菊花不完全双列杂交F1代遗传关系的SRAP分析

Genetic Relationship Among Chrysanthemum F_1 Hybrids Derived from an Incomplete Diallel Cross Unraveled by SRAP Markers

利用SRAP分子标记研究了6个切花菊品种及其2×4不完全双列杂交(NCⅡ)的38个F1代单株的遗传关系。结果表明,17对SRAP引物组合共获得229条带,其中多态性条带127条,平均每个引物获得7.5个多态性条带,多态性比率为56.0%,说明切花菊亲本品种及其杂交后代的分子多样性适中。6个亲本品种之间的Nei’s遗传距离介于0.11~0.25之间,平均为0.19,说明亲本品种之间的亲缘关系较近。亲本和杂交后代的遗传相似系数分别介于0.42~0.72和0.40~0.85之间,杂交后代遗传相似系数的中位数(0.61)高于亲本品种(0.55),说明杂交产生了一些变异株系,但是总的遗传基础有变窄或同质化趋势。基于遗传相似系数,UPGMA聚类将亲本和杂交后代划分为两大类,聚类结果与母本和杂交组合类型相符,说明SRAP分子标记可有效用于鉴定菊花不同杂交组合后代。

Genetic relationship amongst the 6 cultivars of cut chrysanthemum and their 38 F_1 hybrids derived from a 2 × 4 incomplete diallel cross was unraveled by SRAP markers. The SRAP genotyping suggested that of the 229 fragments produced by 17 SRAP primer combinations 127 were polymorphic,with an average of 7.5 polymorphic fragments per primer combination,thus indicative of a moderate molecular diversity present in the entries. The Nei＇s genetic distances were estimated between 0.11–0.25 and averaged at 0.19,denoting a close genetic relationship among the parental cultivars. The SRAP-based genetic similarity was calculated at 0.42–0.72 and 0.40–0.85,respectively,for the parental cultivars and the F_1 hybrids,and the median of genetic similarity（0.61）for the hybrids were higher than that（0.55）for parental cultivars. This suggests a narrowing genetic base or homogenization during hybridization in chrysanthemum,despite the occurrence of some variant lines. Based on genetic similarity matrix,the UPGMA clustering classified the investigated entries into two major groups well congruent with female parents and cross combinations,reinforcing the reliability of SRAP markers in distinguishing F_1 hybrids resulted from different combinations in chrysanthemum.