Genetic Basis Of Tea Tree Plants’ Flavors And Benefits Revealed; First Ever Draft Of Whole Genome Sequencing Of Tea Tree Plant Published
Tea, a beverage that is consumed by people all over the world, has high socio-economic implications. Green tea, white tea, black tea and "chai" are made from the leaves of the tea tree plant (Camellia sinensis). The genus Camellia encompasses around a hundred species, out of which C. sinensis. var. assamica and C. sinensis var. sinensis are the only two that are grown commercially.
Even though tea has been used by people as a beverage since time immemorial, not much is known about the biomolecular properties of the plant parts, except for the leaves. To get an insight into the genetic aspects of the tea tree plant's antioxidant properties, scientists from Kunming Institute of Botany, China, sequenced its whole genome. The first draft of the deduced sequence was published yesterday in the Molecular Plant journal.
Some of the previous studies made on the biochemistry of the tea tree plant had revealed that the distinctive taste of the tea comes from the unique blend of caffeine and catechin, an inherently bitter tasting compound. The levels of these molecules vary between the various species of Camellia genus.
The recent genomic study revealed that C. sinensis, the commercially cultivated tea tree plant species, contains high catechins and caffeine levels. The higher levels of these compounds were found to be simultaneous with the presence of multiple copies of the genes responsible for flavonoids and caffeine production.
According to Phys.org, though caffeine and catechin are not proteinaceous compounds that can be directly expressed by the genes, their cellular levels in tea tree leaves depend on the level of expression of multiple proteins associated with their manufacture via various biochemical pathways. The variable expression of these genes dictates the taste and commercial demand in the beverage industry.
Lizhi Gao, the lead author of the study, further explained that around 67 percent of the total number of base pairs of the tea tree genome are "retrotransposons" or jumping genes. It is speculated that during evolution, these sequences may have been copied and pasted multiple times at various locations of the genome. This has not only led to the increase in the total genomic size of the plant but it seems it may also have helped the tea tree plant to survive in adverse conditions.