Gasotransmitter H 2 S accelerates seed germination via activating AOX mediated cyanide-resistant respiration pathway.

Hydrogen sulfide (H ₂ S) has been witnessed as a crucial gasotransmitter involving in various physiological processes in plants. H ₂ S signaling has been reported to involve in regulating seed germination, but the underlying mechanism remains poorly understood. Here, we found that endogenous H ₂ S production was activated in germinating Arabidopsis seeds, correlating with upregulated both the transcription and the activity of L-cysteine desulfhydrase (EC 4.4.1.28, LCD and DES1) responsible for H ₂ S production. Moreover, seed germination could be significantly accelerated by exogenous NaHS (the H ₂ S donor) fumigation and over-expressing DES1, while H ₂ S-generation defective (lcd/des1) seeds exhibited decreased germination speed. We also confirmed that the alternative oxidase (AOX), a cyanide-insensitive terminal oxidase, can be stimulated by imbibition. Furthermore, exogenous H ₂ S fumigation and over-expressing DES1 could significantly reinforced imbibition induced increase of both the AOX1A expression and AOX protein abundance, while this increase could be obviously weakened in lcd/des1. Additionally, exogenous H ₂ S fumigation mediated post-translational modification to keep AOX in its reduced and active state, which might involve H ₂ S induced improvement of the reduced GSH content and the cell reducing power. The promotive effect of H ₂ S on germination was clearly impaired by inducing aox1a mutation, indicating that AOX acts downstream of H ₂ S signaling to accelerate seed germination. Consequently, H ₂ S signaling was activated during germination then acted as a trigger to induce AOX mediated cyanide-resistant respiration to accelerate seed germination. Our study correlates H ₂ S signaling to cyanide-resistant respiration, providing evidence for more extensive studies of H ₂ S signaling.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2022 Elsevier Masson SAS. All rights reserved.)