Fungal communities of bark tissues of European chestnut was accessed using amplicon sequencing (ITS2). Impact of chestnut blight caused by Cryphonectria parasitica was evaluated by comparing fungal communities between healthy and infected samples.. CRYPHO2021

Chestnut blight caused by Cryphonectria parasitica in chestnut trees typically results in the formation of bark cancer, thus presumably leading to novel environmental properties of the bark tissues. In this study, we investigated the bark-inhabiting fungal communities of European chestnut (Castanea sativa) and analyzed how environmental changes due to chestnut blight are reflected in the fungal community structure of infected plants using Illumina amplicon sequencing. A further objective was to assess the cooccurrence of C. parasitica and Gnomoniopsis smithogilvyi, another cancer fungal pathogen of C. sativa. The results supported a strong effect of C. parasitica infection on fungal community composition and diversity. Fungal community composition and diversity significantly differed between healthy and disease samples. The most prevalent species in the overall detected fungal community were C. parasitica (12%) and G. smithogilvyi (8%). The fungal communities in infected samples were dominated by C. parasitica, which reached up to 93% relative abundance in individual samples. Similarly, G. smithogilvyi, detected in two-thirds of the healthy samples, was the predominant species, reaching up to 43% relative abundance in individual samples. In contrast, G. smithogilvyi was detected, and at the lowest level (1% relative abundance), in only 10% of infected samples. This knowledge on mycobiota shifts in C. sativa bark tissues infected by C. parasitica and the spatial distribution pattern with possible mutual exclusion of C. parasitica and G. smithogilvyi may be highly relevant to the understanding and management of cancer diseases of C. sativa.