Diatom resting cells form sedimentary seed banks that drive algal bloom recurrence, yet the mechanisms enabling long-term survival in dark, cold deep waters remain unclear. Using multi-omics and physiology in the bloom-forming diatom Thalassiosira pseudonana, we show that resting-cell formation is triggered by decreased light and temperature, leading to storage catabolism, cytoplasmic acidification, and chloroplast remodeling. Long-term survival (up to 402 days) involves phased metabolic reconfiguration and extensive lipid remodeling: suppressed respiration/photosynthesis via cardiolipin and glycolipid shifts, increased sphingolipids/sterols/ether lipids, and reduced membrane unsaturation, which lower fluidity/permeability and limit toxic anthracene uptake. Concurrently, downregulation of the grazing stimulant DMSP and accumulation of its antioxidant derivative DMSO reduce predation and oxidative stress. Our findings reveal a multi-layered active defense, centered on membrane restructuring, that ensures cellular resilience and underpins diatom bloom dynamics, providing a mechanistic basis for understanding bloom recurrence and informing future mitigation strategies.
Key words: diatom, resting cells, long-term survival, metabolic reprogramming, stress tolerance, seed bank for blooms
Funding source: National Natural Science Foundation of China (Grant Nos. 42076115, 41576138)