Small peptide from extracellular leucine-rich repeat domain protein 2 modulates cadmium tolerance through regulating...

With the accelerating global industrialization, cadmium (Cd) pollution in rice has become a significant threat to both ecological safety and human health. Currently, little is known about the small secreted peptides (SSPs) involved in the regulation of the Cd stress response. Here, high-throughput identification of SSPs in Oryza sativa was performed by bioinformatics approaches, and a novel SSP family, small peptide from extracellular leucine-rich repeat (LRR) domain protein (OsSPL), was identified. Hydroponic experiments validated that exogenous application of OsSPL2 alleviated Cd-induced oxidative damage and significantly improved plant phenotypes. Transcriptomic analysis further unveiled potential molecular pathways underlying OsSPL2-mediated Cd stress responses, suggesting its involvement in modulating photosynthetic pathways in leaves and lignin biosynthesis pathways in roots to mitigate Cd stress in rice. Evolutionary analysis indicated that OsSPL family members emerged after plant terrestrialization, underwent gene losses, and predominantly evolved under purifying selection. Additionally, a recombinant protein RPOsSPL2 containing five OsSPL2 repeat units was constructed via a prokaryotic expression system. In vitro assays confirmed its capacity to maintain Cd tolerance in rice, while its stability and scalable production characteristics provided a highly translatable solution for agricultural field applications. The study not only identified a novel signaling molecule of rice responding to Cd stress, but also established the application value of OsSPL2 in the development of environmental adaptive biopesticides through functional validation.