Accumulating experimental evidence in mammalian, and recently plant, systems has led to a change in our understanding of the role played by hydrogen sulfide in life processes. In plants, hydrogensulfide mitigates stress and regulates important plant processes such as photosynthesis, stomatal movement, and autophagy, although the underlying mechanism is not well known.

In this study, we provide new experimental evidence that, together withour previous findings, demonstrates the role of hydrogen sulfide in regulating autophagy. We used green fluorescent protein fluorescence associated with autophagic bodiesand immunoblot analysis of the ATG8 protein to show that sulfide (and no other molecules such as sulfur-containing moleculesor ammonium) was able to inhibit the autophagy induced in Arabidopsis (Arabidopsis thaliana) roots under nitrogen deprivation.

Our results showed that sulfide was unable to scavenge reactive oxygen species generated by nitrogen limitation, in contrast towell-established reducers. In addition, reducers were unable to inhibit the accumulation of autophagic bodies and ATG8 protein forms to the same extent as sulfide. Therefore, we conclude that sulfide represses autophagy via a mechanism that is independent of redox conditions.