Research Progress in Natural TheobromineEnriched Tea Plants

Theobromine-enriched tea is a kind of rare tea germplasm resource with theobromine as the representative alkaloid, which has unique health care effect and utilization value. In this paper, four newly discovered natural theobromineenriched tea plants, including cocoa tea, Hongya tea, Camellia gymnogyna Chang and Camellia crassicoluma Chang were compared and reviewed from the aspects of the biochemical component characteristics, biological metabolism pathways and molecular mechanism of theobromine in tea plants. Theobromine accounts as high as 2%-6% of the dry weight of these tea leaves while caffeine is less than 0.5%. The dominant catechin monomer is gallocatechin gallate, while the content of epicatechin gallate is low. The mutation of arginine to histidine at the active site of caffeine synthetase changes the substrate specificity of N-methyltransferase, which leads to the termination of caffeine synthesis by caffeine synthetase and the enrichment of theobromine in tea plants. The natural theobromine-enriched tea resources enrich the diversity of tea species, but the level of excavation and utilization is still limited. Combining with the current development of tea breeding technology, the breeding and resource exploitation of natural theobromine-enriched tea germplasm are prospected.