Abstract: MYB transcription factor is one of members in the largest family of transcription factors in plants;it is mainly involved in the regulation of plant secondary metabolism,the response of hormones and environmental factors,and thus plays a crucial role in plant growth and development. A study reveals that the core sequence of E-box is CANNTGN（N：A/G/C/T）,which is a cis-element associated with the response to light and phenylpropanoid biosynthesis pathway. A library of cis-acting elements was constructed in our previous study,and results by a transcription factor-centered yeast one-hybrid technology showed that the BplMYB46 transcription factor bound to the E-box cis-acting element with a core sequence of CAAATG in birch;however,it is unclear whether BplMYB46 may bind to other core sequence of E-box. Therefore,in this study,the renaturation of the double-stranded DNA of every core sequence of E-box cis-acting element was performed and connected to the pHIS2 vector. Further,the yeast one-hybrid technique was used to select E-box cis-acting elements that specifically bound to the BplMYB46 transcription factor. The results showed that the yeast colony grew on TDO/3AT medium when the third nucleotide of the core sequence of E-box was A/T/C and the fourth was A/G/C,respectively,indicating that the specific sequence of E-box cis-acting element bound by BplMYB46 transcription factor was CA（A/T/C）（A/G/C）TG. This study provides a data basis for improving the genetic traits of birch by analyzing the regulation of BplMYB46 transcription factor to downstream genes and screening downstream genes via the binding of BplMYB46 transcription factor with E-box cis-acting element,

Key words: BplMYB46 transcription factor, E-box cis-acting element, yeast one-hybrid