A newly identified photosystem II Subunit P gene TaPsbP4A-1 in Triticeae species negatively regulates wheat powdery mildew resistance

The photosystem II (PSII) Subunit P (PsbP) protein is a component of its oxygen-evolving complex, which can oxidize water to produce oxygen using light energy and is critical to the core components and stability of PSII. Using the whole-genome information, the <i>PsbP</i> genes of 10 plant species were comprehensively identified. The expression patterns of wheat <i>PsbP</i>s under <i>Blumeria graminis</i> f. sp. <i>tritici</i> (<i>Bgt</i>) infection were assessed using qRT-PCR, and the functions of <i>TaPsbP</i>s in wheat powdery mildew resistance were studied using barley stripe mosaic virus-induced gene silencing. In total, 122 <i>PsbP</i> genes were divided into 8 classes with similar gene structures. No tandem repeat events were identified in wheat <i>PsbP</i>, suggesting that the <i>PsbP</i> genes in common wheat were donated by its diploid progenitor species. The expression levels of <i>TaPsbP2A-1</i>, <i>TaPsbP3A-1</i>, <i>TaPsbP4A-1</i>, <i>TaPsbP4A-2</i>, and <i>TaPsbP7A-2</i> were induced by <i>Bgt</i>. The silencing of <i>TaPsbP4A-1</i> increased the resistance of common wheat 'Bainong AK58' to <i>Bgt</i>. This study provides valuable information for functional and evolutionary research on the <i>PsbP</i> gene family.