The Return of the American The Return of the American The Return of the American The Return of the American The Return of the American The Return of the American The Return of the American The Return of the American Chestnut Tree (Castanea dentata) Chestnut Tree (Castanea dentata) Chestnut Tree (Castanea dentata) Chestnut Tree (Castanea dentata) Chestnut Tree (Castanea dentata) Chestnut Tree (Castanea dentata) Chestnut Tree (Castanea dentata) Chestnut Tree (Castanea dentata) Gary P. Carver, PhD [email protected]301-831-9151 www.carverscarvings.com Six species of chestnut trees Several species of Asian and North American chinquapins All hybridize to some degree All in the Fagaceae family, which includes beech (Fagus) and oak (Quercus) Chestnut Classification Chestnut Classification – Castanea Castanea 2 Castanea Leaf Identification (L to R): American Chestnut (C. dentata), Chinese Chestnut (C. mollissima), Chinkapin (C. pumila), European Chestnut (C. sativa), and Japanese Chestnut (C. crenata). 3 Castanea Nut Identification (L to R): American, Chinese, Japanese, European 4 Dispersal and evolution of Castanea from Asia to Europe to North America. Chloroplast DNA sequences suggest a common Castanea ancestor originated in Asia about 40 – 60 million years ago. Castanea dentata probably diverged from C. sativa in the late Eocene epoch – approximately 35 million years ago. Castanea Castanea Migration Pathway Migration Pathway 5 Historic Historic Natural Natural Range of Range of Castanea Castanea dentata dentata 6
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Return of the American Chestnut - University Of Maryland...The Return of the American Chestnut Tree (Castanea dentata) Gary P. Carver, PhD [email protected] 301-831-9151 Six species
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The Return of the American The Return of the American The Return of the American The Return of the American The Return of the American The Return of the American The Return of the American The Return of the American
Chestnut Tree (Castanea dentata)Chestnut Tree (Castanea dentata)Chestnut Tree (Castanea dentata)Chestnut Tree (Castanea dentata)Chestnut Tree (Castanea dentata)Chestnut Tree (Castanea dentata)Chestnut Tree (Castanea dentata)Chestnut Tree (Castanea dentata)
� Reforestation benefits: � Fast growing (suited for clear cuts)
� Tolerant of relatively acidic and dry soils (suited for strip-mined land),
� Coppices (resulting in less need for replanting)
� Educational opportunities
� Moral imperative
Why Restore the American Why Restore the American Chestnut Tree?Chestnut Tree?
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1. Backcross breeding
2. Intercrossing large survivors
3. Genetic modification
4. Hypovirulence
5. The “Phil Rutter genetic storm”
6. Natural evolution
Paths to Blight ResistancePaths to Blight Resistance
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� The American Chestnut Foundation (TACF) backcross breeding program uses resistance from Castanea mollissima (Chinese chestnut species common in United States)
� Three stages of backcross breeding; six generations in 30 years
� Intercross American and Chinese chestnuts to make an F1
� Backcross F1 to pure Americans three times
� Intercross third backcross trees two times
� Assumption: three “incompletely dominant” genes convey resistance