Mostofa et al. 2015 — Hydrogen sulfide modulates Cd-induced responses in rice
A controlled hydroponic experiment on rice seedlings (Oryza sativa L. cv. BRRI dhan52) examining how exogenous hydrogen sulfide, supplied as sodium hydrosulfide (NaHS), alters cadmium uptake, mineral homeostasis, oxidative stress, and antioxidant defense under pharmacological CdCl2 exposure. The paper is mechanistic plant-biology evidence on the rice–cadmium interaction; it does not measure cadmium in rice grain as sold or consumed, and the CdCl2 doses (250–1000 µM) are well above environmentally relevant soil-pore-water concentrations. Relevance to the wiki is as supporting evidence for how rice plants respond to cadmium stress at the seedling stage, the role of sulfur-containing metabolites in restricting cadmium translocation, and the underlying biochemistry that informs sulfur-amendment mitigation strategies.
Key numbers
- Plant material: Oryza sativa L. cv. BRRI dhan52, 13-day-old seedlings, exposed for 3 days in hyponex hydroponic solution (diluted 5,000-fold).
- Treatments (eight groups, n = 3 each): control (nutrient only); 100 µM NaHS (H2S); 100 µM NaHS + 200 µM hypotaurine (H2S + HT); 250 µM CdCl2 (Cd1); 100 µM NaHS + 250 µM CdCl2 (H2S + Cd1); 500 µM CdCl2 (Cd2); 100 µM NaHS + 500 µM CdCl2 (H2S + Cd2); 100 µM NaHS + 200 µM hypotaurine + 500 µM CdCl2 (H2S + HT + Cd2). A 1000 µM CdCl2 group (Cd3) was discontinued because NaHS-mediated recovery was insufficient at that dose.
- Cd accumulation (µg seedling⁻¹, Fig. 1a,b): NaHS reduced Cd accumulation in roots by 20% (Cd1) and 19% (Cd2); in leaves by 23% (Cd1) and 41% (Cd2), relative to the corresponding Cd-only groups.
- Cd concentration (mg g⁻¹ DW, Fig. 1c,d): NaHS reduced root Cd by 26% (Cd1) and 30% (Cd2); reduced leaf Cd by 30% (Cd1) and 65% (Cd2). Roots accumulated the bulk of Cd.
- Endogenous H2S (Fig. 2c): NaHS application raised leaf H2S by 55% (H2S vs. control), 27% (H2S + Cd1 vs. Cd1), and 35% (H2S + Cd2 vs. Cd2); co-application of HT cut H2S by 22% in H2S + HT + Cd2 vs. H2S + Cd2.
- Plant height (Fig. 2d): Cd1 and Cd2 reduced height by 23% and 39%; NaHS restored 21% (H2S + Cd1) and 24% (H2S + Cd2) relative to the Cd-only groups; HT co-application cut the recovery by 11%.
- Plant fresh weight (FW): Cd1 reduced FW by 10%, Cd2 by 24%; NaHS increased FW by 15% (H2S + Cd1) and 21% (H2S + Cd2) vs. the Cd-only groups.
- Plant dry weight (DW): Cd1 reduced DW by 11%, Cd2 by 20%; NaHS increased DW by 19% (H2S + Cd1) and 21% (H2S + Cd2) vs. the Cd-only groups.
- Mineral homeostasis under Cd (Table 1, leaves): Cd1 reduced Ca/Mg/Fe/Zn/Mn by 23%/10%/13%/22%/53%; Cd2 reduced them by 23%/23%/61%/26%/68%. NaHS partially restored these (Ca/Mg/Fe/Zn/Mn increases of 21–217% in H2S + Cd1 and H2S + Cd2 vs. corresponding Cd-only groups).
- Photosynthetic pigments (Table 2): Cd1/Cd2 reduced Chl a by 16%/45%, Chl b by 20%/43%, total Chl by 17%/45%, carotenoids by 22%/42%; H2S co-application restored Chl a by 16% (Cd1) and 50% (Cd2), and similar partial recoveries across the other pigments.
- Oxidative stress (Table 3): Cd1/Cd2 increased H2O2 by 40%/75% and MDA by 49%/204% vs. control; H2S reduced H2O2 by 26%/29%, LOX by 21%/29%, and MDA by 30%/42% vs. corresponding Cd-only groups.
- Non-enzymatic antioxidants (Table 4): Cd1/Cd2 reduced AsA by 23%/47%; H2S increased AsA by 22% (Cd1) and 38% (Cd2); GSH content increased 124% in H2S + Cd2 vs. Cd2 with a 304% increase in GSH/GSSG ratio.
- Methylglyoxal (Fig. 5a): Cd1/Cd2 increased MG by 38%/84% vs. control; H2S reduced MG in both Cd groups; HT reversed the H2S effect.
Methods (brief)
Seedling cultivation: hyponex nutrient solution (N 8%, P 6.43%, K 20.94%, Ca 8%, S 11.8%, Mg 3.08%, Fe 0.07%, B 0.24%, Mn 0.03%, Mo 0.0014%, Zn 0.008%, Cu 0.003%) diluted 5,000-fold; 13-day-old seedlings exposed to nutrient solution supplemented with CdCl2 (250, 500, or 1000 µM) in the presence or absence of NaHS (100 µM) for 3 days. Hypotaurine (200 µM) was used as an H2S scavenger. Three biological replicates per treatment.
Cd and mineral analysis: roots and leaves harvested separately, oven-dried at 80 °C for 48 h, ground, and digested with HNO3:HClO4 (5:1 v/v) at 80 °C. Cd, Ca, Mg, Fe, Zn, and Mn quantified by flame atomic absorption spectrophotometry. Results expressed both as µg seedling⁻¹ (accumulation) and mg g⁻¹ DW (concentration).
Endogenous H2S: rice leaves (0.25 g) homogenized in K-P buffer with EDTA, centrifuged, and the supernatant reacted with 5,5′-dithiobis(2-nitrobenzoic acid); absorbance read at 412 nm against an NaHS standard curve.
Photosynthetic pigments quantified spectrophotometrically (663, 645, 470 nm) using Arnon and Lichtentaler-Wellburn formulas. Water-soluble proteins, proline, relative water content, H2O2, MDA, LOX, and the AsA-GSH cycle enzymes (SOD, CAT, APX, MDHAR, DHAR, GR, GPX, GST) and glyoxalase enzymes (Gly I, Gly II) measured by standard published assays.
Statistics: one-way ANOVA with Duncan’s multiple range test (P < 0.05); values reported as mean ± SD of three independent replications.
Note: the experimental CdCl2 concentrations (250, 500, 1000 µM ≈ 28, 56, 112 mg L⁻¹ Cd²⁺) are pharmacological doses for mechanism dissection and are several orders of magnitude above typical paddy-soil pore-water Cd. The paper’s findings inform the biochemistry of rice Cd tolerance, not the magnitude of Cd accumulated in grain at field-relevant exposures. Cd is reported as total Cd; no inorganic vs. organo-Cd speciation is performed (Cd is non-redox and predominantly Cd²⁺ in plant tissue, so this is not a defect).
Implications
Certification: Sulfur metabolism modulates Cd uptake and translocation in rice seedlings under pharmacological Cd exposure; the paper contributes mechanistic evidence for agronomic sulfur-amendment as a Cd-mitigation lever. The effect was reversed by an H2S scavenger, strengthening causal attribution to H2S signaling rather than confounded sulfur nutrition.
Courses: Illustrates the antioxidant-defense and glyoxalase systems engaged by rice under Cd stress and how exogenous H2S coordinates ROS detoxification, methylglyoxal detoxification, and redox homeostasis. Useful as a mechanism narrative paired with field-occurrence papers.
App: Contributes mechanism context for the rice ingredient page; does not contribute occurrence numbers for rice grain as sold or consumed.
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Verification notes
Source PDF: raw/manual-fetch/seasonal-geographic-variance/auto-fetched/auto-mineral-water-cd-product_2015_10-1038-srep14078.pdf. The auto-fetched filename slug (mineral-water-cd-product) is incorrect for this paper — the paper is a hydroponic rice–Cd–H2S mechanism study, not a mineral-water occurrence survey. The slug was assigned upstream by the discovery harness and is preserved in raw_handle: for provenance only; frontmatter matrices:, ingredients:, and products: reflect the actual content. No mineral-water content in this paper.
Evidence tier B reflects the mechanistic / pharmacological-dose nature of the experiment; the work is well-controlled and peer-reviewed but the Cd concentrations are not field-relevant and the values are seedling-tissue, not rice-grain-as-consumed.
No brand-attributed contamination data. Methods name instrument category (flame AAS) and reagents (HNO3:HClO4, hypotaurine, NaHS) without vendor brand attribution; nothing to redact under Part 12.
Audit subagent (2026-05-30) flagged two transposed values in ## Key numbers (Cd accumulation leaf-Cd1 26% should be 23%; Cd concentration root values 30%/30% should be 26%/30% and leaf-Cd1 26% should be 30%); verified against PDF p.2 (“decreased by 20 and 19% in roots and 23 and 41% in leaves… Cd content was reduced by 26 and 30% in roots, and 30 and 65% in leaves”) — both corrections applied.
Audit subagent also flagged the Certification implication’s “supplier specifications for low-Cd rice” framing as policy-flavored (Part 2 concern); softened to describe the paper’s mechanistic contribution without prescribing a supplier-spec posture.
Page history
The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Description |
|---|---|---|
| ddfd414 | 2026-05-30 | ingest: yildirim2021-humic-fulvic-cd-garden-cress fresh from manual-fetch/seasonal-geographic-variance/auto-fetched |