The invention relates to a 
gene for regulating the synthesis of flavonoids, its coded 
protein and its application, and belongs to the technical field of 
plant genetic engineering.  The 
gene regulating 
flavonoid synthesis, the sequence is shown in SEQ ID NO: 1, which is derived from common tobacco, named NtMYB27, the NtMYB27 
gene is 1240bp in length, contains 3 introns and 4 exons, and its 
coding region is complete  597 bp long.  The present invention finds that the NtMYB27 
transcription factor can inhibit the synthesis of 
flavonols in leaves through 
cloning analysis of gene sequences, construction of expression vectors, and 
gene expression detection, and this inhibition is achieved by inhibiting the expression of NtFLS and NtCHS genes  of.  Therefore, the present invention confirms that NtMYB27 is a 
negative regulator of 
plant flavonol synthesis. When the expression of this gene is inhibited or its function is lost, it can significantly increase the content of 
flavonols in 
plant leaves, providing a basis for the subsequent use of gene editing technology to enhance plant 
flavonols.  Assays provide clear target genes.