Saturday, March 20

Apple Genetics

"Why do we need so many kinds of apples? Because there are so many folks. A person has a right to gratify his legitimate taste. If he wants twenty or forty kinds of apples for his personal use…he should be accorded the privilege. There is merit in variety itself. It provides more contact with life, and leads away from uniformity and monotony." 
-- Liberty Hyde Baily


Apples are a mysterious fruit, a metaphor for the uncertainty that life has refused to relinquish to the human desire for predictability.  I myself find the whimsical fickleness of the apple seed incredibly refreshing and even comforting in the face of an increasingly mono-culture.  For centuries, the secret hidden within the apple seed has captivated the minds of everyone from geneticists to Johnny Appleseed.  But the same phenomenon that instills such mystery in the apple, also gives it a fleeting nature.  Here is how I look at it:  Say I were to plant an apple tree from a seed I found, giving me a tree baring the most delectable, tasty (and yes taste is a matter of personal opinion and favor) apples I had ever sunk my teeth into.  Year after year I harvested these apples and each spring the tree bore anew.  Then one fall after the branches had been picked bare, a cold winter wind fell the tree.  Knowing this I saved all the seeds from the fall harvest.  Yet in all those seeds, not one would contain the genetic code capable of growing a tree that could reproduce the apple I had come to love.  No matter how many seeds were planted, that apple would never again exist.  Fleeting.  The art of grafting fruit trees has allowed growers and breeders to have a say in how long of an appearance a particular apple variety makes on this planet, but the principle remains the same: inside each apple seed of every single apple that has ever existed, lies the potential for uniqueness.   


 Apples have a genetic property referred to as extreme hetrozygosity, meaning that alleles  of a gene can be radically different from each other.  Alleles are an alternative form of a gene that arise from mutation, but occur at the same loci or place on a chromosome.  For instance, human DNA has three different alleles of the gene responsible for blood type; that for A blood type, B blood type and O blood type.   The variation within an apple’s alleles, even if small, can affect everything from the color of its skin, to its susceptibility to a particular disease.  
Humans, who also display hetrozygosity, do not show as extreme a difference in  alleles, allowing for there to be resemblance among siblings and between parents and their children.  This is not the case for apples.  Alleles of genes can be radically different and almost always a seedling apple tree will bear fruit nothing like the apple from whence the seed came.  Most apples that come from seedling trees are deemed "spitters" meaning one is prone to spit them out upon tasting.  However the continual recombination of genes into new possibilities, can yield visually unique if not tasty apples worthy of the cider press, the pie pan or even greater gustatory distinction.   
This phenomenon also allows the apple to easily adapt to new environmental conditions.  A seedling apple tree may have the ability to thrive in an ecosystem where the parent trees could only cope: 

“Whenever the apple tree goes, its offspring propose so many different variations on what it means to be an apple –at least five per apple, several thousand per tree –that a couple of these novelties are almost bound to have whatever qualities it takes to prosper in the tree’s adopted home.”
                                                                                                                                --Michael Pollan

The capacity of a seedling apple tree to find a home away from home is largely what shaped orchards in North America.  Where many established European varieties struggled and died in unwelcoming winters, brutal heat, or spring freezes, seedling apple trees found their niche.  It could be more aptly said, that the apple seed not the apple itself made the journey on immigrant boats to the eastern shores of New England, giving us many of the varieties we know today along with many heirlooms lost and forgotten in the cider orchards of a time fare removed.     
In a world where it seems as though there are few accessible places humans have not tread, islands in the ocean that have not been discovered or waterfalls in the woods that have not been stumbled upon, the idea of taking a seed from the heart of an apple and placing it in the ground gives me an almost childlike giddiness.

3 comments:

  1. Very interesting article, you did a very good job of displaying the information with a unique writing style.

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  2. Thank you for this article. I too found it very interesting.

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  3. Thank you for your article. I only just recently became aware of this wonderful topic. I find it fascinating!

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