Beech cupules share endophytic fungi with leaves and twigs

• Endophytic fungi on beech cupules were compared with those of leaves and twigs.
• Phomopsis sp., Xylaria sp., Ascochyta fagi, and Geniculosporium sp. were frequent.
• Endophytic fungal assemblages of cupules were intermediate between leaves and twigs.
• The fungal assemblages of cupules shared component taxa with leaves and twigs.

Endophytic mycobiota on leaves, twigs and cupules of Fagus crenata were investigated using a culture-dependent method over a growing season to test the hypothesis that endophytic fungi of cupule (a woody phyllome) share some components of the endophytic fungal assemblages with both leaves and twigs. A total of 14 fungal taxa were isolated, and the most frequent taxon was Phomopsis sp., followed by Xylaria sp., Ascochyta fagi and Geniculosporium sp. The compositions of fungal assemblages of leaf laminae and petioles were generally relatively dissimilar to those of current and first-year twigs when compared for each sampling month, and those of cupules and cupule stalks were intermediate between those of leaves and twigs. Permutational multivariate analysis of variance confirmed that month and organ were significant factors of the variation of the composition of endophytic fungal assemblages. Phomopsis sp., a common twig endophyte, and A. fagi, a common leaf endophyte, were common in cupules and cupule stalks. These results suggested that the endophytic fungal assemblages of cupules shared component taxa with those of both leaves and twigs.