Multiple mycorrhization at the coldest place known for Angiosperm plant life

Abstract

The so far coldest location for flowering plant life was found at 4,505 m asl at the Dom summit in Valais (Switzerland). On an ice-free crest, Saxifraga oppositifolia, a typical arctic-alpine arbuscular mycorrhizal (AM) plant forms several cushions. Here, we report on a surprisingly diverse fungal community of mycorrhizal and non-mycorrhizal species at this particular location. A few grams of fine sand and organic material obtained from the rhizospheric lithic ‘soil’ and fine roots of S. oppositifolia were examined for fungal spores and hyphae. We found five different species of AM fungi (Glomeromycota) that belonged to all three glomeromycotan classes, to four orders and five different families. We also found hyphae of dark-septate endophytes (unidentified on the species and genus level, members of Vibrisseaceae, Helotiales, Ascomycota) and a few cleistothecia of a putative fungal leaf pathogen resembling Podosphaera alpina (Erysiphaceae, Erysiphales, Ascomycota), which is known to cause powdery mildew on S. oppositifolia. Given the size of the cushions and their annual growth, these microcosms of life may not be older than 30 years, obviously sufficient time to establish a rich fungal community despite the extreme cold at this location, which in terms of higher level mycorrhizal fungal taxa is obviously comparable with fungal communities of well-established alpine, mountainous and even temperate lowland grasslands.