Salinity changes root occupancy by arbuscular mycorrhizal fungal species

Abstract

Understanding the diversity and community composition of arbuscular mycorrhizal (AM) fungi in stressful conditions is fundamental to predicting the occurrence and function of indigenous AM fungal associations in a changing soil environment. Here, using whole-soil inoculum, we investigated the effects of salinity on community structure and colonization rate of AM fungi in roots, and assessed their influence on maize (Zea mays L.) performance. Three different salinity treatments (0, 75, and 150 mM NaCl) were applied to mycorrhizal inoculated and non-inoculated plants. Results showed that salinity levels significantly influenced AM fungal composition and diversity as well as vesicular and hyphal colonization in roots. The AM fungal community composition and diversity index differed slightly under the 0 and 75 mM NaCl treatments, but changed significantly under the 150 mM NaCl treatment. Increased vesicular and declined hyphal colonization were observed under 75 and 150 mM NaCl treatments relative to the control. Further analyses uncovered that plants under the 0 and 75 mM NaCl treatments, where Glomeraceae predominated as root symbionts, had a higher mycorrhizal growth response than plants under the 150 mM NaCl treatment, where Claroideoglomeraceae abundance increased significantly. This study provides evidence that saline stress plays a vital role in community structure and root colonization by AM fungal communities. Additionally, our data suggested that community composition may be more important for mycorrhizal symbiotic function than the rate of root colonization. Finally, while the relative abundance of Claroideoglomeraceae was found to increase with stress in saline soil, their role needs to be further clarified in future studies.