Comparison of culturing and metabarcoding methods to describe the fungal endophytic assemblage of brachypodium rupestre growing in a range of anthropized disturbance regimes

Fungal endophytes develop inside plants without visible external signs, and they may confer adaptive advantages to their hosts. Culturing methods have been traditionally used to recognize the fungal endophytic assemblage, but novel metabarcoding techniques are being increasingly applied. This study aims to characterize the fungal endophytic assemblage in shoots, rhizomes and roots of the tall grass Brachypodium rupestre growing in a large area of natural grasslands with a continuum of anthropized disturbance regimes. Seven out of 88 taxa identified via metabarcoding accounted for 81.2% of the reads (Helotiaceae, Lachnum sp. A, Albotricha sp. A, Helotiales A, Agaricales A, Mycena sp. and Mollisiaceae C), revealing a small group of abundant endophytes and a large group of rare species. Although both methods detected the same trends in richness and fungal diversity among the tissues (root > rhizome > shoot) and grasslands (low-diversity >high-diversity grasslands), the metabarcoding tool identified 5.8 times more taxa than the traditional culturing method (15 taxa) but, surprisingly, failed to sequence the most isolated endophyte on plates, Omnidemptus graminis. Since both methods are still subject to important constraints, both are required to obtain a complete characterization of the fungal endophytic assemblage of the plant species.

M.D. got funding through UPNA’s doctorate scholarship. This research was supported by 'la Caixa' Foundation and CAN foundation (LCF/PR/PR13/51080004), Ecoembes-SEO/Birdlife (Libera 2017), Government of Navarra (STEM research project 2018) and Interreg Sudoe Programme, European Regional Development Fund, European-Union, Open2preserve Project (SOE2/P5/E0804).