Phosphorylation of a Wheat Aquaporin at Two Sites Enhances Both Plant Growth and Defense

Eukaryotic aquaporins share the characteristic of functional multiplicity in transporting distinct substrates and regulating various processes, but the underlying molecular basis for this is largely unknown. Here, we report that the wheat (Triticum aestivum) aquaporin TaPIP2;10 undergoes phosphorylation to promote photosynthesis and productivity and to confer innate immunity against pathogens and a generalist aphid pest. In response to elevated atmospheric CO concentrations, TaPIP2;10 is phosphorylated at the serine residue S280 and thereafter transports CO into wheat cells, resulting in enhanced photosynthesis and increased grain yield. In response to apoplastic HO induced by pathogen or insect attacks, TaPIP2;10 is phosphorylated at S121 and this phosphorylated form transports HO into the cytoplasm, where HO intensifies host defenses, restricting further attacks. Wheat resistance and grain yield could be simultaneously increased by TaPIP2;10 overexpression or by expressing a TaPIP2;10 phosphomimic with aspartic acid substitutions at S121 and S280, thereby improving both crop productivity and immunity.