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02-16-2024

Great tasting tea comes from healthy root microbes in the plants

Did you know there’s more to tea than just its flavor? Every sip of tea holds a hidden universe that was born in the plant, teeming with microscopic life that shapes its unique flavor. 

Scientists from Chinese universities including Fujian Agriculture and Forestry University have revealed the secrets of this miniature world within the roots of tea plants.

The experts have uncovered how specific microbes at the roots act as tiny alchemists coordinating the chemical reactions defining a perfect cup of tea

Mini tea ecosystem

Curious about how tiny creatures in tea plant roots impact flavor, the scientists started collecting samples from different tea plants, especially the prized Rougui variety, known for its calming taste. They identified the different types of microorganisms living in the roots and soil. 

Next, to see how these organisms work together, the experts created a mini-version of the community. Basically, they created a tiny tea plant ecosystem in a lab. The researchers named this synthetic community “SynCom21.”

Then came the fun part: growing plants. The researchers planted tea plants and even lab plants like Arabidopsis, both within and without SynCom21.

This experiment was conducted under conditions where there wasn’t enough nitrogen in the soil, a nutrient crucial for plant growth. 

By carefully watching how the plants grew and how much nitrogen they absorbed, the experts could see how the microbes made a difference.

Outside the SynCom21, the researchers also wanted to understand the natural production of a calming compound called theanine.

To gauge this, they compared the roots of two different tea plants- Rougui, known for its high theanine content, to Maoxie, which has lower levels.

Enhanced tea plant growth

Plants with SynCom21 grew taller and stronger, and were better at using nitrogen. Even better, they made more theanine.

“Crucially, through the isolation and assembly of a synthetic microbial community from high-quality tea roots, we managed to notably enhance the amino acid content in various tea plant varieties, resulting in an improvement in tea quality,” said Tongda Xu from Fujian Agriculture and Forestry University in Fujian, China.

Key insights

High-theanine roots had more “good” microbes that helped grab nitrogen from the soil. The plant uses this nitrogen to make theanine, especially in the fall when it makes the most.

The experts also found that the tiny microbes living in tea plant roots change throughout the year, especially those that help the plant use nitrogen. These “nitrogen helpers” are most plentiful in the fall, which is also when the tea plant makes the most of calming theanine. 

The results suggest that the relationship between plants and these tiny helpers is constantly changing and depends on the time of year.

Broader implications for tea plants

The discovery could help farmers grow more food while being kinder to the Earth. It isn’t just about delicious, calming tea. It suggests similar strategies could be used for other crops. 

“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,” said 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.”

Sustainable food

The tiny helpers in the roots seem to make plants better at using nitrogen and creating special compounds, like theanine in tea. This means we might be able to use the same idea to make fruits, vegetables, and grains tastier, healthier, and even tougher in changing weather. 

The research could be a big step towards growing food in a way that’s good for both humans and the planet.

The study is published in the journal Current Biology.

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