Picea schrenkiana is a keystone species in Central Asian ecosystems currently threatened by climate-driven disease outbreaks. Here, we investigated the causal agent of needle blight and characterized the associated microbial dynamics. By integrating tissue isolation, Koch’s postulates, and high-throughput amplicon sequencing across a disease severity level, we confirmed Lirula macrospora as the etiological agent. Community analysis revealed that disease severity is the primary driver of succession, with alpha diversity peaks at the moderate infection stage. Notably, the abundance of Lirula surged from 2.56% in healthy needles to 65.10% in severe cases, displacing the core endophyte Phaeococcomyces, while potentially beneficial bacteria like Sphingomonas showed only transient enrichment. Furthermore, cross-kingdom co-occurrence network analysis revealed marked topological restructuring whereby the system reached a complex ecological “tipping point” during moderate stage before undergoing significant simplification. As the disease progressed, L. macrospora shifted from a peripheral node to a central hub, effectively dismantling the native microbial network. We conclude that L. macrospora infection triggers a cascading collapse of the needle microbiome, driving a phase shift from a healthy homeostasis to a pathogen-dominated state. These findings elucidate the critical mechanisms of pathogen-microbiome interactions and provide a theoretical basis for the ecological management of P. schrenkiana forests.
Halifu et al. (Sun,) studied this question.