The influence mechanisms of earthworm amendment on lettuce growth and aphid suppression from the perspective of rhizosphere bacterial community

Earthworms hold great promise for promoting plant growth and pest resistance. Notably, earthworms can influence rhizosphere microbial communities, which play crucial roles in regulating plant performance-related processes. This study aimed to investigate whether earthworms exert growth-promoting and aphid-resistant effects through modifying rhizosphere bacteria, using a lettuce pot experiment combined with 16S rDNA sequencing. Results showed that the introduction of earthworms enhanced the accumulation of soil organic carbon (14.9 ± 1.6 %), nitrogen (8.2 ± 0.4 %), and phosphorus (9.3 ± 3.5 %). While earthworm introduction promoted lettuce growth and increased chlorophyll content to varying degrees at different sampling periods, it inhibited aphid colonization on lettuce during the initial exposure period. Additionally, earthworms significantly altered the structure and composition of the bacterial community in the lettuce rhizosphere and increased the relative abundances of phyla Bacteroidota, Sumerlaeota, and Verrucomicrobiota. Furthermore, functional changes of Biomarker subcommunity in terms of carbon, protein and amino acid, and phosphate metabolisms, as well as the Biosynthesis of other secondary metabolites were significantly correlated with lettuce growth promotion. The interplay between Biomarker subcommunity and non-Biomarker subcommunity in Glycan biosynthesis and metabolism and Environmental adaptation was linked with stage-specific suppression to aphids. These findings provide practical guidance for leveraging earthworms and rhizosphere microbiota in agricultural settings. • Earthworm amendment was conductive to the promotion of lettuce growth (PLG). • Earthworm amendment suppressed of aphid colonization (AC) on lettuce. • Biomarker rhizobacterial potential nutrient & secondary metabolism was linked to PLG. • Potential glycan metabolism of overall rhizobacteria was linked to AC suppression.