Strain-specific modulation of host growth, biomass composition, and transcriptomic responses in Spirodela polyrhiza by duckweed-associated bacteria

Transcriptome analysis revealed that PS05 induced 1,108 differentially expressed genes, compared with 454 genes for PS02, indicating substantially greater host transcriptomic reprogramming. Functional enrichment analyses demonstrated that PS05 preferentially regulated carbohydrate biosynthesis and central carbon metabolism. Consistently, both transcriptomic and RT-qPCR analyses showed up-regulation of key genes involved in starch biosynthesis and carbon allocation, resulting in significantly enhanced starch accumulation and turion formation without reducing protein or photosynthetic pigment content.

This study provides the first integrated evidence linking bacterial colonization strategy, host transcriptomic regulation, carbon allocation, and biomass production in duckweed, thereby establishing a mechanistic basis for engineering high-performance duckweed–microbiome systems for sustainable biomass production.