# Hydrogen-rich water regulates cucumber adventitious root development in a heme oxygenase-1/carbon monoxide-dependent manner.
> 水素水によるキュウリ不定根発達の促進：ヘムオキシゲナーゼ-1／一酸化炭素依存的シグナル経路の関与


## Abstract

Using cucumber explants, this study examined how hydrogen-rich water (HRW) influences adventitious root (AR) formation and the underlying signaling mechanisms. At 50% concentration, HRW mimicked the action of hemin, a heme oxygenase-1 (HO-1) inducer, restoring AR formation under auxin-depleted conditions. HRW elevated HO-1 gene expression and protein levels, and upregulated auxin-related genes including CsDNAJ-1, CsCDPK1/5, CsCDC6, CsAUX22B-like, and CsAUX22D-like. These responses were suppressed by the HO-1 inhibitor zinc protoporphyrin IX (ZnPP) and rescued by exogenous carbon monoxide (CO), confirming HO-1/CO pathway specificity. Co-treatment with the auxin transport inhibitor NPA further blocked HRW-induced AR formation. Notably, ascorbic acid, a known antioxidant, had no effect on HRW-induced rooting, indicating that redox homeostasis is not a primary mediator. Collectively, the findings suggest that HRW promotes AR organogenesis in cucumber at least partly through an HO-1/CO-dependent signaling cascade.

### Mechanism

HRW upregulates HO-1 gene expression and protein levels in cucumber explants; the resulting CO production activates auxin signaling-related genes (CsDNAJ-1, CsCDPK1/5, CsCDC6, CsAUX22B/D-like), driving adventitious root elongation independently of redox homeostasis.

## Bibliographic

- **Authors**: Lin Y, Zhang W, Qi F, Cui W, Xie Y, Shen W
- **Journal**: J Plant Physiol
- **Year**: 2014 (2014-01-15)
- **PMID**: [24331413](https://pubmed.ncbi.nlm.nih.gov/24331413/)
- **DOI**: [10.1016/j.jplph.2013.08.009](https://doi.org/10.1016/j.jplph.2013.08.009)
- **Study type**: in vitro study
- **Delivery route**: in vitro
- **Effect reported**: positive
- **H2 concentration**: 50%

## Delivery context

This is basic research at the cellular or molecular level. For human application, inhalation is the most promising delivery route, but inhalation carries explosion risk and concentration matters (empirical LFL of 10%; high-concentration devices are not recommended).

## Safety notes

This is basic research at the cellular or molecular level. For human application, inhalation is the most promising delivery route, but inhalation carries explosion risk and concentration matters (empirical LFL of 10%; high-concentration devices are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 24331413. https://h2-papers.org/en/papers/24331413
> **Source**: PubMed PMID [24331413](https://pubmed.ncbi.nlm.nih.gov/24331413/)