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Pine wilt disease (PWD), caused by the pine wood nematode Bursaphelenchus xylophilus, is one of the most devastating forest diseases in Asia and Europe. In addition to causing rapid pine mortality, it can alter soil nutrient status and soil nitrogen transformation processes. At the same time, nitrogen (N) deposition is an important external nitrogen input to forest ecosystems and may further influence rhizosphere nitrogen dynamics under B. xylophilus infection; however, its effects on N forms and microbial community characteristics in the rhizosphere soil of infected pine trees remain poorly studied. Therefore, this study aimed to investigate the effects of simulated N deposition on PWD, rhizosphere soil chemical properties, and rhizosphere microbial community characteristics under B. xylophilus infection, by inoculating 4-year-old Pinus thunbergii seedlings with ddH2O (CK) and B. xylophilus (BX). For each inoculation condition, two simulated N deposition levels (N1: 50 mg N kg−1 dry soil; N2: 100 mg N kg−1 dry soil) and one control without N deposition (N0) were established. Generally, simulated N deposition significantly prolonged disease progression in B. xylophilus-infected pines, with mean times of 32, 43, and 46 days for BXN0, BXN1, and BXN2, respectively, and rhizosphere NO3−–N and NH4+–N contents were significantly higher in N1 and N2 for both the CK and BX groups. Under the same N deposition, BX treatment significantly enhanced the accumulation of NO3−–N but had a limited effect on NH4+–N. The microbial community analysis indicated that Ascomycota, Mortierellomycota, and Basidiomycota were the dominant fungal phyla across all experimental groups, while the Talaromyces, Apiotrichum, and Aspergillus genera showed significant abundance changes between the CK and BX groups. In addition, Actinobacteriota, Proteobacteria, and Acidobacteriota were the top bacterial phyla across all experimental groups, while the genera Nocardioides and RB41 showed changes in relative abundance between the CK and BX groups. These findings suggest that short-term nitrogen deposition can influence the PWD process and modulate rhizosphere nitrogen dynamics and microbial community structure.
Liao et al. (Sat,) studied this question.