and semiarid regions of the western United States. Locoweeds contain the toxic alkaloid swainsonine, which is produced by the endophytic fungi Undifilum species. Two chemotypes of plants can coexist within toxic populations of locoweeds: chemotype 1 plants are defined as individuals containing swainsonine concentrations greater than 0.01% and quantitatively greater amounts of Undifilum, while chemotype 2 plants are defined as individuals containing less than 0.01% swainsonine and quantitatively smaller amounts of Undifilum. To elucidate the mechanisms that govern chemotypes, the amount of Undifilum in seeds/embryos was manipulated, thus altering subsequent swainsonine concentrations in three locoweed species: Astragalus mollissimus, Astragalus lentiginosus, and Oxytropis sericea. Chemotype 1 seeds that were fungicide-treated or had the seed coat removed resulted in plants with swainsonine concentrations comparable to those in chemotype 2 plants. Conversely, embryos from seeds of chemotypes 1 and 2 that were inoculated with the endophyte resulted in plants with swainsonine concentrations comparable to those of chemotype 1 plants. This reproducible interconversion between the two swainsonine chemotypes suggests that the quantity of endophyte present in the seed at the time of germination is a key determinant of the eventual chemotype. Additionally, this is the first report of the inoculation of locoweeds with the endophyte Undifilum species.  相似文献   

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