Integration of multi-omics analyses reveals molecular mechanisms of L-phenylalanine-induced root to shoot cadmium translocation in Kentucky bluegrass

Exogenous _L-phenylalanine application enhances cadmium (Cd) uptake and translocation in Kentucky bluegrass (Poa pratensis L.), offering a potential strategy for the phytoremediation of Cd-contaminated soils. This study investigated the role of exogenous _L-phenylalanine in Cd uptake, translocation, and detoxification in Kentucky bluegrass. We employ a comprehensive approach combining integrated phenotypic analysis, antioxidant characteristics, Cd content determination, full-length transcriptome sequencing, transcriptomic analysis, proteome, and metabolome analyses to elucidate the molecular mechanisms underlying the long-distance Cd transport promotion by exogenous Lphenylalanine in Kentucky bluegrass, and to validate the function of the candidate gene PpNAS in Arabidopsis thaliana. _L-phenylalanine at concentrations of 0.1, 1, and 10 mg·L⁻¹ induced the Cd content in the leaves by 21%, 45%, and 64%. However, the malondialdehyde content was not significantly different under 1 mg·L⁻¹ _L-phenylalanine and Cd treatment compared to that under Cd treatment alone, but the Cd content significantly increased. In addition, 1 mg·L⁻¹ _L-phenylalanine and Cd treatment improved the antioxidant enzyme activity and biomass of Kentucky bluegrass under Cd stress. _L-phenylalanine application upregulated genes associated with Cd uptake (HIPPs), long-distance translocation (HMAs, YSLs, and NAS), and vacuolar compartmentalization pathways (OPTs, ABCCs, and MTPS). Overexpression of PpNAS in Arabidopsis thaliana increased the Cd content in leaves and roots, supporting the positive role of _L-phenylalanine in long-distance Cd transport. These results demonstrate that exogenous _L-phenylalanine targets multiple metabolic pathways and Cd transporters to regulate Cd redistribution in Kentucky bluegrass, providing new strategies for the phytoremediation of Cd-contaminated soils utilizing _L-phenylalanine.