Garlic-released NO and H₂S modulate Arabidopsis metabolism by reshaping redox balance and redox-dependent...

Nitric oxide (NO) and hydrogen sulfide (H₂S) are key gasotransmitters acting as signaling molecules in plants and animals. Garlic, known for its sulfur-rich compounds, had not previously been identified as a source of NO or H₂S emission. Using specific sensors, we show that garlic cloves simultaneously release both gases. To assess their biological impact, 30-day-old Arabidopsis thaliana plants were exposed for 24 h to a garlic-released NO/H₂S-enriched atmosphere. Biochemical analyses revealed significant changes in components of reactive oxygen species (ROS), NO, and H₂S metabolism, including protein S-glutathionylation, S-nitrosation and tyrosine/tryptophan nitration. Major effects were detected in the antioxidant enzyme catalase (CAT), the H₂O₂-producing glycolate oxidase (GOX), and hydroxypyruvate reductase (HPR), all central to peroxisomal redox metabolism. The activity of the H₂S-producing enzyme L-cysteine desulfhydrase (LCD) and the expression of PAO4, encoding a peroxisomal H₂O₂-generating polyamine oxidase, were also modified. Conversely, nitrite/NADH-dependent NO generation and nitrosoglutathione reductase (GSNOR) activity remained unchanged. These results collectively indicate that garlic-released NO and H₂S modulate the metabolism of A. thaliana through redox-dependent post-translational modifications, thereby promoting adaptive redox responses. This suggests that garlic may act as a natural dual donor of both NO and H₂S.