Associations between cadmium uptake and leaf-root expression of candidate YSL/HMA transporters in Solanum nigrum

This study profiled physiological, biochemical, and transcriptional responses of Solanum nigrum to cadmium (Cd) in potted soil across graded treatments. Growth, assessed as fresh and dry mass, and chlorophyll a declined only at higher doses, whereas carotenoids increased by about 70%. Proline rose by roughly 302% and soluble proteins by 173% in a dose-responsive manner, consistent with up to 9.1-fold increases in P5CS transcripts. Malondialdehyde and hydrogen peroxide increased with Cd, accompanied by antioxidant responses. Shoots accumulated substantial Cd in soil, reaching 170 mg kg^-1 DW at 100 mg kg^-1 soil Cd, while the tolerance index remained ≥ 60% at the highest dose. The translocation factor exceeded one at all additions and peaked at ~ 1.28 at 50-100 mg kg^-1Bioavailability-aware enrichment remained high: BCF_available (shoot) referenced to DTPA-Cd was ~ 19.4 at 12.5-25 mg kg^-1 16.9 at 50 mg kg^-1, and 12.6 at 100 mg kg^-1. Whole-plant removal increased monotonically, with total Cd uptake of approximately 166, 303, 392, and 518 µg plant^-1 at 12.5, 25, 50, and 100 mg kg^-1, respectively. Candidate transporter transcripts showed distinct dose-dependent patterns in soil: SnYSL3 peaked at the intermediate dose (~ 7.6-fold), whereas HMA3 rose progressively and was highest at 100 mg kg^-1 (~ 7.2-fold). Principal component analysis separated treatments and grouped stress markers with P5CS and HMA3 at higher Cd. This work provides a gradient-resolved, soil-based dataset linking Cd partitioning, bioavailability-normalized indices, and total uptake with coordinated shifts in candidate YSL and HMA transporters and key metabolites. The resulting framework establishes a standardized baseline for functional validation and field translation.