The most popular varieties of tea -- including black tea, green tea, Oolong tea, white tea, and chai -- all come from the leaves of the evergreen shrub Camellia sinensis, otherwise known as the tea tree. Despite tea's immense cultural and economic significance, relatively little is known about the shrub behind the tea leaves. However, the first draft of the tea tree genome published online on May 1, 2017 in Molecular Plant may help explain why tea leaves are so rich in antioxidants and caffeine. The open-access article is titled “The Tea Tree Genome Provides Insights into Tea Flavor and Independent Evolution of Caffeine Biosynthesis.” Understanding how the tea tree differs genetically from its close relatives may help tea growers figure out what makes Camellia sinensis leaves so special. The genus Camellia contains over 100 species--including several popular decorative garden plants and C. oleifera, which produces "tea tree" oil--but only two major varieties (C. sinensis. var. assamica and C. sinensis var. sinensis) are grown commercially for making tea. "There are many diverse flavors, but the mystery is what determines or what is the genetic basis of tea flavors?" says plant geneticist Li-Zhi Gao, PhD, of Kunming Institute of Botany in China. Previous studies have suggested that tea owes much of its flavor to a group of antioxidants called flavonoids, molecules that are thought to help plants survive in their environments. One, a bitter-tasting flavonoid called catechin, is particularly associated with tea flavor.
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