Melatonin mitigates cadmium-induced oxidative damage and modulates polysaccharide biosynthesis in Bletilla striata

作者：D. Niu, Zhonghai Dao, Zhifeng Xiao, Ping Xiang, Shiyong Zhou, Jin-Run Dong · 发表于：Frontiers in Plant Science · 年份：2025 · DOI：10.3389/fpls.2025.1713721 · 被引用次数：4 · 研究领域：Biological and pharmacological studies of plants、Plant Molecular Biology Research、Plant and Biological Electrophysiology Studies

Introduction Cadmium (Cd), a highly toxic heavy metal, threatens ecosystems and human health. Bletilla striata ( B . striata ), a medicinal plant valued for its polysaccharide-rich rhizomes, exhibits significant tolerance to Cd stress. Melatonin (MT), a phytohormone, has emerged as a key regulator of plant resilience to heavy metal toxicity. However, the mechanisms underlying MT-mediated biosynthesis of B . striata polysaccharides (BSP) under Cd exposure, as well as its role in alleviating Cd-induced oxidative damage, remain poorly characterized. Methods Soil was passivated with 250 μmol/L CdCl 2 · 2.5H 2 O for one month before transplanting one-year-old B . striata seedlings. One week after transplantation, the leaves of B . striata were sprayed with MT (50, 100, and 200 μmol/L) weekly. After 60 days, samples were collected and analyzed for physiological and biochemical indices (chlorophyll, osmoregulatory substances, Cd, reactive oxygen species, antioxidant enzyme activities, polysaccharides, flavonoids and saponins). Additionally, samples from CK, Cd-only, and Cd+50MT groups were collected for integrated transcriptomic and metabolomic analyses, and the transcriptome data were validated via qRT-PCR. Results Our findings revealed that Cd stress substantially suppressed seedling growth, manifesting as significant reductions in fresh weight, dry weight, chlorophyll content, and proline accumulation relative to control plants. Under Cd stress, application of 50 μmol/L MT achiev...