Climate change threatens tea -- but its DNA could save it

Chungui Lu is Professor of Sustainable Agriculture at the Nottingham Trent University. The views expressed in this commentary are solely those of the writer. CNN is showcasing the work of The Conversation, a collaboration between journalists and academics to provide news analysis and commentary. The content is produced solely by The Conversation

(CNN)The world's most popular drink (after water) is under threat.

We already know much about the threat of climate change to staple crops such as wheat, maize and rice, but the impact on tea is just coming into focus.
Early research indicates that tea grown in some parts of Asia could see yields decline by up to 55% thanks to drought or excessive heat, and the quality of the tea is also falling.
    The intensive use of pesticides and chemical fertilizers in tea plantations has also led to soil degradation at an average annual rate of 2.8%. This also causes chemical runoff into waterways, which can lead to serious problems for human health and the environment.

      DNA to the rescue

      However, hope may be on the horizon now that scientists at the Kunming Institute of Botany at the Chinese Academy of Sciences have sequenced the entire tea genome.
      Mapping the exact sequence of DNA in this way provides the foundation for extracting all the genetic information needed to help breed and speed up development of new varieties of the tea plant. And it could even help improve the drink's flavor and nutritional value.
        Freshly picked tea leaves.
        In particular, the whole tea tree genome reveals the genetic basis for tea's tolerance to environmental stresses, pest and disease resistance, flavor, productivity and quality.
        Breeders could more precisely produce better tea varieties that produce higher crop yields and use water and nutrients more efficiently. And they could do this while widening the genetic diversity of tea plants, improving the overall health of the tea plant population.
        This is also an important milestone for scientists because it provides a deeper understanding of the complex evolution and the functions of key genes associated with stress tolerance, tea flavor and adaptation.

        Larger than coffee

        The new tea genome is very large, with nearly 37,000 genes -- more than four times the size of the coffee plant genome.
        The process of evolution by natural selection has already helped the tea plant develop hundreds of genes related to resisting environmental stress from drought and disease.
        These genes are like molecular markers that scientists can identify when selecting plants for use in breeding. This will allow them to be more certain that the next generation of plants they produce will have the genes and so the traits they want, speeding up the breeding process.
        Tea pickers in the outskirts of Hangzhou of Zhejiang Province, China.
        Sequencing the genome also raises the possibility of using genetic modification (GM) technologies to turn on or enhance desirable genes (or turn off undesirable ones).
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