4.1. Bathyarchaeia inhabiting paddy soil is highly abundant but not diverse
Bathyarchaeia exhibits a widespread distribution in diverse environments. Past investigations have predominantly concentrated on marine, mangrove, and freshwater sediments, where Bathyarchaeiahave been notably abundant (Baker et al. 2020; Lazar et al. 2015; Pan et al. 2019; Yu et al. 2017). Nevertheless, the presence ofBathyarchaeia in arable soils has received limited scrutiny. Within this study, we have determined that the proportion ofBathyarchaeia relative to all archaea varies significantly among distinct paddy soils, constituting an average of approximately 31.2%.
Concerning the community structure of Bathyarchaeia in paddy soils, the Bathy-6 subgroup exclusively predominates across all surveyed sites, accompanied by a smaller representation of ASVs associated with Bathy-11 , Bathy-15 , Bathy-5bb , andBathy-17 . In comparison with our recent meta-analysis (Xue et al. 2023), the subgroup diversity of Bathyarchaeia in paddy soils within eastern China (comprising 5 subgroups) appeared lower than the global scale (comprising 7 subgroups), as Bathy-18 andBathy-5b were not detected in our study. This discrepancy might be elucidated by the greater diversity observed in paddy soils worldwide. Furthermore, previous studies have indicated thatBathyarchaeia exhibit a relatively low relative abundance in certain paddy soils (Jiao et al. 2019), while Zheng et al. reported a higher abundance of Bathyarchaeia in water-saturated paddy soils compared to cultivar-rotation paddy soils and upland soils (Zheng et al. 2019). All these findings collectively suggest that the abundance and diversity of Bathyarchaeia in paddy soils are considerably influenced by pedoclimatic conditions. Therefore, it would be beneficial to explore the specific soil conditions that favor either low or high relative abundance of Bathyarchaeia in future research.