Black spruce (Picea mariana) foliage hosts numerous and potentially endemic fungal endophytes

Abstract

Fungal foliar endophytes (hereinafter endophytes) were isolated on malt agar from black spruce ( Picea mariana (Mill.) BSP) needles from the Quebec boreal forest during 2 successive years to study their distribution along a latitudinal transect. Twenty sites were sampled in 2002, 8 of which were sampled again in 2003, in an area located between 47°N and 54°N in the province of Quebec. The endophytes were named whenever possible, using homologies of ITS rDNA sequences from GenBank. In 2002, 232 morphotypes were classified in 40 operational taxonomic units (OTUs), and in 2003, 93 morphotypes were classified in 16 OTUs, for a total of 44 OTUs. Isolation frequencies of the most common endophyte species were 28% for Lophodermium piceae (Fuchel) Höhn., 17% for Darkera parca Whitney, Reid & Piroz, and 9% for Dwayaangam colodena Sokolski & Bérubé. Of the 44 OTUs identified, 18 were unique to P. mariana and found on one site only, possibly constituting rare endemic species. There was some evidence that needles colonized with rare endophyte species were more abundant in the western and southern regions than in the northern region. This supports our hypothesis that as the diversity of tree species surrounding the P. mariana decrease from the southern region to the northern region, the diversity of endophytes also decreases.