New traits

Chengcheng county in Shaanxi province is home to Piperis dahongpao, a variety of spice commonly known as big red robe peppercorn that is widely employed in Chinese cuisine.

The spice has been used since the Han Dynasty (202 BC-220 AD) for cooking, medicine, rituals and even for palace decorations, according to the Kunming Institute of Botany, Chinese Academy of Sciences.

However, it has a notoriously low yield and is difficult to harvest, as the plant stems are covered with sharp thorns. For centuries, it was considered a "tribute spice" enjoyed only by the privileged, the best-known being Empress Dou of the Han Dynasty, who decorated her chamber with the condiment to signify fertility and prestige.

It is still not cost-effective to produce this spice. Guo said, "A laborer can only pick about 7.5 kilograms of this peppercorn per day, and after it is dried in the sun, less than 2 kg is left."

In 2016, Guo and his team sent some of the spice seeds into orbit for 12 days aboard the Shijian-10 recoverable science satellite.

The team was aiming to create a new variety of peppercorn with stronger resistance to wind and disease, but it discovered something far more exciting－the thorns on the stems had disappeared.

"Generating unexpected new traits is one of the main features of space-induced mutation breeding," Guo said.