Development of EST-SSR markers and construction of a linkage map in faba bean (Vicia faba)

To develop a high density linkage map in faba bean, a total of 1,363 FBES (Faba bean expressed sequence tag [EST]-derived simple sequence repeat [SSR]) markers were designed based on 5,090 non-redundant ESTs developed in this study. A total of 109 plants of a ‘Nubaria 2’ × ‘Misr 3’ F₂ mapping population were used for map construction. Because the parents were not pure homozygous lines, the 109 F₂ plants were divided into three subpopulations according to the original F₁ plants. Linkage groups (LGs) generated in each subpopulation were integrated by commonly mapped markers. The integrated ‘Nubaria 2’ × ‘Misr 3’ map consisted of six LGs, representing a total length of 684.7 cM, with 552 loci. Of the mapped loci, 47% were generated from multi-loci diagnostic (MLD) markers. Alignment of homologous sequence pairs along each linkage group revealed obvious syntenic relationships between LGs in faba bean and the genomes of two model legumes, Lotus japonicus and Medicago truncatula. In a polymorphic analysis with ten Egyptian faba bean varieties, 78.9% (384/487) of the FBES markers showed polymorphisms. Along with the EST-SSR markers, the dense map developed in this study is expected to accelerate marker assisted breeding in faba bean.     

西瓜已知品种DUS性状数据库构建与应用

[目的]通过西瓜品种审查和近似品种的筛选,建立西瓜已知品种数据库,为西瓜DUS测试申请品种筛选近似品种提供比较依据.[方法]收集适宜于新疆种植的75个西瓜品种并设置种植试验,按照我国西瓜DUS指南性状观测,将观测值转换为代码,根据性状类型和观测方法的不同分别对数据进行分析,探讨为西瓜申请品种筛选近似品种方法.[结果]确定了西瓜测量性状测量值与表达状态及代码的对应阈值范围,在近似品种筛选中,倍性、果实:表皮条纹和种子:种皮底色等性状在区分品种中起到重要作用,优先考虑这些性状区分品种,分组性状和聚类两种方法均能排除特异性测试时需要种植比较的已知品种范围,但测试专家的综合判断具有重要意义.[结论]建立了西瓜已知品种的DUS性状描述数据库,为新品种测试提供参考.     

Pasture use and management strategies in the Ankole pastoral system in Uganda

The Bahima ethnic group have been crossbreeding autochthonous Ankole with Holstein‐Friesian cattle. Separate herds (pure Ankole and crossbreds) are common. A survey was conducted to characterize pasture utilization and management in the Ankole region to gain a better understanding of current and emerging practices. Herds are largely grazed by continuous stocking although there are efforts to establish paddocks. Factors considered for pasture allocation to cattle genotypes were high‐quality feed, limited shrubs/weeds and close proximity to homestead for 80, 80 and 30% of farmers, respectively. Cross‐bred cattle were kept on medium/high‐quality, and Ankole cattle on medium/low‐quality pastures. Pastures for cross‐bred cattle yielded 0·17 t ha^?1 more dry matter than pastures allocated to Ankole cattle. Crude protein (CP) content of Ankole pasture was significantly (P < 0·05) lower than CP of cross‐bred pasture (6·3% compared with 7·3%). Neutral detergent fibre content was similar (72·8% vs. 69·8%) for both pasture types. Farmers’ perceptions of indicator plant species were important for allocation of pasture. Hyparrhenia rufa, Brachiaria spp., Themeda triandra and Chloris gayana were identified as the preferred pasture species. Sporobolus pyramidalis and Cymbopogon afronardus were the most undesirable pasture species. Brachiaria spp. offers an opportunity for utilization as hay for dry season supplementation.     

十字花科作物根肿病的侵染生理与抗性遗传研究进展

十字花科植物根肿病是由芸薹根肿菌侵染而引起的危害最大的病害之一,近年来,该病在世界范围尤其是在欧洲、北美、东亚等地区日趋严重,我国很多地区的十字花科作物也正面临着根肿病的严重威胁。本文就芸薹根肿菌侵染过程中寄主植物的生理生化变化及其分子基础、根肿病抗性遗传规律和分子标记与遗传图谱等多方面的研究进展做一概述,并对该领域今后的研究进行了展望。     

犬基因组研究进展

人类基因组计划逐渐发展成熟使比较基因组学研究成为必然。犬由于具有遗传多样性和疾病易感性等特点,是一个极好的比较基因组学的动物模型。在此,综述了犬基因图谱、基因组测序、犬基因组比较图谱及犬基因组研究应用等方面的研究进展,并提出目前研究中面临的问题。     

台北市震度微区图在建筑防灾之运用

“9·21”大地震在台北市造成了一定程度的灾害,制定震度微区图在对建筑工程有很重要的参考作用。震度微区图可以在建筑物规划之前提供有关资料,作为建筑师参考,以达到减低震灾损失之目的。     

SSR技术及其在果树研究上的应用

SSR分子标记技术有丰富的多态性、重复性好和操作简便等优点,它已经成为植物遗传育研究中不可缺少的分子标记技术。对SSR技术的原理和特点作了介绍,分析了如何获得SSR引物,着重介绍了SSR技术在果树种质资源和构建果树遗传图谱的研究现状,指出了SSR技术将在果树科研上起到重要的作用。     

AFLP fingerprinting in Medicago spp.: Its development and application in linkage mapping

Cultivated alfalfa (Medicago sativa L., 2n= 4x= 32) is one of the most important forage crops in temperate climates. The genus Medicago includes diploid species that are a valuable source of wild germplasm for studying the reproductive system of alfalfa and its abnormalities. A linkage map of an apomeiotic mutant of Medicago falcata (L.) Arcang. (2n= 2x= 16) that spanned 368.6 cM and included 29 amplified fragment length polymorphism (AFLP), 35 random amplified polymorphic DNA (RAPD) and three restriction fragment length polymorphism (RFLP) loci was constructed using a one-way pseudo-testcross mapping strategy. The success of such a strategy depends on the presence of sufficiently high levels of heterozygosity in the individual plant which is being mapped and on the informativeness of the marker system that is used. In general: (1) highly informative and reproducible RAPD and AFLP fingerprints were generated and several genome-specific primers selected; (2) of 67 marker loci mapped, 51 were arranged in 11 main linkage groups and eight additional couples of linked marker loci were detected; (3) mapping of an F₁ population theoretically allowed a better estimation of linkage distances since it avoided segregation distortion (x² analyses revealed segregation distortion in only 5.2% of marker loci); (4) the high frequency of unlinked marker loci obtained suggests that, in this alfalfa genotype, DNA markers are distributed throughout the genome. This type of genetic map should find application and prove useful in marker-assisted selection and map-based breeding programmes in meiotic mutants of alfalfa for which there is a lack of suitable genetic markers.     

AFLPs in leek ( Allium porrum) are not inherited in large linkage blocks

Genetic linkages of 1:1 segregating amplified fragment length polymorphism (AFLP^TM) markers in leek (2n=4x=32) were studied with the aim of detecting block inheritance resulting from strong suppression of crossing over in chromosomal arms. The study comprised 97 markers in 70 plants originating from a cross between two highly heterozygous parents. At LOD≥3, 52 markers were linked in 23 linkage groups, spanning 405 of an expected 6400 cM. Cytogenetic data in previous studies indicated that recombination may be suppressed in two-thirds of the leek genome, supposedly leading to large linkage blocks of markers. In the present study, however, comparison of AFLP linkages with simulations indicates that the linkage blocks are much smaller, comprising no more than one-third of the leek genome. This revised version was published online in August 2006 with corrections to the Cover Date.     

陆海杂交棉产量及重要农艺性状QTL定位

[目的]通过海7124和军棉1号构建的陆海杂交棉产量及重要农艺性状的QTL定位研究,筛选与产量及重要农艺性状紧密连锁的分子标记,提高棉花育种效率.[方法]选用陆地棉品种军棉1号和海岛棉品种海7124配制的一个包含148株F_2单株的群体,利用97对SSR标记构建了一个包含17个连锁群,长673.3 cM,标记间平均距离为17.3 cM的遗传图谱,覆盖整个棉花基因组12.2;.在此基础上对果枝始节、果枝台数、结铃数、单铃重、衣分和叶面积6个农艺性状进行了QTL定位研究.[结果]检测到3个稳定的QTL:1个与衣分相关的QTL,位于第4连锁群上;1个与果枝台数相关的QTL,位于第1连锁群上;1个与叶面积相关的QTL,位于第6连锁群上.[结论]这些QTL的效应值较大,对今后的棉花育种的分子辅助选择具有较大的意义.