Rare Taxa Drive the Response of Soil Fungal Guilds to Soil Salinization in the Taklamakan Desert

Abstract

Salinization poses great threats to soil fungal communities that would cause the losses of ecosystems services. Soil fungal communities are composed of different functional guilds such as saprotrophic, symbiotrophic, and pathotrophic fungi, and each guild includes many rare taxa and a few abundant taxa. Despite of low abundance, rare taxa may be crucial in determining the responses of entire soil fungal communities to salinization. However, it remains poorly understood how rare taxa mediate the impacts of soil salinization on soil fungal community structure. Here, we took advantage of a salinity gradient in a desert ecosystem ranging from 0.60 to 31.09 g kg−1 that was created by a 12-year saline-water irrigation and assessed how the rare vs. abundant taxa of soil saprotrophic, symbiotrophic, and pathotrophic fungi respond to soil salinization through changes in the community biodiversity and composition. We found that the rare taxa of soil saprotrophic, symbiotrophic, and pathographic fungi were more sensitive to changes in soil salinity compared to the abundant taxa. In addition, the community composition of rare taxa of the saprotrophic and pathotrophic fungi not the symbiotrophic fungi was positively associated with soil salinity change. However, the symbiotrophic fungi showed greater variations in the species richness along the salinity gradient. These findings highlight the importance to differentiate rare taxa in predicting how the biodiversity and functional groups of soil fungal communities respond to soil salinization.

Altitudinal Variation Influences Soil Fungal Community Composition and Diversity in Alpine–Gorge Region on the Eastern Qinghai–Tibetan Plateau

“…The positive correlation between EC and richness of symbiotic fungi was greater than that of saprophytic fungi ( Figure 6 ), which may be due to the fact that the plasticity of symbiotic fungi was higher than that of saprophytic fungi under salinity stress [ 105 ]. Symbiotic fungi were able to adjust richness by themselves and with the help of plants to counteract the detrimental effects of salinity, while saprophytic fungi could only adapt to high salt stress by adjusting their richness by themselves [ 105 ]. Inconsistent with the findings of Du et al [ 106 ], there was a weak relationship between SOC and α-diversity of pathogenic fungi in our study, suggesting that other ecological factors may have a greater effect on α-diversity of pathogenic fungi [ 107 ].…”

“…Low phosphorus could stimulate increased phosphorus requirements in host plants, thereby increasing the richness of symbiotic fungi used for mycelial soil exploration [ 103 ]. The positive correlation between EC and richness of symbiotic fungi was greater than that of saprophytic fungi ( Figure 6 ), which may be due to the fact that the plasticity of symbiotic fungi was higher than that of saprophytic fungi under salinity stress [ 105 ]. Symbiotic fungi were able to adjust richness by themselves and with the help of plants to counteract the detrimental effects of salinity, while saprophytic fungi could only adapt to high salt stress by adjusting their richness by themselves [ 105 ].…”

Diversity and functional traits of indigenous soil microbial flora associated with salinity and heavy metal concentrations in agricultural fields within the Indus Basin region, Pakistan

“…Unfortunately, using the FUNGuild tool (Nguyen et al, 2016), we noted a negative correlation between salinity and some HM on fungi with symbiotrophic activity, and positive correlation between pathotrophic fungi and N and some HM within the soils of this region (Supplementary Figure S5F1). Relationships between fungi with these trophic modes and soil chemical properties have been mixed in other studies (Lin et al, 2022;Zhu et al, 2022), indicating that other site-specific factors are likely to play a role in mediating these dynamics and further research is needed to elucidate the mechanisms responsible. Fortunately, fungi with saprotrophic capabilities were positively correlated with salinity and some metals, providing further evidence of the adaptability of this important group of fungi in these soils.…”

Soil salinization increases the stability of fungal not bacterial communities in the Taklamakan desert

“…Fungal species have different functions or/and habitat preference and are likely in different modules (Fan et al, 2020). Symbiotrophic fungi strengthen their associations with aboveground plants in high-saline conditions (Lin et al, 2022), thus promoting its potential functions and niches. The fungal diversity increased with increasing salinity (Fig.…”

“…Environmental stress (e.g., soil salinization) is accompanied by sharply increased human activities since the middle of 20th century (Ivushkin et al, 2019), triggering shift interspecific interactions even species extinctions. For instance, soil salinization cause osmotic pressure, nutritional imbalance, and ion toxic effects to microbiota and alter the abundance of mycorrhizal fungi (Lin et al, 2022), genus black yeasts (Chung et al, 2019), and denitrifying bacteria (Thiem et al, 2018). Salinization could decrease competitive interactions between microbial taxa and increase the facilitative interactions between fungi and plants (Mo et al, 2021;Dong et al, 2022;Hu et al, 2022), which have a great role in regulating population declines and extinctions.…”