TaTLP1 interacts with TaPR1 to contribute to wheat defense responses to leaf rust fungus

Thaumatin-like proteins (TLPs), which are defined as pathogenesis-related protein family 5 (PR5) members, are common plant proteins involved in defense responses and confer antifungal activity against many plant pathogens. Our earlier studies have reported that theTaTLP1gene was isolated from wheat and proved to be involved in wheat defense in response to leaf rust attack. The present study aims to identify the interacting proteins of TaTLP1 and characterize the role of the interaction between wheat andPuccinia triticina(Pt). Pull-down experiments designed to isolate the molecular target of TaTLP1 in tobacco resulted in the identification of TaPR1, a pathogenesis-related protein of family 1, and the interaction between TaTLP1 and TaPR1 was confirmed by yeast two-hybrid experiments (Y2H), bimolecular fluorescence complementation (BiFC), and co-immunoprecipitation (Co-IP).In vitro, TaTLP1 and TaPR1 together increased antifungal activity againstPt.In vivo, the disease resistance phenotype, histological observations of fungal growth and host responses, and accumulation of H(2)O(2)in TaTLP1-TaPR1 in co-silenced plants indicated that co-silencing significantly enhanced wheat susceptibility compared to single knockdown TaTLP1 or TaPR1 plants. The accumulation of reactive oxygen species (ROS) was significantly reduced in co-silenced plants compared to controls duringPtinfection, which suggested that the TaTLP1-TaPR1 interaction positively modulates wheat resistance toPtin an ROS-dependent manner. Our findings provide new insights for understanding the roles of two different PRs, TaTLP1 and TaPR1, in wheat resistance to leaf rust. Author summary In host-pathogen interactions, novel proteins that are specifically involved in pathological response are collectively referred to as "pathogenesis-related proteins" (PRs). PR proteins encoded by plant defense genes play key roles in plant defense responses, particularly in systemic-acquired resistance. However, their molecular roles in the response of wheat to fungal infection are typically not well characterized. PR5 family proteins are referred to as thaumatin-like proteins (TLPs), are able to rapidly accumulate to high levels in response to biotic or abiotic stress and exhibit antifungal activity in various plant species. Thus, investigation of PR5 proteins is crucial for understanding the mechanism of wheat defense againstPtand searching for new ways to control the wheat leaf rust disease.