Interspecific hybridization is a common breeding approach for introducing novel traits and genetic diversity to breeding populations. Southern highbush blueberry (SHB) is a blueberry cultivar group that has been intensively bred over the last 60 years. Specifically, it was developed by multiple interspecific crosses between northern highbush blueberry [NHB, Vaccinium corymbosum L. (2 n = 4 x = 48)] and low-chill Vaccinium species to expand the geographic limits of highbush blueberry production. In this study, we genotyped polyploid blueberries, including 105 SHB, 17 NHB, and 10 rabbiteye blueberry (RE) ( Vaccinium virgatum Aiton), from the accessions planted at Poplarville, Mississippi, and accessions distributed in Japan, based on the double-digest restriction site-associated DNA sequencing. The genome-wide SNP data clearly indicated that RE cultivars were genetically distinct from SHB and NHB cultivars, whereas NHB and SHB were genetically indistinguishable. The population structure results appeared to reflect the differences in the allele selection strategies that breeders used for developing germplasm adapted to local climates. The genotype data implied that there are no or very few genomic segments that were commonly introgressed from low-chill Vaccinium species to the SHB genome. Principal component analysis-based outlier detection analysis found a few loci associated with a variable that could partially differentiate NHB and SHB. These SNP loci were detected in Mb-scale haplotype blocks and may be close to the functional genes related to SHB development. Collectively, the data generated in this study suggest a polygenic adaptation of SHB to the southern climate, and may be relevant for future population-scale genome-wide analyses of blueberry.

中文翻译：

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对南部高丛蓝莓种群发展历史的基因组洞察

种间杂交是一种常见的育种方法，用于将新性状和遗传多样性引入育种种群。南方高丛蓝莓 (SHB) 是一个蓝莓品种组，在过去 60 年中一直在密集培育。具体来说，它是通过北部高丛蓝莓 [NHB, Vaccinium corymbosum L. (2 n = 4 x = 48)] 和低寒越橘物种之间的多种种间杂交开发的，以扩大高丛蓝莓生产的地理范围。在这项研究中，我们对多倍体蓝莓进行了基因分型，包括 105 个 SHB、17 个 NHB 和 10 个兔眼蓝莓 (RE) (Vaccinium v​​irgatum Aiton)，来自密西西比州 Poplarville 种植的种质和分布在日本的种质，基于双重消化限制性位点相关的 DNA 测序。全基因组 SNP 数据清楚地表明，RE 品种在遗传上与 SHB 和 NHB 品种不同，而 NHB 和 SHB 在遗传上无法区分。种群结构结果似乎反映了育种者用于开发适应当地气候的种质的等位基因选择策略的差异。基因型数据暗示没有或很少基因组片段通常从低寒越橘物种渗入到 SHB 基因组。基于主成分分析的异常值检测分析发现了一些与可以部分区分 NHB 和 SHB 的变量相关的基因座。这些 SNP 位点在 Mb 级单倍型块中检测到，可能接近与 SHB 发育相关的功能基因。集体，