Extensive dispersal of Roanoke logperch (Percina rex) inferred from genetic marker data

The dispersal ecology of most stream fishes is poorly characterised, complicating conservation efforts for these species. We used microsatellite DNA marker data to characterise dispersal patterns and effective population size (N_e) for a population of Roanoke logperch Percina rex, an endangered darter (Percidae). Juveniles and candidate parents were sampled for 2 years at sites throughout the Roanoke River watershed. Dispersal was inferred via genetic assignment tests (ATs), pedigree reconstruction (PR) and estimation of lifetime dispersal distance under a genetic isolation‐by‐distance model. Estimates of N_e varied from 105 to 1218 individuals, depending on the estimation method. Based on PR, polygamy was frequent in parents of both sexes, with individuals spawning with an average of 2.4 mates. The sample contained 61 half‐sibling pairs, but only one parent–offspring pair and no full‐sib pairs, which limited our ability to discriminate natal dispersal of juveniles from breeding dispersal of their parents between spawning events. Nonetheless, all methods indicated extensive dispersal. The AT indicated unrestricted dispersal among sites ≤15 km apart, while siblings inferred by the PR were captured an average of 14 km and up to 55 km apart. Model‐based estimates of median lifetime dispersal distance (6–24 km, depending on assumptions) bracketed AT and PR estimates, indicating that widely dispersed individuals do, on average, contribute to gene flow. Extensive dispersal of P. rex suggests that darters and other small benthic stream fishes may be unexpectedly mobile. Monitoring and management activities for such populations should encompass entire watersheds to fully capture population dynamics.     

Genetic Diversity Analysis of Microsatellite DNA Markers in Swamp Buffalo

This study was aimed to investigate the genetic diversity of swamp buffalo breeds in China.The analysis of genetic diversity was performed in 40 buffalo individuals from 8 buffalo breeds（Dechang buffalo,Dehong buffalo,Wenzhou buffalo,Guizhou buffalo,Xilin buffalo,Fuzhong buffalo,Murrah buffalo and Nili-Ravi buffalo）by 30 microsatellite loci and LabChip chip test method.The results showed that 332 alleles at 30 microsatellite loci were found in 8 buffalo breeds,the average values of gene diversity and PIC were 0.7808 and 0.7554,respectively.Cluster analysis indicated that Dechang buffalo and Dehong buffalo firstly clustered together,followed by Fuzhong buffalo,Guizhou buffalo,Wenzhou buffalo and Xilin buffalo.Moreover,Murrah buffalo and Nili-Ravi buffalo clustered together.Our findings revealed that the 30 microsatellite loci could be used as an effective genetic marker for the analysis of genetic diversity among the buffalo breeds,which enriched the current SSR marker resources in buffalo.     

基于26个微卫星标记的三江水系草鱼遗传多样性分析

选取26个微卫星标记对来自长江(监利、邗江)、黑龙江、珠江3个水系的4个野生草鱼(Ctenopharyngodon idellus)群体的遗传多样性进行了检测。结果表明,26个微卫星位点均为高度多态位点,草鱼4个地理群体的多态信息含量(PIC)平均值为0.581 3~0.638 6;共检测出141个等位基因,其中有102个为共有等位基因;每个位点有等位基因2~11个,平均等位基因5.46,平均有效等位基因3.455 6。4个地理群体野生草鱼的平均杂合度在0.711 4~0.804 5之间。群体间遗传固定指数(FST)及AMOVA分析表明,群体间遗传分化并不显著(FST=0.031 73)。基于DA遗传距离构建的UPGMA聚类树表明,监利群体与邗江群体这两个长江水系野生地理群体聚为一支,然后与珠江群体聚为一支,黑龙江群体单独聚为一支。长江群体是原始群体。综上所述,三江水系野生草鱼具有较高的遗传多样性,4个群体之间遗传分化并不明显。     

广灵驴分子系谱的建立及群体遗传结构分析

旨在对广灵县优种驴场保种群体进行调查的基础上构建分子系谱,并对其种群的遗传结构进行分析。本研究采集保种群成年、体况良好的广灵驴（体重350~400 kg）颈静脉血10 mL（n=107）,其中公驴13份,母驴94份,抗凝处理后提取全血DNA。采用12个微卫星标记进行荧光PCR扩增后,用ABI3730测序仪进行分型。分型结果采用Cervus 2.0和Pedigraph 2.4软件构建分子系谱,同时采用STRUCTURE2.3和Fstat软件计算群体遗传参数,采用R语言的hclust函数绘制7头公驴及其后代的系统发生NJ树（邻接树）。结果,对107头种驴进行了分子系谱构建,找到了30头子代的父亲和7头子代的母亲,系谱可靠性>90%;微卫星标记的平均观测杂合度（H_Obs）和多态信息含量（PIC）分别为0.676 5和0.593 9,标记遗传多样性较高;NJ树对7个公驴家系进行了聚类;群体分化系数（F_ST）为0.184,群体平均近交系数（F_IT）为0.033,群体内近交系数（F_IS）为-0.238,且群体处于哈代-温伯格平衡状态,存在很弱的近交。本研究建立了广灵驴保种群可靠性较高的分子系谱并对其遗传结构进行了分析,证明该群体遗传多态性较高,群体近交系数较低,处于较好的保种状态,具有较大的品种资源开发潜力。     

Molecular mapping determines that Hessian fly resistance gene H9 is located on chromosome 1A of wheat

Hessian fly [Mayetiola destructor (Say)] is one of the major insect pests of wheat (Triticum aestivum L.) worldwide. Hessian fly resistance gene H9 was previously reported to condition resistance to Hessian fly biotype L that is prevalent in many wheat‐growing areas of eastern USA and an RAPD marker, OPO05₁₀₀₀, linked to H9 in wheat was developed using wheat near‐isogenic lines (NILs). However, marker‐assisted selection (MAS) with RAPD markers is not always feasible. One of the objectives in this study was to convert an RAPD marker linked to the gene H9 into a sequence characterized amplified region (SCAR) marker to facilitate MAS and to map H9 in the wheat genome. The RAPD fragment from OPO05₁₀₀₀ was cloned, sequenced, and converted into a SCAR marker SOPO05₉₀₉, whose linkage relationship with H9 was subsequently confirmed in two F₂ populations segregating for H9. Linkage analysis identified one sequence tagged site (STS) marker, STS‐Pm3, and the eight microsatellite markers Xbarc263, Xcfa2153, Xpsp2999, Xgwm136, Xgdm33, Xcnl76, Xcnl117 and Xwmc24 near the H9 locus on the distal region of the short arm of chromosome 1A, contrary to the previously reported location of H9 on chromosome 5A. Locus Xbarc263 was 1.2 cM distal to H9, which itself was 1.7 cM proximal to loci Xcfa2153, Xpsp2999 and Xgwm136. The loci Xgwm136, Xcfa2153 and SOPO05₉₀₉ were shown to be specific to H9 and not diagnostic to several other Hessian fly resistance genes, and therefore should be useful for pyramiding H9 with other Hessian fly resistance genes in a single genotype.     

Distribution of microsatellite alleles linked to Rht8 dwarfing gene in wheat

A wheat microsatellite locus, Xgwm 261, whose 192-bp allele closelylinked to the dwarfing gene Rht8, on chromosome 2D, was used toscreen 71 wheat cultivars from 13 countries to assess the variation at thislocus. Screening of this wheat collection showed that a 165-bp allele anda 174-bp allele were the most frequent. None of the New Zealand cultivarspossessed a 192-bp allele specific to Rht8, while only one cultivarfrom the US produced this important allele. The frequency of a 192-bpallele among these wheat cultivars was 5.63%. The highest allelefrequency was observed for a 174-bp fragment (52.11%) followed by a165-bp fragment (26.76%). The only durum wheat `Cham 1', did notshow any amplification due to the absence of D genome. Four new novelalleles, 180-bp, 198-bp, 200-bp and 204-bp present in the US and NewZealand wheat cultivars are reported.     

Studying genetic relationships among coconut varieties/populations using microsatellite markers

The extent of genetic diversity and the genetic relationships among 94 coconut varieties/populations (51 Talls and 43 Dwarfs) representing the entire geographic range of cultivation/distribution of the coconut was assessed using 12 pairs of coconut micro satellite primers. A high level of genetic diversity was observed in the collection with the mean gene diversity of 0.647±0.139, with that of the mean gene diversity of Talls 0.703±0.125 and 0.374±0.204 of Dwarfs. A phenetic tree based on D_AD genetic distances clustered all the 94 varieties/populations into two main groups, with one group composed of all the Talls from southeast Asia, the Pacific, west coast of Panama, and all Dwarfs and the other of all Talls from south Asia, Africa, and the Indian Ocean coast of Thailand. The allele distribution of Dwarfs highlighted a unique position of Dwarf palms from the Philippines exhibiting as much variation as that in the Tall group. The grouping of all Dwarfs representing the entire geographic distribution of the crop with Talls from southeast Asia and the Pacific and the allele distribution between the Tall and Dwarf suggest that the Dwarfs originated from the Tall forms and that too from the Talls of southeast Asia and the Pacific. Talls from Pacific Islands recorded the highest level of genetic diversity (0.6±0.26) with the highest number of alleles (51) among all the regions. This revised version was published online in August 2006 with corrections to the Cover Date.     

Allelic variation at the dwarfing gene Rht8 locus and its significance in international breeding programmes

A microsatellite marker WMS261 developed at I.P.K., Gatersleben,Germany, co-segregates with the semi-dwarfing gene Rht8. Screens ofover 800 wheat varieties from 20 countries show 90% carry WMS-261alleles with 165, 174 or 192 base pairs (bp). The 192bp allele diagnosticof Rht8 occurs in most screened Southern European varieties. Anallele with 165 bp occurs in the majority of CIMMYT Mexican varieties andin most varieties bred in countries that utilize CIMMYT germplasm.Agronomic studies of single chromosome recombinant line mappingpopulations segregating for WMS 261 alleles with 165, 174 or 192 bp,show compared to the 174bp allele the 192bp allele reduces height byaround 8 cm and the 165 bp allele increases height by around 3cm. Theresults indicate the importance and widespread utilization of Rht8 asa dwarfing gene in southern Europe and suggest an adaptative significanceto the height promoting 165 bp allele in CIMMYT material.     

微卫星标记与永康灰鹅体重、体尺及屠体状的相关分析

采用最小二乘分析法,分析了30对鹅微卫星标记与永康灰鹅体重、体尺和屠宰性能的关联性。结果表明：30对引物中,有28条引物表现丰富的多态性,其中有16个标记与永康灰鹅体重和体尺的8个性状存在不同程度的相关;3个标记分别与屠宰率、半净膛率、全净膛率、胸肌率和腿肌率等5个屠宰性状存在不同程度的相关。这些标记位点可能是控制永康灰鹅体重、体尺和屠宰性状的主效基因,或与控制性状的主效基因连锁。     

北京鸭与樱桃谷鸭的分子遗传关系分析

为了分析北京鸭和樱桃谷鸭的遗传关系,采集包括北京鸭、在英国培育而成的肉鸭品种樱桃谷鸭及其它5个中国地方鸭品种共248个个体,利用11个微卫星标记对这7个鸭品种进行遗传关系分析.FST分析结果表明北京鸭与樱桃谷鸭的遗传分化程度最低,只有0.0795;遗传距离(Ds)分析发现北京鸭与樱桃谷鸭的遗传距离最近,为0.1079;群体分化时间分析表明二者的分化时间为98年,北京鸭与其它地方鸭品种的分化时间在282至694年之间;聚类结果显示北京鸭、樱桃谷鸭和建昌鸭聚为一类;巢湖鸭、高邮鸭、绍兴鸭和金定鸭聚为另一类.这些结果表明了北京鸭与引进品种樱桃谷鸭有非常密切的遗传关系,为樱桃谷鸭培育自北京鸭这一说法提供了分子遗传学的证据,同时本研究还发现北京鸭与樱桃谷鸭在遗传背景上已经发生了一定程度的分化.