花生表型及SSR遗传多样性的研究

对山西省农业科学院经济作物研究所保存的75份花生材料(包括28个已审定的花生品种和47个地方品种)进行了包括株型、茸毛的有无、叶色、粒形、叶形、生长习性、开花习性、粒大小、粒色等表型性状的Shannon-Weaver遗传多样性指数(简称SWI)和Simpson遗传多样性指数(简称SI)分析。结果表明:参试的75份花生品种遗传多样性指数分别为SWI=0.924,SI=0.500,其中以开花习性最低(SWI=0.139,SI=0.014),而Shannon-Weaver指数以粒色最高为1.841,Simpson指数为0.712。利用48对SSR引物对这些材料进行了遗传多样性分析,结果如下:(1)在48对花生的SSR引物中,有35对(占所用引物总数的72.9%)具有多态性,共检测到215条多态性条带,平均每对引物可扩增6条多态性带。(2)根据SSR扩增结果对75份材料的聚类分析结果表明,这些材料的相似系数(GS)为0.25～0.85,平均GS值为0.55。28个审定品种的相似系数为0.39～0.85,平均为0.60。     

红掌品种亲缘关系SRAP分析

利用相关序列扩增多态性（SRAP）分子标记,从100对引物组合中筛选出 26对多态性高、条带清晰的SRAP引物,对33个红掌品种进行遗传多样性和亲缘关系分析。结果如下：（1）26对引物共扩增出366条条带,其中有314条多态性条带,多态性比率为85.79%。引物组合产生的条带数在9～23之间,平均每对引物组合扩增出14.1条和12.1条多态性条带。（2）根据SRAP扩增结果,利用UPGMA法进行聚类分析,33份材料的遗传相似系数在0.55～0.94之间,在遗传相似系数0.786处可将33个红掌品种分为5个类群。结果表明,供试品种遗传多样性丰富,本研究为品种鉴定和杂交育种提供了参考信息。     

SSR标记分析国家北方花生区试品种的遗传多样性

利用10对SSR引物对参加我国北方区域试验的27份花生品种进行PCR扩增分析,共扩增出57条带,其中45条呈现多态,多态性比率为78.95%.引物的多态性信息含量(PIC)变幅为0.417～0.857,平均值为0.688.27个品种间的遗传相似系数在0.311～0.962之间,平均为0.651.聚类分析结果表明,27个参试花生品种在遗传相似系数0.61处分为3个类群,同一类型的参试品种优先聚为一类,同一地区或同一育种单位提供的品种往往首先聚为一类.系谱分析表明亲本来源相近的品种优先聚在一起,利用农家品种和辐照诱变材料对于拓宽花生遗传基础发挥作用较明显.SSR分析结果基本上与系谱相吻合.     

基于ISSR标记的烤烟种质遗传多样性研究

利用ISSR标记分析了24份代表性烤烟种质的遗传多样性。从100个ISSR引物中筛选出10个引物,通过聚丙烯酰胺凝胶电泳可以检测到208条稳定的条带,片段大小介于200~2 400 bp之间,条带数在7~37条之间;扩增片段中多态性带141条,平均多态性比率(PPB)为67.79%。 通过UPGMA聚类分析,24个烤烟品种分为5类,最大一类有12个材料,主要衍生于Coker319。品种间遗传相似指数(GS)范围为0.66~0.85,表明其遗传多样性较低,需要拓宽烤烟种质的遗传基础。同时,利用2个多态性好的ISSR引物可以将这24份烤烟材料区分开,每个品种都有各自独特的指纹图谱,表明ISSR标记适于烟草品种鉴定和遗传多样性研究。     

中国主要黑芝麻品种的遗传多样性分析

利用SRAP和SSR各23对引物对20个中国主要黑芝麻品种进行了遗传多样性分析。结果显示,23对SRAP引物共扩增出DNA带672条,其中多态性带152条,比率为22.62%,平均每对引物扩增总带数和多态性条带分别为29.22条和6.61条。23对SSR多态性引物共扩增出DNA带92条,每对引物扩增出3~6条,平均4.00条;每对引物扩增出多态性带1~5条,平均3.09条,多态性带比率平均为77.17%。20个黑芝麻品种间的遗传相似系数为0.8547~0.9804,遗传距离为0.0159~0.0921,遗传多样性匮乏,遗传基础狭窄。聚类结果表明,来自主产区江西的11个品种明显聚在一起,且江西黑芝麻品种的遗传相似系数高于其他省份品种,遗传距离低于其他省份品种,与其他省份品种的差异均达到极显著水平。加强资源引进和利用是拓宽中国黑芝麻品种遗传基础的迫切要求。     

51个春兰(Cymbidium goeringii)品种的AFLP遗传多样性分析

为了揭示春兰品种的遗传多样性和亲缘关系,为春兰种质资源的有效利用和开发提供依据,采用AFLP技术对51个春兰品种进行了遗传多样性分析,经筛选得到了8对条带清晰、多态性高的引物,共扩增出1315条DNA片段,其中多态性条带为1217条,平均1对引物扩增条带164条,多态性带152条,多态性位点频率为92.5%,表明春兰品种具有丰富的遗传多态性。49个品种含有特有带。51个品种间遗传相似系数变化范围为0.501~0.716,聚类分析表明,51个春兰品种共分为5个类群,来自同一地区的品种并没有聚在一起,表明春兰品种的遗传背景混乱。AFLP分子标记技术能有效地分析春兰品种的遗传多样性和亲缘关系。     

巨峰葡萄系谱的SSR与RAPD分析

利用RAPD和SSR 2种标记分别对系谱关系明确的22个巨峰系葡萄品种进行聚类分析,以验证2种标记方法的正确性与可靠性.结果显示,11条RAPD引物和12对SSR引物,分别扩增了82和43个清晰的条带.RAPD与SSR引物扩增的条带中分别有58和31条多态性带,其多态性比率分别为70.7％和72.1％.2种分子标记聚类结果基本一致,并且都能有效地将品种区分开来以及正确反映22个葡萄品种的亲缘关系.研究结果说明RAPD和SSR 2种分子标记均适合于巨峰系葡萄的系谱分析和种质遗传多样性研究.     

牛鞭草品种EST-SSR指纹图谱构建及遗传多样性分析

为探讨牛鞭草(Hemarthria spp.)品种间的遗传多样性,从86对EST-SSR引物中筛选出8对引物对牛鞭草属6个品种进行指纹图谱的构建及遗传多样性分析。结果表明,8对EST-SSR引物对牛鞭草属6个品种共扩增出193条清晰条带,多态性条带161条,多态性比例为83.4%。每条引物的多态信息含量(PIC)为0.480~0.695,平均为0.602。UPGMA聚类分析表明,牛鞭草属6个品种在相似系数为0.652处可分为两大类群。8对EST-SSR引物均能将6个品种完全区分开,以3对EST-SSR引物扩增的电泳图谱为基础,建立了牛鞭草属6个品种的指纹图谱标准模式图,每个品种都有唯一的指纹图谱。牛鞭草属6个品种的平均Nei’s基因多样性指数为0.333,平均Shannon信息指数为0.496,品种间的相似系数介于0.399~0.782之间。可见,牛鞭草属植物品种的遗传多样性较丰富,种间差异明显。     

河南大豆遗传多样性的ISSR分析

用ISSR标记技术对10个大豆品种进行遗传多样性分析.从44条随机引物中筛选出8个多态性引物,共扩增出89条带,其中有55条为多态性条带,多态性比率为61.8%,条带大小为220~1 500 bp,平均每个引物可扩增出11条带.Shannon多样性指数评价结果表明,平均多样性指数为0.286 5,观察等位基因数和有效等位基因数分别为1.618和1.300 8;统计分析结果表明,10个品种间的相似系数为0.60~0.75,平均相似系数为0.69;聚类分析结果表明,10个大豆品种可聚成2组:第一组包括豫豆15、豫豆11、豫豆24、周豆12和周豆11;第二组包括豫豆22、周豆13、豫豆6、中作98-3和豫豆26;主成分分析结果支持聚类分析结果.本研究为大豆品种鉴定和种质资源利用奠定了基础.     

用ISSR标记技术分析山药品种遗传多样性

利用ISSR标记技术对28个山药品种的遗传多样性进行分析。结果表明,从44条ISSR引物中可筛选出7条能够扩增出清晰、稳定条带的引物;这7条ISSR引物对28个山药品种扩增条带间存在较大差异,多态性条带比率为83.01%,Shannon多样性指数为0.3191;构建的分子树状图将28个山药品种划分为4组:第一组含有日本白、花山药和日本园3个品种;第二组为小叶山药;第三组为嵩野1号;其余23个品种归入第四组。而且主成分分析结果支持上述的聚类分析结果。这为利用ISSR标记技术鉴定山药品种,为有效地利用山药种质资源提供了依据。     

On a method of estimating the genetic correlation between characters measured in different experimental units

Summary Yamada's method of estimating genetic co-variances between traits measured in different experimental units is discussed. It is shown that if the data are unbalanced, this method gives biased estimates of genetic covariances unless the traits have identical genetic and residual variances. An alternative unbiased procedure is suggested.     

植物种质群体遗传结构改变的测度

本文旨在探讨植物种质资源保存中由于人为和自然缘故导致遗传结构改变的评价指标和评价方法.在介绍植物种质资源保存研究一些基本概念的基础上,归纳了测度种质库(收集品)遗传潜势的6种遗传多样性统计指标,包括同一变异层次的类型数、类型分布均衡度、遗传相似性与遗传距离、遗传方差与遗传变异系数、多元变异指数以及亲本系数.指出若无遗传丰富度相伴,单有遗传离散度并未提供遗传多样性的完整测度.探讨了人为条件导致植物种质资源遗传结构改变的遗传流失、环境胁迫所致植物种质资源遗传结构改变的遗传脆弱性和种子扩繁所引发的植物种质资源遗传结构改变的遗传漂变和遗传漂移等的统计指标.文末给出了自花授粉植物和异花授粉植物群体适宜样本容量研究的个例.     

Genetic differentiation among local populations of Asian elephant

Electrohoretically detectable enetic variation for 29 kinds of blood protein encoded by 33 loci was analyzed for 78 Asian eletants (Elephas maximus) which were collected from its four local populations: Sri Lanka, Souti India, Thailand and Nepal. Elehants in Sri Lanka are classified into the subspecies E.m. maximus, and those from the other tlree localities into the subspecies E. m. indicus. Six variable loci were detected, and one of them, the tetrazolium oxidase locus, was observed to show a complete allele substitution between the subspecies. Average heterozgosity within local populations were in a range of 0.0152 ? 0.0303. Whereas the Nei's genetic distance among three local populations of the subspecies indicus were 0.0013 ? 0.0031, the distance between the subspecies indicus and maximus were 0.0328 ? 0.0370, indicating that the two subspecies were well differentiated genetically.     

Remarkable genetic divergence of Gymnodiptychus dybowskii between south and north of Tianshan Mountain in northwest China

Gymnodiptychus dybowskii is endemic to Xinjiang, China and has been locally listed as protected animals. To investigate its genetic diversity and structure, specimens were collected from six localities in Yili River system and Kaidu River. Fragments of 1092bp Cyt b gene were sequenced for 116 individuals. A total of 21 haplotypes were found in all samples, and no haplotype was shared between Yili River system and Kaidu River population. Sequence comparisons revealed 123 variable sites, with eight singleton sites and 115 parsimony informative sites. For all the populations examined, the haplotype diversity (h) was 0.8298 ± 0.0226, nucleotide diversity (π) was 0.2521 ± 0.1202, and average number of pairwise nucleotide differences (k) was 275.3369 ± 118.5660. AMOVA analysis showed that the differences were significant for total populations except for Yili River system populations. The pairwise F_st values revealed same conclusion with AMOVA analysis: Kaidu River population was divergent from Yili River system populations. The genetic distance between two groups was 0.108 and the divergence time was estimated at 5.4–6.6 Ma, the uplift of Tianshan Mountain might have separated them and resulted in the genetic differentiation. The neutrality test and mismatch analysis indicated that both two groups of G. dybowskii had went through population expansion, the expansion time of Yili River system and Kaidu River population was estimated at 0.5859–0.7146 Ma and 0.5151–0.6282 Ma, respectively. The climate changes of Qinghai-Tibetan Plateau might have influenced the demographic history of G. dybowskii.     

Genetic polymorphism in varietal identification and genetic improvement

Summary New sources of genetic polymorphisms promise significant additions to the number of useful genetic markers in agricultural plants and animals, and prompt this review of potential applications of polymorphic genetic markers in plant and animal breeding. Two major areas of application can be distinguished. The first is based on the utilization of genetic markers to determine genetic relationships. These applications include varietal identification, protection of breeder's rights, and parentage determination. The second area of application is based on the use of genetic markers to identify and map loci affecting quantitative traits, and to monitor these loci during introgression or selection programs. A variety of breeding applications based on these possibilities can be envisaged for Selfers, particularly for those species having a relatively small genome size. These applications include: (i) screening genetic resources for useful quantitative trait alleles, and introgression of chromosome segments containing these alleles from resource strain to commercial variety; (ii) development of improved pure lines out of a cross between two existing commercial varieties; and (iii) development of crosses showing increased hybrid vigor. Breeding applications in segregating populations are more limited, particularly in species with a relatively large genome size. Potential applications, however, include: (i) preliminary selection of young males in dairy cattle on the basis of evaluated chromosomes of their proven sire; (ii) genetic analysis of resource strains characterized by high values for a particular quantitative trait, and introgression of chromosome segments carrying alleles contributing to the high values from resource strain to recipient strain.Contribution from The Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel, No. 767-E, 1983 Series     

Loss of genetic diversity from heterogeneous self-pollinating genebank accessions

Genebank seed accessions of predominantly self-pollinating species may be stored either as bulked (mixed) seed lines or as pure line cultivars. If seed lines are bulked in storage then when considered over several regeneration cycles, loss of genetic diversity within heterogeneous self pollinating genebank accessions is shown to be severe. This within-accession loss of diversity represents opportunities foregone through the random loss of individual genotypes. Amongst working collections, the utility and repeatability of genebank accessions is paramount in the justification of the germ plasm resource. Therefore, the only practical solution to the management of predominantly self-pollinating species is to preserve individual accessions as pure lines.     

Genetic traits

Recognizing that all traits are the result of an interaction between genes and environment, I offer a set of criteria for nevertheless making sense of our practice of singling out certain traits as genetic ones, in effect making a distinction between causes and mere conditions. The central criterion is that a trait is genetic if it is genetic differences that make the differences in that trait variable in a given population. A second criterion requires that genetic traits be individuated in a way that matches what some genetic factors cause specifically. Clarifying our causal and classificatory language here can help us to avoid confusions of both theoretical and practical significance.     

Population demography and genetic characteristics of the Pacific Oyster Crassostrea gigas in Japan

The Pacific oyster Crassostrea gigas is a commercially important bivalve distributed along the northwest Pacific coast. Here C. gigas in Japan was investigated using mtDNA and microsatellite markers to elucidate its genetic structure and phylogeny. On the basis of mtDNA all populations showed high genetic diversity with limited genetic differentiation among populations. The pattern of MtDNA diversity suggested that C. gigas had experienced population expansion about 112 Kya, prior to the last glacial maximum (LGM), which accorded well with other marine organisms. For microsatellites, a Bayesian-based assignment test demonstrated that C. gigas is nearly panmictic. However, on the basis of estimates of F_ST, Kumano populations differed significantly from other populations, a recent occurrence based on low R_ST. Irrespective of geographical distance, genetic similarity was observed in the main aquaculture regions with large-scale transportation of cultured spat. Unlike in the Yellow Sea, a genetic bottleneck was not detected in Japanese populations. These results imply, contrary to the prevailing view, that C. gigas in Japan was demographically stable during the LGM. Gene flow by larval dispersal seems to be regionally restricted to localities of congenital areas by ocean currents, while genetic homogenization by cultivated oysters might have occurred in aquaculture areas.     

Study of the genetic code adaptability by means of a genetic algorithm

We used simulated evolution to study the adaptability level of the canonical genetic code. An adapted genetic algorithm (GA) searches for optimal hypothetical codes. Adaptability is measured as the average variation of the hydrophobicity that the encoded amino acids undergo when errors or mutations are present in the codons of the hypothetical codes. Different types of mutations and point mutation rates that depend on codon base number are considered in this study. Previous works have used statistical approaches based on randomly generated alternative codes or have used local search techniques to determine an optimum value. In this work, we emphasize what can be concluded from the use of simulated evolution considering the results of previous works. The GA provides more information about the difficulty of the evolution of codes, without contradicting previous studies using statistical or engineering approaches. The GA also shows that, within the coevolution theory, the third base clearly improves the adaptability of the current genetic code.     

Genetic diversity and structure of the noxious alien grass Praxelis clematidea in southern China

Praxelis clematidea (Asteraceae), a plant species native to South America, is a noxious weed in southern China. We examined the genetic variation and population structure of 12 populations (76 individuals) of P. clematidea from Fujian, Guangdong, and Hainan Provinces in China using inter-simple sequence repeat (ISSR) analysis. From an initial set of 69 ISSR primers, 10 were selected which yielded 80 reproducible bands. Polymorphic bands (P) were 100%, Shannon's information index (I) was 0.4226, and Nei's gene diversity (H) was 0.2791. We infer that the high levels of genetic diversity exhibited by P. clematidea may have contributed to its invasiveness. Gene flow among populations was 2.4930, which has led to homogenization. The coefficient of population differentiation (Gst = 0.1671) indicated low levels of genetic variation among populations and high levels of genetic polymorphism within populations. There was a negative correlation between population elevation and genetic diversity, while there was a significant positive correlation between genetic distance and geographic distance based on a Mantel test (r = 0.5820, P < 0.01). Some populations from different provinces clustered together in principal coordinate and UPGMA analyses indicating that human-mediated events may have contributed to the dispersal of the species.