Abstract: Kucha is a unique tea resource rich in theacrine (1,3,7,9-tetramethyluric acid) in southwest China. Theacrine has a variety of physiological activities such as sedation, hypnosis and antidepressant. Theacrine synthesis enzyme, the key gene for theacrine biosynthesis, had been cloned and studied. However, there were few reports on the regulation mechanism of theacrine metabolism. In order to obtain the transcription factors related to theacrine metabolism, kucha (GKC and LKC) and normal tea cultivar (YK10) were used as research materials. Purine alkaloid content and related gene expressions in the samples were detected by HPLC and RNA-seq, respectively. And the reliability of the transcriptome data were verified by quantitative real-time PCR (qRT-PCR). The results show that the contents of theacrine in GKC and LKC were 21.82 mg·g^-1 and 14.70 mg·g^-1, respectively, while the content of theacrine in YK10 was not detected. In addition, the caffeine contents of GKC and LKC were both lower than 15.00 mg·g^-1. Based on RNA-seq, 3 948 differentially expressed genes (DEGs) had the consistent expression trends in GKC vs YK10 and LKC vs YK10. These DEGs included 96 transcription factors belonging to 29 families. Among them, 30 candidate transcription factors might be the key genes involved in the regulation of theacrine metabolism, especially NAC and HD-ZIP family transcription factors such as CSS0012182, CSS0013789, CSS0041233, novel.16084 and CSS0014547.

Key words: Kucha, theacrine, RNA-seq, transcription factor