What is the role of the nitrate reductase (euknr) gene in fungi that live in nitrate-free environments? A targeted gene knock-out study in Ampelomyces mycoparasites. Issue 11 (November 2021)

• Record Type: Journal Article
• Authors: Németh, Márk Z.; Li, Guofen; Seress, Diána; Pintye, Alexandra; Molnár, Orsolya; Kovács, Gábor M.; Kiss, Levente; Gorfer, Markus
• Is Part Of: Fungal biology. Volume 125:Issue 11(2021)
• Page Start: 905
• Page End: 913
• Publication Date: 2021-11
• Subjects: Functional genetics -- Yeast recombinational cloning -- Agrobacterium tumefaciens-mediated transformation -- Powdery mildew -- Nitric oxide; Mycology -- Periodicals; Fungi -- Periodicals; 579.505
• DOI: 10.1016/j.funbio.2021.06.004
• Languages: English
• ISSNs: 1878-6146

Abstract

Abstract: Mycoparasitic fungi can be utilized as biocontrol agents (BCAs) of many plant pathogens. Deciphering the molecular mechanisms of mycoparasitism may improve biocontrol efficiency. This work reports the first functional genetic studies in Ampelomyces, widespread mycoparasites and BCAs of powdery mildew fungi, and a molecular genetic toolbox for future works. The nitrate reductase ( euknr ) gene was targeted to reveal the biological function of nitrate assimilation in Ampelomyces . These mycoparasites live in an apparently nitrate-free environment, i.e. inside the hyphae of powdery mildew fungi that lack any nitrate uptake and assimilation system. Homologous recombination-based gene knock-out (KO) was applied to eliminate the euknr gene using Agrobacterium tumefaciens -mediated transformation. Efficient KO of euknr was confirmed by PCR, and visible phenotype caused by loss of euknr was detected on media with different nitrogen sources. Mycoparasitic ability was not affected by knocking out euknr as a tested transformant readily parasitized Blumeria graminis and Podosphaera xanthii colonies on barley and cucumber, respectively, and the rate of mycoparasitism did not differ from the wild type. These results indicate that euknr is not involved in mycoparasitism. Dissimilatory processes, involvement in nitric oxide metabolism, or other, yet undiscovered processes may explain why a functional euknr is maintained in Ampelomyces . HIGHLIGHTS: Ampelomyces mycoparasites have a functional nitrate reductase ( euknr ) gene. euknr may have diverse functions as Ampelomyces thrives in a nitrate-free environment. Ampelomyces is amenable to homologous recombination-based gene knock-out. Mycoparasitic activity of Ampelomyces was not affected when euknr was knocked-out. The new molecular toolbox is useful for functional genetic studies in Ampelomyces .