甜瓜遗传图谱与基因定位研究进展

甜瓜是重要的葫芦科蔬菜作物之一,其遗传育种学广受研究者的关注。高密度分子遗传图谱有助于提高甜瓜的育种水平,加快育种进程。自1996年第一张甜瓜分子遗传图谱报道后,AFLP等分子标记逐步被应用于甜瓜分子遗传图谱的构建及基因定位。近年来,基因组测序技术发展迅速,全基因组重测序、简化基因组测序、转录组测序等技术逐渐被应用于构建覆盖全基因组的、更加饱和的甜瓜遗传连锁图谱。本研究着重对甜瓜分子遗传图谱、重要农艺性状基因定位研究进展进行了综述,以期为甜瓜生物学研究及分子改良提供理论参考。     

基于限制性内切酶简化基因组测序的两种主要技术

随着二代测序技术的发展,其在基因分型、连锁图谱构建、QTLs定位、系统进化、生物多样性、全基因组关联等生物研究领域中的应用越来越广泛。为了降低测序成本,采用一套简化测序的数据已经能满足大多数生物学研究。本研究主要从基于限制性内切酶简化基因组测序的2种主要技术(RAD-seq和GBS)进行介绍,从其原理、测序群体选择、限制性内切酶筛选、测序后数据分析等方面予以阐述。目前,GBS技术以其过程简单且使用甲基化敏感酶回避了基因组重复区域成为了简化测序的主要技术,尤其适合大样本量的研究,可快速鉴定出高密度的变异,加快生物研究的进程。     

多倍体植物复杂性状全基因组关联分析研究进展

多倍体普遍存在于植物界尤其是被子植物中,多倍化的发生有利于植物进化,其在物种遗传多样性和适应性等方面有着显著优势。研究表明植物几乎所有的重要经济性状均为复杂性状,这些复杂性状往往由多基因控制,且与非遗传(环境)因素共同决定。高通量测序技术的发展使得测序成本不断降低,高密度覆盖的标记使得基因型鉴定更加精确化,因此全基因组关联分析(genome-wide association study, GWAS)已成为研究多倍体植物复杂性状的新策略。本综述介绍了植物多倍体研究的意义、复杂性状的遗传学背景以及GWAS的一般流程,简要分析了多倍体GWAS的特点,并回顾了当前多倍体植物GWAS在复杂性状基因位点中所取得的研究进展,旨在为多倍体植物重要性状的遗传改良及分子辅助育种提供理论支持。     

植物全基因组选择育种技术原理与研究进展

优势杂交育种是选育高产优质新品种的有效育种途径,该方法需要在田间选配大量的杂交组合进行试验。而作物的主要经济性状如产量等大多是数量性状,该类性状由多基因控制,受环境影响大,常规的育种选择过程耗时很长且选择能力有限。随着基因组测序技术和计算机科学的快速发展,通过高密度的分子标记准确预测作物产量等复杂性状成为可能。植物全基因组选择育种技术通过训练群体收集表型数据和基因型数据,使用特定的模型估计分子标记效应值或个体育种值,再根据待测群体的基因型数据和模型拟合结果对待测群体的表型值进行预测。全基因组选择育种技术可以对目标性状进行预测和定向选择,减少育种工作量,显著缩短育种周期,提高育种效率,具有广阔的应用前景。本研究从植物优势杂交育种预测方法研究进展、全基因组选择育种原理与模型算法研究进展、模型预测能力验证方法研究进展、植物全基因组选择育种应用、全基因组选择育种的局限性和植物全基因组选择育种展望等6个方面阐述植物全基因组选择育种的发展现状。     

大豆籽粒蛋白质含量相关QTL定位研究进展

籽粒蛋白质含量是大豆品质性状改良的主要目标之一。笔者介绍了大豆遗传图谱的构建与基因组测序发展历程,从基于分离群体的连锁分析和基于自然群体的关联分析两方面阐述了大豆籽粒蛋白质含量QTL定位研究进展,进而讨论了大豆蛋白质含量MAS育种存在的问题,最后展望了大豆蛋白质含量分子遗传改良的研究趋势。以期为大豆高蛋白育种提供参考。     

棉花功能基因组研究进展

棉花是重要的经济作物。近年来棉花功能基因组研究发展迅速,高通量测序技术应用于棉花研究,二倍体和四倍体棉花基因组测序陆续完成,棉花全基因组重测序及关联分析相继涌现,大量的棉花功能基因被分离鉴定。本文回顾了棉花功能基因组研究的历程,重点介绍了棉花基因组测序和棉花栽培品种全基因组关联分析相关研究成果,并总结了棉花纤维和腺体发育中的关键功能基因及棉花抗旱、抗盐碱等功能基因研究进展,为全面了解棉花重要农艺性状形成的遗传基础和棉花遗传改良提供理论参考。     

棉花数量性状遗传与QTL定位研究进展

棉花许多重要的性状多为数量性状。现代分子生物技术的发展为植物数量性状基因的定位、分离等研究提供了条件。从数量性状基因座(QTL)作图群体类型及其特点,QTL定位方法,QTL精细定位、克隆、利用等方面进行了综述,并对今后QTL研究进行了展望。     

棉花数量性状遗传与QTL定位研究进展

棉花许多重要的性状多为数量性状。现代分子生物技术的发展为植物数量性状基因的定位、分离等研究提供了条件。从数量性状基因座(QTL)作图群体类型及其特点,QTL定位方法,QTL精细定位、克隆、利用等方面进行了综述,并对今后QTL研究进行了展望。     

构建数量性状基因图谱的统计方法

随着分子生物学研究的迅速发展和人类基因组统计的深入，数量遗传学在数量性状基因（ＱＴＬ）的定位方面正在经历着一场深刻的变化。人类和动、植物基因组计划的早期成果之一，就是建立人类以及实验、家养动物和栽培植物的遗传连锁图、利用这些连锁图，可以对许多ＱＴＬ进行单个分离测定和定位。许多复杂疾病和具有重要农 生物学意义的性状都属于数量性状。在ＱＴＬ定位的研究中，统计分析起着很重要的作用。近年来有许多新的统计方     

基于SLAF-seq技术的树莓SNP位点开发

为分析树莓群体的遗传进化关系,开发特异性SNP标记。选用23 个栽培种树莓以用SLAF-seq技术测序,从树莓全基因组范围开发SNP位点,以黑树莓基因组为参考基因组,通过生物信息学分析进行电子酶切预测,筛选特异长度的DNA片断,构建SLAF-seq 文库。通过高通量测序的方式获得海量序列标签,利用软件分析比对,获得多态性SLAF标签,进而开发大量特异性SNP位点。对照水稻的测序数据与参考基因组比对结果,双端比对效率为95.60%,酶切效率为93.52%,说明SLAF建库正常。通过测序共产生59.93 Mb的读长数据,测序质量值Q30 平均为95.07%,所有样品GC含量均值为39.16%,GC含量普遍不高,说明达到测序要求。本研究共获得425402 个SLAF标签,其中多态性的SLAF标签共有121610 个。获得749811 个有效单核苷酸多态(SNP),利用这些SNP分析了23 个树莓种质的群体结构与系统发生树。利用简化基因组测序技术SLAF-seq 可以高效地、低成本地开发出大量的可用于群体遗传结构分析的SNP标记。     

Identification of near-isogenic lines: an innovative approach,validated for root and shoot morphological characters in a mapping population of rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Near-isogenic lines (NILs) constitute valuable tools in genetic investigations and plant breeding programs. Conventional methods for developing these are time consuming and tedious. An innovative method for identifying NILs is proposed and validated. The method involves computation of simple correlation coefficients of all possible pairs of genotypes within a mapping population using molecular marker data, and phenotypic characterization of those pairs with very high positive correlation. The pairs having both genomic and phenotypic similarity except for a single trait are considered as NILs. This strategy was tested with a doubled haploid mapping population involving CT9993 and IR62266. This population was saturated with 315 markers and comprised 154 lines. The pairs showing very high correlation coefficients (0.70–0.97) and differing for less than 10% of the markers were considered as Genotypically Closely Related Pairs (GCRPs). Graphical genotyping was employed to visualize the genome of the closely related lines. A total of 39 such pairs were subjected to rigorous evaluation for root and shoot morphological traits in two contrasting moisture regimes. Four GCRPs under well-watered condition and ten GCRPs under low moisture stress condition are statistically significant for a single phenotypic trait and are considered as NILs for their respective traits and would be the valuable materials for genetic studies. Mapped QTLs and candidate genes were employed to explain the probable cause of phenotypic difference in NILs.     

Molecular markers: actual and potential contributions to wheat genome characterization and breeding

The demands for increasing global crop production have prompted the development of new approaches relying on molecular marker technologies to investigate and improve the plant genome. The merits of molecular markers make them valuable tools in a range of research areas. This review describes novel approaches based on modern molecular marker technologies for characterization and utilization of genetic variation for wheat improvement. Large-scale genome characterization by DNA-fingerprinting has revealed no declining trends in the molecular genetic diversity in wheat as a consequence of modern intensive breeding thus opposing the genetic ‘erosion’ hypothesis. A great number of important major genes and quantitative trait loci have been mapped with molecular markers. Marker-assisted selection based on a tight linkage between a marker allele and a gene(s) governing a qualitative or quantitative trait is gaining considerable importance as it facilitates and accelerates cultivar improvement through precise transfer of chromosome regions carrying the gene of interest. The implementations of molecular markers in wheat genotyping, mapping and breeding complemented by specific approaches associated with the complex polyploid nature of common wheat are analyzed and presented.     

烤烟6个农艺性状的QTL定位

由于烟草的分子标记开发和遗传图谱构建十分困难,迄今烟草中有关数量性状基因座(QTL)的定位研究仍非常有限。本研究利用一个由207个株系组成的烤烟DH群体及基于该群体所构建的含有24个连锁群、611个SSR标记,总长为1 882.1 cM的遗传图谱,采用复合区间作图方法,对株高(PH)、茎围(SG)、节距(IL)、叶片数(LN)、最大腰叶长(LWL)和最大腰叶宽(WWL) 6个与叶片产量有关的农艺性状进行QTL定位分析。共检测到69个QTL,大部分QTL的效应值较小,仅有4个具有较大的效应值,可解释大约15%~20%的表型变异。6个性状之间大多彼此相关。与此相符,在基因组中发现存在许多小区域,每个区域包含两个或两个以上紧密连锁的不同性状的QTL。     

Mapping quantitative trait loci and expressed sequence tags related to brown planthopper resistance in rice

To map genes responsible for brown planthopper (BPH) resistance in rice, a rice genetic map was constructed based on a recombinant inbred line population from a cross between a BPH‐resistant line ‘B5’ and a susceptible variety ‘Minghui 63’. Four quantitative trait loci (QTLs) for BPH resistance were detected. ESTs differentially regulated by BPH feeding were isolated by suppressive subtractive hybridization (SSH) and assigned to chromosomes based on RFLP mapping and searches of the rice genome database. The distribution of ESTs showed some clustering, and some ESTs are related to known QTLs and known BPH resistance genes. These findings suggest that the mapping of differentially induced ESTs may be a useful strategy for the identification of candidate plant defence genes, which could be beneficial in the development of a BPH‐resistant rice variety.     

An SSR-based molecular genetic map of cassava

Summary Microsatellites or simple sequence repeats (SSR) are the markers of choice for molecular genetic mapping and marker-assisted selection in many crop species. A microsatellite-based linkage map of cassava was drawn using SSR markers and a F₂ population consisting of 268 individuals. The F₂ population was derived from selfing the genotype K150, an early yielding genotype from an F₁ progeny from a cross between two non-inbred elite cassava varieties, TMS 30572 and CM 2177-2 from IITA and CIAT respectively. A set of 472 SSR markers, previously developed from cassava genomic and cDNA libraries, were screened for polymorphism in K150 and its parents TMS 30572 and CM 2177-2. One hundred and twenty two polymorphic SSR markers were identified and utilized for linkage analysis. The map has 100 markers spanning 1236.7 cM, distributed on 22 linkage groups with an average marker distance of 17.92 cM. Marker density across the genome was uniform. This is the first SSR based linkage map of cassava and represents an important step towards quantitative trait loci mapping and genetic analysis of complex traits in M. esculenta species in national research program and other institutes with minimal laboratory facilities. SSR markers reduce the time and cost of mapping quantitative trait loci (QTL) controlling traits of agronomic interest, and are of potential use for marker-assisted selection (MAS).     

Molecular markers in Brassica oilseed breeding: current status and future possibilities

As PCR techniques have developed over the last 15 years, a wealth of new DNA marker technologies have arisen which have enabled the generation of high‐density molecular maps for all the major Brassica crop species. Molecular markers have also been heavily used in analyses of genetic diversity in Brassica crops. The majority of the work utilizing molecular markers in Brassica oilseed breeding has to date been based on genetic mapping using various DNA marker systems in segregating populations generated for specific investigations of particular traits of interest. For numerous qualitative traits, traditional mapping approaches have led to the development of marker‐assisted selection strategies in oilseed Brassica breeding, and in some cases to map‐based cloning of the responsible genes. For quantitative traits, however, it has become apparent that traditional mapping of quantitative trait loci (QTL) is often not sufficient to develop effective markers for trait introgression or for identification of the genes responsible. In this case, allele‐trait association studies in non‐structured genetic populations represent an interesting new approach, provided the degree of gametic phase disequilibrium between the QTL and the marker loci is sufficient. Because Brassica species represent the closest crop plant relatives to the model plant Arabidopsis thaliana, significant progress will be achieved in the coming years through integration of candidate gene approaches in crop brassicas, using the detailed information now available for the Arabidopsis genome. Integration of information from the model plant with the increasing supply of data from physical mapping and sequencing of the diploid Brassica genomes will undoubtedly give great insight into the genetics underlying both simple and complex traits in oilseed rape. This review describes the current use of available genetic marker technologies in oilseed rape breeding and provides an outlook for use of new technologies, including single‐nucleotide polymorphism markers, candidate gene approaches and allele‐trait association studies.     

Genetic analysis of plant height using two immortalized populations of “CRI12 × J8891” in Gossypium hirsutum L.

Plant height is an important plant architecture trait that determines the canopy structure, photosynthetic capacity and lodging resistance of upland cotton populations. To understand the genetic basis of plant height for marker-assisted breeding, quantitative trait loci (QTL) analysis was conducted based on the genetic map of recombinant inbred lines (RILs) derived from the cross “CRI12 × J8891” (Gossypium hirsutum L.). Three methods, including composite interval mapping, multiple interval mapping and multi-marker joint analysis, were used to detect QTL across multiple environments in the RILs and in the immortalized F₂ population developed through intermating between RILs. A total of 19 QTL with genetic main effects and/or genetic × environment interaction effects were identified on 15 chromosomes or linkage groups, each explaining 5.8–14.3 % of the phenotypic variation. Five digenic epistatic QTL pairs, mainly involving additive × additive and/or dominance × dominance, were detected in different environments. Seven out of eight interacting loci were main-effect QTL, suggesting that these loci act as major genes as well as modifying genes in the expression of plant height. The results demonstrate that additive effects, dominance and epistasis are all important for the genetic constitution of plant height, with additive effects playing a more important role in reducing plant height. QTL showing stability across environments that were repeatedly detected by different methods can be used in marker-assisted breeding.     

GBS高密度遗传连锁图谱定位甘蓝型油菜粉色花性状

甘蓝型油菜花瓣颜色是重要的观赏性状,花瓣颜色的选育和改良已成为材料创制的主要研究方向。目前对甘蓝型油菜粉色花性状定位研究未见报道。本研究以甘蓝型油菜纯系黄花62和甘蓝型油菜纯系粉花77为亲本构建双单倍体(doubled haploid,DH)群体。利用简化基因组测序技术(genotyping-by-sequencing,GBS)筛选出3253个单核苷酸多态性(single nucleotide polymorphism,SNP)标记,构建了全长1766.06 cM甘蓝型油菜连锁图谱,标记间平均遗传距离为0.54 cM;使用WinQTL Cartographer复合区间作图方法对粉色花性状进行数量性状座位(quantitative trait locus,QTL)定位,检测到位于A07和C03染色体上各1个QTL;将定位区间内基因与甘蓝和白菜同源基因进行线性比对,在这些区间中找到了一些存在于3个物种的同源基因;对粉色花定位区间内基因进行可变剪切分析发现,2个花色相关基因BnaA07g15980D和BnaA07g17500D在亲本粉色花瓣中发生内含子保留可变剪切。上述研究结果为甘蓝型油菜粉色花相关基因精细定位和分子连锁标记开发提供了更多线索。     

Molecular markers: It’s application in crop improvement

Over the past few decades, plant genomics research has been studied extensively bringing about a revolution in the field of plant biotechnology. Molecular markers, useful for plant genome analysis, have now become an important tool in crop improvement. The development and use of molecular markers for the detection and exploitation of DNA polymorphism is one of the most significant developments in the field of molecular genetics. The presence of various types of molecular markers, and differences in their principles, methodologies and applications require careful consideration in choosing one or more of such methods. No molecular markers are available yet that fulfill all requirements needed by researchers. In this article we attempt to review most of the available DNA markers that can be routinely employed in various aspects of plant genome analysis such as characterization of genetic variability, genome fingerprinting, genome mapping, gene localization, analysis of genome evolution, population genetics, taxonomy, plant breeding, and diagnostics. The emerging patterns make up a unique feature of the analyzed individual and are currently considered to be the ultimate tool for biological individualization.