But Rosling said there still is no evidence that Archaeorhizomycetes form mycorrhizal structures in pine roots, and instead may coexist with other fungi in single root tips, showing no preferential growth toward main, primary or secondary roots, and not altering root tip morphology.
Prior to the work researchers were unsure of Archaeorhizomyces' role in the ecosystem, and had theorized that the fungi were mycorrhizal, or obligately associated with the roots of plants, getting carbon from those plants. The new findings provide evidence that Archaeorhizomyces is not mycorrhizal and their apparent association with roots of plants is possibly though association with mycorrhizal fungi.
"Our feeling now is that plant host and habitat specificity for different species of Archaeorhizomycetes may not necessarily be explained by specificity towards the plant, but may instead reflect an association with other root-associated fungi," she said. "When we inoculated onto sterile pine seedlings, the mycelium of one Archaeorhizomycetes, A. finlayi, associated with roots, but no mycorrhizal structures are observed. Yet the inoculated seedlings remained healthy for months with no signs of fungal pathogenicity."
Archaeorhizomycetes is phylogenetically placed within the subphylum Taphrinomycotina in the Ascomycota phylum. Commonly known as sac fungi, Ascomycota is the largest phylum in the fungi kingdom, comprising about 75 percent of all fungi, or more than 64,000 species. Species in the new class are filamentous and threadlike, and because they lack macroscopic features they can not be identified without DNA testing. And while not recognized as forming mycorrhizal structures, they potentially receive nutrition from dead and decaying plant material, the paper reported.
With the new class now properly sequenced, researche
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