Fungal endophytes affecting the health and recovery of Long’s Braya (Braya longii) and Fernald’s Braya (Braya fernaldii), endangered endemic species of Newfoundland, Canada

Abstract

Long’s ( Braya longii Fernald) and Fernald’s ( B. fernaldii Abbe) Braya are endemic to the Great Northern Peninsula of Newfoundland, Canada. These herbaceous perennials are endangered due to habitat loss and degradation, as well as ongoing threats from fungal infections and insect herbivory. While recovery plans are being implemented, the identity of pathogenic fungi and their origins remain largely unknown. This study was initiated to describe the associated fungal community and infection symptoms. Plant tissues from three populations were sampled over 5 years yielding 326 fungal isolates identified primarily by nucleotide sequence analysis of the internal transcribed spacer rDNA region. Isolates included 36 taxa, 16 of which were detected once and 5 detected three times or less. In contrast, 12 taxa were detected across multiple sites, sampling intervals and years. These included two species of Alternaria,  Boeremia exigua, closely related species of the Didymellaceae, Botrytis cinerea,  Fusarium sp., Colletotrichum sp., Stagonosporopsis sp., Pleospora sp., and Truncatella angustata. Some common taxa showed seasonal trends. The isolated fungi included known pathogens of Brassicaceae. The plants in this study frequently showed symptoms indicative of fungal infection and insect herbivory. These findings improve our knowledge of Braya endophyte communities and will inform recovery efforts for these endangered species.