Wheat Brefeldin-A ADP-Ribosylated Substrate TaANGUSTIFOLIA Negatively Regulates Cuticular Wax Biosynthesis

Cuticular wax covers the epidermal surface of bread wheat (Triticum aestivum L.) and plays a key role in regulating wheat environmental adaptation. Elucidating the molecular mechanism underlying cuticular wax biosynthesis could facilitate wheat genetic improvement for stress resistance. Herein, we reveal that wheat brefeldin-A (BFA) ADP-ribosylated substrate TaANGUSTIFOLIA (TaAN) negatively regulates the biosynthesis of cuticular wax. Silencing of the TaAN gene in bread wheat resulted in significantly increased cuticular wax accumulation and decreased rates of water loss and chlorophyll leaching. Furthermore, we demonstrate that the TaAN protein directly suppresses transcription of the TaMYB46 gene, and identify the wax biosynthesis gene TaKCS1 as a target gene of the transcriptional activator TaMYB46. Moreover, we found that the TaMYB46 and TaKCS1 genes are epistatic to the TaAN gene in the regulation of cuticular wax biosynthesis. These findings elucidate that wheat BFA ADP-ribosylated substrate TaAN negatively regulates cuticular wax accumulation, probably via suppressing the TaMYB46-TaKCS1 module, providing valuable information for wheat genetic improvement in cuticular wax-associated traits.