Almonds ! Their mere mention, at least to me, brings to mind snacks to accompany an evening drink. And that ought to remind us of their domestication: wild almonds are bitter and toxic due to amygdalin — synonymous with cyanide — in their content. What happened to delete
almost entirely that poison from those seeds?
The answer is selection by mankind of the almond trees carrying the sweeter seeds. It occurred millennia ago.
To elucidate it further, in the bitter genotype, prunasin synthesized in the tegument is transported into the cotyledon via transfer cells and converted into amygdalin in the developing almond seed; whereas in the sweet genotype, amygdalin formation is prevented because the prunasin is degraded upon passage of the β-glucosidase-rich cell layer into the inner epidermis of the tegument.
To quote from a scholarly 2008 article,
The knowledge about hydrogen cyanide (HCN) formation in plants has its origin in antiquity. In ancient Egypt, traitorous priests in Memphis and Thebes were poisoned to death with pits of peaches. The first known detection of HCN liberated from damaged plant tissue was made in 1802 by the pharmacist Bohm in Berlin upon distillation of bitter almonds. In 1830, Robiquet and Boutron-Chalard discovered the structure of the HCN-liberating compound in bitter almonds. Because the compound was isolated from Prunus amygdalus (synonym
Prunus dulcis), it was named amygdalin. Amygdalin has subsequently been found widespread in seeds of other members of the Rosaceae like in apples, peaches, apricots, black cherries, and plums. “
To put it another way, mankind has thus benefited from mutations — so
characteristic of plants — that deprived almond trees of a defense
mechanism (the amygdalin) against predators. It’s not only the crunchiness: almonds supply us with beneficial molecules, that protect us from ailments
such as diabetes, obesity, metabolic syndrome and cardiovascular diseases.
Provence owes some of its appeal to almond trees and their stunning
bloom in February. Their white flowers with pinkish reflections are the
harbingers of spring, which will soon follow. These flowers appear well before
the leaves and veil the tree in a white dress, making it the symbol of love and
virginity.
Moreover, a true local gastronomic heritage, the calisson sweet owes
its fame to the almond, that thus is emblematic of Provence. The Greeks
introduced almond trees in Provence during the fifth century BC.