Camellia ptilophylla RNA-seq
Tea is consumed worldwide because of its charming flavor and the refreshing effectsconferred by caffeine. Nonetheless, caffeine has undesirable side effects, such as sleepdisturbance. Therefore, discovery of a naturally decaffeinated tea plant has become a hottopic and Camellia ptilophylla is known for its low caffeine content. In this study, the accumulationof purine alkaloids in a natural C. ptilophylla population (32 plants) was analyzed, and theresults showed that 81.25% of this population were caffeine-free, containing onlytheobromine (TB), while six plants contained both theobromine and caffeine (CAF). RNA-seq analysis of two C. ptilophylla plants with contrasting purine alkaloid contents (TB andCAF) revealed that xanthosine synthesis genes of the SAM cycle and AMP pathway weresignificantly related to the differential accumulation of purine alkaloids between TB andCAF. The high theobromine content in TB was attributed to the significantly higherexpression of TCS-2, TCS-3 and MXMTs and downregulation of the xanthosine degradationpathway in comparison to CAF. Additionally, CsMYB184 was significantly upregulated inTB, opposing the expression pattern of TCS1, but consistent with that of other TCSs andMXMTs. Furthermore, the upregulated expression of catechin biosynthesis genes, F3'H,F3'5'H and SCPLs in TB corresponded to a higher gallocatechin gallate (GCG) content.Overall, these findings provide new insights into the accumulation of theobromine andGCG, which may facilitate the development of tea plant cultivars with low-caffeine or highGCG to meet the diverse demands of consumers.