Tubby‐like protein TaTLP5 enhances stripe rust resistance in wheat by regulating TaCAT1 protein degradation

Although tubby-like proteins (TLPs) are evolutionarily conserved across eukaryotes, their roles in orchestrating plant immune responses, particularly against obligate biotrophic pathogens, remain poorly defined. In this study, we found that TaTLP5, a member of the tubby-like F-box gene family, is rapidly upregulated following Puccinia striiformis f. sp. tritici (Pst) infection. Silencing TaTLP5 in wheat enhances susceptibility to Pst, whereas its overexpression confers resistance by promoting reactive oxygen species (ROS) accumulation. In addition, the molecular interaction mechanism underlying TaTLP5-mediated wheat disease resistance has been elucidated. The results showed that TaTLP5 forms an SKP1-Cullin1-F-box (SCF)-type E3 ubiquitin ligase complex with TaSKP1 (S-phase kinase-associated protein 1) and TaCullin1. Notably, this complex mediates the ubiquitination and degradation of TaCAT1 (Catalase1), a key susceptibility factor in wheat. This ubiquitination-dependent degradation of TaCAT1 elevates ROS accumulation, thereby enhancing wheat resistance against Pst. Our findings revealed a conserved regulatory module by which the TaTLP5-TaSKP1-TaCullin complex modulates ROS-dependent immunity via ubiquitination-mediated degradation of TaCAT1 during wheat-Pst interactions. These mechanistic insights highlight potential actionable targets for the rational breeding of disease-resistant crop varieties.