基于微卫星亲权鉴定技术的短蛸性选择研究

为研究短蛸(Octopus ocellatus)的性选择行为，本研究利用14个多态性微卫星标记，对3个母本、176个子代及17个候选父本进行亲权鉴定，对3个家系中有子代和无子代雄蛸、子代比例高和子代比例低的雄蛸的各形态参数进行t检验，并对子代比例高和子代比例低的父本与母本的遗传相似性与遗传距离进行分析。结果显示，短蛸为多雌多雄的交配模式，为真正意义的雌性混交动物；雄蛸有无子代与其形态参数无相关性；子代比例与父本的形态大小参数无关，而与父母本的遗传相似性和遗传距离有关，父母本遗传相似性越高，遗传距离越小，后代比例越高。本研究为揭示短蛸交配前后的性选择机制提供了重要线索，也为海洋头足类动物的性选择机制研究提供了基础资料。     

我国苏南地区美洲鲥7个养殖群体的遗传多样性分析

为探讨苏南地区美洲鲥（Alosa sapidissima）养殖群体的种质资源现状及遗传多样性水平,本研究采用15个微卫星标记和线粒体D-loop序列,对7个不同群体：镇江丹徒（Dtq）、镇江扬中（Yzq）、苏州张家港（Zjg）、苏州相城（Xcq）、南通中洋（Zyq）、常州滆湖（Ghq）和常州武进（Czq）共计210尾个体,进行了群体多样性分析。结果显示,15个SSR位点中除Asa-12外,其余位点均表现为高度多态性（PIC > 0.5）。其中,7个群体期望杂合度He为0.615～0.758,多态信息含量PIC为0.568～0.723,两者均以Zjg群体最高。D-loop序列共检测到32个变异位点,定义了20个单倍型,其中Zjg群体单倍型最多（11个）。7个群体的单倍型多样性、核苷酸多样性指数分别为0.618～0.945、0.003～0.008。基于SSR和D-loop序列的遗传距离分析,发现Ghq群体和Zyq群体的Nei’s遗传距离（0.058）和K2P遗传距离（0.003）最近,低于其他群体间的遗传距离（分别为0.073～0.397和0.003～0.006）。综合分析,我们发现7个美洲鲥群体的遗传多样性较为丰富,而群体间遗传变异程度不高,基因流Nm > 1和镶嵌式排列的个体进化树也证实7个群体的亲缘关系较近。基于本研究,可初步了解苏南地区鲥的种质现状,为后续进一步开展育种工作奠定理论基础。     

Assessment of Genetic Diversity of Drought Tolerant and Susceptible Rice Genotypes Using Microsatellite Markers

The introgression of wild chromosomal segments into popular rice varieties is one of the potential approaches for developing varieties for drought stress condition. Sixteen genotypes, including nine indica, two tropical japonica and five chromosome segments substitution lines(CSSLs) with different levels of tolerance/susceptibility to drought stress, were selected for diversity study. Sixty-three microsatellite markers were utilized for assessing genetic diversity. A total of 95 alleles were amplified, and out of them, 60 were polymorphic. Six unique alleles, amplified by the microsatellite loci RM276, RM472,RM488, RM537, RM541 and RM28089, were identified in six genotypes, namely FR13A, Brahamanakhi,RUF44, Swarna-sub1, Brahamanakhi and Satyabhama. The highest genetic similarity was found among CSSLs. Polymorphism information content(PIC) value varied from 0 to 1.00 with an average of 0.66 per locus. Twenty-eight microsatellites were found to be polymorphic, which could be used in marker-assisted selection programme. All the sixteen genotypes were grouped into two major clusters at genetic similarity of 0.64. In the cluster I, five CSSLs identified as diverse genotypes had wild ancestor segments responsible for drought tolerance, and hence they could be utilized as potential donors. The popular Indian varieties, Swarna-sub1 and IR64-sub1, could be used as recurrent parents in the future breeding program for developing varieties for abiotic stresses such as submergence and drought.     

驯食配合饲料的大口黑鲈3个选育世代的遗传多样性分析

为了检测驯食配合饲料的大口黑鲈(Micropterus salmoides)3个选育世代群体遗传多样性水平变化,利用微卫星标记技术对驯食配合饲料大口黑鲈选育基础群体(Sp0)和第二、三和四代选育群体(Sp2、Sp3和Sp4)共240尾样品进行检测。结果显示,18个微卫星位点共获得44个等位基因。Sp0、Sp2、Sp3和Sp4的平均观测杂合度(H_o)分别为0.4895、0.4802、0.4579和0.4206,平均期望杂合度(H_e)分别为0.4615、0.4454、0.4621和0.3916,平均多态信息含量(PIC)分别为0.3791、0.3659、0.3764和0.3257。4个群体间的配对比较群体间遗传分化指数(F_(st))值在0.01612～0.16162之间、遗传距离(D_a)在0.0249～0.1434之间。遗传变异来源(AMOVA)分析显示,只有8.38%的变异来自于群体间,其余遗传变异均来自于个体间。研究表明,经连续多代选育之后,易驯食配合饲料的快长大口黑鲈选育群体具有中度遗传多样性,具备选育潜力,可继续进行选育。     

秦巴山区黄牛群体的微卫星DNA遗传多样性

为分析秦巴山区西镇牛、赤崖牛、陨巴牛和宣汉牛4个黄牛(Bos taurus)品种的遗传多样性,本研究以蜀宣花牛和郏县红牛作对照,利用12对微卫星引物对6个黄牛品种的289头黄牛个体进行了遗传多样性检测,统计了各品种的等位基因及频率、有效等位基因数、遗传杂合度、多态信息含量及各群体间遗传距离,并对其进行聚类分析.结果表明,6个黄牛品种在12个微卫星位点共发现110个等位基因,等位基因频率为0.001 6～0.517 3,总群体各位点平均有效等位基因数为2.787 7～7.132 6;各位点多态信息含量为0.5192～0.895 3;平均杂合度为0.667 2～0.724 1.群体间发现特有等位基因11个,基因频率为0.008 1～0.381 6;优势等位基因(P＞0.4) 19个,基因频率为0.403 2～0.820 0;共有等位基因41个,占全部等位基因的37.27％,仅有13个共有等位基因为优势等位基因(P＞0.4),占37.71％.群体间Nei's遗传一致度为0.596 5～0.840 8,标准遗传距离(Ds)为0.173 5～0.524 7.聚类分析结果显示,6个黄牛品种聚为3类,陨巴牛与宣汉牛首先聚在一起,然后同西镇牛聚在一类;赤崖牛与郏县红牛聚为一类;蜀宣花牛自成一类.研究结果表明,12对微卫星标记可用于秦巴山区黄牛遗传多样性的分析,秦巴山区各黄牛品种遗传多样性丰富,选育程度不同,4个黄牛品种虽然地理分布格局相近,自然环境相似,但亲缘关系并非相近,应为来源不同的品种.因此,西镇牛、赤崖牛、陨巴牛和宣汉牛不宜合并为1个品种.本研究所揭示的秦巴山区黄牛品种的遗传分化特点及亲缘关系,为研究品种的遗传共适应特点,预测杂交优势,制定育种战略等提供了科学依据.     

Molecular identification of Pm12-carrying introgression lines in wheat using genomic and EST-SSR markers

The traditional process of obtaining maize hybrids involves the generation of inbred lines through successive generations of selfing and subsequent testcrosses in order to identify the best combining ability by allelic complementation. A fast alternative to obtain inbred lines is to induce the formation of haploids followed by chromosome doubling. However, even with the aid of haploid-inducing genetic sources, this strategy has not been widely used in maize breeding programs, partly due to difficulties inherent to haploid generation and identification. In order to evaluate the possibility of using dihaploids to generate homozygous maize tropical lines, we used the androgenetic haploid inducer line W23 as a female parent in crosses with the tropical single-cross hybrid BRS1010. Within the progeny of these crosses, 462 seeds were phenotypically selected as putative haploids by the purple-colored endosperm and colorless embryo conditioned by the R1-nj gene. Among these, only four individuals were confirmed as being haploids using SSR markers, chromosome counting and flow cytometry, showing that the phenotypic marker was not efficient in detecting haploids in the tropical maize genotype used. All four haploids as well as some diploid plants presented reduced size, corroborating the difficulties for haploid identification by phenotypic evaluation. Genetic diversity analysis revealed by SSR markers divided the haploids in two groups represented by flint and dent maize inbred lines, which could be helpful in identifying complementary dihaploid lines. The present article demonstrates that a combination of haploid production and SSR fingerprinting is a feasible strategy for maize hybrid development in tropical germplasm.     

一粒系小麦的微卫星分析

利用普通小麦A基因组含有微卫星位点的引物对在3种一粒系小麦的部分同源微卫星位点进行了检测。结果发现，59％的小麦A基因组微卫星位点的引物对可在3种一粒系小麦的多个种质中检测到部分同源微卫星位点，表明A基因组含有的微卫星位点在普通小麦和一粒系小麦间并不完全保守。一粒系小麦的微卫星位点之间在扩增条带数目以及扩增条带长度上均存在广泛差异。同一微卫星位点在不同一粒系小麦种质中的扩增条带数目以及扩增条带长度上也表现明显差异。     

一个抗大豆疫霉根腐病新基因的分子鉴定

利用微卫星标记技术在大豆品种诱变30中鉴定和定位了一个抗大豆疫霉根腐病基因RpsYB30。该基因位于大豆分子遗传图谱L连锁群微卫星标记Satt497和Satt313之间，与这两个标记的遗传距离分别为4.4 cM 和3.3 cM。RpsYB30是大豆分子遗传图谱L连锁群鉴定的第1个抗疫霉根腐病基因，为新基因。     

A 192bp allele at the <Emphasis Type="Italic">Xgwm261</Emphasis> locus is not always associated with the <Emphasis Type="Italic">Rht8</Emphasis> dwarfing gene in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

The height-reducing gene Rht8 was introduced into Italian wheats by breeder Nazareno Strampelli from the Japanese landrace Akakomugi, and has been widely used in wheats adapted to southern and eastern European conditions. Following identification of a close linkage to Rht8, microsatellite marker Gwm261 has been used extensively to screen large numbers of diverse international germplasm. A 192bp allele at this locus has been taken as “diagnostic” for Rht8 and used to infer the international distribution of Rht8. In this paper, we report several instances of cultivars and mapping populations that vary for the presence of the 192bp allele at the Xgwm261 locus (Xgwm261 ₁₉₂ ), but with no associated reduction in height, suggesting a lack of association with Rht8. For instance, in the population derived from a cross between Sunco (Rht-B1b, Xgwm261 ₁₆₅ ) and Tasman (Rht-D1b, Xgwm261 ₁₉₂ ), there were significant height differences associated with the segregation of Rht-B1b and Rht-D1b, but no height differences between Xgwm261 genotypes. Similar results were obtained in a population derived from the cross between Molineux (Rht-B1b, Xgwm261 ₁₉₂ ) and Trident (Rht-D1b Xgwm261 ₂₀₈ ). In contrast, the cross between Trident and Chuanmai 18 (Xgwm261 ₁₉₂ ) gave significant height effects at both the Rht-D1 and Xgwm261 loci, with no epistatic interaction between loci. Chuanmai 18 is closely related to the Strampelli wheat Mara (ancestrally derived from Akakomugi) and is therefore likely to carry Rht8. The old Japanese cultivar Norin 10, used by Norman Borlaug to introduce Rht-B1b and Rht-D1b into Mexican wheats, also has a 192bp allele at the Xgwm261 locus, and the sequence of the amplified product is identical to that of Akakomugi. We suggest that the widespread use of Norin 10-derived germplasm during and after the Green Revolution introduced a second haplotype into international germplasm, in which Xgwm261 ₁₉₂ has no association with Rht8. Therefore, the presence of Xgwm261 ₁₉₂ is only indicative of Rht8 in wheat cultivars that have inherited this allele from Akakomugi or a Strampelli wheat ancestor.     

Genetic Structure of Severe Combined Immunodeficiency Carrier Horses in Morocco Inferred by Microsatellite Data

A total of 17 microsatellite deoxyribonucleic acid loci used routinely for horse parentage control were used to evaluate genetic diversity among normal Arabian horses and severe combined immunodeficiency (SCID) carrier Arabian horses (ArS) and normal Arab-Barb horses and SCID carrier Arab-Barb horses (ArbeS). On the basis of the genotype of 186 horses, mean allelic diversity was estimated as 6.82, 5.53, and 6.7059 in normal Arabian horses, ArS, and for both groups of Arab-Barb horses, respectively. Five specific alleles were observed in ArS and ArbeS, with one common with ArS at HMS6, whereas five alleles common between ArS and ArbeS had a high frequency. Expected and observed heterozygosity showed great heterogeneity in the population studied and were similar or higher when compared with other studies on Arabian horses. Coefficient of gene differentiation G_st of Nei associated with Nei’s genetic distance and multivariate correspondence analysis indicated a possible differentiation between the studied populations when analyzed separately according to breed. Probability of assignment of a horse to a specific group was assessed using a full and partial Bayesian approach. In all, 80.6% of Arab horses and 78.2% of Arab-Barb horses were assigned properly with a partial Bayesian test, which provided better results than the full one. These findings will be useful for identification of SCID carrier horses by using the microsatellite deoxyribonucleic acid loci used routinely for horse parentage control in our laboratory.