Newswise – One might assume that the complex flavor of a high-quality cup of tea depends primarily on the types of tea from which it is made. But a study appears in the journal Current Biology on February 15 shows that making a delicious cup of tea depends on another important ingredient: the accumulation of microbes found on the tea roots. By changing this composition, the authors showed that they could make good quality tea even better.
“Significant differences in microbial communities, particularly in microorganisms related to nitrogen metabolism, have been identified in the roots of tea plants with different properties through microbiomics,” says Tongda Xu of Fujian Agriculture and Forestry University in Fujian, China. “Crucially, by isolating and building a synthetic microbial community from high-quality tea plant roots, we managed to significantly increase the amino acid content in different tea plant varieties, resulting in an improvement in tea quality.”
China has a wealth of genetic resources for growing tea plants. However, improving tea quality through molecular genetic breeding methods is a challenge, the researchers explain. There is interest in finding other ways to modify and improve the tea, possibly including the use of microbial agents. Previous studies have shown that soil microbes living in plant roots influence the way nutrients are absorbed and used in plants. In the new study, the researchers wanted to learn more about how root microbes specifically influence tea quality.
They found that the microbes in the tea roots affected their ammonia absorption, which in turn affected the production of theanine, which is crucial to a tea’s taste. They also saw differences in the microbes that colonized different types of tea. By comparing tea varieties with different amounts of theanine, they identified a number of microbes that showed promise for altering nitrogen metabolism and increasing theanine levels.
Next, they built a synthetic microbial community called SynCom, which was very similar to the one found in association with a high-theanine tea variety called Rougui. When they applied SynCom to tea roots, they found that it increased theanine levels. The microbes allowed it too Arabidopsis thalianaa plant commonly used in basic biological studies to better tolerate low nitrogen conditions.
“The original expectation of the synthetic microbial community derived from high-quality tea plant roots was to improve the quality of low-quality tea plants,” says Wenxin Tang, co-author of the study. “However, to our surprise, we found that the synthetic microbial community not only increases the quality of low-quality tea plants, but also has a significantly beneficial effect on certain high-quality tea varieties. Furthermore, this effect is particularly pronounced in nitrogen-poor soil conditions.”
The results suggest that synthetically created microbial communities could improve teas, especially when grown in nitrogen-poor soil conditions, they say. Since tea trees require a lot of nitrogen, the discovery could help reduce the use of chemical fertilizers while improving the quality of tea trees. The results could have important implications for agricultural crops more broadly.
“Based on our current experimental findings, the inclusion of the SynCom21 microbial community not only improved the absorption of ammonium nitrogen in various tea varieties, but also the uptake of ammonium nitrogen in Arabidopsis thalianasays Xu. “This suggests that the ammonium nitrogen uptake promoting function of SynCom21 may be applicable to various plants, including other crops.”
For example, they say it could allow the cultivation of rice with improved qualities, including higher protein content. They now plan to further optimize SynCom and evaluate its use in field trials. They also hope to learn more about how root microbes influence other secondary metabolites in tea trees.