Occurrence of theobromine synthase genes in purine alkaloid-free species of Camellia plants

Abstract

Caffeine (1,3,7-trimethylxanthine) and theobromine (3,7-dimethylxanthine) are purine alkaloids that are present in high concentrations in plants of some species of Camellia. However, most members of the genus Camellia contain no purine alkaloids. Tracer experiments using [8-(14)C]adenine and [8-(14)C]theobromine showed that the purine alkaloid pathway is not fully functional in leaves of purine alkaloid-free species. In five species of purine alkaloid-free Camellia plants, sufficient evidence was obtained to show the occurrence of genes that are homologous to caffeine synthase. Recombinant enzymes derived from purine alkaloid-free species showed only theobromine synthase activity. Unlike the caffeine synthase gene, these genes were expressed more strongly in mature tissue than in young tissue.

Biosynthesis and Catabolism of Purine Alkaloids

“…This involved designing degenerated primers based on conserved regions in tea caffeine synthase (AB031280) and unknown proteins of Arabidopsis thaliana. The evolutionary relationship of caffeine synthase family enzymes has been summarized elsewhere (Ashihara, Kato, et al, 2011;Ishida et al, 2009). Comparisons of the amino acid sequences of the caffeine synthase family in Coffea and Camellia plants have been reported.…”

“…Consumption of purine alkaloids can have a diversity of impacts on human health (Lean, Ashihara, Clifford, & Crozier, 2012). In this context, the occurrence of theobromine synthase genes in apparently non-purine alkaloid accumulating species of Camellia, such as C. japonica and C. kissii (Table 4.2; Ishida, Kitao, Mizuno, Tanikawa, & Kato, 2009), is of interest. as a consequence the distribution of purine alkaloids is restricted to species in six families of higher plants.…”

Identification and isolation of full-length cDNA sequences by sequencing and analysis of expressed sequence tags from guarana (Paullinia cupana)

“…However, there was no group formed exclusively by caffeine synthase or theobromine synthase. These two enzymes seem to share the same phylogenetic profile, which was also observed in several studies (Uefuji et al, 2003;Yoneyama et al, 2006;McCarthy and McCarthy, 2007;Ângelo et al, 2008;Freitas, 2009;Ishida et al, 2009).…”

Biosynthesis of Caffeine Underlying the Diversity of Motif B’ Methyltransferase

“…The analysis of orthologous genes of TCS1 in Camellia plants is indispensable for clarifying which of the two synthases is ancestral-caffeine or theobromine synthase. Ishida et al demonstrated the occurrence of theobromine synthase gene in purine alkaloid-free species derived from Camellia plants that belonged to the sub-genera Protocamellia, Camellia, and Metacamellia [17]. This observation strongly suggested that caffeine synthase has evolved from theobromine synthase in Camellia plants.…”