No sooner do we hear about the sequencing of the wheat genome, than word comes this week that the genome of the apple has been decoded. The feat was accomplished through a collaboration between 18 research institutions in the US, Belgium, France, New Zealand and Italy, and was coordinated by Italy’s Istituto Agrario S. Michele all'Adige (IASMA). DNA sequences of the Golden Delicious apple were produced in 2007/08, and over 82 percent of the genome was assembled into the total 17 apple chromosomes in 2009. Now, over 90 percent of the genes have been anchored to a precise position in the chromosomes. It may all sound like Greek (or Italian) to us non-geneticists, but the upshot of the whole thing is that we should now be able to selectively breed apples like never before, resulting in hardier, tastier fruits.
In the course of the study, some interesting facts were uncovered regarding the history of the humble apple. For one thing, its genome underwent duplication about 50 million years ago, bringing the total number of chromosomes up from 9 to the current 17. More recently – three to four thousand years ago – the domestic apple was cultivated from Malus sieversii, a wild apple species that can still be found in forests throughout China and Kazakhstan. Currently, at 57,000, apples have more genes than any other plant sequenced so far.
Given that the study has identified all 992 genes responsible for disease resistance, the IASMA researchers hope that crop breeders will now be able to create new types of apples that are hardier than any that have come before, and that are perhaps also better tasting and more nutritious. They would also like to see these new apples requiring less in the way of “agro-technical interventions”, be those irrigation, herbicides, pesticides or fertilizers, resulting in a lower impact on the environment.
The research has just been published in the journal Nature Genetics.