Communities and populations of arbuscular mycorrhizal fungi (Glomeromycota) in agricultural settings : effects of short-term and long-term soil disturbance by tillage

A large proportion of the well-documented deleterious effects of agriculture on arbuscular mycorrhizal fungal (AMF, Glomeromycota) communities may be due to tillage, depending on the tolerance of particular AMF species or genotypes to mechanical disturbance. Understanding the dynamics of AMF communities and populations in agroecosystems is a requirement for managing these beneficial symbionts in the context of moving towards sustainable agriculture. We studied the effects of tillage on the composition of AMF community composition in a long-term field experiment, as well as in combination with fertilization treatments in a small-scaled field trial over a period of three months. We used high-throughput sequencing of the marker gene rpb1, which was used for the first time in AMF community analysis. We detected a high diversity of molecular taxa in both experimental systems and no significant reduction of AMF diversity attributable to tillage. In fact, disturbance slightly increased AMF species richness in the short-term experiment. Significant shifts were detected in the relative abundance of sequences of molecular taxa. Intraspecific genotypes of R. irregularis, which are known to be differentiated between grasslands and arable soils, showed a partial transition away from grassland genotypes. Our results indicate that disturbance has the strongest impact on AMF communities over short periods of time, but that at the same time these effects are modulated by fertilization