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Klaus Michael Weltring - One of the best experts on this subject based on the ideXlab platform.

  • an atp binding cassette multidrug resistance transporter is necessary for tolerance of Gibberella pulicaris to phytoalexins and virulence on potato tubers
    Molecular Plant-microbe Interactions, 2002
    Co-Authors: Andre Fleissner, Claudia Sopalla, Klaus Michael Weltring
    Abstract:

    The necrotrophic pathogen Gibberella pulicaris infects potato tubers through wounds that contain fungitoxic secondary metabolites such as the phytoalexins rishitin and lubimin. In order to colonize tuber tissue, the fungus must possess a mechanism to tolerate potato defense compounds. In this paper, we show that a gene, Gpabc1, that codes an ATP-binding cassette (ABC) transporter is required for tolerance to these phytoalexins and for virulence on potato. The Gpabc1 gene, isolated in the course of a differential cDNA screen, shares high sequence homology with the ABC1 gene of Magnaporthe grisea. G. pulicaris mutants deficient in Gpabc1 were still able to metabolize rishitin but lost their tolerance to this phytoalexin as well as their virulence on potato. These results strongly suggest that the Gpabc1-encoded ABC transporter is necessary for tolerance of G. pulicaris to rishitin and that this tolerance is required for virulence on potato.

  • the fungal acl1 and acl2 genes encode two polypeptides with homology to the n and c terminal parts of the animal atp citrate lyase polypeptide
    Current Genetics, 2000
    Co-Authors: Minou Nowrousian, Ulrich Kuck, Karin Loser, Klaus Michael Weltring
    Abstract:

    ATP citrate lyase (ACL) catalyzes the formation of cytosolic acetyl-CoA, which is mainly used for the biosynthesis of fatty acids and sterols. In this paper, we show for the first time that in filamentous fungi two different subunits of ACL are encoded by two separate genes. This is in contrast to animals where ACL is encoded by a single gene. Data are presented on acl genes from the filamentous fungi Sordaria macrospora and Gibberella pulicaris. In S. macrospora, both genes, acl1 and acl2, are clustered within a region of 10 kb and are divergently transcribed.

  • Metabolism of the tomato saponin α-tomatine by Gibberella pulicaris
    Phytochemistry, 1998
    Co-Authors: Klaus Michael Weltring, Judith Wessels, Guido F. Pauli
    Abstract:

    Abstract The ascomycete Gibberella pulicaris is able to metabolize the saponin α-tomatine within 2 h by first removing the complete lycotetraose moiety leading to the aglycone tomatidine. This product is further converted into 7α-hydroxy-tomatidine and the corresponding Δ5-dehydro product 7α-hydroxy-tomatidenol. Structural evidence for the hydroxylated main metabolite as well as the unsaturated minor product is based on MS and NMR measurements. The latter include the application of modern soft pulse 1H NMR techniques allowing the definitive localization of the position of hydroxylation even for the few milligram quantities that could be obtained.

Klausm Weltring - One of the best experts on this subject based on the ideXlab platform.

  • metabolism of the potato saponins α chaconine and α solanine by Gibberella pilicaris
    Phytochemistry, 1997
    Co-Authors: Klausm Weltring, Judith Wessels, Rudolf Geyer
    Abstract:

    Abstract Potato tubers accumulate varying amounts of several saponins preferentially in the peel. These compounds are toxic to living cells containing sterols in their plasma membrane and are therefore thought to be preformed chemical defence compounds. Two strains of the potato pathogen Gibberella pulicaris (Fusarium sambucinum) , R-6380 and R-7843, were analysed for their ability to metabolize the most predominant saponins found in tubers, α-chaconine and α-solanine. The first compound is degraded by both strains via removal of α-1,2- l -rhamnose leading to β 2 -chaconine. This product is converted to the aglycone, solanidine, which is further metabolized to unknown products. The release of α-1,2- l -rhamnose is also the first step in the break down of α-solanine by strain R-6380, followed by the removal of the β-1,3-bound glucose molecule leading to γ-solanine, which is not metabolized any further. Strain R-7843 is not able to metabolize α-solanine. Crude protein extracts of the culture fluid of both strains contained enzymes able to convert α-chaconine to β 2 -chaconine, but with no α-solanine metabolic activity. This result indicates that G. pulicaris excretes enzymes specific for different saponins.

  • detoxification of sesquiterpene phytoalexins byGibberella pulicaris fusarium sambucinum and its importance for virulence on potato tubers
    Journal of Industrial Microbiology & Biotechnology, 1992
    Co-Authors: Anne E Desjardins, Harold W Gardner, Klausm Weltring
    Abstract:

    Gibberella pulicaris (Fusarium sambucinum) is a major cause of dry-rot of stored potatoes (Solanum tuberosum) worldwide. The ability of field strains ofG. pulicaris to cause dry-rot is correlated with their ability to detoxify sesquiterpene phytoalexins produced by potato. All highly virulent field strains can detoxify the sesquiterpenes rishitin and lubimin. Meiotic recombinational analysis indicates that rishitin detoxification can be controlled at two or more loci. High virulence has been associated with one of these loci, designatedRiml. Detoxification of rishitin and lubimin comprises a complex pattern of reactions involving epoxidation, dehydrogenation, and cyclization. To date, seven lubimin metabolites and one rishitin metabolite have been characterized. Genes for rishitin and lubimin detoxification are being cloned fromG. pulicaris in order to more rigorously analyze the role and regulation of sesquiterpene metabolism in potato dry-rot. Our results indirectly support a role for sesquiterpene phytoalexins in resistance of potato tubers to dry-rot and may enhance research on alternative control strategies for this economically important potato disease.

A. E. Desjardins - One of the best experts on this subject based on the ideXlab platform.

  • isolation and gene disruption of the tox5 gene encoding trichodiene synthase in Gibberella pulicaris
    Molecular Plant-microbe Interactions, 1992
    Co-Authors: T. M. Hohn, A. E. Desjardins
    Abstract:

    The trichodiene synthase gene (Tox5) was isolated from Gibberella pulicaris, and its nucleotide sequence was determined. Tox5 was disrupted through transformation with a plasmid carrying a doubly truncated copy of the coding region and a selectable marker for resistance to hygromycin B (Hygr). Analysis of 82 transformants for their ability to produce the trichothecene, 4,15-diacetoxyscirpenol (DAS), resulted in the identification of five DAS- strains. Southern hybridization analysis of DAS- Hygr transformants indicated that the plasmid integrated at the Tox5 locus. The disrupted Tox5 gene was shown to be mitotically stable. Analysis of nine tetrads revealed either the cosegregation of the disrupter plasmid and the DAS- phenotype or the loss of the disrupter plasmid. These results demonstrate the feasibility of using gene disruption in G. pulicaris and suggest a general method for obtaining Tox5- mutants in other trichothecene-producing fungi.

Judith Wessels - One of the best experts on this subject based on the ideXlab platform.

  • Metabolism of the tomato saponin α-tomatine by Gibberella pulicaris
    Phytochemistry, 1998
    Co-Authors: Klaus Michael Weltring, Judith Wessels, Guido F. Pauli
    Abstract:

    Abstract The ascomycete Gibberella pulicaris is able to metabolize the saponin α-tomatine within 2 h by first removing the complete lycotetraose moiety leading to the aglycone tomatidine. This product is further converted into 7α-hydroxy-tomatidine and the corresponding Δ5-dehydro product 7α-hydroxy-tomatidenol. Structural evidence for the hydroxylated main metabolite as well as the unsaturated minor product is based on MS and NMR measurements. The latter include the application of modern soft pulse 1H NMR techniques allowing the definitive localization of the position of hydroxylation even for the few milligram quantities that could be obtained.

  • metabolism of the potato saponins α chaconine and α solanine by Gibberella pilicaris
    Phytochemistry, 1997
    Co-Authors: Klausm Weltring, Judith Wessels, Rudolf Geyer
    Abstract:

    Abstract Potato tubers accumulate varying amounts of several saponins preferentially in the peel. These compounds are toxic to living cells containing sterols in their plasma membrane and are therefore thought to be preformed chemical defence compounds. Two strains of the potato pathogen Gibberella pulicaris (Fusarium sambucinum) , R-6380 and R-7843, were analysed for their ability to metabolize the most predominant saponins found in tubers, α-chaconine and α-solanine. The first compound is degraded by both strains via removal of α-1,2- l -rhamnose leading to β 2 -chaconine. This product is converted to the aglycone, solanidine, which is further metabolized to unknown products. The release of α-1,2- l -rhamnose is also the first step in the break down of α-solanine by strain R-6380, followed by the removal of the β-1,3-bound glucose molecule leading to γ-solanine, which is not metabolized any further. Strain R-7843 is not able to metabolize α-solanine. Crude protein extracts of the culture fluid of both strains contained enzymes able to convert α-chaconine to β 2 -chaconine, but with no α-solanine metabolic activity. This result indicates that G. pulicaris excretes enzymes specific for different saponins.

Guido F. Pauli - One of the best experts on this subject based on the ideXlab platform.

  • Metabolism of the tomato saponin α-tomatine by Gibberella pulicaris
    Phytochemistry, 1998
    Co-Authors: Klaus Michael Weltring, Judith Wessels, Guido F. Pauli
    Abstract:

    Abstract The ascomycete Gibberella pulicaris is able to metabolize the saponin α-tomatine within 2 h by first removing the complete lycotetraose moiety leading to the aglycone tomatidine. This product is further converted into 7α-hydroxy-tomatidine and the corresponding Δ5-dehydro product 7α-hydroxy-tomatidenol. Structural evidence for the hydroxylated main metabolite as well as the unsaturated minor product is based on MS and NMR measurements. The latter include the application of modern soft pulse 1H NMR techniques allowing the definitive localization of the position of hydroxylation even for the few milligram quantities that could be obtained.