Wheat Chromatin Assembly Factor-1 Negatively Regulates the Biosynthesis of Cuticular Wax and Salicylic Acid to Fine-Tune Powdery Mildew Susceptibility

Powdery mildew caused by phytopathogen Blumeria graminis f. sp. tritici (Bgt) negatively impacts wheat production. Although reduced Bgt susceptibility is aimed at wheat improvement, the chemical mechanism underlying the compatible wheat-Bgt interaction remains unknown. Herein, we identified chromatin assembly factor 1 (CAF-1) as an epigenetic suppressor of chemical cues governing the compatible wheat-Bgt interaction. Silencing of wheat TaFAS1, TaFAS2, and TaMSI1 genes encoding essential CAF-1 components resulted in enhanced cuticular wax and salicylic acid (SA) biosynthesis, as well as altered compatible wheat-Bgt interaction. We found that CAF-1 components facilitate chromatin assembly and histone deacetylation at the wax biosynthesis gene TaECR and the SA biosynthesis activator gene TaSARD1, which leads to the epigenetic suppression of cuticular wax and SA biosynthesis essential for the wheat-Bgt interaction. These findings implicated that the chromatin assembly factor epigenetically suppresses biosynthesis of cuticular wax and SA, thereby fine-tuning the compatible wheat-powdery mildew interaction.