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John F Leslie - One of the best experts on this subject based on the ideXlab platform.

  • Gibberella konza (Fusarium konzum) sp. nov. from prairie grasses, a new species in the Gibberella fujikuroi species complex
    Mycologia, 2003
    Co-Authors: Kurt A Zeller, Brett A. Summerell, Suzanne Bullock, John F Leslie
    Abstract:

    The Gibberella fujikuroi species complex (Fusarium section Liseola and allied taxa) is composed of an increasingly large number of morphological, biological and phylogenetic species. Most of the known species in this group have been isolated from agricultural ecosystems or have been described from a small number of isolates. We sampled Fusarium communities from native prairie grasses in Kansas and recovered a large number of isolates that superficially resemble F. anthophilum. We used a combination of morphological, biological and molecular characters to describe a new species, Gibberella konza (Gibberella fujikuroi mating population I [MP-I]), from native prairie grasses in Kansas. Although female fertility for field isolates of this species appears to be low, G. konza is heterothallic, and we developed reliably female fertile mating population tester strains for this species. The F. konzum anamorph is differentiated from F. anthophilum and from other Fusarium species in section Liseola by mating compatibility, morphology, AFLP fingerprint profile and differences in β-tubulin DNA sequence.

  • molecular standardization of mating type terminology in the Gibberella fujikuroi species complex
    Applied and Environmental Microbiology, 1999
    Co-Authors: Zoltan Kerenyi, Laszlo Hornok, Kurt A Zeller, John F Leslie
    Abstract:

    Mating type in the Gibberella fujikuroi species complex is controlled by a single locus with two alleles and is usually identified following sexual crosses with standard, female-fertile tester isolates. The mating type alleles have been arbitrarily designated “+” and “−” within each biological species, and the nomenclature is tied to the standard tester strains. We developed a pair of PCR primers that can be used to amplify a unique fragment of one of the mating type alleles (MAT-2) from at least seven of the biological species in this species complex. Based on the amplification pattern, we propose a replacement for the existing, arbitrary +/− terminology that is presently in use. The new terminology is based on DNA sequence similarities between the mating type allele fragments from the biological species of the G. fujikuroi species complex and the corresponding fragments from other filamentous ascomycetes.

  • A genetic map of Gibberella fujikuroi mating population A (Fusarium moniliforme).
    Genetics, 1996
    Co-Authors: John F Leslie
    Abstract:

    We constructed a recombination-based map of the fungal plant pathogen Gibberella fujikuroi mating population A (asexual stage Fusarium moniliforme). The map is based on the segregation of 142 restriction fragment length polymorphism (RFLP) markers, two auxotrophic genes (arg1, nic1), mating type (matA+/matA-), female sterility (ste1), spore-killer (Sk), and a gene governing the production of the mycotoxin fumonisin B1 (fum1) among 121 random ascospore progeny from a single cross. We identified 12 linkage groups corresponding to the 12 chromosome-sized DNAs previously observed in contour-clamped homogeneous electric field (CHEF) gels. Linkage groups and chromosomes were correlated via Southern blots between appropriate RFLP markers and the CHEF gels. Eleven of the 12 chromosomes are meiotically stable, but the 12th (and smallest) is subject to deletions in 3% (4/121) of the progeny. Positive chiasma interference occurred on five of the 12 chromosomes, and nine of the 12 chromosomes averaged more than one crossover per chromosome. The average kb/cM ratio in this cross is approximately 32.

  • Gibberella fujikuroi: available populations and variable traits
    Canadian Journal of Botany, 1995
    Co-Authors: John F Leslie
    Abstract:

    Gibberella fujikuroi is a complex species comprised of at least seven distinct mating populations (biological species) with Fusarium anamorphs. These fungi are common pathogens of maize, rice, and sorghum and cause billions of dollars of losses in these crops worldwide. Mating populations are biological species defined by cross-fertility of members of the same mating population with one another, and sterility whenever members of two different mating populations are crossed. Mating populations also differ in their electrophoretic karyotypes, their general ability to synthesize secondary metabolites, and their sensitivity to antifungal agents such as benomyl and hygromycin B. Within a mating population strains can be distinguished on the basis of their ability to form a heterokaryon with one another. This polygenic trait has been used to study the structure of some populations of these fungi. In some cases, pathogenic strains appear to be clones that are limited to a crop and (or) geographic location. More ...

  • genetic diversity of fusarium section liseola Gibberella fujikuroi in individual maize stalks
    Phytopathology, 1994
    Co-Authors: C J Kedera, John F Leslie, L E Claflin
    Abstract:

    Isolates belonging to Fusarium section Liseola (teleomorph Gibberella fujikuroi), primarily F. moniliforme, F. proliferatum, and F. subglutinans, are recovered from maize worldwide. Consistent isolation of these fungi from symptomatic and asymptomatic plant tissues suggests that the fungus can systemically colonize maize plants; however, the number of strains that colonize a single plant has not been determined. Using vegetative compatibility groups to differentiate among strains, we have shown that most maize plants are infected by two to three strains belonging to Fusarium section Liseola. Some of the strains recovered from the stalk usually are recovered from the ear as well [...]

Eduardo Agosin - One of the best experts on this subject based on the ideXlab platform.

  • Effect of water activity on gibberellic acid production by Gibberella fujikuroi under solid-state fermentation conditions
    Process Biochemistry, 2005
    Co-Authors: Andrés Corona, Doris Saez, Eduardo Agosin
    Abstract:

    The evolution of water activity during solid-state cultivation of Gibberella fujikuroi was followed. A typical organic substrate, wheat bran and soluble starch, was used. Culture sorption isotherms were determined verifying that, as culture evolves, higher moisture contents were necessary to maintain the same water activity level. Optimal values for Gibberella fujikuroi growth and gibberellic acid production rates and yields were established, around aw 0.99. A non-linear model, based on neural networks, is proposed to represent the sorption curves of the substrate during the fermentation process.

  • Modelling Gibberella fujikuroi growth and GA3 production in solid-state fermentation
    Process Biochemistry, 2002
    Co-Authors: Claudio A Gelmi, Ricardo Pérez-correa, Eduardo Agosin
    Abstract:

    A simple differential equation model was developed to represent the growth and production of a secondary metabolite in solid-state cultivation (SSC) under conditions of limited nitrogen. The model was used to interpret data obtained from SSCs of the fungus Gibberella fujikuroi, under different temperatures (25 and 31 °C) and water activity conditions (0.985, 0.992, 0.999). The model was calibrated in two steps. An innovative procedure to achieve good initial guesses for key parameters, such as maintenance coefficients and death rates was first applied. These initial guesses were then used in a non-linear optimisation routine to get a minimum least squares fit for the model. The mathematical model was able to reproduce the measured variables: biomass, urea, starch, CO2 ,O 2 and GA3 satisfactorily. Moreover, the model indicated that the fungus does not assimilate the nitrogen source, urea, directly. The model will be useful in developing optimal feeding policies and on-line biomass estimators. © 2002 Elsevier Science Ireland Ltd. All rights reserved.

  • Capture of volatile metabolites for tracking the evolution of gibberellic acid in a solid-state culture of Gibberella fujikuroi
    Biotechnology Letters, 2000
    Co-Authors: Mauricio González-sepúlveda, Eduardo Agosin
    Abstract:

    The evolution of volatile compounds produced during solid substrate cultivation (SSC) of Gibberella fujikuroi on wheat bran was tracked looking for volatile metabolites related with GA3 production. Ethyl acetate and isoamyl acetate gave identical profiles and sharp increases that abated as the production of GA3 began, while ent-kaurene displayed a profile matching that of the development of GA3. ent-Kaurene is a precursor in the synthesis of gibberellins and was the most abundant compound found.

  • solid substrate cultivation of Gibberella fujikuroi on an inert support
    Process Biochemistry, 2000
    Co-Authors: Claudio A Gelmi, Ricardo Perezcorrea, M Gonzalez, Eduardo Agosin
    Abstract:

    Growth of Gibberella fujikuroi on Amberlite, an inert support, and gibberellic acid (GA3) production was studied in glass columns under different conditions of temperature and water activity (aw). Maximum biomass concentration and GA3 production were respectively 40 (mg:g inert support) and 0.73 (mg:g inert support). While high specific growth rates were obtained, low initial nitrogen resulted in low biomass concentrations. Maximum GA3 (31°C, aw 0.985) was not produced by the maximum concentration of biomass (25°C, aw0.992). Peaks in the rate curves of either outlet gas, CO2 or O2, occurred on exhaustion of urea indicating, for future works, just when to feed the culture additional nitrogen. © 2000 Elsevier Science Ltd. All rights reserved.

  • Glutamine Involvement in Nitrogen Control of Gibberellic Acid Production in Gibberella fujikuroi
    Applied and environmental microbiology, 1993
    Co-Authors: Gastón Muñoz, Eduardo Agosin
    Abstract:

    When the fungus Gibberella fujikuroi ATCC 12616 was grown in fermentor cultures, both intracellular kaurene biosynthetic activities and extracellular GA3 accumulation reached high levels when exogenous nitrogen was depleted in the culture. Similar patterns were exhibited by several nonrelated enzymatic activities, such as formamidase and urease, suggesting that all are subject to nitrogen regulation. The behavior of the enzymes involved in nitrogen assimilation (glutamine synthetase, glutamate dehydrogenase, and glutamate synthase) during fungal growth in different nitrogen sources suggests that glutamine is the final product of nitrogen assimilation in G. fujikuroi. When ammonium or glutamine was added to hormone-producing cultures, extracellular GA3 did not accumulate. However, when the conversion of ammonium into glutamine was inhibited by L-methionine-DL-sulfoximine, only glutamine maintained this effect. These results suggest that glutamine may well be the metabolite effector in nitrogen repression of GA3 synthesis, as well as in other nonrelated enzymatic activities in G. fujikuroi.

Braulio M. Fraga - One of the best experts on this subject based on the ideXlab platform.

  • microbiological transformation of an ent pimaradiene hydrocarbon by Gibberella fujikuroi
    Phytochemistry Letters, 2009
    Co-Authors: Braulio M. Fraga, Pedro Gonzalez, Melchor G. Hernández, María C. Chamy, Juan A. Garbarino
    Abstract:

    Abstract The hydrocarbon 9,13- epi - ent -pimara-7,15-diene has been obtained from its 18-hydroxy derivative by treatment with Ph 3 /CCl 4 and subsequent reduction with tri- n -butyltin hydride. The incubation of this diterpene with the fungus Gibberella fujikuroi afforded 1α,9α-dihydroxy-7α,8α-epoxy-13- epi - ent -pimara-15-ene. The main difference between the biotransformation of the hydrocarbon and that of the corresponding 18-alcohol is that in the former, the rearrangement of the epoxy group to give 7-oxo-derivatives was not observed. However, the sequence of reactions 7α,8α-epoxidation, hydroxylation at C-9α and subsequent C-1α hydroxylation occurred in both biotransformations.

  • Biotransformation of two ent-Pimara-9(11),15-diene derivatives by Gibberella fujikuroi.
    Journal of natural products, 2009
    Co-Authors: Braulio M. Fraga, Melchor G. Hernández, Ricardo Guillermo, María C. Chamy, Juan A. Garbarino
    Abstract:

    The incubation of 19-hydroxy-13-epi-ent-pimara-9(11),15-diene (4) with Gibberella fujikuroi gave 8α,19-dihydroxy-9α,11α-epoxy-13-epi-ent-pimara-15-ene (6), 7-oxo-11α,19-dihydroxy-13-epi-ent-pimara-...

  • biotransformation of 7 oxo ent kaur 16 ene derivatives by Gibberella fujikuroi
    Tetrahedron, 2005
    Co-Authors: Braulio M. Fraga, Pedro Gonzalez, Melchor G. Hernández, Sergio Suarez
    Abstract:

    Abstract The microbiological transformation of 7-oxo- ent -kaur-16-ene by the fungus Gibberella fujikuroi gave fujenoic acid as the main compound, whilst the incubation of 18-hydroxy-7-oxo- ent -kaur-16-ene and 3α,18-dihydroxy-7-oxo- ent -kaur-16-ene afforded the corresponding 6β-hydroxy-derivatives. These facts indicate that the formation of fujenoic acid in this biotransformation should occur via a 7-oxo-6β-hydroxy derivative. In the three biotransformations, an 11β-hydroxylation was also produced, in low yield, indicating that a 7-oxo-group also directs hydroxylation at C-11.

  • The biotransformation of the diterpene 2β-hydroxy-ent-13-epi-manoyl oxide by Gibberella fujikuroi
    Phytochemistry, 2003
    Co-Authors: Braulio M. Fraga, Pedro Gonzalez, Melchor G. Hernández, Sergio Suarez
    Abstract:

    Incubation of the diterpene 2β-hydroxy-ent-13-epi-manoyl oxide with Gibberella fujikuroi afforded in good yield 2β,6β-dihydroxy-ent-13-epi-manoyl oxide, 2β,12β-dihydroxy-ent-13-epi-manoyl oxide and 2β,20-dihydroxy-ent-13-epi-manoyl oxide, confirming that although ent-13-epi-manoyl oxide is a final metabolite of a biosynthetic branch in this fungus, more polar derivatives of this compound can be transformed by this micro-organism.

  • Microbial transformation of 18-hydroxy-9,13-epi-ent-pimara-7,15-diene by Gibberella fujikuroi.
    Journal of natural products, 2003
    Co-Authors: Braulio M. Fraga, Pedro Gonzalez, Melchor G. Hernández, María C. Chamy, Juan A. Garbarino
    Abstract:

    The incubation of the diterpene 18-dihydroxy-9,13-epi-ent-pimara-7,15-diene (3) with the fungus Gibberella fujikuroi gave 14 metabolites, 4 and 6-18. The carbons functionalized were the C-20 methyl and all the secondaries, except C-12. The main reaction observed was the epoxidation of the 7,8-double bond, which rearranged to form 7-keto derivatives, such as 10-17, or the allylic alcohol 18. Compound 9 was the only one obtained in which the 7,8-double bond of the substrate remained unaltered. This work confirms that, in the feeding of this type of diterpene with this fungus, the oxidation at C-19, typical of the biosynthesis of gibberellins from ent-kaur-16-ene, is inhibited.

Juan A. Garbarino - One of the best experts on this subject based on the ideXlab platform.

  • microbiological transformation of an ent pimaradiene hydrocarbon by Gibberella fujikuroi
    Phytochemistry Letters, 2009
    Co-Authors: Braulio M. Fraga, Pedro Gonzalez, Melchor G. Hernández, María C. Chamy, Juan A. Garbarino
    Abstract:

    Abstract The hydrocarbon 9,13- epi - ent -pimara-7,15-diene has been obtained from its 18-hydroxy derivative by treatment with Ph 3 /CCl 4 and subsequent reduction with tri- n -butyltin hydride. The incubation of this diterpene with the fungus Gibberella fujikuroi afforded 1α,9α-dihydroxy-7α,8α-epoxy-13- epi - ent -pimara-15-ene. The main difference between the biotransformation of the hydrocarbon and that of the corresponding 18-alcohol is that in the former, the rearrangement of the epoxy group to give 7-oxo-derivatives was not observed. However, the sequence of reactions 7α,8α-epoxidation, hydroxylation at C-9α and subsequent C-1α hydroxylation occurred in both biotransformations.

  • Biotransformation of two ent-Pimara-9(11),15-diene derivatives by Gibberella fujikuroi.
    Journal of natural products, 2009
    Co-Authors: Braulio M. Fraga, Melchor G. Hernández, Ricardo Guillermo, María C. Chamy, Juan A. Garbarino
    Abstract:

    The incubation of 19-hydroxy-13-epi-ent-pimara-9(11),15-diene (4) with Gibberella fujikuroi gave 8α,19-dihydroxy-9α,11α-epoxy-13-epi-ent-pimara-15-ene (6), 7-oxo-11α,19-dihydroxy-13-epi-ent-pimara-...

  • Microbial transformation of 18-hydroxy-9,13-epi-ent-pimara-7,15-diene by Gibberella fujikuroi.
    Journal of natural products, 2003
    Co-Authors: Braulio M. Fraga, Pedro Gonzalez, Melchor G. Hernández, María C. Chamy, Juan A. Garbarino
    Abstract:

    The incubation of the diterpene 18-dihydroxy-9,13-epi-ent-pimara-7,15-diene (3) with the fungus Gibberella fujikuroi gave 14 metabolites, 4 and 6-18. The carbons functionalized were the C-20 methyl and all the secondaries, except C-12. The main reaction observed was the epoxidation of the 7,8-double bond, which rearranged to form 7-keto derivatives, such as 10-17, or the allylic alcohol 18. Compound 9 was the only one obtained in which the 7,8-double bond of the substrate remained unaltered. This work confirms that, in the feeding of this type of diterpene with this fungus, the oxidation at C-19, typical of the biosynthesis of gibberellins from ent-kaur-16-ene, is inhibited.

  • the biotransformation of 18 hydroxy 9 epi ent pimara 7 15 diene by Gibberella fujikuroi
    Phytochemistry, 2000
    Co-Authors: Braulio M. Fraga, Pedro Gonzalez, Melchor G. Hernández, María C. Chamy, Juan A. Garbarino
    Abstract:

    Abstract Incubation of 18-hydroxy-9- epi-ent -pimara-7,15-diene with the fungus Gibberella fujikuroi gave the compounds 18-hydroxy-7α,8α-epoxy-9- epi-ent -pimara-15-ene, 18-hydroxy-7-oxo- ent -pimara-15-ene, 6β,18-dihydroxy-7α,8α-epoxy-9- epi-ent -pimara-15-ene, 9β,18-dihydroxy-7α,8α-epoxy- ent -pimara-15-ene and 6β,14α,18-trihydroxy-9- epi-ent -pimara-7,15-diene. Oxidation of C-19, which is characteristic of the biosynthesis pathway of the gibberellins is not produced.

  • The biotransformation of 18-hydroxy-9-epi-ent-pimara-7,15-diene by Gibberella fujikuroi.
    Phytochemistry, 2000
    Co-Authors: Braulio M. Fraga, Pedro Gonzalez, Melchor G. Hernández, María C. Chamy, Juan A. Garbarino
    Abstract:

    Incubation of 18-hydroxy-9-epi-ent-pimara-7,15-diene with the fungus Gibberella fujikuroi gave the compounds 18-hydroxy-7 alpha,8 alpha-epoxy-9-epi-ent-pimara-15-ene, 18-hydroxy-7-oxo-ent-pimara-15-ene, 6 beta, 18-dihydroxy-7 alpha, 8 alpha-epoxy-9-epi-ent-pimara-15-ene, 9 beta,18-dihydroxy-7 alpha, 8 alpha-epoxy-ent-pimara-15-ene and 6 beta, 14 alpha, 18-trihydroxy-9-epi-ent-pimara-7,15-diene. Oxidation of C-19, which is characteristic of the biosynthesis pathway of the gibberellins is not produced.

Melchor G. Hernández - One of the best experts on this subject based on the ideXlab platform.

  • microbiological transformation of an ent pimaradiene hydrocarbon by Gibberella fujikuroi
    Phytochemistry Letters, 2009
    Co-Authors: Braulio M. Fraga, Pedro Gonzalez, Melchor G. Hernández, María C. Chamy, Juan A. Garbarino
    Abstract:

    Abstract The hydrocarbon 9,13- epi - ent -pimara-7,15-diene has been obtained from its 18-hydroxy derivative by treatment with Ph 3 /CCl 4 and subsequent reduction with tri- n -butyltin hydride. The incubation of this diterpene with the fungus Gibberella fujikuroi afforded 1α,9α-dihydroxy-7α,8α-epoxy-13- epi - ent -pimara-15-ene. The main difference between the biotransformation of the hydrocarbon and that of the corresponding 18-alcohol is that in the former, the rearrangement of the epoxy group to give 7-oxo-derivatives was not observed. However, the sequence of reactions 7α,8α-epoxidation, hydroxylation at C-9α and subsequent C-1α hydroxylation occurred in both biotransformations.

  • Biotransformation of two ent-Pimara-9(11),15-diene derivatives by Gibberella fujikuroi.
    Journal of natural products, 2009
    Co-Authors: Braulio M. Fraga, Melchor G. Hernández, Ricardo Guillermo, María C. Chamy, Juan A. Garbarino
    Abstract:

    The incubation of 19-hydroxy-13-epi-ent-pimara-9(11),15-diene (4) with Gibberella fujikuroi gave 8α,19-dihydroxy-9α,11α-epoxy-13-epi-ent-pimara-15-ene (6), 7-oxo-11α,19-dihydroxy-13-epi-ent-pimara-...

  • biotransformation of 7 oxo ent kaur 16 ene derivatives by Gibberella fujikuroi
    Tetrahedron, 2005
    Co-Authors: Braulio M. Fraga, Pedro Gonzalez, Melchor G. Hernández, Sergio Suarez
    Abstract:

    Abstract The microbiological transformation of 7-oxo- ent -kaur-16-ene by the fungus Gibberella fujikuroi gave fujenoic acid as the main compound, whilst the incubation of 18-hydroxy-7-oxo- ent -kaur-16-ene and 3α,18-dihydroxy-7-oxo- ent -kaur-16-ene afforded the corresponding 6β-hydroxy-derivatives. These facts indicate that the formation of fujenoic acid in this biotransformation should occur via a 7-oxo-6β-hydroxy derivative. In the three biotransformations, an 11β-hydroxylation was also produced, in low yield, indicating that a 7-oxo-group also directs hydroxylation at C-11.

  • The biotransformation of the diterpene 2β-hydroxy-ent-13-epi-manoyl oxide by Gibberella fujikuroi
    Phytochemistry, 2003
    Co-Authors: Braulio M. Fraga, Pedro Gonzalez, Melchor G. Hernández, Sergio Suarez
    Abstract:

    Incubation of the diterpene 2β-hydroxy-ent-13-epi-manoyl oxide with Gibberella fujikuroi afforded in good yield 2β,6β-dihydroxy-ent-13-epi-manoyl oxide, 2β,12β-dihydroxy-ent-13-epi-manoyl oxide and 2β,20-dihydroxy-ent-13-epi-manoyl oxide, confirming that although ent-13-epi-manoyl oxide is a final metabolite of a biosynthetic branch in this fungus, more polar derivatives of this compound can be transformed by this micro-organism.

  • Microbial transformation of 18-hydroxy-9,13-epi-ent-pimara-7,15-diene by Gibberella fujikuroi.
    Journal of natural products, 2003
    Co-Authors: Braulio M. Fraga, Pedro Gonzalez, Melchor G. Hernández, María C. Chamy, Juan A. Garbarino
    Abstract:

    The incubation of the diterpene 18-dihydroxy-9,13-epi-ent-pimara-7,15-diene (3) with the fungus Gibberella fujikuroi gave 14 metabolites, 4 and 6-18. The carbons functionalized were the C-20 methyl and all the secondaries, except C-12. The main reaction observed was the epoxidation of the 7,8-double bond, which rearranged to form 7-keto derivatives, such as 10-17, or the allylic alcohol 18. Compound 9 was the only one obtained in which the 7,8-double bond of the substrate remained unaltered. This work confirms that, in the feeding of this type of diterpene with this fungus, the oxidation at C-19, typical of the biosynthesis of gibberellins from ent-kaur-16-ene, is inhibited.