Metabolite Profiling and Transcriptome Analysis Revealed the Conserved Transcriptional Regulation Mechanism of Caffeine Biosynthesis in Tea and Coffee Plants

Caffeine is a characteristic bioactive
compound in tea and coffee
plants, which is synthesized and accumulated extensively in leaves
and seeds. However, little is known about the regulatory mechanism
of caffeine synthesis in plants. This study compared the caffeine
metabolite between tea and coffee plants. We found that tea leaves
contained significantly higher caffeine than coffee leaves, which
is perhaps due to more members of N-methyltransferase (NMT) genes as well as higher expression levels
in tea plants. Substantial numbers of transcription factors were predicted
to be involved in caffeine biosynthesis regulation, combining weighted
gene co-expression network analysis and the cis-element
of NMT promoter analysis in tea and coffee plants.
Furthermore, analysis of the transcription factors from the caffeine-related
modules suggested that the regulatory mechanism of caffeine biosynthesis
was probably partly conservative in tea and coffee plants. This study
provides an essential resource for the regulatory mechanism of caffeine
biosynthesis in plants.