Monocropping decouples plant-bacteria interaction and strengthens phytopathogenic fungi colonization in the rhizosphere of a perennial plant species

Aims Despite the high economic benefits of using an intensive agriculture system, the sustainable development of Lycium barbarum L. cultivation in Northwest China is hindered by serious negative plant-soil feedback, which may be paralleled by the variation in the microbial rhizosphere community. Methods Here, we assessed the shift in the bacterial and fungal rhizosphere communities of L. barbarum across a 20-year-old chronosequence of stands at two independent experimental sites in Ningxia, China via real-time PCR and high-throughput sequencing. Results Stand age significantly influenced the alpha-diversity and abundance of the fungal rhizosphere community (p < 0.05) but did not affect the bacterial community. Phytopathogenic fungi, including Alternaria, Fusarium, Gibberella, and Stemphylium, were progressively enriched in the rhizosphere as the plant aged. Structure equation model suggested that soil abiotic properties were the direct drivers for bacterial community, whereas stand age and edaphic factor coexplained the succession of the fungal rhizosphere community. Conclusion Long-term monocropping decoupled plant-bacteria interaction and strengthened the colonization of fungal phytopathogens in L. barbarum rhizosphere. This study presents novel assessments of the links between the shifts in microbial rhizosphere community and the negative plant-soil feedback of L. barbarum.