Fungal endophytes, which live in plant tissue without causing obvious signs of disease, constitute an understudied, hyper-diverse group that has been implicated in mediating interactions between plants and herbivores, other fungi, and abiotic factors. This study examines the effect of climate warming on endophytic fungal communities. We sampled leaves from Picea glauca and Populus tremuloides in experimental plantings at Cloquet, MN. These plants are included in the B4Warmed project, which examines how boreal forest trees respond to above and belowground warming in open air plots maintained at ambient temperature or heated to 1.8°C or 3.8°C above ambient. Plots were replicated in closed and open canopy forest. Over 1,500 leaf samples were collected from each tree species, surface sterilized, and plated on 2% malt extract agar to isolate endophytes.
Results/Conclusions
We found a low occurrence of endophytic fungi in foliage of both P. glauca and P. tremuloides, with fewer than 5% of samples yielding cultures. A slightly increased frequency of endophytes was found in high heat treatment plots for P. glauca and in low heat for P. tremuloides. For both hosts, more isolates were found in open than in closed canopy plots. ITS-LSU sequencing revealed some fungi previously identified as endophytes in leaves and wood. To our knowledge, our efforts represent the first characterization of the repercussions of experimental warming on endophytes of boreal forest trees.