If you were to make a list of what it takes to get a good cup of tea, microorganisms likely wouldn’t make the list. Sure, the tea plant quality is critical. Water can make a difference. Sugar, milk, or anything else you add also matters. But according to a new study, the flavor of a cup of tea also depends on the collection of microbes in the tea plant roots.

“Significant disparities in microbial communities, particularly nitrogen metabolism-related microorganisms, were identified in the roots of tea plants with varying qualities through microbiomics,” says Tongda Xu of Fujian Agriculture and Forestry University in Fujian, China. “Crucially, through the isolation and assembly of a synthetic microbial community from high-quality tea plant roots, we managed to notably enhance the amino acid content in various tea plant varieties, resulting in an improvement in tea quality.”

A better cup of tea

Tea is one of the most popular beverages in the world, and improving its quality would not only make millions of people a bit happier — but it would also be pretty lucrative.

However, improving the quality of tea through genetic breeding methods is difficult so instead, the authors of the new study looked at something else.

They found that there’s a complex community of microbes around tea roots. This community affects how plants absorb ammonia, which in turn, influences the production of theanine, a crucial component for determining a tea’s taste. They also found that microbes colonize different types of tea differently, which points to an intricate relationship between tea plants and root microbiota — and suggests that these microbes may be a way to change the taste of tea.

This was the first step. The next step involved constructing a synthetic microbial community, which they call SynCom. The SynCom mirrors natural microbial communities in tea, but researchers can tweak it to indirectly increase theanine levels.

“The initial expectation for the synthetic microbial community derived from high-quality tea plant roots was to enhance the quality of low-quality tea plants,” says study co-author Wenxin Tang. “However, to our astonishment, we discovered that the synthetic microbial community not only enhances the quality of low-quality tea plants but also exerts a significant promoting effect on certain high-quality tea varieties. Furthermore, this effect is particularly pronounced in low-nitrogen soil conditions.”

More than just tea

Essentially, this discovery could lead to better tea varieties down the road. The findings suggest that such synthetically produced microbial communities could improve teas, particularly in nitrogen-deficient soil, they say. Tea often requires lots of nitrogen to grow, which highlights another potential benefit of the finding: synthetic microbial communities can reduce the use of chemical fertilizers for growing tea.

Now, this is where it gets really interesting: it’s not just tea. There’s reason to believe that many or all plants have similar communities that can be tweaked.

“Based on our current experimental findings, the inclusion of the SynCom21 microbial community has not only improved the absorption of ammonium nitrogen in different tea varieties but also enhanced the uptake of ammonium nitrogen in Arabidopsis thaliana,” Xu says. “This suggests that the ammonium nitrogen uptake-promoting function of SynCom21 may be applicable to various plants, including other crops.”

Arabidopsis thaliana is a plant commonly used in basic biological studies and SynCom allowed the plant to better tolerate low nitrogen conditions.

By highlighting the potential to improve tea quality through microbial management, this research sets a new horizon in agricultural science. As we move towards more sustainable and environmentally friendly farming practices, the manipulation of root microbiota emerges as a promising tool in the agricultural toolkit, offering benefits that extend across crops and ecosystems.

However, this raises another question. Will consumers embrace this type of product, or will it receive a GMO-like rejection in many parts of the world?

That remains to be seen, but the prospect of having better tea is something we can all raise a cup to.

Journal Reference: Current Biology, Xin et al.: “Root microbiota of tea plants regulate nitrogen homeostasis and theanine synthesis to influence tea quality.” https://www.cell.com/current-biology/fulltext/S0960-9822(24)00079-4