Occurrence of dark septate endophytes in Nothofagus seedlings from Patagonia, Argentina

Abstract

Temperate forests of southern Argentina and Chile cover a wide latitudinal and altitudinal range on both sides of the Andes, Nothofagus species being one of the main tree species. Most of the larger remnants are protected within the limits of national parks and forest reserves. However, some of them are invaded by exotic conifers such as Pseudotsuga menziesii. In order to better understand the mycorrhizal condition within the Nothofagus – P. menziesii interaction, transects were established in 6 study sites along the effective recruitment area. Three treatments were established: Nothofagus forest without P. menziesii invasion (Forest), Nothofagus – P. menziesii matrix (Interface) and P. menziesii plantation lacking Nothofagus specimens (Plantation). A 2 kg mixed soil sample was taken at each treatment site and kept in brand-new plastic bags. A soil bioassay with Nothofagus seedlings acting as bites was set to evaluate the mycorrhizal inoculum potential and soil-fungi composition at each sampling treatment. Forty percent of the evaluated seedlings were found to be colonized by Dark septate endophytes (DSE) fungi. Ectomycorrhizal colonization percentage was significantly higher in plants growing in Forest soils (mean=57.77%) when compared with Interface (mean=42.53%) and Plantation (mean=44.65%). The high incidence of DSE in young roots of Nothofagus seedlings of this study support the hypothesis that DSE might be pioneering colonizers of young tree seedlings in secondary successional environments. For future interventions in the forest, either with productive or protection intentions, it should be taken into account the incidence of these fungi, which may have an important positive role in Nothofagus forests post invasion recovery.