AUTHOR=Fan Shenghua , Georgi Laura L. , Hebard Frederick V. , Zhebentyayeva Tetyana , Yu Jiali , Sisco Paul H. , Fitzsimmons Sara F. , Staton Margaret E. , Abbott Albert G. , Nelson C. Dana TITLE=Mapping QTLs for blight resistance and morpho-phenological traits in inter-species hybrid families of chestnut (Castanea spp.) JOURNAL=Frontiers in Plant Science VOLUME=Volume 15 - 2024 YEAR=2024 URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1365951 DOI=10.3389/fpls.2024.1365951 ISSN=1664-462X ABSTRACT=Chestnut blight (caused by Cryphonectria parasitica, Cp), together with Phytophthora root rot (caused by Phytophthora cinnamomi, Pc), has nearly extirpated American chestnut (Castanea dentata) from its native range. In contrast to the susceptibility of American chestnut, many Chinese chestnut (C. mollissima) genotypes are resistant to blight. In this research, we performed a series of genome-wide association studies (GWAS) for blight resistance originating from three unrelated Chinese chestnut trees (Mahogany, Nanking and M16) and a Quantitative Trait Locus (QTL) study on a Mahogany-derived interspecies F2 family. We evaluated trees for resistance to blight after artificial inoculation with two fungalCp strains and scored nine morpho-phenological (M/P) traits that are the hallmarks of species differentiation between American and Chinese chestnuts. Results support a moderately complex geneticnomic architecture for blight resistance, as 31 QTLs were found on 12 chromosomes across all studies. Additionally, although most morpho-phenologicalM/P trait QTLs overlap or are adjacent to blight resistance QTLs, they tend to aggregate in a few genomic regions. This indicates that it will be difficult, but still possible to eliminate Chinese chestnut alleles for these traits while achieving relatively high blight resistance in athe backcross hybrid tree. Finally, comparison between QTL intervals for blight resistance and those previously published for Phytophthora root rot resistance, revealed five common disease resistance regions on chromosomes 1, 5, and 11.