Arbuscular mycorrhizal (AM) fungi can form symbiosis with 90% of the vascular plants and play important roles in ecosystem. To realize the AM fungal colonization at different succession stages in saline-alkali land and screen AM fungi species with great functions, roots and soil samples were collected from the three succession stages of Songnen saline-alkali grassland. The soil properties and AM fungal colonization were measured, and the fungus distributed extensively in three stages was annotated by sequencing for AML1/AML2 target, subsequently, maize was selected as the host to verify its colonization. The results showed that the soil properties improved with the succession of saline-alkali grassland. The plants' communities of the three stages could be colonized by AM fungi, and the colonization rate of Leymus chinensis (the third stage) ranged from 66.67% to 100%, Puccinellia tenuiflora (the second stage) ranged from 50% to 80%, while the Suaeda glauca (the first stage) was only 35%-60%. Glomeraceae sp1 was identified as the dominant AM fungi species which occurred frequently in the succession of saline-alkali land with the isolation frequency, relative abundance, and importance value of 100%, 18.1%, and 59.1%, respectively. The colonization rate of Glomeraceae sp1 in maize ranged from 80% to 87% and similar mycorrhizal characteristics were detected in the roots of P. tenuiflora, S. glauca, and L. chinensis, indicating that Glomeraceae sp1 colonized the samples in the field. The correlation matrix indicated that colonization rate, colonization intensity, and vesicle abundance were closely related to soil conditions most, and they were related significantly to all the soil properties except cellulase activity. Besides, redundancy analysis (RDA) showed that soil properties drove the changes of AM fungal colonization and sporulation. These results will provide theoretical support for realizing the relationship between AM fungal colonization and soil conditions, and also for the exploration of AM fungi species with great functions.

Salinization has led to the deterioration of the ecological environment, affected the growth of plants, and hindered the development of agriculture and forestry. Arbuscular mycorrhizal (AM) fungi, as important soil microorganisms, play significant physiological and ecological roles in promoting plant nutrient absorption and improving soil structure. Puccinellia tenuiflora (Turcz.) Scribn. et Merr. in Songnen saline-alkaline grassland was selected as the research object to observe AM fungal colonization of the roots and explore the species and diversity of AM fungi in symbiotic association with P. tenuiflora. This study showed that AM fungi colonized in P. tenuiflora roots and formed a typical Arum-type mycorrhizal structure. A significant correlation was observed between vesicular abundance and the colonization intensity of mycorrhiza. Isolation and identification revealed 40 species of AM fungi in the rhizosphere of P. tenuiflora, belonging to 14 genera, of which two species could not be identified. The richness of the genus Glomus was the highest, accounting for 30% of the total species. Funneliformis mosseae and Rhizophagus intraradices were isolated from all the samples and were the species with the widest distribution in the rhizosphere of P. tenuiflora. Correlation analysis showed that pH only had a significant impact on the distribution of a few species, such as Glomus pustulatum, Diversispora spurca, Glomus aggregatum, Rhizophagus clarum, and Acaulospora foveata.The present study provides a theoretical basis for further exploring the resources of AM fungi in saline-alkaline soil.