Global Crotonylome Profiling Identifies TaPRXIIB Crotonylation as a Modulator H₂O₂ Homeostasis in Wheat Resistance to...

Wheat food security is severely threatened by Puccinia triticina infection. Although lysine crotonylation (Kcr) plays pivotal roles in plant stress responses, its function and regulation in biotic stress remain largely unknown. In this study, we investigated Kcr levels in wheat upon P. triticina infection and found that elevated protein crotonylation enhances resistance to P. triticina. We first performed a global crotonylome profiling of wheat in response to P. triticina infection and identified 3333 quantifiable Kcr sites across 952 proteins. Kcr sites were preferentially flanked by aliphatic amino acids, suggesting a sequence preference for this modification. Functional enrichment and protein-protein interaction (PPI) analyses based on crotonylated differentially expressed proteins (DEPs) further highlighted a strong association between Kcr-modified antioxidant enzymes and stress response processes. Furthermore, we investigated the modification pattens of two antioxidant enzymes and confirmed that TaPRXIIB negatively regulates wheat resistance to P. triticina by modulating H₂O₂ homeostasis. We found that crotonylation at K172 of TaPRXIIB disrupts the hydrogen bond between H187 and its prosthetic group, thereby reducing its enzymatic activity. This study presented a global crotonylome profile of wheat in response to P. triticina infection and revealed that the Kcr of TaPRXIIB at K172 negatively regulates its enzymatic activity.