Isolation of the glucose oxidase gene from Talaromyces flavus and characterisation of its role in the biocontrol of Verticillium dahliae

• Published in: Current genetics Vol. 32; no. 5; pp. 367 - 375
• Main Authors: Murray, F.R, Llewellyn, D.J, Peacock, W.J, Dennis, E.S
• Format: Journal Article
• Language: English
• Published: United States 01-11-1997
• Subjects: Amino Acid Sequence; amino acid sequences; antagonism; Ascomycota - enzymology; Ascomycota - genetics; Ascomycota - isolation & purification; Aspergillus niger; Aspergillus niger - enzymology; Aspergillus niger - genetics; Base Sequence; biological control; comparisons; DNA Primers - genetics; enzyme activity; genbank/u56240; gene expression; gene overexpression; gene transfer; Genes, Fungal; genetic transformation; glucose oxidase; Glucose Oxidase - genetics; Gossypium - microbiology; Gossypium hirsutum; hyphae; inhibition; Mitosporic Fungi - growth & development; Mitosporic Fungi - pathogenicity; Molecular Sequence Data; nucleotide sequences; open reading frames; Plant Diseases - microbiology; promoter regions; sclerotia; Sequence Homology, Amino Acid; Soil Microbiology; Species Specificity; structural genes; Talaromyces; Talaromyces flavus; talaromyces macrosporus; Verticillium dahliae; wilts
• ISSN: 0172-8083; 1432-0983
• DOI: 10.1007/s002940050290

The glucose oxidase gene from the biocontrol fungus Talaromyces flavus has been isolated and shown to be only 64% identical at the amino-acid sequence level to the similar enzyme from Aspergillus niger. A transformation system has been developed for both T. flavus and the related T. macrosporus and has been used to create Talaromyces spp. which either over-express or are deficient in glucose oxidase. In vitro inhibition experiments on Verticillium dahliae using culture filtrates from these transformants indicates that secreted glucose oxidase is responsible for a large part of the growth inhibition of V. dahliae microsclerotia and hyphae by T. flavus, although other inhibitory compounds may also play a role. In pot trials with cotton plants, both Talaromyces species had some biocontrol activity, but there was no significant difference in the incidence of Verticillium wilt with either the presence or absence of glucose oxidase activity in the biocontrol fungus. Under the experimental conditions used, insufficient glucose is presumably present in the soil around cotton roots to generate sufficient hydrogen peroxide to inhibit V. dahliae and the observed biocontrol activity must be attributed to other factors.