Multi-omics profiling unveils drought adaptation mechanisms in the peat moss Sphagnum palustre

Under the influence of global climate change, it is anticipated that the incidence and extent of drought conditions will increase in numerous regions across the globe. Sphagnum palustre, a dominant species in peatlands, is instrumental in maintaining hydrological regulation and enhancing carbon sequestration. However, the mechanisms underlying its drought response remain poorly characterized at the molecular and metabolic levels. This study analyzed the response of S. palustre to drought stress through integrated physiological, transcriptomic, and metabolomic approaches. Physiological results indicated that drought reduced the relative water content, chlorophyll and soluble protein content, while increased the content of soluble sugars and malondialdehyde, and antioxidant enzyme activity. Transcriptomic profiling identified 21,145 differentially expressed genes (DEGs) under drought stress. The DEGs associated with photosynthesis were significantly down-regulated, whereas those involved in other key pathways, such as hormone signal transduction, cutin and wax biosynthesis, and phenylalanine and linoleic acid metabolism, were significantly up-regulated. A total of 3668 differentially abundant metabolites were detected, with a significant accumulation of phenylpropanoids and flavonoids. Integrated multi-omics analyses highlight that S. palustre employs osmotic adjustment to enhance antioxidant defense, triggering adaptive responses through soluble sugar accumulation, hormone signaling, phenylpropanoid and flavonoid biosynthesis, and activation of ATP-binding cassette transporters. These findings provide insights into bryophytes drought adaptation, facilitating predictions of peatland ecosystem resilience and guiding conservation strategies under climate change.