Lipid-mediated photoprotection confers strong light resilience in hyperaccumulator Sedum alfredii

The heavy metal hyperaccumulator Sedum is limited by sensitivity to intense sunlight. This study compared light-tolerant Sedum alfredii and light-sensitive Sedum plumbizincicola under light intensities (600-1400 μmol m⁻² s⁻¹). Sedum plumbizincicola exhibited complete mortality at 1400 μmol m⁻² s⁻¹ after six days, while Sedum alfredii showed minimal to moderate mortality. Physiological analyses revealed Sedum alfredii maintained higher Rubisco activity and reduced membrane damage under stress. Lipidomics identified elevated ceramides and glycerophospholipids in Sedum alfredii, enhancing membrane stability. Transcriptomics detected 6501 shared differentially expressed genes (DEGs) under strong light, with 977 unique to Sedum alfredii, implicating chloroplast function, protein phosphorylation, and defense responses in its resilience. Weighted Gene Co-expression Network Analysis highlighted the MEturquoise module, linked to lipid metabolism and stress responses. Sedum alfredii displayed a surge in DEGs at 1200/1400 μmol m⁻² s⁻¹ , activating microtubule reorganization, cytokinin signaling, and circadian regulation. Notably, DN1992 gene expression in Sedum alfredii under high light stress significantly exceeded Sedum plumbizincicola, suggesting its role in differential stress tolerance. The coordinated interplay of lipid metabolism, gene regulation, and hormonal adaptation underpins Sedum alfredii enhanced light tolerance. These findings advance mechanistic insights into Sedum photo stress adaptation and provide targets for breeding robust hyperaccumulators for ecological restoration in sun-exposed contaminated environments.