Researchers at Umeå University have discovered that applying two soil bacteria together produces a significantly stronger effect on potato development than using either strain individually. Led by Benedict Albrechtsen from the Department of Plant Physiology, the scientific team analyzed the impact of Pseudomonas protegens and Pseudomonas simiae on potato plants under greenhouse conditions. Their experiments revealed that treating plants with a combination of both strains accelerated tuber formation, with gene expression analysis confirming heightened activity in genes responsible for tuber initiation. Furthermore, this synergistic bacterial duo triggered qualitatively distinct plant responses compared to single-strain applications. To unravel the underlying mechanisms, the researchers collaborated with the Swedish Metabolomics Centre and identified that when cultivated together, the bacteria produce a unique set of chemical compounds, indicating active cross-talk and mutual influence between the two strains.
Beyond promoting growth and development, the bacterial treatment also affected genes associated with disease resistance and stress defense in potatoes, while also altering tuber quality traits such as starch and vitamin C content. However, the magnitude of these responses varied between the widely cultivated Swedish varieties Mandel and Désirée, highlighting a cultivar-specific effect. Published in the Journal of Experimental Botany, these greenhouse findings pave the way for the next crucial step: field trials. The research team plans to test natural combinations of beneficial bacteria in real agricultural systems to validate their practical applicability. They also aim to investigate how overall soil microbiota diversity influences potato development and explore whether these promising strategies can be extended to other important food crops.
