Variation of arbuscular mycorrhizal fungi (AMF) biological diversity in the mosses crust layer of desert during snow cover season

Abstract:

[Background] Up to now, there was very limited research exploring the symbiotic relationship between bryophytes and arbuscular mycorrhizal fungi (AMF) in temperate desert with the context of snow. [Objective] To reveal the difference of AMF biological diversity in mosses crust layer of desert during the period of early winter (before snowfall), mid-winter (snow-accumulation) and snow melt, we further understand the crucial win-win survival strategy between desert characteristic plants and microorganisms in winter snow accumulation. [Methods] High-throughput sequencing technique was used to study the community composition and diversity of AMF in the dominant bryophyte crusts growing in Gurbantonggut Desert under stable snowfall period, and the difference of AMF community structure before and after snowfall is analyzed. [Results] All operational taxonomic units (OTUs) belonged to 5 orders, 9 families and 11 genera. Of these, these species assigned to the taxonomy of Claroideoglomus, Archaeospora, Paraglomus and Glomus were the dominant groups. There was no significant difference among the dominant genus of AMF in the mosses crust layer between early winter (December) and snow melt (March), and the absolutely dominant genus (>50%) was Claroideoglomus. However, the relative abundance of different AMF groups have different trends between early winter and snow melt. The proportion of Claroideoglomus increased significantly during snow melt period. Compared with early winter, the abundance of AMF assigned to the level of Paraglomus and Glomus decreased. The value of Chao1 index and ACE index used to measure the community richness were in the following order: before snowfall>snow-accumulation>snow melt. It showed that the abundance of AMF community decreased due to snowfall. The visual analysis of taxonomic composition information based on MEGAN software suggested that low abundance AMF groups were more easily affected. Acaulospora was mainly from the samples collected before snowfall, while Diversispora was mainly from the samples collected during the snow melt period. Based on the cluster analysis of genus level communities, it was found that the types of high abundance taxons decreased from 5 before snowfall to 2 after snowfall, which indicated that snowfall had a certain selectivity to AMF groups in bryophyte crusts. The results of principal component analysis (PCA) showed that the characteristics of AMF community structure, including early winter and snow melt, could be effectively distinguished by PCA1. This further verified that the snowfall factors have a significant screening effect on AMF community in the moss crusts. A competitive relationship may exist between the high abundance genus, Claroideoglomus and Glomus, Paraglomus and Archaeospora, due to the negative correlation among them. But because of positively correlated, a cooperative relationship may exist to survive in environment of snowfall between low abundance genus : Gigaspora, Septoglomus, Ambispora and Scutellospora. [Conclusion] The winter snowfall in Gurbantonggut Desert has different selection strategies for the dominant genera and low abundance genera for the AMF group of moss crusts. During the snow melt period, the absolute dominant genus will reduce the proportion of competitive dominant genus, thus further consolidate the dominant position. While the existence of positive correlation of low abundance will synchronously reduce the proportion. Unlike the Tengger Desert, the dominant genus of AMF in the moss crusts is Claroideoglomus but not Glomus in this desert.