Complex interactions among soil physicochemical interactions and microbial community associations with potato common scab severity

Potato common scab, a disease caused by the pathogenic Streptomyces species, produces cork lesions on tubers, leading to significant reductions in marketable yield and crop quality worldwide. Although the established correlation between soil physicochemical properties and microbial communities with disease severity, the interactive effects of these factors remain to be fully understood. In this study, we conducted a comprehensive, multi-year investigation of 124 potato fields in South Korea. This investigation was undertaken to elucidate the combined influence of soil properties and microbial communities on the development of common scab disease. An analysis of the soil physicochemical characteristics was conducted in conjunction with high-throughput 16s rRNA and ITS amplicon sequencing. The application of random forest modeling, based on soil physicochemical properties, exhibited a moderate predictive accuracy. Consistent with this, the importance feature of individual variables remained low, suggesting complex interactions among soil factors. The analysis of microbial communities revealed taxa that described a correlation with severity levels, thus distinguishing between distinct severity groups. Rhodanobacteraceae and Mortierellaceae were identified as indicators of low-severity fields, whereas Sphingomonadaceae, Chaetomiaceae, and Cystofilobasidiaceae were associated with high-severity fields. Despite the identification of several severity-associated soil and microbial features, no predominant factor explaining common scab severity was detected. This finding suggests that disease development is influenced by complex interactions among soil physicochemical conditions and microbial communities rather than by a single dominant driver.