• DNA analysis has uncovered how the common apple first reached Europe
• Traders travelling west on the Silk Road would munch of large, bland wild apples
• The fruit typically came from an area west of Shan Tai mountain in Kazakhstan
• As they tossed apple cores on their westward journey, the pips would sprout
• The ‘Kazakh’ apple crossbred with the sour crab apples growing in Europe
• This led to the familiar fruits we know and the 7,500 varieties grown today
By Colin Fernandez, Science Correspondent
Originally published in The Daily Mail, 15th August 2017
The crisp, juicy apple in your shopping basket originated in a mountainous region of Kazakhstan around 10,000 years ago, scientists have discovered.
DNA analysis has pinpointed where the first wild apples grew – and uncovered the remarkable story of how apples first reached these shores, a journey of around 4,500 miles (7,200 km).
Traders travelling west on the Silk Road, the fabled caravan trail from China to Europe, would munch on large, bland wild apples, in an area west of Shan Tai mountain in Kazakhstan.
As they tossed aside their well-gnawed apple cores on their westward journey, the pips would sprout and grow into apple trees.
The breakthrough happened when the ‘Kazakh’ apple crossbred with the sour crab apples growing in western Europe, Siberia and the Caucasus mountains.
While crab apples are extremely bitter, they became cross-bred with their more edible cousins, a process that may first have happened accidentally.
And it was this that led to the familiar fruits we know and love – and the 7,500 different varieties of apples grown today.
Researchers at BTI, Cornell University and Shandong Agricultural University in China have attempted to discover how the apple evolved.
Writing in Nature Communications, the researchers reveal surprising insights into the genetic exchange that brought us today’s modern, domesticated apple, ‘Malus domestica’.
First author Dr Yang Bai, of New York’s Boyce Thompson Institute, said: ‘For the ancestral species, Malus sieversii, the fruits are generally much larger than other wild apples.
‘They are also soft and have a very plain flavour that people don’t like much.’
The hybridization between ancient cultivated apples and M. sylvestris, followed by extensive human selection, gave us new apples that are larger and fuller in flavour, and with a crispy firmness that gives them a longer shelf life.
Dr Bai added that the sourness introduced by the crabapple made the kind of apple we know today.
She said: ‘The modern domesticated apples have higher and well-balanced sugar and organic acid contents.
‘That is how the apple started to become a popular and favoured fruit.’
The researchers said that they believe the apples left Kazakhstan between 4,000 and 10,000 years ago, where they were taken along the Silk Road, a route along which goods ranging from textiles, horses and spices were traded.
The researchers came to their conclusions by sequencing and comparing the DNA of 117 Types of apple, including M. domestica and 23 wild species from North America, Europe, and East and central Asia.
Previous studies have shown that the common apple, Malus domestica, arose from the central Asian wild apple, Malus sieversii, with contributions from crabapples along the Silk Road as it was brought west to Europe.
The latest study has pinpointed where the first apple trees sprouted.
Zhangjun Fei, BTI professor and lead author said: ‘We narrowed down the origin of domesticated apple from very broad central Asia to Kazakhstan [in an] area west of Tian Shan Mountain.’
As well as travelling west, the first domesticated apple had travelled to the east, hybridising with wild apples on the way to China, creating varieties of apple.
He added: ‘We pointed out two major evolutionary routes, west and east, along the Silk Road, revealing fruit quality changes in every step along the way.’
Although wild M. sieversii grows east of Tian Shan Mountain, in the Xinjiang region of China, these apples were never cultivated, and has remained isolated for centuries.
This pool of genetic diversity is as yet untapped by human selection.
Dr Bai said: ‘It is a hidden jewel for apple breeders to explore further.’
The untapped wild apples in China could be used to grow much bigger apples.
Dr Bai said: ‘It has great potential for further enlarging fruit size in breeding programs.’
She added: ‘Well, in my wild imagination, maybe one day it can be as big as a watermelon.’