196,528 research outputs found
Differences in ergot vulnerability among sorghum genotypes and the relationship between stigma receptivity and ergot vulnerability
No full textDue to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaves 116-121).Issued also on microfiche from Lange Micrographics.The arrival of sorghum ergot (Claviceps africana) to the Americas poses a new threat to sorghum production. Reported for the first time in Brazil in 1995, the disease quickly moved to North America in less than two years. By determining if there are differences in ergot vulnerability between and among types of sorghum germplasms, and determining the reasons for such differences, researchers might be able to develop more effective ergot control strategies, such as ergot resistant germplasm for the future. The objectives of this research were (1) to characterize the relative rate of ergot vulnerability of a set of publicly available and commercially used A, B, R-lines, and hybrids; (2) to determine the relationship between the duration of stigma receptivity and ergot vulnerability; and (3) to determine the stability of ergot resistance among the inbred lines and hybrids evaluated. Ergot vulnerability ratings were determined for twelve pairs of sorghum A/B-lines, twelve R-lines, and twelve hybrids at seven environments in four locations during 1998. A-lines were the most vulnerable to the disease, followed by hybrids, R-lines and B-lines. Variation in ergot vulnerability among types of sorghum germplasm was detected as well; however, all genotypes evaluated were vulnerable to the disease. To determine the relationship between stigma receptivity and ergot vulnerability, sixteen sorghum genotypes that resulted from crossing four sorghum B-lines in all possible combinations (n�� diallel) were evaluated. It was determined that stigma receptivity is not the only factor that influences ergot infection, since the data indicate that ovules no longer receptive to pollen can still be infected by ergot. Also, inconsistency across environments of the genetic effects related to the "resistance" of the genotypes evaluated, indicated a possible "pseudoresistance" mechanism that is operating accordingly to specific environmental conditions, which allow certain germplasms to escape disease infection
Epidemiological aspects of Claviceps africana, causal agent of Sorghum ergot
No full textSorghum ergot, caused by Claviceps africana Frederickson, Mantle & de Milliano, is a disease that affects non-fertilized ovaries in sorghum male-sterile plants and infects hybrids if there is pollen sterility at flowering time. Sphacelia containing macroconidia could play a role in the survival of the pathogen. This study developed risk assessment models and evaluated environmental conditions affecting viability of macroconidia and transition from sphacelial to sclerotial tissues. Effect of weather on ergot severity was evaluated under natural conditions (in monthly planting dates) in nine sorghum genotypes at College Station, Weslaco, Rio Bravo, and Celaya. Panicles were inoculated daily beginning at flower initiation with a suspension of 1.6 x 106 C. africana conidia ml-1. Weather triad values were used to identify weather parameters correlated with the disease. Ergot severity was statistically greater in A-lines than hybrids because of the possible interference of pollen on some dates. Celaya had the greatest amount of ergot in hybrids. A-line ATx2752 had the lowest average ergot severity throughout years, locations and planting dates, as did the hybrid NC+8R18. Maximum and minimum temperature had a negative correlation with ergot at Rio Bravo, College
Station and Weslaco, while at Celaya it was positive. The highest correlation was 7 to 9 days before initiation of flowering, suggesting that cooler temperatures during this period could cause male sterility. A-lines showed the same relationships between ergot and maximum and minimum temperatures after initiation of flowering. Minimum relative humidity had a positive correlation with ergot after initiation of flowering in both sorghum plant types. Sphacelia stored under cool temperatures (-3oC to 7oC) maintained conidial viability, and newly-formed sphacelia located on the sphacelia surface had the highest conidial viability. However, they show a greater viability reduction through time compared with conidia from older sphacelia, showing that conidial maturity can play a role in the survival of the conidia. Sphacelia on plants grown at 10oC, 20oC and 30oC with low relative humidity did not had any sclerotial development up to 4 weeks after formation of sphacelia. However, higher temperatures promoted an increase in the sphacelia dry weight during that time
The evaluation of sorghum contaminated with ergot on broiler chicken performance
No full textDue to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaves 53-55).Issued also on microfiche from Lange Micrographics.The objective of these four experiments was to conduct an evaluation of the performance of broiler chickens fed sorghum contaminated with ergot sphacelia/sclerotia of Claviceps africana present in tailings removed by conditioning of seed from grain sorghum hybrid seed production gelds near Uvalde (Experiments 1 and 2) and Dumas (Experiments 3 and 4), Texas. Percentage of sphacelia/sclerotia and total alkaloid content, respectively, in the sorghum contaminated with ergot tailings were 8% and 11.3 ppm for Uvalde, and 75% and 235 ppm for Dumas in Experiment 3. Total alkaloid content in the extracted Dumas sample in Experiment 4 was 266.9 ppm. All diets were based on the NRC (1994) requirements for broilers. Hatch to 3-week-old male broilers in Experiment 1 fed sorghum contaminated with ergot showed significant reduction in growth at week three. Relative liver weights in ergot fed birds were significantly greater than control. Hatch to 6-week-old straight-run broilers in Experiment 2 were raised on a three-phase feeding program. Sorghum contaminated with ergot significantly reduced growth in broilers at Weeks 4, 5, and 6. Feed conversion was significantly reduced during all three phases of feeding. In Experiment 3, control sorghum and the 75% ergot tailings were added to corn-soy basal diets at 2.5, 5, and 10% by weight. These male chicks were fed from hatch to 3-weeks of age. Sorghum contaminated with ergot did not significantly reduce growth, but, during Weeks 2 and 3, feed conversions were significantly higher. Neither type nor concentration of sorghum contaminated with ergot significantly affected relative liver weights. In Experiment 4, alkaloids were extracted from ergot sphacelia/sclerotia, added to a corn-soy basal diet, and fed from hatch to 4-week-old male broilers. Sorghum contaminated with ergot significantly increased feed conversion in Week 2. Significantly higher levels of glucose and triglycerides were found in broilers fed sorghum contaminated with ergot. We did not observe significant mortality or obvious signs of ergot toxicity, such as necrotic lesions of the feet or comb, in any of the four experiments. We can conclude that the effects of sorghum contaminated with ergot on broilers will be negligible to broiler production operations
Evaluation and heritability of ergot resistance derived from sorghum germplasm IS8525.
No full textSorghum (Sorghum bicolor [L.] Moench) is fifth among the major cereal crops in the world in terms of production area and total production. Grain sorghum can be successfully produced in a wide range of environments, its productivity is severely limited by pathogens, insects and abiotic stresses. One of these pathogens is Claviceps africana Frederickson Mantle & de Milliano, commonly known as ergot. As is the case with many sorghum diseases, the best long term approach to control ergot may be the use of genetic resistance. There is limited information about resistance to C. africana in sorghum, and the reported resistance in most lines is fertility-based. Dahlberg (1999) first reported the line IS8525 to have the most tolerance to ergot of any of the accessions screened in Puerto Rico. The specific objectives of this research are: (1) to confirm the presence of C. africana resistance in IS8525 germplasm, (2) to determine if the resistance in IS8525 is pollen mediated or ovule based, and (3) to determine if the resistance in IS8525 is heritable and stable across environments. Ergot vulnerability ratings were determined for two recombinant inbred line populations, IS8525D and IS8525J, in four locations during 2001. Also, ergot vulnerability ratings were evaluated in four test-cross populations (using as testers A3Tx623 and A3Tx623) in two locations. Evaluations of the original parents indicate that ergot tolerance in IS8525D parent was consistently better than that in IS8525J parent. As expected, neither parent provided complete resistance. The IS8525J recombinant inbred line population showed significantly more ergot susceptibility than the IS8525D recombinant inbred line population and this trend was consistent across environments. Variation for ergot vulnerability amo ng recombinant inbred lines for both populations was detected, but the amount of variability was environment dependent. In the testcross hybrids, all four populations were susceptible to ergot, primarily due to male sterility in the hybrids, confirming that the tolerance shown in IS8525 germplasm is mostly pollen mediated. However, a greater level of tolerance in the IS8525 hybrid checks confirmed the reports of tolerance by Dahlberg et al. (1998) and Reed et al. (2002)
Ergot poisoning in cattle
No full textpeer reviewedIn addition to the financial losses that ergot ( Claviceps purpurea) contamination causes in crops, the ingestion of ergot-contaminated food by cattle results in an intoxication that develops in several patterns. The observed clinical troubles may involve different systems. In this paper, we reviewed the clinical signs observed in ergot-poisoned cattle and some diagnostic and prevention aspects
Ergot alkaloid biosynthesis in Aspergillus fumigatus : Association with sporulation and clustered genes common among ergot fungi
No full textErgot alkaloids, indole-derived mycotoxins, interact with multiple monoamine neurotransmitter receptors and cause disease in exposed individuals. They have been well studied in the ergot fungus, Claviceps purpurea, and have been reported in some closely related grass endophytes, as well as the distantly related opportunistic human pathogen Aspergillus fumigatus. A. fumigatus, which sporulates prolifically, produces clavines, specifically festuclavine and fumigaclavines A, B, and C in association with asexual spores and the total mass of alkaloids constitutes over 1% of the spore mass. These alkaloids differ from those of most clavicipitaceous fungi, which consist of different clavines and often more complex lysergic acid derivatives. However, the ergot alkaloid pathways of A. fumigatus and ergot fungi are hypothesized to share early biosynthetic steps, diverging at some point after the formation of the intermediate chanoclavine. A homologue of dmaW, a gene encoding dimethylallyltryptophan synthase in Neotyphodium endophytes, was found in the A. fumigatus genome. By gene knockout analysis, dmaW was shown to be required for ergot alkaloid production in A. fumigatus. Comparison of genes clustered around A. fumigatus dmaW to those clustered with dmaW in the ergot fungi revealed potential homologues that could encode proteins controlling early, shared steps in the pathway. Functional analysis via gene knockout of three additional A. fumigatus genes (easA, easE, and easF) rendered mutants with altered alkaloid profiles, demonstrating their involvement in ergot alkaloid biosynthesis. All mutants lacked normal ergot alkaloid production from the latter part of the pathway; complementation with a functional copy of the respective gene, restored normal ergot alkaloid production in each mutant. Analyses of intermediates positioned the products of easF and easE as the second and third enzymatic steps of the pathway. Knockout of easA caused accumulation of multiple intermediates, including chanoclavine; complementation with the C. purpurea easA gene resulted in accumulation of agroclavine, setoclavine, and its isomer isosetoclavine. These data confirm easA involvement post chanoclavine synthesis and more specifically assign its role to reduction of chanoclavine aldehyde, the branch point of the two lineage-specific pathways. These mutants, due to their differing ergot alkaloid profiles, are valuable for testing the role of specific ergot alkaloids in animal pathogenesis and toxicoses. Elucidation of ergot alkaloid biosynthesis, along with the capacity to control the spectrum of alkaloids produced, may be beneficial to agriculture and medicine. Additional studies demonstrated that production of ergot alkaloids was restricted to conidiating cultures. Disruption of brlA, a regulatory gene involved in conidiation, interfered with conidiophore development, as well as ergot alkaloid production. The association of these toxins with sporulation may offer insight into their ecological significance and utility to the fungus
Extension of the ergot alkaloid gene cluster
No full textSpecialized metabolites produced by fungi impact human health. A large portion of the pharmaceuticals currently on the market are derived from metabolites biosynthesized by microbes. Ergot alkaloids are a class of fungal metabolites that are important in the interactions of environmental fungi with insects and mammals and also are used in the production of pharmaceuticals. In animals, ergot alkaloids can act as partial agonists or antagonists at receptors for 5-hydroxytryptamine (serotonin), dopamine, and noradrenaline as ergot alkaloids have chemical structures similar to those neurotransmitters. Therefore, they affect insects and mammals that consume them and can be used to produce drugs that can aid in treatment of migraines, dementia, Parkinson’s and gynecological issues. The conserved ergot alkaloid synthesis pathway is responsible for the biosynthesis of these tryptophan-derived toxins in ergot alkaloid-producing fungi. Clusters of ergot alkaloid synthesis (eas) genes present in genomes of ergot alkaloid-producing fungi encode enzymes that catalyze synthesis of these chemicals. The fungus Metarhizium brunneum produces lysergic acid α-hydroxyethylamide (LAH), an ecologically and pharmaceutically important compound. The final steps of LAH synthesis involve two monomodular nonribosomal peptide synthetases: lysergyl peptide synthetase 2 (Lps2); encoded by lpsB and Lps3,encoded by lpsC. A novel two-module Lps gene, lpsD, was discovered via genome mining in three species of lysergic acid amide-producing Aspergillus. Heterologous expression of lpsD from Aspergillus leporis in a lysergic acid-accumulating strain of Aspergillus fumigatus yielded ergonovine and lysergyl-alanine, end products typically derived from Lps2 and Lps3 in Clavicipitaceous fungi. Addition of the A. leporis easO gene to this strain resulted in accumulation of LAH, the pathway end product observed in both A. leporis and M. brunneum. This study established that the product of the lpsD gene is the functional equivalent of the two monomodular peptide synthetases of the Clavicipitaceae. While most biosynthetic steps in the ergot alkaloid pathway are well characterized, the regulation of the genes is unknown. Understanding the regulatory mechanisms may aid in insect biocontrol strategies and may be of value for the pharmaceutical industry, as upregulation of the pathway could result in increased biosynthetic yields. In this study, the role of two novel genes with regulatory potential, easR and easS were studied to determine their role in ergot alkaloid biosynthesis. CRISPR-mediated knockout of easR in M. brunneum resulted in a strain with no detectable ergot alkaloids. Infection of Galleria mellonella larvae with the easR knockout of M. brunneum compared to a wild-type control showed a significantly lower virulence rate for the knockout strain, supporting previous evidence that ergot alkaloids contribute to fungal virulence to this insect. Knockout of easR greatly reduced or eliminated accumulation of mRNA from the eas genes. This study provided evidence that easR plays a role in regulating ergot alkaloid biosynthesis. The functional copy of the easS gene identified in M. majus was transformed into M. brunneum. The introduction of this potential repressor gene did not yield any significant difference in ergot alkaloid accumulation. Thus, despite its presence in the eas cluster, the easS gene may not play a role in ergot alkaloid accumulation. Collectively, the components of this study expanded the ergot alkaloid synthesis cluster and provided information on novel biosynthetic and regulatory gene
Sorghum Ergot - Field Identification
No full text1 p.Sorghum ergot is a disease that attacks the unfertilized ovaries of the flowers of grain and forage sorghums and johnsongrass. This publication contains 3 color photographs to aid in diagnosis
Vasoactive Effects of Acute Ergot Exposure in Sheep
No full textErgotism is a common and increasing problem in Saskatchewan’s livestock. Chronic exposure to low concentrations of ergot alkaloids is known to cause severe arterial vasoconstriction and gangrene through the activation of adrenergic and serotonergic receptors on vascular smooth muscles. The acute vascular effects of a single oral dose with high-level exposure to ergot alkaloids remain unknown and are examined in this study. This study had two main objectives; the first was to evaluate the role of α1-adrenergic receptors in mediating the acute vasocontractile response after single-dose exposure in sheep. The second was to examine whether terazosin (TE) could abolish the vascular contractile effects of ergot alkaloids. Twelve adult female sheep were randomly placed into control and exposure groups (n = 6/group). Ergot sclerotia were collected and finely ground. The concentrations of six ergot alkaloids (ergocornine, ergocristine, ergocryptine, ergometrine, ergosine, and ergotamine) were determined using HPLC/MS at Prairie Diagnostic Services Inc., (Saskatoon, SK, Canada). Each ewe within the treatment group received a single oral treatment of ground ergot sclerotia at a dose of 600 µg/kg BW (total ergot) while each ewe in the control group received water. Animals were euthanized 12 h after the treatment, and the pedal artery (dorsal metatarsal III artery) from the left hind limb from each animal was carefully dissected and mounted in an isolated tissue bath. The vascular contractile response to phenylephrine (PE) (α1-adrenergic agonist) was compared between the two groups before and after TE (α1-adrenergic antagonist) treatment. Acute exposure to ergot alkaloids resulted in a 38% increase in vascular sensitivity to PE compared to control (Ctl EC50 = 1.74 × 10−6 M; Exp EC50 = 1.079 × 10−6 M, p = 0.046). TE treatment resulted in a significant dose-dependent increase in EC50 in both exposure and control groups (p < 0.05 for all treatments). Surprisingly, TE effect was significantly more pronounced in the ergot exposed group compared to the control group at two of the three concentrations of TE (TE 30 nM, p = 0.36; TE 100 nM, p < 0.001; TE 300 nM, p < 0.001). Similar to chronic exposure, acute exposure to ergot alkaloids results in increased vascular sensitivity to PE. TE is a more potent dose-dependent antagonist for the PE contractile response in sheep exposed to ergot compared to the control group. This study may indicate that the dry gangrene seen in sheep, and likely other species, might be related to the activation of α1-adrenergic receptor. This effect may be reversed using TE, especially at early stages of the disease before cell death occurs. This study may also indicate that acute-single dose exposure scenario may be useful in the study of vascular effects of ergot alkaloids
Methods of Lysergic Acid Synthesis—The Key Ergot Alkaloid
No full textErgot is the spore form of the fungus Claviceps purpurea. Ergot alkaloids are indole compounds that are biosynthetically derived from L-tryptophan and represent the largest group of fungal nitrogen metabolites found in nature. The common part of ergot alkaloids is lysergic acid. This review shows the importance of lysergic acid as a representative of ergot alkaloids. The subject of ergot and its alkaloids is presented, with a particular focus on lysergic acid. All methods of total lysergic acid synthesis—through Woodward, Hendrickson, and Szantay intermediates and Heck coupling methods—are presented. The topic of biosynthesis is also discussed
- …
