Foliar application of biological nano-selenium reduces cadmium accumulation in peppers with concentration-associated regulation under controlled conditions
Yu Tang, Guandi He, Zicheng Guo, Minmin Su, Piao Liu, Yulin Song, Tengbing He, Siew Ling Lee
Abstract
Guizhou karst soils exhibit elevated cadmium background levels, increasing cadmium accumulation risk in chili peppers. Research regarding foliar bio-selenium nanoparticle (Bio-SeNP) regulation of cadmium stress remains limited. This study examined Bio-SeNP effects through germination, hydroponic, soil experiments, and transcriptomics. Bio-SeNP (2–20 mg/L) enhanced germination (100% at 5 mg/L), while concentrations>50 mg/L inhibited growth. Foliar application of 5 mg/L Bio-SeNP improved growth, photosynthesis, and antioxidant defense under cadmium stress: SOD, POD, CAT activities increased 2.51%–54.90%, malondialdehyde decreased 173.40 nmol/g, root cadmium decreased 23.20%. Soil experiments demonstrated 5 mg/L Bio-SeNP increased plant height 10.78%, fruit fresh weight 27.78%, yield 27.86%, and decreased fruit cadmium 30.00%. Transcriptomic analysis identified 1,762 differentially expressed genes enriched in detoxification pathways. Bio-SeNP treatment modified the expression of cadmium-responsive transcription factors, with WRKY53 upregulated 2.46-fold and CRF1 downregulated 5.09-fold. In auxin signaling, AUX1 downregulation (5.64-fold) and TIR1 upregulation (7.34-fold) indicated Bio-SeNP modulates hormone perception for growth-defense balance. This establishes 5 mg/L as optimal for cadmium mitigation, informing safe chili production in contaminated soil. • 5 mg/L Bio-SeNP optimally alleviates cadmium stress in chili peppers; • Foliar Bio-SeNP treatment reduces fruit cadmium content by 30.00%; • Bio-SeNP enhances antioxidant enzyme activities and photosynthetic capacity; • WRKY53 and auxin signaling pathways respond to Bio-SeNP treatment; • AUX 1 downregulation and TIR1 upregulation modulate auxin perception.