基于SLAF-seq技术的猕猴桃种间“拟正反交”群体高密度遗传图谱构建

High-density genetic map of fruit trees is developed to supply markers for breeding novel cultivars and provide tools for fine mapping of QTLs, and is of theoretical and practical value in genetic studies. Two interspecific pseudo-reciprocal crosses between Actinidia chinensis and A. eriantha are designed as mapping populations to develop a high-density genetic map for Actinidia with markers evenly cover the whole genome, adopting the pseudo-testcross procedure. SLAF-seq markers and EST-SSR markers will be developed based on Actinidia EST database and EST data from A. eriantha respectively. Competition between different genomes of Actinidia can be understood by analyzing segregation distortion of markers in the two populations. The effiency of QTL mapping will be improved by choosing polymorphic markers from interspecific populations.Linkage groups of the parents can be integrated better and more accurately by comparing genetic maps of the two reciprocal cross populations. Most of the kiwifruit cultivars are selected from A. chinensis, leading to a narrow genetic background, the project will be of great help to marker-assisted selection in kiwifruit, and guide introgression breeding by interspecific crosses to improve genetic diversity and select novel cultivars.

果树高密度遗传图谱的构建对QTL精细定位和分子辅助育种具有重要的理论研究和应用价值。本项目采取"拟测交"作图策略，拟以中华猕猴桃(Actinidia chinensis)和毛花猕猴桃(A. eriantha)的种间"拟正反交"后代为作图群体，利用猕猴桃EST文库信息建立猕猴桃的SLAF-seq标记技术，利用毛花猕猴桃的EST序列开发EST-SSR标记，构建更好地覆盖猕猴桃全基因组的高密度遗传连锁图谱，并分析分子标记在两个群体中发生偏分离的规律，揭示猕猴桃不同基因组间的竞争机制。利用种间杂交后代开发均匀覆盖全基因组的分子标记可有效提高遗传图谱的QTL检测能力；采用"拟正反交"群体可以更好地锚定亲本图谱并校正由偏分离导致的误差，获得更精确的遗传图谱。项目研究结果将为猕猴桃的分子标记辅助选择奠定基础，为猕猴桃的种间渐渗育种提供理论指导。

果树高密度遗传图谱的构建对QTL精细定位和分子辅助育种具有重要的理论研究和应用价值。猕猴桃属植物的基因组比较大，染色体基数为29，遗传图谱的构建相对较难开展。本项目采取“拟测交”的作图策略，以“江山娇”×中华猕猴桃的两个亲本和108个后代单株为作图群体，基于SLAF-seq技术开发SNP标记，构建了猕猴桃的高密度遗传图谱，主要结果如下：开发了134,049个SLAF标记，多态性标记16,474个，可以用于遗传图谱构建的SNP标记5,320个；利用Joinmap 4.0 进行连锁分析，以LOD值为4-20采用最短距离法进行聚类分析，最后成功得到猕猴桃的29个连锁群，包含SNP标记4,301个，总图距达5504.50cM，平均图距1.28cM。上图标记中偏分离标记380个，占总标记数的8.84%，上图标记中亲本的平均测序深度为78.63X，后代群体的平均测序深度为10.73 X。到目前为止，本图谱为猕猴桃的最高密度遗传图谱，为猕猴桃的分子标记辅助选择奠定了基础，同时本图谱将853个Scafflold锚定到了猕猴桃的基因组上，辅助了中华猕猴桃全基因组序列的成功组装。