Bigger, sweeter, less acidic: Dal researchers trace the evolution of apples and how they were improved – Dal News

They are one of the most widely produced fruit crops in the world, with their cultivation dating back at least 7,000 years to Central Asia before moving west along the Silk Road to Europe and beyond.

But apples found in the forests of Kazakhstan millennia ago stand in stark contrast to the large, sugary, predominantly red fruits that now fill grocery store shelves around the world, according to new research from the Dalhousie Faculty of Agriculture. .

Researchers who follow the evolution of apples over the years have found that modern varieties are 3.6 times heavier, about half as sour, and significantly less bitter than wild ancestral species, much like the crabapples from which apples are derived. modern apples.

Using historical records, they also determined that apple breeding over the past 200 years has allowed the fruit to stay firm and soften less during storage.

Sean Myles (seen left), associate professor of agriculture, and his team looked at 10 apple phenotypes – or traits – to assess how apples have changed due to domestication and selection.

“We knew apples had changed over time, but never before had we had the chance to quantify the degree of change so precisely,” says Dr Myles, who described the findings in a new paper by PLOS ONE.

“Indeed, the fact that apples are now more than three times larger than their wild ancestors suggests that we have come a long way since the early days of harvesting tiny berries from wild forests. We should be grateful to all the people over thousands of years who have sown the seeds of the most promising trees: that’s why we now enjoy big, sweet apples that keep well for weeks in the fridge!”

Witness evolution in action

The team tapped into Canada‘s Apple Biodiversity Collection (ABC), an orchard in the Annapolis Valley that contains more than 1,000 different apple varieties, like Gala and Honeycrisp, but also heirloom varieties and wild apples. forests of Kazakhstan. They are distributed among cultivated apples, or malus domesticaand their main wild progenitor species, Malus sieversii.

Because the wild ancestors of modern apples are grown alongside modern apples under identical conditions in the ABC, scientists have an unprecedented chance to see evolution in action.

“You can imagine our ancestors when they moved from place to place they would have taken their favorite apple seeds with them and when you do that for generations and generations you get slow improvements and deviation from ancestral state,” Tommy said. Davies, a PhD student at the Faculty of Agriculture and lead author of the study.

The team measured firmness, weight, acidity, harvest time and flowering time, then examined how these characteristics differed between wild apples of past and current apple varieties.

They found that improving apples over the past few thousand years has largely consisted of making apples tastier. Compared to the past, we now appreciate apples that are less acidic and less bitter, sweeter and keep better, says Dr. Myles.

Future improvements

Although apples are sweeter today, they seem to contain far fewer antioxidants than their ancestral relatives. It is this kind of data that could allow breeders to guide future improvements in breeding strategies. It can also mitigate some of the high costs of growing apple trees, which often pay off five years into the life cycle, requiring growers to invest heavily before generating income.

“We may want to tap into these heirloom apple varieties when breeding new varieties so that our future apples offer more protective effects against common diseases,” Dr. Myles said.

“This is one of the main goals of establishing and maintaining the Canadian Apple Biodiversity Collection: not only to maintain the incredible natural diversity of the apple, but also to harness this diversity for the improvement future of the apple.

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