Cross-kingdom synthetic microbial communities outperform single-kingdom consortia in promoting potato growth under continuous cropping

Continuous cropping obstacles, including soilborne plant pathogen accumulation and soil microbial community degradation, present a critical bottleneck limiting sustainable potato production worldwide. To tackle the prominent obstacles associated with potato continuous cropping, this study explored the potential of synthetic microbial communities (SynComs) in regulating soil microbial ecology and promoting potato growth. Three SynComs were constructed, including a single bacterial consortium (SB), a single fungal consortium (SF), and a bacteria-fungal mixed consortium (SBF), using four bacterial strains (Bacillus licheniformis, Streptomyces sp., Pseudomonas lundensis, and Microbacterium sp.) and three fungal strains (Penicillium sp., Aspergillus fumigatus, and Aspergillus terreus). These SynComs were then evaluated for their effectiveness to overcome continuous cropping obstacles for potato in potted experiments, with non-inoculated group set as the blank control (CK). Our results demonstrated that the SBF consortium exhibited the most pronounced growth-promoting effect throughout the entire potato growth season. Specifically, SBF inoculation increased plant height, stem diameter, root length, and total biomass by 16.24%, 40.84%, 25.84%, and 13.86%, respectively, at the seedling stage; and 27.71%, 22.27%, 28.73%, and 39.31%, respectively, at the flowering stage. SynCom inoculation significantly altered both alpha and beta diversity of soil microbial communities and showed pronounced temporal dynamics. Mantel test analysis suggested that SynCom and pivotal bacterial taxa were the core driving factors for biomass accumulation in potato plants (P < 0.05). Collectively, SynComs effectively increased the abundance of inoculate-related microbes and restructured rhizosphere microbiota to promote potato growth. This study provides a sustainable strategy for alleviating potato continuous cropping obstacles and improving potato productivity.