Abstract
Hydrogen sulfide (H2S) is a key gaseous signaling molecule involved in plant growth and stress responses, yet its role in wheat resistance to stripe rust remains poorly understood. Here, we show that exogenous H2S enhances resistance of wheat (Triticum aestivum L.) to Puccinia striiformis f. sp. tritici (Pst), the causative agent of stripe rust. Comparative persulfidation proteomics identified the autophagy-related protein TaATG6c as a Pst-responsive H₂S target. Site-specific mass spectrometry and a modified biotin-switch assay demonstrated that Cys177 and Cys180 of TaATG6c undergo H₂S-induced persulfidation. Structural modeling based on AlphaFold predicted that these two site mutations reduced the binding activity of ATG6c to ATG14. Functional characterization using virus-induced gene silencing (VIGS) revealed that TaATG6 positively regulates wheat immunity against Pst, as silencing TaATG6 promoted fungal growth. Moreover, TaATG6 expression was markedly induced during Pst infection. Notably, the resistance-promoting effect of NaHS was compromised in TaATG6-silenced plants. Conversely, transient overexpression of TaATG6 enhanced wheat resistance to stripe rust, whereas mutation of Cys177 and Cys180 attenuated this effect. Endogenous biotin-switch assays further showed that TaATG6c persulfidation exhibits pathogen-responsive and dynamic characteristics, which were abolished in the TaATG6C177A/C180A mutant. Consistently, H₂S treatment and Pst infection stimulated the accumulation of lipidated ATG8 (ATG8-PE), indicating activation of autophagy, while this response was largely abolished in TaATG6-silenced plants. Together, these results suggest that H₂S promotes autophagy initiation through persulfidation of TaATG6c, thereby enhancing wheat resistance to stripe rust and highlighting a redox-regulated mechanism underlying plant stress adaptation.