Pedigree analysis of nationally approved soybean cultivars from 1984 to 2013 and implications for breeding

To reveal origins of 316 state authorized varieties from 1984 to 2013, rules of their parentsJ selection including types and hybrid configurations of direct parents, geo-graphical sources and types of their ancestors were analyzed. Various important direct parents and ancestors were summarized and nuclear contribution of ancestors was also estimated by pedigree analysis. Among 316 registered cultivars, 298 （94.3%） were bred by hybridization, and most of their direct parents were cultivars or breeding lines （65.5%）. Cultivars and breeding lines were mostly used as female parents, with 53.0% and 38.7% respectively. The 316 released cultivars were traced to 373 final ancestors, mainly com-posed of landraces （55.5%） and breeding lines （36.7%）. The 373 final ancestors came from different regions, including 121 from northern area, 110 from Huang-Huai-Hai area, 53 from southern area and 76 from abroad. These ancestors were mainly from the same ecologic zone as the approved cultivars. Newly approved cultivars always have more ancestors and a broader genetic base. However, distribution of these ancestors was unbalanced, and a few ancestors provided significant genetic contributions to later generations, such as the most concentrated final ancestors from Huang-Huai-Hai region followed by northern and southern regions. These results offer more information regarding their important parents and provide valuable references to soybean breeding. We should increase soybean germplasm exchanges with different regions and make use of elite lines, foreign cultivars and wild soybean germplasm to broaden the genetic background.

Genetic dissection of and genomic selection for seed weight, pod length,and pod width in soybean

A biparental soybean population of 364 recombinant inbred lines(RILs)derived from Zhongdou 41×ZYD02.878 was used to identify quantitative trait loci(QTL)associated with hundred-seed weight(100-SW),pod length(PL),and pod width(PW).100-SW,PL,and PW showed moderate correlations among one another,and 100-SW was correlated most strongly with PW(0.64–0.74).Respectively 74,70,75 and19 QTL accounting for 38.7%–78.8%of total phenotypic variance were identified by inclusive composite interval mapping,restricted two-stage multi-locus genome-wide association analysis,3 variancecomponent multi-locus random-SNP-effect mixed linear model analysis,and conditional genome-wide association analysis.Of these QTL,189 were novel,and 24 were detected by multiple methods.Six loci were associated with 100-SW,PL,and PW and may be pleiotropic loci.A total of 284 candidate genes were identified in colocalizing QTL regions,including the verified gene Seed thickness 1(ST1).Eleven genes with functions involved in pectin biosynthesis,phytohormone,ubiquitin-protein,and photosynthesis pathways were prioritized by examining single nucleotide polymorphism(SNP)variation,calculating genetic differentiation index,and inquiring gene expression.The prediction accuracies of genomic selection(GS)for 100-SW,PL,and PW based on single trait-associated markers reached 0.82,0.76,and 0.86 respectively,but selection index(SI)-assisted GS strategy did not increase GS efficiency and inclusion of trait-associated markers as fixed effects reduced prediction accuracy.These results shed light on the genetic basis of 100-SW,PL,and PW and provide GS models for these traits with potential application in breeding programs.

Estimation of Genetic Divergence and Character Association Studies in Local and Exotic Diversity Panels of Soybean(Glycine max L.)Genotypes

The availability of favorable genetic diversity is a thriving vitality for the success of a breeding program.It provides a firm basis of selecting superior breeding lines for the development of high yielding crop genotypes.In this context,present investigation aimed to generate information on genetic divergence and character association in a diversity panel of 123 local and exotic soybean genotypes.Analysis of variance revealed significant response of the evaluated genotypes based on studied attributes.It depicted the probability of selecting desirable soybean genotypes by focusing on character association studies and genetic diversity analysis.Correlation analysis revealed that seed yield per plant showed high positive correlation with 100-seed weight followed by pods per plant and plant height.Furthermore,path coefficient analysis exposed that pods per plant had maximum direct contribution in seed yield per plant followed by 100-seed weight,days to flowering and SPAD measurement.Genotype named“G-10”showed maximum yield per plant followed by 24607,G-52,24593,Arisoy,24566,17426,A-3127,24570 and 24567.Genetic diversity analysis grouped the evaluated germplasm into 17 clusters.All clusters showed zero intra-cluster variability;while inter-cluster divergence ranged from 9.00 to 91.11.Cluster V showed maximum inter-cluster distance with cluster XII followed by that of between V and VIII.Moreover,cluster IV with superior genotypes(G-10,24607,24593 and 24566),VI(17426 and 24567),XIII(24570)and X(Arisoy and G-52)showed above mean values for most of the studied characters.Overall,the results of hybridization between the superior genotypes of these cluster pairs might be useful for soybean breeding with improving agronomic traits and adaptability.

银杏种子数量遗传分析及多性状选择

对中国 12个产地 50个银杏品种主要经济性状进行遗传分析和多性状选择。分析结果表明 ,最大单核质量为 3.89g ,出核率 33.58% ,出仁率 82 .4 9%。单核质量遗传力为0 .9759。核形系数和单核质量间的rG 达 0 .9986,单果质量对单核质量的直接遗传PY·i达1.4 0 7。全国 12个种源可以分成 4大类。采用指数选择或直接选择法优化出 3个核用品种。

DNA导入和系选大豆品种及其亲本遗传关系的SSR标记分析

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。

福建栽培大豆品种RAPD标记多样性分析

利用RAPD分子标记技术对福建18份栽培大豆品种遗传多样性进行研究。结果表明,12个引物共扩增出91条带,其中多态条带6 5条,多态性程度为71 4 3%。D =0 6 2时,聚类分析结果可以将供试材料分为3个大类群,即菜用大豆品种、杂交育成品种和地方品种、有半野生血缘的品种各聚成1类,揭示了福建省栽培大豆品种间的亲缘关系,同时还反映出品种间关系与地理起源有一定的相关。

晋大62×诱处4号杂交后代群体遗传多样性分析

选用晋大62×诱处4号杂交亲本和后代群体为试验材料，通过微卫星（SSR）标记分析，利用SPSS软件对其进行了聚类分析，探讨了亲本及后代群体间的遗传特性和亲缘关系，研究了大豆群体的遗传多样性，为大豆杂交育种亲本的选配、杂交后代的筛选、种质创新及大豆遗传多样性研究提供了理论和实践依据。结果表明，以亲本的基因组DNA为模板，选用40对不同的引物进行电泳共筛选出23对位于多条染色体上的差异引物，其多态性比例为55.0%。通过聚类分析所有材料可聚类为以下几类：母本晋大62（CK1）和后代6-13号材料聚为第一大类，父本诱处4号（CK2）和后代25-31号材料聚为第二大类，而1-5、14-20聚为第一小类，21-24、32-35聚为第二小类，这两小类材料与亲本的亲缘关系较远。