Survival wisdom of Tradescantia spathacea Sw: Trade-off be-tween anthocyanin mediated photoprotection and photosyn-thetic capacity under high light stress

Tradescantia spathacea Sw, with green upper and purple-red lower leaf surfaces, exhibits both shade tolerance and high-light acclimation, but the functional specialization of its leaf sides and the underlying trade-off mechanisms are poorly understood. This study exposed T. spathacea to 100% (FL) and 30% (LL) sunlight for 2 years and systematically assessed light adaptation mechanisms through morphological observation, physiological and biochemical detection, and transcriptomic analyses.

Results showed that under FL conditions, leaf morphology underwent adaptive remodeling. Anthocyanins accumu-lated specifically in the lower side, thermal dissipation and antioxidant systems were fully activated, while photosynthetic capacity was markedly inhibited, reflecting a survival-priority strategy. Under LL conditions, leaves became broader and flatter, chlorophyll content increased, and the expression of photosynthesis-related genes was upregulated.