The Camellia sinensis, or tea plant, can produce a wide variety of teas, like Oolong, black, green, and white. How is it that the leaves from a single plant species can produce such a variety of tea flavors?
In spite of the fact that tea has been around for thousands of years, we don't really know much about the plant. Perhaps when something is so ubiquitous and common, we tend to take it for granted. A team of botanists from China has finally looked into what makes the plant so special.
There are six kinds of tea that come from the C. sinensis. These are Oolong, black, white, green, yellow, and post-fermented. We can tell each kind apart by their color, aroma, and flavor. The qualities of each tea are quite distinct, and the fact that each kind comes from just one plant species is quite curious. Different chemical compositions give rise to each different type of tea.
But what is the genetic basis of these chemical compositions? There are a hundred species in the Camellia genus, but only the C. sinensis produces leaves suitable for brewing. This is because the other Camellia species don't produce as much flavor as those of the tea plant. The flavor of tea comes from chemicals like flavonoids and caffeine, which other Camellia species don't have much of.
Researchers wanted to find the “genetic basis of tea flavors”. Decoding the genome of the C. sinensis took over five years, with 3.02 billion DNA base pairs. The C. sinensis has a larger genome than many other plant species, including the coffee plant. The researchers also found that the tea plant has several copies of caffeine and flavonoid genes. These duplicates actually also made sequencing the large C. sinensis genome more difficult than the researchers expected.
However difficult the sequencing may have been, the efforts were certainly rewarding. The researchers also found that the synthesis of flavor compounds are a remnant from the ancestors of the tea plant. Thus, the biochemical pathways that influence this synthesis have been in existence for over six million years.
The research may have been tough, but it can have far-reaching benefits. Tea plant breeders can take the information and use it to improve the flavor of the tea they produce, or even produce new tea varieties. Of course, the research can also benefit other industries. The study can also help those that deal with using plants for medicinal and cosmetic purposes.
The team managed to accomplish quite a lot in five years of work. However, as with any other large scientific undertaking, there is still more work to be done. Believe it or not, the tea plant genome sequence is still in its draft stage, and the researchers still need to double-check it. It probably won't take another five years, but it's certainly a huge task. The researchers also want to study other C. sinensis varieties from around the world. With further study, they may find out how multiple gene copies affect flavor.
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