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

The arbuscular mycorrhizal ( AM ) symbiosis is widespread throughout the plant kingdom but most terrestrial ecosystems also contain a considerable number of non‐mycorrhizal plants. The interaction of such non‐host plants with AM fungi is still poorly understood. In this study, we investigated whether the non‐mycorrhizal plant A rabidopsis thaliana , the model organism for plant molecular biology and genetics , interacts with AM fungi. We demonstrate, for the first time, that the presence of fungal networks formed by the AM fungus R hizophagus irregularis reduces A . thaliana growth by 50% or more. In addition, by using bright field, confocal and electronic microscopy we show that this fungus can colonize roots of A . thaliana , although arbuscules were never observed. These results reveal high susceptibility of A . thaliana to R . irregularis , suggesting that A . thaliana is a suitable model plant to study non‐host/ AM fungi interactions and the biological basis of AM incompatibility. Commentary: Interactions between arbuscular mycorrhizal and non‐mycorrhizal plants: do non‐mycorrhizal species at both extremes of nutrient‐availability play the same game?