A New Slice out of the Apple

I often eat without thinking, either while listening to the news or writing. It’s a poor habit for several reasons, one of which is my ever-growing waistline.

But the next time you bite into an apple, I implore you to take just a moment to really savor its taste, aroma, and texture. Those characteristics vary a lot between a Granny Smith and a Golden Delicious, or a McIntosh and a Braeburn. The variation is one reason apples are a delight.

Apples come from an ancestor tree that had small and acidic fruit. We don’t know exactly how it was that people coaxed substantial improvement out of acid apples, but around 2000 B.C. people produced sweet apple stock. That was also when they began grafting branches from one tree onto another, a clever idea if ever there was one. Much later the Romans, who knew a good thing when they saw it, spread the sweet apple and grafting technology to many lands.

Now skip with me up to the present, because there’s some big news about apples. In the parlance of biologists, the full genome of the apple has recently been described.

As it happens, scientists mapped the genome of the Golden Delicious apple. The Golden Delicious appeared on the scene as a “sport” in the soil of West Virginia, so it’s as American as apple pie. It was propagated and sold starting in 1914.  Other types of apples have come from it.

But what is a genome and why should you care about it? Some years back you likely heard that scientists described the human genome. But, as you’ve noticed, the people around you haven’t improved even one bit. So what’s to be excited about with respect to our growing knowledge of genomes?

Let’s focus on apples. The apple genome is the total of genetic information that governs how apples sprout, grow and yield fruit. It’s genetics that help determine firmness and taste of the flesh, as well as the aroma of the peel. Genetics also influence the resistance to disease an apple tree is likely to have.

If apples went through their whole life cycle every year like our grain crops, we could try crossing two related types and seeing what resulted about 12 months later. But apples are perennials, taking years to take root, grow and reproduce. On that ground alone, we could expect that manipulating apples to suit us by traditional methods would be slower than dealing with annual plants.

The day will soon come that knowing the apple genome will make us better at helping trees produce more apples. And apples that ripen at times and rates that are useful to us are another possibility, giving us the hope of more efficient harvests. Most importantly for us gluttons, apples could taste and smell like we want, giving us a way to directly blend a Granny Smith with a Gala.

As we zoom in and focus our knowledge of particular regions of the genome that do things like govern resistance to disease, we’ll know more and more about what part of the genetic material of the apple we want to change. And we can then do exactly that in a lab, not in experimental orchards where we wait years to see the fruits of our labors.

An international team of researchers led by a group in Italy undertook the challenge of describing the apple genome to get a start on all this work. Professor Amit Dhingra of Washington State University was one person involved in the work, and he recently was kind enough to try to explain apple genetics to this rock-head.

Dhingra told me scientists estimate there are 900 genes related to disease in apples. As knowledge about those genes increases, scientists can help trigger useful mutations or sports, and then trees will have the ability – on their own – to stand up to natural diseases that sometimes really plague them.

As a geologist, I’m not sure I followed the details of genomic research. But I do know that in a world of growing population, anything that can help increase, diversify and secure the food supply is indeed good news.