The epidermal surface of bread wheat (Triticum aestivum) is coated with a hydrophobic cuticular wax layer that protects plant tissues against environmental stresses. However, the regulatory mechanism of cuticular wax biosynthesis remains to be uncovered in bread wheat. Here, we identified wheat Enoyl-CoA Reductase (TaECR) as a core component responsible for biosynthesis of wheat cuticular wax. Silencing of TaECR in bread wheat resulted in a reduced cuticular wax load and attenuated conidia germination of the adapted fungal pathogen powdery mildew (Blumeria graminis f.sp. tritici). Furthermore, we established that TaECR genes are direct targets of TaECR promoter-binding MYB transcription factor1 (TaEPBM1), which could interact with the adapter protein Alteration/Deficiency in Activation2 (TaADA2) and recruit the histone acetyltransferase General Control Nonderepressible5 (TaGCN5) to TaECR promoters. Most importantly, we demonstrated that the TaEPBM1-TaADA2-TaGCN5 ternary protein complex activates TaECR transcription by potentiating histone acetylation and enhancing RNA polymerase II enrichment at TaECR genes, thereby contributing to the wheat cuticular wax biosynthesis. Finally, we identified very-long-chain aldehydes as the wax signals provided by the TaECR-TaEPBM1-TaADA2-TaGCN5 circuit for triggering B. graminis f.sp. tritici conidia germination. These results demonstrate that specific transcription factors recruit the TaADA2-TaGCN5 histone acetyltransferase complex to epigenetically regulate biosynthesis of wheat cuticular wax, which is required for triggering germination of the adapted powdery mildew pathogen.

面包小麦（Triticum aestivum）的表皮表面涂有疏水性表皮蜡层，可保护植物组织免受环境胁迫。然而，面包小麦中表皮蜡生物合成的调控机制尚待发现。在这里，我们确定了小麦Enoyl-CoA还原酶（TaECR）是负责小麦表皮蜡生物合成的核心成分。面包小麦中TaECR的沉默导致适应真菌病原体白粉病（Blumeria graminis f.sp. tritici）的表皮蜡含量降低和分生孢子萌发减弱。此外，我们确定TaECR基因是TaECR的直接靶标启动子结合MYB转录因子1（TaEPBM1），可与衔接蛋白改变/激活中的缺陷2（TaADA2）相互作用，并将组蛋白乙酰转移酶一般控制不可抑制5（TaGCN5）募集到TaECR启动子。最重要的是，我们证明了TaEPBM1-TaADA2-TaGCN5三元蛋白复合物通过增强组蛋白乙酰化并增强TaECR基因上的RNA聚合酶II富集来激活TaECR转录，从而促进了小麦表皮蜡的生物合成。最后，我们确定了非常长链的醛作为TaECR-TaEPBM1-TaADA2-TaGCN5电路提供的触发B的蜡信号。菌病菌 小麦分生孢子萌发。这些结果表明，特定的转录因子募集了TaADA2-TaGCN5组蛋白乙酰转移酶复合物，以表观遗传调控小麦表皮蜡的生物合成，这是触发适应的白粉病病原体萌发所必需的。