Divergent Trajectory in the Succession of Maize Straw Decomposing Fungal Populations Due to Different Fertilizer Regime as Revealed by Stable Isotope Probing
摘要
Crop straw decomposition is crucial for carbon (C) turnover in agricultural soil, and fungi are generally considered the main decomposers of this process. Elucidating the response of straw decomposing fungi to different fertilizer regimes can provide a useful reference for efficient straw utilization. Soils under 8-yr fertilizations (CK, no N fertilizer; NPK, chemical fertilizer; NPKS, chemical fertilizer with straw addition) with 13C-labeled maize straw were mixed and incubated for 360 days. With DNA-stable isotope probing (SIP) approach and high-throughput sequencing, the community composition and structure of straw C fungal assimilators and their co-occurrence interaction under different treatments and incubation time were analyzed. Straw C utilizing fungal community was primarily shaped by decomposition time with higher diversity by Day90. Ascomycota, Basidiomycota and Mortierellomycota generally showed increasing relative abundance over time, while Mucoromycota decreased in relative abundance. Succession from Exophiala and Cephalotheca (lower relative abundance) to Mortierella, Neocosmospora, Fusarium, and Solicoccozyma (higher relative abundance) was observed with decomposition time. Meanwhile, 13C-fungal members showed tighter co-occurrence interaction at the initial stage, with Talaromyces_pinophilus and Phaeosphaeria identified as connectors of the network. NPKS soil especially collaborated straw C fungal assimilators for straw utilization than NPK soil, with Setophoma_terrestris identified as the keystone for straw decomposing fungal community. Straw decomposing fungal community exhibited a clear succession along with 1-yr incubation, and its community composition and interactions affected by different fertilizations strongly regulated straw C and N turnover in soils. The identified key fungal taxa may provide an important reference for further exploration of microbial ecological functions and the development of relevant microbial agents.