Identification of a Regulatory Module (PsMYB12L/PsDFR) with Potential Involved in Double-Color Formation in Paeonia suffruticosa “Shima Nishiki”

Paeonia suffruticosa “Shima Nishiki” is a extremely precious double-color cultivar in the world because of its unique and attractive flower color. However, the underlying molecular mechanisms of its double-color formation have not been completely unravelled until now. In the present study, firstly, the full-length cDNA sequence, genomic DNA sequence, promoter region sequence of the key structural gene ( PsDFR ) in the red and pink petals of the “Shima Nishiki” cultivar were cloned and analyzed, respectively. Meanwhile, the methylation level of CpG island and promoter region of this gene in the red and pink petals was also measured. Moreover, the identification of regulatory effect of PsMYB114L/PsMYB12L and PsDFR was performed. Here, we found that the full-length cDNA sequence, genomic DNA sequence, promoter region sequence of PsDFR were identical in the red and pink petals. There were some differences for the methylation level of this gene in the red and pink petals, but these differences were little and did not show obvious regularity. Therefore, the differential expression of PsDFR should be not caused by its own sequence differences. In addition, the regulatory effect of PsMYB12L and PsDFR was successfully identified. Based on these above results, we concluded that PsMYB12L regulating the differential expression of PsDFR may be a key reason for the double-color formation. These results will advance our understanding of the molecular regulatory mechanisms of double-color formation in P. suffruticosa “Shima Nishiki”.