117 genomes of the fruit analysed

The modern crisp apple originated in a mountainous region of Kazakhstan, according to a study which reveals a surprising two-way journey on the Silk Road for one of the world’s most popular fruit.

As travellers journeyed east and west along the Silk Road, they brought with them apple seeds from the choicest fruit they took from wild trees, researchers said.

This early selection would eventually lead to the 7,500 varieties of apple that exist today, they said.

Researchers, including those at Boyce Thompson Institute (BTI) in the U.S., sequenced and compared the genomes of 117 diverse apple accessions, including Malus domestica and 23 wild species from North America, Europe, and east and central Asia.

“We narrowed down the origin of the domesticated apple from very broad central Asia to Kazakhstan area west of Tian Shan Mountain,” said Zhangjun Fei, a professor at BTI.

Researchers discovered that the first domesticated apple had travelled to the east, hybridising with local wild apples along the way, yielding the ancestors of soft, dessert apples cultivated in China today.

Researchers also found that as the apple travelled west along the Silk Road, trees grew from dropped seeds and crossed with other wild apple varieties, including the sour European crabapple (Malus sylvestris).

They found that Malus sylvestris has contributed so extensively to the apple’s genome that the modern apple is actually more similar to the sour crabapple than to its Kazakhstan ancestor, Malus sieversii.