A native PGPR SynCom boosts potato micropropagation, minituber production, and ware tuber yield and quality via convergent mechanisms

Potato ( Solanum tuberosum L.) is the world's fourth most important food crop, yet its conventional production relies heavily on agrochemical inputs that can adversely affect soil health and microbial diversity. Here, we constructed a seven-strain bacterial synthetic community (SynCom-114) from native plant growth-promoting rhizobacteria (PGPR) and evaluated its effects in three potato production contexts: microplant growth, minituber production, and field ware tuber production. Primary screening of 1013 strain combinations in ‘Jizhangshu 12’ yielded six candidate SynComs, from which cross-cultivar validation identified the seven-member SynCom-114 as the final consortium. SynCom-114, comprising Bacillus sp. A42, Chryseobacterium sp. R19, Arthrobacter sp. R17, Hymenobacter sp. B81, Priestia sp. 188, Pseudomonas sp. BP16, and Niveispirillum sp. W39, consistently promoted microplant growth across all five cultivars. In pot experiments, SynCom-114 increased the number and weight of qualified minitubers per plant by 70.97% and 101.35%, respectively. In the 2024 field experiment with ‘Jizhangshu 12’, SynCom-114 increased total ware tuber yield and qualified marketable ware tuber yield by 77.47% and 100.79%, respectively; in the 2025 experiment with ‘Huangxin 226’, the corresponding increases were 43.55% and 37.59%. Tuber starch and vitamin C contents were also increased in both field experiments. SynCom-114 was associated with increased rhizospheric enzyme activities and greater available nitrogen, available phosphorus, and soil organic matter. In the pot experiment, SynCom-114 was further associated with shifts in bacterial and fungal community structures and enrichment of candidate keystone taxa that were positively correlated with minituber traits. Piecewise SEM indicated significant positive paths from SynCom-114 to bacterial and fungal candidate keystone taxa, while only the bacterial pathway linking the microbial composite to rhizospheric soil nutrient–enzyme status was significant. This pattern was consistent with a potential mediating role of bacterial community changes in minituber performance. This study establishes a rapid, micropropagation-based strategy for constructing effective SynComs and provides evidence that a single native PGPR consortium can consistently improve potato production across three production scenarios—micropropagation, minituber production, and field ware tuber production—through integrated physiological, edaphic, and microbiome-mediated processes.