Effect of Treatment of Beech Seeds with Copper Nanoparticles on Seed Coat Mycoflora

Seeds harbor a complex fungal community, of which some members may be pathogenic. For this reason, seeds are often treated with fungicides before sowing. Plant protection is constantly looking for environmentally friendly technological solutions and nanotechnology can provide a solution that is a green and environmentally friendly alternative to fungicide treatment. The aim of this study was to conduct a quantitative and qualitative analysis of the composition of fungal communities inhabiting the seed coats of healthy and damaged European beech seeds and to assess the effect of copper nanoparticles (CuNPs) on the composition of these communities. The seeds were soaked in a solution of CuNPs at a concentration of 50 ppm for 30 min. There were four groups of seeds: control—not treated with CuNPs, seeds examined 1 day after CuNP (CuNP_1day) treatment, seeds examined 3 weeks after CuNP (CuNP_3weeks) treatment, and damaged seeds—not treated. A community analysis was conducted based on the ITS1 region using Illumina sequencing. In total, we found 70 taxa of fungi and Oomycota. The community on the control seeds numbered 38 taxa, on damaged seeds—67, on seeds treated with CuNPs after 1 day—40, and after 3 weeks—15, respectively. In terms of biological diversity and species composition, the community on damaged seeds differed significantly from that on CuNP_3weeks seeds and both of these treatments differed from the remaining two. On the damaged seeds, the dominant species were as follows: Botritis cinerea Pers., Globisporangium intermedium (de Bary) Uzuhashi, Tojo & Kakish., and Pythium dissotocum Drechsler. The communities of the other seed groups were dominated by Fusicoccum quercus Oudem. and Apiognomonia errabunda (Roberge ex Desm.) Höhn., which proved resistant to CuNPs. Taxa belonging to the Oomycota, fungi of the genera Fusarium, Mucor, and Penicillium, were sensitive to CuNPsanddidnot occur on CuNP_3weeks seeds. The significant reduction in the number of taxa and the most favorable structure of trophic groups being found on the CuNP_3weeks seeds suggest that NPs could potentially replace traditional fungicides for seed treatment.