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Hawthorne, VA, United States

Clark S.L.,U.S. Department of Agriculture | Schlarbaum S.E.,University of Tennessee at Knoxville | Saxton A.M.,University of Tennessee at Knoxville | Hebard F.V.,The American Chestnut Foundation
New Forests | Year: 2016

European and American chestnut species (Castanea) have been decimated by exotic species, most notably chestnut blight (Cryphonectria parasitica), since the early nineteenth century. Backcross breeding programs that transfer blight disease resistance from Chinese chestnut (C. mollissima) into American chestnut (C. dentata) offer promise for chestnut restoration, particularly for the American chestnut which was a keystone species in eastern North America. Nursery prescriptions and conformity to desired American chestnut traits following planting must be tested, however, before blight resistance can even be evaluated. We tested early field performance of American and Chinese chestnut and hybrid seedlings from the third backcross generation (e.g., BC3F3) in two-aged regeneration harvests on highly productive sites in the southern Appalachians, USA. We also tested a common nursery prescription of grading seedlings by size prior to planting. BC3F3 seedlings had similar 4-year survival to American chestnut seedlings, but generally had smaller stem heights and ground-line diameters (GLD). Although blight had not yet substantially challenged some sites, the BC3F3 seedlings had blight incidence similar to the Chinese chestnut which was lower than the American chestnut. Visual seedling grading affected planting shock and stem height and GLD by the end of year 4. Large size-class seedlings had more stem dieback and 5 % lower survival compared to small size-class seedlings, but larger trees exhibited the same height in year 3 as small trees in year 4. Advanced breeding material (BC3F3) was successfully established during the stand initiation phase of forest development on highly productive sites, but deviations in desired growth rate of the American chestnut was evident. Visual grading of seedlings affected establishment of breeding material, and should be considered in the restoration process. © 2015, Springer Science+Business Media Dordrecht (outside the USA).

Kremer A.,French National Institute for Agricultural Research | Kremer A.,University of Bordeaux 1 | Abbott A.G.,Clemson University | Carlson J.E.,Pennsylvania State University | And 7 more authors.
Tree Genetics and Genomes | Year: 2012

An overview of recent achievements and development of genomic resources in the Fagaceae is provided, with major emphasis on the genera Castanea and Quercus. The Fagaceae is a large plant family comprising more than 900 species belonging to 8-10 genera. Using a wide range of molecular markers, population genetics and gene diversity surveys were the focus of many studies during the past 20 years. This work set the stage for investigations in genomics beginning in the early 1990s and facilitated the application of genetic and quantitative trait loci mapping approaches. Transferability of markers across species and comparative mapping have indicated tight macrosynteny between Quercus and Castanea. Omic technologies were more recently developed and the corresponding resources are accessible via electronic and physical repositories (expressed sequence tag sequences, single-nucleotide polymorphisms, candidate genes, cDNA clones, bacterial artificial chromosome (BAC) libraries) that have been installed in North America and Europe. BAC libraries and physical maps were also constructed in Castanea and Quercus and provide the necessary resources for full nuclear genome sequencing projects that are currently under way in Castanea mollissima (Chinese chestnut) and Quercus robur (pedunculate oak). © 2012 The Author(s).

Kubisiak T.L.,Southern Research Institute | Nelson C.D.,Southern Research Institute | Staton M.E.,Clemson University | Zhebentyayeva T.,Clemson University | And 9 more authors.
Tree Genetics and Genomes | Year: 2013

The Chinese chestnut (Castanea mollissima) carries resistance to Cryphonectria parasitica, the fungal pathogen inciting chestnut blight. The pathogen, introduced from Asia, devastated the American chestnut (Castanea dentata) throughout its native range early in the twentieth century. A highly informative genetic map of Chinese chestnut was constructed to extend genomic studies in the Fagaceae and to aid the introgression of Chinese chestnut blight resistance genes into American chestnut. Two mapping populations were established with three Chinese chestnut parents, 'Mahogany', 'Nanking', and 'Vanuxem', totaling 337 progeny. The transcriptome-based genetic map was created with 329 simple sequence repeat and 1,064 single nucleotide polymorphism markers all derived from expressed sequence tag sequences. Genetic maps for each parent were developed and combined to establish 12 consensus linkage groups spanning 742 cM, providing the the most comprehensive genetic map for a Fagaceae species to date. Over 75 % of the mapped markers from the Chinese chestnut consensus genetic map were placed on the physical map using overgo hybridization, providing a fully integrated genetic and physical map resource for Castanea spp. About half (57 %) of the Chinese chestnut genetic map could be assigned to regions of segmental homology with 58 % of the peach (Prunus persica) genome assembly. A three quantitative trait loci (QTL) model for blight resistance was verified using the new genetic markers and an existing interspecies (C. mollissima × C. dentata) F2 mapping population. Two of the blight resistance QTLs in chestnut shared synteny with two QTLs for powdery mildew resistance in peach, indicating the potential conservation of disease resistance genes at these loci. © 2012 The Author(s).

Saielli T.M.,University of Vermont | Schaberg P.G.,U.S. Department of Agriculture | Hawley G.J.,University of Vermont | Halman J.M.,University of Vermont | Gurney K.M.,The American Chestnut Foundation
Canadian Journal of Forest Research | Year: 2012

American chestnut (Castanea dentata (Marsh.) Borkh.) was functionally removed as a forest tree by chestnut blight (caused by the fungal pathogen Cryphonectria parasitica (Murr.) Barr). Hybrid-backcross breeding between blight-resistant Chinese chestnut (Castanea mollissima Blume) and American chestnut is used to support species restoration. However, preliminary evidence suggests that backcross material may not have the cold hardiness needed for restoration in the northern portions of the species' range. The cold tolerance of nuts is of concern because reproductive tissues are particularly sensitive to freezing damage. We assessed nut cold tolerance for 16 American chestnut, four Chinese chestnut, and four red oak (Quercus rubra L.) (a native competitor) sources to better assess genetic variation in nut hardiness. We found that Chinese chestnut nuts were less cold tolerant than American chestnut and red oak nuts and that American chestnut sources from the south were less cold tolerant than sources from the north, with significant differences among sources within all regions. We also assessed how sources varied among temperature zones (sources separated by average winter temperature lows at source locations). Sources from the cold temperature zone were more cold tolerant and less variable in hardiness than sources from warm and moderate zones.

The American Chestnut Foundation | Date: 2008-12-16

Printed materials, namely, brochures, pamphlets, a newsletter, and a scientific journal, all featuring information about the American chestnut tree, the American chestnut tree blight, and efforts to develop a blight-resistant American chestnut tree. coffee mugs. t-shirts, [ sweatshirts, ] and hats. chestnut tree seeds and seedlings for planting. Educational services, namely, the development and dissemination of education materials of others about the American chestnut tree, the American chestnut tree blight, and efforts to develop a blight-resistant American chestnut tree; educational services, namely, conducting conferences and workshops related to the American chestnut tree, the American chestnut tree blight, and efforts to develop a blight-resistant American chestnut tree. Scientific research in the field of developing a blight-resistant American chestnut tree; providing an online website containing scientific research materials related to the American chestnut tree, the American chestnut tree blight, and efforts to develop a blight-resistant American chestnut tree. Providing an online website containing botanical information related to the American chestnut tree, the American chestnut tree blight, and plant breeding efforts to develop a blight-resistant American chestnut tree; plant breeding services. Indicating membership in an organization seeking to restore the American chestnut tree to its native forests through a scientific research and breeding program.

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