Plants employ aquaporins (AQPs) of the plasma membrane intrinsic protein (PIP) family to import environmental substrates, thereby affecting various processes, such as the cellular responses regulated by the signaling molecule hydrogen peroxide (H2O2). Common wheat (Triticum aestivum) contains 24 candidate members of the PIP family, designated as TaPIP1;1 to TaPIP1;12 and TaPIP2;1 to TaPIP2;12. None of these TaPIP candidates have been characterized for substrate selectivity or defense responses in their source plant. Here, we report that T. aestivum AQP TaPIP2;10 facilitates the cellular uptake of H2O2 to confer resistance against powdery mildew and Fusarium head blight, two devastating fungal diseases in wheat throughout the world. In wheat, the apoplastic H2O2 signal is induced by fungal attack, while TaPIP2;10 is stimulated to translocate this H2O2 into the cytoplasm, where it activates defense responses to restrict further attack. TaPIP2;10-mediated transport of H2O2 is essential for pathogen-associated molecular pattern-triggered plant immunity (PTI). Typical PTI responses are induced by the fungal infection and intensified by overexpression of the TaPIP2;10 gene. TaPIP2;10 overexpression causes a 70% enhancement in wheat resistance to powdery mildew and an 86% enhancement in resistance to Fusarium head blight. By reducing the disease severities, TaPIP2;10 overexpression brings about >37% increase in wheat grain yield. These results verify the feasibility of using an immunity-relevant AQP to concomitantly improve crop productivity and immunity.
Keywords: Fusarium head blight; H2O2 transport; PTI; aquaporin; disease resistance; plant immune responses; powdery mildew.