Multi‐omics dissection of dormancy transition reveals mechanisms underlying long‐term survival in the diatom Thalassiosira pseudonana resting cells

SUMMARY Diatom resting stages are crucial for their long‐term survival in unfavorable conditions. However, the molecular mechanisms enabling these cells to maintain viability over extended periods while remaining capable of rapid revival are poorly understood. We employed an integrated multi‐omics approach, combined with physiological assays, to track the molecular and phenotypic dynamics of the diatom Thalassiosira pseudonana during the transition from vegetative cells to newly formed and finally long‐term surviving resting cells (up to 402 days). We discovered that resting cells achieve longevity via phased metabolic reconfiguration and extensive lipid remodeling. Hypometabolism was underpinned by suppressed respiration and photosynthesis, linked to mitochondrial cardiolipin degradation and thylakoid glycolipid shifts. Crucially, an increase in sphingolipids, sterols, and ether lipids, coupled with a reduction in membrane unsaturation, led to a decrease in membrane fluidity and permeability, which limited the uptake of toxic anthracene. Concurrently, cells downregulated the grazing stimulant dimethylsulfoniopropionate (DMSP) while accumulating its antioxidant derivative dimethyl sulfoxide (DMSO), reducing predation and oxidative stress. Our findings reveal an active survival strategy where membrane restructuring forms a primary defense barrier, integrated with biochemical adaptations to ensure resilience in fluctuating environments.