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
Forest Health Research and Education Center, Department of Horticulture, University of Kentucky, Lexington, KY, United States.
Forest Health Research and Education Center, U.S. Department of Agriculture (USDA) Forest Service, Southern Research Station, Lexington, KY, United States.
Front Plant Sci. 2024 Apr 8;15:1365951. doi: 10.3389/fpls.2024.1365951. eCollection 2024.
Chestnut blight (caused by ), together with root rot (caused by ), has nearly extirpated American chestnut () from its native range. In contrast to the susceptibility of American chestnut, many Chinese chestnut () genotypes are resistant to blight. In this research, we performed a series of genome-wide association studies 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 inter-species F2 family. We evaluated trees for resistance to blight after artificial inoculation with two fungal strains and scored nine morpho-phenological traits that are the hallmarks of species differentiation between American and Chinese chestnuts. Results support a moderately complex genetic architecture for blight resistance, as 31 QTLs were found on 12 chromosomes across all studies. Additionally, although most morpho-phenological trait QTLs overlap or are adjacent to blight resistance QTLs, they tend to aggregate in a few genomic regions. Finally, comparison between QTL intervals for blight resistance and those previously published for root rot resistance, revealed five common disease resistance regions on chromosomes 1, 5, and 11. Our results suggest that it will be difficult, but still possible to eliminate Chinese chestnut alleles for the morpho-phenological traits while achieving relatively high blight resistance in a backcross hybrid tree. We see potential for a breeding scheme that utilizes marker-assisted selection early for relatively large effect QTLs followed by genome selection in later generations for smaller effect genomic regions.
栗疫病（由 引起），连同根腐病（由 引起），已几乎将美国栗（ ）从其原生范围内根除。与美国栗的易感性形成对比的是，许多中国栗（ ）基因型对疫病具有抗性。在本研究中，我们对来自三株不相关的中国栗树（桃花心木、南京和M16）的疫病抗性进行了一系列全基因组关联研究，并对一个源自桃花心木的种间F2家系进行了数量性状位点（QTL）研究。在用两种真菌菌株人工接种后，我们评估了树木对疫病的抗性，并对九个形态 - 物候性状进行了评分，这些性状是美国栗和中国栗之间物种分化的标志。结果支持疫病抗性具有中等复杂的遗传结构，因为在所有研究中，在12条染色体上发现了31个QTL。此外，虽然大多数形态 - 物候性状QTL与疫病抗性QTL重叠或相邻，但它们倾向于聚集在几个基因组区域。最后，对疫病抗性的QTL区间与先前发表的根腐病抗性的QTL区间进行比较，发现在第1、5和11号染色体上有五个共同的抗病区域。我们的结果表明，在回交杂种树中实现相对较高的疫病抗性的同时，消除中国栗形态 - 物候性状的等位基因将是困难的，但仍然是可能的。我们认为有一种育种方案具有潜力，即早期利用标记辅助选择针对效应相对较大的QTL，随后在后代中针对效应较小的基因组区域进行基因组选择。
