Overview
This study investigated how silica nanoparticles (nSiO2) affect the physiological and molecular response of Pisum sativum L. seedlings to cadmium toxicity. The study measured cadmium content in roots and leaves of hydroponically grown pea seedlings exposed to 9 uM CdCl2, with or without 50 mg/L nSiO2, over 12 days. It is a nanobiotechnology and plant physiology experiment, not a food survey.
Key numbers
Cadmium content in pea seedling tissues (Figure 4A, p.10, ICP-MS, basis: mg/kg, n = 3):
- cadmium (Cd) treatment alone: roots accumulated approximately 120 mg/kg (Cd), leaves accumulated a lower concentration (exact leaf values readable from Figure 4A graph only).
- Cd plus nSiO2 treatment: root Cd content decreased by 22.24% relative to Cd-only group; leaf Cd content decreased by 67.88% relative to Cd-only group (abstract, p.1).
Iron in pea roots (Figure 4B, p.10):
- Cd treatment increased root Fe accumulation by 44.06% and 42.51% above control, in roots and leaves respectively.
- Cd plus nSiO2 treatment had no significant effect on Fe accumulation compared to Cd alone.
Growth responses under Cd stress versus control (abstract, p.1):
- Plant height reduced 49.43%; primary root length reduced 34.81%; lateral root number reduced 27.03%; leaf dry weight reduced 39.87%; root dry weight reduced 24.83%.
- nSiO2 application under Cd stress increased lateral root number 25.00%, primary root length 33.93%, leaf dry weight 29.18%, root dry weight 17.41%, photosynthesis rate 13.84% above Cd-alone group.
Reactive oxygen species under Cd stress versus control:
- Superoxide anion (O2-) in pea roots increased 151.24%; hydrogen peroxide (H2O2) increased 119.57% (p.5).
- Cd plus nSiO2 reduced O2- by 31.68% and H2O2 by 39.9% in roots relative to Cd alone (p.5).
Methods (brief)
Hydroponic experiment, 1/4-strength Hoagland nutrient solution, controlled conditions (25/16 degrees C day/night, 60% humidity, 20000 lux light intensity, 18 h/6 h photoperiod). Ten-day-old pea seedlings exposed to 9 uM CdCl2 (CdCl2 used as Cd source), 50 mg/L nSiO2 (McLean Biotechnology, purity 99%, size 50 ± 5 nm), or both, for 12 days. Growth parameters, root activity, chlorophyll content, photosynthetic parameters measured after 12 days. Mineral elements (Cd, Zn, Cu, Mg, Fe, Si) by ICP-MS (n = 3). H2O2 assayed by spectrophotometer (Shimadzu UV-1800). Superoxide anion by NBT staining. MDA by thiobarbituric acid method. Antioxidant enzymes (SOD, CAT, POD) by spectrophotometry. Transcriptome analysis by RNA-seq (BMKCloud). Statistical analysis: Student’s t-test (IBM SPSS Statistics 23.0); one-way ANOVA with Tukey’s test for multiple comparisons (p < 0.05). No LOD/LOQ or certified reference material reported for plant tissue Cd measurements.
Implications
Directly relevant to the frozen peas pathway section: documents that cadmium is taken up by pea roots from hydroponic solution (9 uM applied) and translocated to leaves, with roots accumulating substantially more Cd than leaves at this exposure level. The silica nanoparticle results show that root-to-shoot Cd translocation can be partially reduced (leaf Cd reduced 67.88%) by nSiO2 treatment, which acts by suppressing Cd absorption at the root level and improving carbon-nitrogen metabolism. The study also documents competitive inhibition of copper, zinc, and magnesium accumulation by Cd, relevant to nutrient disruption effects. Applied Cd concentration (9 uM approximately 1 mg/L) is experimentally elevated; typical tap water Cd is below 0.003 ug/L. The hydroponic model means root-soil interactions are absent, which may overstate translocation compared to soil-grown plants.
Related evidence
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