# Hydrogen gas promotes the adventitious rooting in cucumber under cadmium stress.
> カドミウムストレス下におけるキュウリの不定根形成に対する水素ガスの促進効果


## Abstract

This study examined the effects of hydrogen-rich water (HRW) on adventitious root development in cucumber (Cucumis sativus L.) explants under cadmium (Cd) stress. Among tested concentrations, 50% HRW elicited the greatest biological response. Compared with Cd exposure alone, combined HRW and Cd treatment markedly reduced oxidative stress markers including malondialdehyde, hydrogen peroxide, superoxide radical, and thiobarbituric acid reactive substances, while also lowering relative electrical conductivity and lipoxygenase activity. Concurrently, the activities and gene expression levels of ascorbate peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, and glutathione reductase were elevated. HRW co-treatment further increased osmotic adjustment substance contents and the activities of peroxidase and polyphenol oxidase, whereas indoleacetic acid oxidase activity declined. These findings indicate that H2 promotes adventitious rooting under Cd stress through a combination of reduced oxidative damage, enhanced osmotic regulation, and modulation of rooting-associated enzyme activities.

### Mechanism

H2 reduces oxidative damage markers (MDA, H2O2, superoxide) and upregulates antioxidant enzymes (APX, DHAR, MDHAR, GR) at both activity and gene expression levels. Simultaneously, osmotic adjustment substances accumulate and indoleacetic acid oxidase activity is suppressed, collectively facilitating adventitious root initiation under cadmium stress.

## Bibliographic

- **Authors**: Wang B, Bian B, Wang CY, Li CY, Fang H, Zhang JH, et al.
- **Journal**: PLoS One
- **Year**: 2019
- **PMID**: [30785953](https://pubmed.ncbi.nlm.nih.gov/30785953/)
- **DOI**: [10.1371/journal.pone.0212639](https://doi.org/10.1371/journal.pone.0212639)
- **PMC**: [PMC6382157](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6382157/)
- **Study type**: in vitro study
- **Delivery route**: hydrogen-rich water
- **Effect reported**: positive
- **H2 concentration**: 50%

## Delivery context

Hydrogen-rich water is a low-risk delivery route, but the achievable systemic hydrogen dose is bounded. For clinical applications, inhalation is the most efficient route; inhalation, however, carries explosion risk, and concentration matters (empirical LFL of 10% applies to inhalation environments; high-concentration devices are documented in the Consumer Affairs Agency accident database and are not recommended).

## Safety notes

Hydrogen-rich water is a low-risk delivery route, but the achievable systemic hydrogen dose is bounded. For clinical applications, inhalation is the most efficient route; inhalation, however, carries explosion risk, and concentration matters (empirical LFL of 10% applies to inhalation environments; high-concentration devices are documented in the Consumer Affairs Agency accident database and 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 30785953. https://h2-papers.org/en/papers/30785953
> **Source**: PubMed PMID [30785953](https://pubmed.ncbi.nlm.nih.gov/30785953/)