A thaumatin‐like effector protein suppresses the rust resistance of wheat and promotes the pathogenicity of <i>Puccinia triticina</i> by targeting <scp>TaRCA</scp>
Jiaying Chang, Johannes Mapuranga, Xiaodong Wang, Haijiao Dong, Ruolin Li, Yingdan Zhang, Hao Li, Jie Shi, Wenxiang Yang
Abstract
Summary Thaumatin‐like proteins (TLPs) in plants play a crucial role in combating stress, and they have been proven to possess antifungal properties. However, the role of TLPs in pathogens has not been reported. We identified a effector protein, Pt9029, which contained a Thaumatin domain in Puccinia triticina ( Pt ), possessing a chloroplast transit peptide and localized in the chloroplasts. Silencing Pt9029 in the Pt physiological race THTT resulted in a notable reduction in virulence and stunted growth and development of Pt hypha in near‐isogenic wheat line TcLr2b. Overexpression of Pt9029 in wheat exerted a suppressive effect on H 2 O 2 production, consequently impeding the wheat's disease resistance mechanisms. The TLP domain of Pt9029 targets the Rubisco activase (TaRCA) in chloroplasts. This interaction effectively inhibited the function of TaRCA, subsequently leading to a decrease in Rubisco enzyme activity. Therefore, this indicates that TLPs in Pt can inhibit host defense mechanisms during the pathogenic process of Pt . Moreover, TaRCA silencing resulted in reduced resistance of TcLr2b against Pt race THTT. This clearly demonstrated that TaRCA positively regulates wheat resistance to leaf rust. These findings reveal a novel strategy exploited by Pt to manipulate wheat rust resistance and promote pathogenicity.