Key to Tasty Tea May Be the Germs Found in Plants' Roots

By   |  February 16, 2024

By Dennis Thompson HealthDay Reporter  |  Copyright © 2024 HealthDay. All rights reserved.

  • Good-tasting tea depends on soil microbes found in the plant’s roots, a new study says

  • Microbes influence the production of theanine, an amino acid that contributes to tea flavor

  • Synthetically produced microbial colonies boosted theanine levels in tea trees

THURSDAY, Feb. 15, 2024 (HealthDay News) -- A delicious cup of complex, flavorful tea depends heavily on microbes found on the roots of the plant, a new study reports.

Researchers found that soil microbes on tea roots affect the tree’s uptake of ammonia, which in turn influences its production of theanine – an amino acid that contributes to tea’s taste.

Further, by altering that collection of microbes, researchers discovered that they could make good tea taste even better.

“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,” researcher Tongda Xu of Fujian Agriculture and Forestry University in Fujian, China, said in a news release.

Attempts to improve tea quality through genetics – selectively combining different types of tasty tea – have proven challenging, researchers said.

Because of this, interest has grown in other ways to improve the quality and flavor of tea.

Earlier studies had found that soil microbes living in plant roots affect the way nutrients are taken up and used in plants.

That gave the research team the idea to investigate how root microbes might affect the quality of tea.

After learning that microbes influence theanine production, the researchers analyzed tea varieties containing different levels of theanine.

By comparing the tea plants, they identified a set of microbes that looked promising for boosting the theanine levels in tea.

They constructed a synthetic microbial community, dubbed SynCom, that closely mirrored one associated with a high-theanine tea variety called Rougui.

SynCom wound up boosting theanine levels when applied to tea roots, researchers report.

“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,” researcher Wenxin Tang of Fujian Agriculture and Forestry University said in a news release.

“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,” Tang continued. “Furthermore, this effect is particularly pronounced in low-nitrogen soil conditions.”

The results suggest that these sort of synthetically produced microbial communities could make teas better, especially when grown in poor soil that’s deficient in nitrogen, researchers said.

Because tea trees require a lot of nitrogen, this discovery also could help reduce the use of chemical fertilizers in tea production.

It also might allow for other improvements in agriculture, researchers added. For example, rice might be grown with greater protein content using synthetic microbes.

The new study was published Feb. 15 in the journal Current Biology.

More information

Harvard T.H. Chan School of Public Health has more about tea.

SOURCE: Cell Press, news release, Feb. 15, 2024