AetMYC1, the Candidate Gene Controlling the Red Coleoptile Trait in Aegilops tauschii Coss. Accession As77.

The red coleoptile trait can help monocotyledonous plants withstand stresses, and key genes responsible for the trait have been isolated from , , and , but no corresponding research has been reported for . In this research, transcriptome analysis was performed to isolate the candidate gene controlling the white coleoptile trait in . There were 5348 upregulated, differentially-expressed genes (DEGs) and 4761 downregulated DEGs in red coleoptile vs. white coleoptile plants. Among these DEGs, 12 structural genes and two transcription factors involved in anthocyanin biosynthesis were identified. The majority of structural genes showed lower transcript abundance in the white coleoptile of accession 'As77' than in the red coleoptile of accession 'As60', which implied that transcription factors related to anthocyanin biosynthesis could be the candidate genes. The and transcription factors and were both isolated from accessions 'As60' and 'As77', and their transcript levels analyzed. The coding sequence and transcript level of showed no difference between 'As60' and 'As77'. encoded a 567-amino acid polypeptide in 'As60' containing the entire characteristic domains, bHLH-MYC_N, HLH, and ACT-like, belonging to the gene family involved in regulating anthocyanin biosynthesis. encoded a 436-amino acid polypeptide in 'As77' without the ACT-like domain because a single nucleotide mutation at 1310 bp caused premature termination. Transient expression of induced anthocyanin biosynthesis in 'As77' with the co-expression of , while could not cause induced anthocyanin biosynthesis under the same circumstances. Moreover, the transcript abundance of was lower than that of . appears to be the candidate gene controlling the white coleoptile trait in , which can be used for potential biotech applications, such as producing new synthetic hexaploid wheat lines with different coleoptile colors.