The American Chestnut (Castanea dentata) is a storied tree. An American epic with books written and legends told. It was a behemoth, not necessarily by the size of individuals, though plenty were taller than the Statue of Liberty and had trunks you could hang a basketball hoop from if it were lying on its side. No, the behemoth legend of the American Chestnut lies in its versatility and pervasive presence in the lives of people living in the Eastern United States during the its reign as the dominant tree in the forests of the Appalachian Mountain range.
“Chestnuts roasting on an open fire…” were the sweet nut of the American Chestnut. The productivity of these tress provided fodder for pig farmer’s herds at no cost of sowing and harvesting. Homes, barns, fences, furniture, and firewood were hewn from these trees. The tannin content in the bark provided natural resistance to insects and made them a valued resource of the tanning industry. “The Perfect American Tree.”
Like many giants of lore, or perhaps more aptly the alien invaders in H.G. Well’s War of the Worlds, the American Chestnut was reduced to nearly nothing by less than a speck of dust. Cryphonectria parasitica, the cause of Chestnut Blight was introduced to the East Coast of the United States in the early 1900s. It took less than 50 years for it to decimate the American Chestnut throughout its range. This ascomycete (sac fungi) was brought to the United States via plant material collected in Asia, where the Asian Chestnut had evolved resistance to the pathogen. Meanwhile the American Chestnut had no resistance, or at least none that people had the presence of mind to look for. Remember, this was the 1920s, 30s, and 40s. The nuances of passive mutations and genetic variation and heritability were far from mainstream knowledge. So, the demise of the American Chestnut was hastened by preempitive harvest of healthy trees, essentially eliminating the possibility of finding a native tree with inherent resistance.
The American Chestnut still persists as a species throughout its original range, but mostly as a resprouting understory “shrub.” But the legend continues, as concentrated efforts are being made to restore this tree, if not to its former magnificence and dominance, at least to having American Chestnuts roasting on open fires once again.
*Here is a video from the University of Maine summarizing the story.
More about efforts to save/restore the American Chestnut:
I haven’t been into genetics work since labs during undergrad, so I wonder how CRISPR might help/influence these efforts
Note: The pathogen is also prevalent on chestnut trees in Europe. Hypovirulence of the pathogen was first discovered here. http://international-pest-control.com/hypovirulence-hope-for-management-of-sweet-chestnut-blight/