Long non-coding RNA profiling reveals lncRNA MslncLOX13S that promotes lipoxygenase gene expression and enhances the...

Alfalfa (Medicago sativa L.) is one of the most widely cultivated forage crops globally. Selenium (Se) is considered beneficial for plants, showing a concentration-dependent dual effect that can promote and inhibit various plant species, including alfalfa. Long non-coding RNAs (lncRNAs), a class of non-protein-coding transcripts, are involved in multiple biological processes in plants. To explore the potential role of lncRNAs in Se accumulation and tolerance in alfalfa, physiological responses were measured, and lncRNA expression was examined in alfalfa leaves exposed to Se concentrations of 0 mg L^-1, 100 mg L^-1, and 500 mg L^-1. Under selenium treatment, lipoxygenase (LOX) activity and antioxidant levels increased significantly. A total of 64,684 novel lncRNAs were identified, with 1414 and 1810 differentially expressed lncRNAs (DELs) found in the 100 mg L^-1 and 500 mg L^-1 Se-treated groups, respectively. Functional enrichment analysis suggested that LOX-targeted lncRNAs could play a pivotal role in Se accumulation and tolerance. Silencing of MslncLOX13S resulted in a yellowing of the leaf edges and lowered levels of LOX, jasmonic acid (JA), antioxidant capacity, and Se content. In comparison, transient overexpression of MslncLOX13S showed the opposite effects. These findings may contribute to the development of alfalfa cultivars enriched in Se, suitable for use as feed or raw material for organic Se extraction. Moreover, this study improves the understanding of lncRNA-mediated gene expression in alfalfa, highlighting MslncLOX13S as a Se-responsive lncRNA that enhances tolerance against Se, potentially offering a strategy for improving Se biofortification in forage crops.