利用现有品种的变异进行系选并培育新品种是一种重要的育种方法。利用SSR标记, 对系选大豆(Glycine max)新品种和其亲本的遗传组成进行分析, 明确二者的遗传关系, 为大豆系选育种提供依据。使用48对SSR引物对22个大豆品种及其亲本进行分析, 结果表明, 由外源DNA导入育成的3个品种与其亲本的一致性为35.42%–95.83%, 虽然供体相同, 但由于导入的外源DNA不同, 故育成的品种间差异很大。另外19个系选品种与其亲本的一致性为27.08%–89.58%, 其中有6个品种与亲本间的差异小于30%。聚类分析发现, 所有参试品种分为东北春大豆及黄淮和南方大豆2类, 其中有8个品种不能与其亲本聚在一起, 说明系选品种并不完全是由于亲本通过突变获得。此外, 农艺性状与分子标记分析结果差异较大, 说明利用有限的农艺性状评价品种间的遗传关系存在一定的局限性。通过比较系选品种和亲本之间的保守位点发现, 特定等位变异出现次数≥7的位点有14个, 分布在11个连锁群, 其中有7个位点与产量和抗病性等重要农艺性状有关, 说明DNA导入和系选品种在选择变异性状的同时, 使一些与重要农艺性状有关的等位变异得到了保留。

Intra-cultivar selection, reselection from existing cultivars by using intra-cultivar variation, is an important method in plant breeding. The main objective of this study is to evaluate the relationship of 22 soybean cultivars and 21 parents by use of 48 simple sequence repeat (SSR) loci. The genetic identity of 3 cultivars, developed by introducing foreign genome DNA through the pollen tube, and their parents was 35.42%–95.83%. Cultivars derived from the same parent showed differences in identity because of the difference in exogenous DNA. The identity of 19 soybean cultivars breeded by intra-cultivar selection and their parents was 27.08%–89.58%. Six cultivars showed < 30% identity with their parents. The 43 cultivars were clustered into Northeast spring, Huanghuai and South groups; 8 cultivars could not be grouped with their corresponding parents. The variation was from natural mutation but may also come from natural outcrossing. Agronomic and molecular data revealed great differences, which shows that use of only agronomic data is limited in evaluating relationship of cultivars. The preserved loci between parents and selected cultivars showed 14 SSR loci distributed in 11 linkage groups, specific allele was observed more than 7 times at each loci, and 7 alleles preserved in different materials were related to yield and disease-resistance quantitative trait loci. The result suggested that selecting for improved agronomic traits of soybean from elite cultivars preserved some alleles related to important characters such as yield.