小豆遗传差异、群体结构和连锁不平衡水平的SSR分析

利用57对小豆SSR标记和31对绿豆SSR标记,用5份日本材料作对照,对249份中国小豆种质进行遗传差异、群体结构和连锁不平衡(LD)分析。结果表明,共检测到630个等位变异,SSR位点等位变异数在2~17之间,遗传多样性指数范围为0.024~0.898,平均为0.574。15个不同地理来源群体间表现出显著的遗传多样性差异,其中中国云南最高,河北、天津最低。聚类分析将254份材料划分为3个类群,在一定程度上和地理生态环境相关。LD分析显示和其他作物相比,小豆LD衰减距离较短,最大衰减距离为5.8 cM (R²>0.1),基因组LD平均衰减距离小于1 cM (R²>0.1,P<0.001)。     

A high-density integrative linkage map for <Emphasis Type="Italic">Gossypium hirsutum</Emphasis>

Sequence-related amplified polymorphism (SRAP) combined with SSRs, RAPDs, and RGAPs was used to construct a high density genetic map for a F₂ population derived from the cross DH962 (G. hirsutum accession) × Jimian5 (G. hirsutum cultivar). A total of 4,096 SRAP primer combinations, 6310 SSRs, 600 RAPDs, and 10 RGAPs produced 331, 156, 17 and 2 polymorphic loci, respectively. Among the 506 loci obtained, 471 loci (309 SRAPs, 144 SSRs, 16 RAPDs and 2 RGAPs) were assigned to 51 linkage groups. Of these, 29 linkage groups were assigned to corresponding chromosomes by SSR markers with known chromosome locations. The map covered 3070.2 cM with a mean density of 6.5 cM per locus. The segregation distortion in this population was 9.49%, and these distorted loci tend to cluster at the end of linkage groups or in minor clusters on linkage groups. The majority of SRAPs in this map provided an effective tool for map construction in G. hirsutum despite of its low polymorphism. This high-density linkage map will be useful for further genetic studies in Upland cotton, including mapping of loci controlling quantitative traits, and comparative and integrative analysis with other interspecific and intraspecific linkage maps in cotton.     

Construction of a linkage map and identification of DNA markers linked to Fom-1, a gene conferring resistance to Fusarium oxysporum f.sp. melonis race 2 in melon

Resistance to Fusarium oxysporum f.sp. melonis race 2 is conferred by a single dominant gene, Fom-1 in melon. Here, we identified DNA markers tightly linked to Fom-1 that could be used for marker assisted selection in breeding programs. First, we developed 125 F₂ plants derived from the cross between melon lines P11 (fom-1fom-1) and MR-1 (Fom-1Fom-1). Using the F₂ population, we constructed a linkage map including 14 SSR markers which had not been mapped previously. Fom-1 was confirmed to be allocated to linkage group 7. Then, we identified four AFLP markers using bulked segregant analysis. The AFLP marker TAG/GCC-470 was completely linked to Fom-1 and other three markers were mapped near Fom-1. TAG/GCC-470 and TCG/GGT-400 were respectively converted to STS and CAPS markers. Usefulness of DNA markers was confirmed in the analysis with several melon cultivars and lines.     

AB-QTL法定位陆海杂种棉花产量相关性状

本研究利用中棉所36和海1配制杂交组合,并用中棉所36为轮回亲本构建高代回交群体。利用3223对SSR引物筛选亲本和F1,筛选到294对含有海1显性带的引物,占筛选引物总数的9.12%。最终对其中的267对引物进行了群体扩增,获得277个SSR标记差异位点。其中,217个标记位点连锁,构建44个连锁群,平均每个连锁群包含4.93个标记位点。图谱覆盖1908.67cM,占棉花基因组的42.89%,平均每个连锁群覆盖43.38cM,标记间平均相距8.80cM。利用陆海杂种BC1F1、BC2F1和BC1S1的表型数据,通过复合区间作图,共检测到9个QTL,解释表型变异6.90%-19.17%。其中3个增效基因来自海岛棉亲本海1,6个增效基因来自陆地棉亲本中棉所36。此外,控制衣分的2个QTL在3个世代都能够检测到,分别解释6.90%和19.17%的表型变异,效应稳定,为进一步分子标记辅助选择奠定了基础。     

Association mapping of quality traits in potato (Solanum tuberosum L.)

In this paper, we describe the assessment of linkage disequilibrium and its decay in a collection of potato cultivars. In addition, we report on a simple regression based association mapping approach and its results to quality traits in potato. We selected 221 tetraploid potato cultivars and progenitor lines, representing the global diversity in potato, with emphasis on genetic variation for agro-morphological and quality traits. Phenotypic data for these agro-morphological and quality traits were obtained from recent trials performed by five breeding companies. The collection was genotyped with 250 AFLP^® markers from five primer combinations. The genetic position of a subset of the markers could be inferred from an ultra dense potato map. Decay of linkage disequilibrium was estimated by calculating the squared correlation between pairs of markers using marker band intensities. Marker-trait associations were investigated by fitting single marker regression models for phenotypic traits on marker band intensities with and without correction for population structure. The paper illustrates the potential of association mapping in tetraploid potato, because existing phenotypic data, a modest number of AFLP markers, and a relatively simple statistical analysis, allowed identifying interesting associations.     

新形势下“粮食龙头企业+农户”创新模式内涵特色与功能强化研究--对湖北省粮食主产区的调查分析

在全面深化农村改革、实施农村一二三产业融合发展的新形势下,以湖北省粮食主产区为典型案例,在深入分析粮食产业化经营主导模式"粮食龙头企业+农户"改革创新实地调查资料的基础上,揭示创新模式的内涵特色、优势显现,提出其功能强化的途径和对策,具有重要的普遍意义、现实意义和长远意义。     

大穗材料高麦1号/ 密小穗F2群体穗长性状的QTL初步定

为了解小麦穗长性状的遗传特性,并将其应用于分子标记辅助育种,以大穗材料高麦1号/密小穗的292个植株的F2群体为材料,利用SSR标记对穗长进行了QTL定位分析.结果表明,选用500对SSR引物对高麦1号和密小穗两个亲本进行多态性检测,共获得180对在双亲问有多态性的引物,多态性引物检出率为36.0％.利用这180对引物进一步进行F2群体筛选,有96对引物在群体中表现出多态性,占多态性标记的53.3％.利用QTL_IciMapping软件构建出小麦染色体组的8个连锁群图谱,并将96对SSR引物定位到遗传连锁图谱上.图谱全长1 383.29 cM,标记间的平均遗传距离15.37 cM.平均每个连锁群有11.25个标记,含有标记最多的是4A和6B染色体,各有17个标记,其次是3A和7B染色体,含有9～14个标记,1B和5D染色体含有的标记最少,只有5～7个.共检测出7个与穗长相关的QTL位点,包括6个加性QTL和1个加性+显性QTL.7个QTL的加性效应值均为正值,单个QTL的贡献率为2.04％～15.26％.其中3A染色体上的QTL位点距离其最近标记只有0.58 cM,为连锁最紧密的一个位点,并且其加性效应值最大,可解释表型变异的15.26％.因此,3A染色体上存在控制穗长的主效基因.     

关联分析在QTL定位中的应用

玉米的许多重要农艺和经济性状都是复杂多基因控制的数量性状。随着分子标记技术的发展,利用分子标记可以将数量性状位点(QTL)定位到染色体上。近年来出现的基于连锁不平衡(LD)原理的关联分析被广泛应用于玉米数量性状位点的定位上。介绍了关联分析的基本原理以及影响定位精度的主要因素。     

Genetic analysis of Turkish apple germplasm using peroxidase gene-based markers

Plant peroxidases belong to a multigene family and posses highly conserved domains allowing to design oligonucleotide primers to amplify DNA sequences coding for peroxidases from plants with unsequenced genomes. Peroxidase gene-based polymorphism among Malus species, and correlation between peroxidase markers were deduced in this study. Turkish apple germplasm was evaluated using 14 peroxidase specific primers. Targeted-PCR amplification of genomic DNA from 192 apple genotypes available in the Turkish genetic resources yielded polymorphisms giving a similarity range from 0.56 to 0.98 with a mean of 0.77. Based on the POGP gene polymorphism, two distinct clusters were detected among the apple accessions, suggesting different evolutionary pathway. Correlation estimates as an indication of linkage disequilibrium between POGP markers ranged from −0.22 to 0.90, suggesting that few POGP markers were clustered and the remaining POGP markers evenly distributed throughout the apple genome. These results demonstrate that primers targeting the peroxidase gene family can be used to study genotypic diversity and evolutionary relationships on an intra- and inter-specific basis.     

黄瓜抗霜霉病的分子生物学研究进展

黄瓜霜霉病(Cucumber downy mildew)是由真菌门鞭毛菌亚门古巴假霜霉菌侵染引起的一种世界性病害,已有70多个国家的黄瓜生产受其危害。本文从抗性遗传、分子标记及图谱构建、抗霜霉病基因相关的分离等方面综述了黄瓜抗霜霉病的分子生物学领域的研究进展,并就分子水平研究中存在的问题进行探讨,对今后的研究方向进行了展望。