Culturable endophytes from carnivorous plant traps in the UK: commonality of endophyte species across host species and sites.

Abstract Fungal endophytes are ubiquitous plant symbionts existing asymptomatically inside plant tissues but playing a crucial role in plant health and function. Endophytes have been extensively studied in many plants, such as agricultural systems, but in carnivorous plants which may engage microbes to aid in digestion, they are poorly understood. To address this deficiency, this study aims to assess the presence and host specificity of fungal endophytes in carnivorous plant traps. Five carnivorous plant species were sampled from two in-situ sites and greenhouse grown plants. Fungal endophytes were isolated from the traps of five carnivorous plant species: Drosera rotundifolia, Drosera anglica, Pinguicula vulgaris, Dionaea muscipula, and Sarracenia purpurea. These represent a range of trapping mechanisms, native and introduced species. We included different carnivorous plant species growing at the same site, and the same species at different sites to test for host and site specificity. Endophytes were cultured on malt extract agar and identified by sequencing the internal transcribed spacer (ITS) region. The isolated fungal endophytes were composed of species from common Ascomycota genera (Alternaria, Cladosporium, Colletotrichum, and Didymocyrtis). Fungal endophytes were present in all plant species, this expands our understanding of endophyte distribution in carnivorous plants, representing the first endophytes isolated from D. anglica and D. muscipula and the first endophytes from the traps of D. rotundifolia and P. vulgaris, along with five new fungal endophyte species in carnivorous plants. There was some host specificity; S. purpurea was the only host plant with Colletotrichum spp., whereas Alternaria spp. were found across multiple hosts and sites. The trap endophytes cultured here differed to root endophytes of Drosera and Pinguicula found in previous studies of plants at the same site, suggesting that above and below ground endophytes may differ, perhaps offering different functions in separate plant tissues.