An international team of researchers from Spain, Switzerland, Denmark, and
Italy has sequenced the first complete almond genome. The sequence
represents almost 95 percent of the genes, or nearly 28,000 genes and
roughly 246 million base pairs. The sequencing project sought to find the
genetic differences between bitter and sweet almonds.

Almonds produced nowadays are sweet, tasty, and safe to eat, but they were
not usually so. Years ago, almonds were bitter and poisonous. In early Greek
writings, breeders inserted chunks of pine into the trunks of almond trees,
resulting in sweeter fruit. It is now believed that doing so stressed the
trees, preventing them from producing amygdalin, the toxin responsible for
the bitter taste.

Over time, farmers bred domesticated almond trees to produce palatable
seeds. The research reveals how a genetic mutation "turned off" almond's
ability to make the toxic compound thousands of years ago. Amygladin gives
wild almond seeds bitterness and toxicity. When ingested, amygladin breaks
down into several chemicals, including benzaldehyde, which tastes bitter,
and cyanide, a deadly poison. The team found that the protein called bHLH2
in wild almond trees binds to two genes, instigating the production of
amygdalin. In sweet domestic varieties, there is a mutated version of bHLH2
that is not able to bind with the genes, thus, production of amygdalin does
not occur.

[www.scientificamerican.com]
nce-the-almond-genome/