# The role and proteomic analysis of ethylene in hydrogen gas-induced adventitious rooting development in cucumber (L.) explants.
> キュウリ外植体における水素ガス誘導不定根形成でのエチレンの役割とプロテオーム解析


## Abstract

Using cucumber (Cucumis sativus L.) explants, this study examined the interplay between hydrogen gas and ethylene during adventitious root formation. Hydrogen-rich water (HRW) and the ethylene-releasing agent ethephon each promoted rooting, with peak responses at 50% HRW and 0.5 µM ethephon, respectively. Application of ethylene biosynthesis inhibitor AVG or the ethylene signaling blocker AgNO3 partially suppressed H2-induced rooting, indicating that ethylene functions downstream of hydrogen signaling. Two-dimensional electrophoresis combined with mass spectrometry revealed distinct proteomic shifts: HRW altered 24 proteins (9 up, 15 down), ethephon altered 14 proteins (4 up, 10 down), and HRW+AVG altered 10 proteins (1 up, 9 down). Six proteins were highlighted for further analysis: photosynthesis-related Rubisco, SBPase, and OEE1; amino acid metabolism-related TDH; antioxidant enzyme CAPX; and protein-folding factor PDI. Real-time PCR data corroborated the proteomic findings at the mRNA level, supporting a model in which ethylene acts as a downstream signaling molecule in hydrogen-induced adventitious rooting.

### Mechanism

Hydrogen gas promotes adventitious rooting by triggering ethylene as a downstream signaling molecule; this cascade modulates expression of photosynthesis-related proteins (Rubisco, SBPase, OEE1), amino acid metabolism enzyme TDH, antioxidant enzyme CAPX, and protein-folding factor PDI.

## Bibliographic

- **Authors**: Huang D, Bian B, Zhang MH, Wang CY, Li CY, Liao W
- **Journal**: PeerJ
- **Year**: 2020
- **PMID**: [32292654](https://pubmed.ncbi.nlm.nih.gov/32292654/)
- **DOI**: [10.7717/peerj.8896](https://doi.org/10.7717/peerj.8896)
- **PMC**: [PMC7147439](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7147439/)
- **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 32292654. https://h2-papers.org/en/papers/32292654
> **Source**: PubMed PMID [32292654](https://pubmed.ncbi.nlm.nih.gov/32292654/)