Arbuscular mycorrhizal fungi reduce growth and infect roots of the non‐host plant Arabidopsis thaliana

Abstract

The arbuscular mycorrhizal (AM) symbiosis is widespread throughout the plant kingdom and important for plant nutrition and ecosystem functioning. Nonetheless, most terrestrial ecosystems also contain a considerable number of nonmycorrhizal plants. The interaction of such non-host plants with AM fungi (AMF) is still poorly understood. Here, in three complementary experiments, we investigated whether the non-mycorrhizal plant Arabidopsis thaliana, the model organism for plant molecular biology and genetics, interacts with AMF. We grew A. thaliana alone or together with a mycorrhizal host species (either Trifolium pratense or Lolium multiflorum) in the presence or absence of the AMF Rhizophagus irregularis. Plants were grown in a dualcompartment system with a hyphal mesh separating roots of A. thaliana from roots of the host species, avoiding direct root competition. The host plants in the system ensured the presence of an active AM fungal network. AM fungal networks caused growth depressions in A. thaliana of more than 50% which were not observed in the absence of host plants. Microscopy analyses revealed that R. irregularis supported by a host plant was capable of infecting A. thaliana root tissues (up to 43% of root length colonized), but no arbuscules were observed. The results reveal high susceptibility of A. thaliana to R. irregularis, suggesting that A. thaliana is a suitable model plant to study non-host/AMF interactions and the biological basis of AM incompatibility.

The Petunia GRAS Transcription Factor ATA/RAM1 Regulates Symbiotic Gene Expression and Fungal Morphogenesis in Arbuscular Mycorrhiza

“…In such cases, nutrition from a nearby growing wild-type plant can potentially enable the fungus to colonize AM-defective mutants, a system known as nurse plant inoculation. Nurse plants represent a very strong inoculum, from which highly AM-resistant mutants (Feddermann et al, 2010), and even nonhost plants (Veiga et al, 2013), can be colonized. Nurse plant inoculation of ata resulted in rapid and efficient colonization (Fig.…”

“…Nurse plants are well-colonized wild-type plants that grow nearby the mutants and represent a very strong source of inoculum. Such inoculum can even result in colonization of the nonhost plant Arabidopsis (Veiga et al, 2013), and in the strongly AM-resistant vapyrin mutant, nurse plant inoculation triggered the induction of the AM-marker gene PT4, although at reduced levels (Feddermann et al, 2010).…”

Mycorrhizal fungi status in organic farms of south Florida

“…Thus, the mycorrhizal fungi relationship of these plants needs further exploration. However, there are several studies reporting mycorrhizal colonization in non-host species (Veiga et al 2013).…”

The evolution of mutualism from reciprocal parasitism: more ecological clothes for the Prisoner’s Dilemma

“…Genetic variation in the strength of mutualistic interactions has been demonstrated in plant-rhizobium systems (Heath and Tiffin 2007;Gorton et al 2012). Similarly, plant-mycorrhizal relationships are not invariably mutualistic: when arbuscular mycorrhizae infect plants that are normally nonmycorrhizal, they may act as parasites (Veiga et al 2013); conversely, plants can be parasitic on the fungi (Merckx and Freudenstein 2010).…”