Crop rotation-driven changes in secondary metabolites of potato rhizosphere soil exert stronger regulation on soil...

Crop rotation promotes ecological effects and production by regulating belowground processes, particularly the shaping of the rhizosphere soil microbiome. Rhizosphere metabolites are a key driver of belowground processes and play a crucial role in shaping soil microbial community composition. However, the rhizosphere metabolites of different potato rotations have rarely been reported, and the regulation of key metabolites on the rhizosphere soil microbiome remains unclear.

This study measured agronomic traits of potatoes, collected potato rhizosphere soils from three crop rotations, including potato monoculture (P-P), maize (Zea mays)-potato rotation (M-P), cowpea (Vigna unguiculata)-potato rotation (V-P), to determine rhizosphere soil metabolites and analyze defense metabolites, and assess the soil bacterial and fungal diversity and community composition.

Compared to monoculture, the potato rotations had positive effects on growth and yield. Potato rotations had more primary metabolites, such as amino acids and carbohydrates and conjugates, but significantly reduced secondary metabolites with defensive functions in rhizosphere soils including phenols and other benzene derivatives, flavonoids, alkaloids and other N-containing compounds, and terpenoids. Potato rotation systems supported higher diversity of bacteria and fungi and enriched beneficial bacteria such as biocontrol, nitrogen fixation, C degradation, denitrification, and pollutant degradation bacteria, while suppressing pathogenic fungi in the rhizosphere soils. Rhizosphere soil metabolites strongly correlated with the microbial community composition. The secondary metabolites, which are predominantly alkaloids, terpenoids, and flavonoids, exerted a dominant regulatory effect on the composition of soil microbial community.

These results demonstrate the important regulation of rhizosphere metabolites on soil microbial community composition, deepening our understanding of the benefits of crop rotation via the belowground effect.