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The history of the beloved lychee stretches back thousands of years, but its origins were a mystery. Photo: Getty Images

From Yunnan to a luxury for emperors: Scientists track down the history of the beloved lychee

  • A team of global scientists sequenced the DNA of various lychee plants to create a genetic history of the fruit
  • They believe the first plants grew in Yunnan province and spread across China via the Xijiang River

With its bumpy peelable skin, large pit and juicy meat, the humble lychee is one of the most iconic fruits in Asia.

It is also steeped in history. The lychee first appeared in historical records in China in 200BC. Centuries later, Chinese leaders during the Tang dynasty (618 to 907) organised a horse relay system to deliver the fruits from southwest China to the imperial courts.

In Guangzhou, a lychee tree thought to be over 1,000 years old consistently bears fruit to this day.

However, despite its status as a luxury for emperors, a popular recipe ingredient or a munchable snack, nobody knew where the lychee first appeared, until this month.

In early January, a group of scientists published a report in Nature Genetics that explained how, by sequencing the DNA of lychee plants, they theorised that the first lychees appeared in the wild in Yunnan province in southwest China tens of thousands of years ago.

“Like a puzzle, we are piecing together the history of what humans did with lychee,” said Victor Albert, a University at Buffalo evolutionary biologist.

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Lychee farmers in Vietnam see profits fall because of Covid-19 trade restrictions

Lychee farmers in Vietnam see profits fall because of Covid-19 trade restrictions

The scientists believe the fruit seeds were transported down the Xijiang River, called the “Golden Waterway”, which travels across southern China before flowing into the Pearl River as a tributary that eventually ends in the ocean at the Pearl River Delta.

As the seeds germinated across the river, they spread into Guangdong and Guangxi in southern China and, outside of China, into Vietnam. Eventually, one type of wild lychee found its way to what is now Hainan province when the island was connected to the mainland.

At this point, domestication of the fruit began, with two distinct lineages starting in Hainan and Yunnan provinces, respectively.

“This is the ‘one origin centre, two domestication events’ hypothesis for lychee evolution, one of the main findings of our study,” said Rui Xia, a professor at South China Agricultural University in Guangdong and author on the study.

The Xijiang River is believed to have helped propagate lychees across China. Photo: Getty Images

The scientists suggested the domestication could have happened 18,000 years ago. Because the distance and water between Hainan and Yunnan would have been insurmountable for most people to cross during their lifetime, they would have developed independently of each other.

However, the scientists also clearly said that the 18,000-year number was an estimate and was far from certain.

Rui said that, over the years, crossbreeding probably occurred by accident, as it would take about 8 years to successfully create new breeds, far too long for ancient farmers.

“The main differences [between the lychees] are fruit size. They are some really big lychees, while many of them are small. The second difference is the seed size, one of the major standards to choose good lychee fruit. Normally the smaller seed the better,” said Rui.

The Yunnan variations tend to fruit earlier than the Hainan species, but eventually the fruits began to crossbreed, leading to varieties like Fei Zi Xiao, which means the concubine smiles”, that are popular today.

While the history of the lychee is fascinating, the third discovery could impact agriculture development in the future.

The scientists also discovered that the Yunnan lychees, which bloom earlier, have a genetic sequence that the Hainan variants, which fruit later, do not.

When they compared the genetic sequences to the Fei Zi Xiao, a hybrid fruit, they found the Fei Zi Xiao had one copy of the genetic sequence passed down from its Yunnan “parents”.

“Fei Zi Xiao appears to be a direct hybrid of the two independently domesticated lines. Thus it fruits early, but not as early as Yunnan wild plants or as late as Hainan wild plants. This crossing was likely done in Guangdong by people during historic times; hard to say how long ago, but since lychees are propagated by repeated grafting, it could have been hundreds of years,” said Albert.

The Fei Zi Xiao lychee is a hybrid between wild plants that grew in Yunnan and Hainan. Photo: Getty Images

This information could be valuable because lychee is exceptionally perishable, meaning that it rarely stays fresh beyond its natural fruiting period. Theoretically, this genetic information could help farmers perfect their fruiting season and lengthen it along the edges.

“This is very useful for breeders. Because the lychee is perishable, flowering times have been important to extending the season for which the lychee is available in markets,” said Albert.

While lychees are typically cheap in local markets, which contributes to their status as a snack, there have been exemptions. In 2002, one lychee fruit was sold for US$67,000 at the time.

It came from a 400-year-old tree named Xiyuangualu that only produces a few dozen fruits per year. These fruits were used as tributes to the imperial court during the Qing dynasty.

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