Wheat MYB46-like Transcription Factor Stimulates Cuticular Wax Biosynthesis

Cuticular wax mixtures are the major components of the lipophilic cuticle coating of plant aerial organs during primary growth and they protect plants from environmental stresses. Decoding cuticular wax biosynthesis in bread wheat (Triticum aestivum L.) could contribute to the genetic improvement of this agriculturally important crop. Herein, we revealed that the wheat MYB46-like transcription factor TaMYB46 positively regulates cuticular wax by activating transcription of the long-chain acyl-CoA synthetase 1 (TaLACS1) gene. Knockdown of the wheat TaMYB46 gene resulted in significantly reduced cuticular wax loads and increased permeability of the wheat leaf cuticle. Furthermore, wheat long-chain acyl-CoA synthetase TaLACS1 was identified as a core component of the cuticular lipid biosynthetic machinery. Knockdown of the TaLACS1 gene led to reduced cuticular wax accumulation and increased leaf cuticle permeability. Moreover, the transcription factor TaMYB46 was found to enrich at the TaLACS1 promoter regions and activate TaLACS1 gene transcription. These findings collectively support the conclusion that the transcription factor TaMYB46 stimulates cuticular wax biosynthesis, likely by activating TaLACS1 transcription.