1. Characterization of N-methyltransferase Genes in Coffea liberica var. liberica.
- Author
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Mondragon, Miguel V., Nagaño, Terrence Ferdinand S., and Santos, Daisy May C.
- Subjects
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COFFEE , *FRUIT ripening , *CHROMOSOME duplication , *POLYMERASE chain reaction , *GEL electrophoresis - Abstract
Caffeine biosynthesis in Coffea evolved independently through tandem gene duplication and subsequent neofunctionalization of ancestral N-methyltransferases (NMTs). The bulk of our understanding of this process in Coffea is centered on two species: C. arabica and C. canephora. To gain a wider perspective of caffeine biosynthesis in Coffea, this study focused on the less popular but commercially available C. liberica var. liberica, locally known as "kapeng barako." This study aimed to determine the genomic and coding sequences of the three NMTs -- mainly, xanthosine methyltransferase (XMT), 7-methylxanthine-N-methyltransferase (MXMT), and dimethylxanthine methyltransferase (DXMT) -- through Sanger sequencing. Relative expression levels of these NMTs in the leaves, flower bud, green fruit, and red fruit stages were also determined through polymerase chain reaction amplification of synthesized cDNA and then gel electrophoresis. Results reveal that the genetic sequences of NMTs of C. liberica were similar to the C. eugenioides-derived NMTs of C. arabica. Results also indicate that there is a possibility that more than one NMT gene for each NMT cluster (XMT, MXMT, DXMT) exists. This study has also identified genomic sequences and transcripts, whose sequences were in between the XMT and MXMT gene clusters. The function of these novel sequences is yet to be determined. NMT expression levels in C. liberica were similar to those observed in C. arabica and C. canephora, wherein expression peaks at the green fruit stage and then diminishes, as the fruit ripens fully. Although the NMTs of C. liberica have a lot of similarities with C. arabica and C. canephora, discovering the function and role in caffeine biosynthesis of these novel genomic sequences and transcripts will help us further understand the evolution of caffeine biosynthesis in Coffea. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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