小麦中与低脱氧雪腐镰刀菌烯醇含量关联的抗性基因类似物

脱氧雪腐镰刀菌烯醇(Deoxynivalenol,DON)是小麦遭受赤霉病危害后由赤霉病菌———禾谷镰刀菌产生的一种真菌毒素,这种毒素对人类和家畜的健康产生危害,严重地影响小麦的利用价值.种植低DON含量的品种是减少这种毒素危害的有效措施,而分子标记辅助育种技术能加速低DON品种的选育进程.在采用AFLP、SSR分子标记的基础上,进一步利用抗性基因类似物(RGA)对‘宁7840’(低DON含量的品种)和‘Clark’(高DON含量的品种)建立的133个重组自交系进行了DON含量的遗传特性分析.研究结果发现两个DON含量的数量特性位点(QTL),它们中含有4个与低DON含量密切相关RGAs,其中三个RGAs(RGA14-1,RGA16-1,RGA18-1)座落在染色体1A的长臂上,另一个(RGA14-2)座落在染色体5B的长臂上.座落在1AL和5BL上的QTL分别解释16.81%和7.84%的DON含量变异.DNA序列分析表明这些RGAs均与现已发现的抗性基因同源/类似,它们可能在小麦的低DON含量和赤霉病抗性上扮演着重要的角色.     

分子标记及AFLP技术

分子标记类型可以基因表达的结果为基础,对基因的间接反映;分子标记则是DNA分子碱基序列变异的直接反映.早期利用限制性内切酶,酶切生物体DNA后来检测不同遗传位点等位变异(RFLP)和以一个碱基顺序随机排列的寡核苷酸序列为引物,利用对基因组DNA随机扩增来鉴别DNA多态性(RAPDs).真核生物基因组中普遍存在的重复序列产生了微卫星(microsatellites)标记技术.而RFLP与RAPDs有机结合形成了有着更为广阔的应用前景的AFLP技术.SNP标记利用大多数基因位点上都会有若干个等位型(alleles)为DNA芯片技术应用于遗传作图提供了基础.     

用5′加尾长引物进行AFLP片段的直接测序

现有的AFLP标记片段测序方法比较费时,成本也较高.设计一个包括EcoRI接头引物和5′端加36个额外核苷酸的长引物AF2SC,用该引物再扩增时可AFLP片段末端增加36个碱基.再利用这36个碱基的末端序列进行测序,只需一次反应就能获得AFLP标记片段的全序列.该方法缩短了AFLP片段测序所需时间,也降低了实验成本.     

小麦赤霉病:从表型鉴定到抗性改良

 赤霉病已成为影响中国小麦安全生产的最重要病害之一。表型鉴定体系对赤霉病抗性准确评价和抗性改良至关重要。本文分析了赤霉病的危害和改良的迫切性、中国抗赤育种的现状、QTL的定位和利用进展等,讨论了赤霉病接种鉴定和评价方法、赤霉病抗源利用和抗赤分子标记辅助育种策略,提出赤霉病改良的思路和建议。     

花椰菜(Brassica oleracea var.botrytis)黑腐病抗性基因同源序列分离及克隆的研究

通过从NBS保守序列设计简并引物PCR的方法，以花椰菜（Brassica oleracea var．botrytis）抗、感黑腐病的近等基因系为材料，分离得到NBS-LRR型抗性基因同源序列，并获得1个克隆，命名为RGA330—7．Southern杂交表明，该片段在近等基因系中存在明显的多态性，且该片段在抗黑腐病基因位点至少存在3个以上类似RGA330—7的同源拷贝．序列分析结果认为该克隆与NBS—LRR型抗性基因的部分CDSs有很高的同源性，说明该片段属于NBS—LRR型．系统进化分析该序列与甘蓝型油菜的2个抗病同源序列归为一类，很可能这3个不同来源的抗性基因同源序列同属于一种抗性基因家族．因此推测该序列与花椰菜抗黑腐病基因紧密相关，为进一步克隆花椰菜抗黑腐病基因提供了可靠的候选基因，对分子标记辅助抗性育种具有重要意义。     

葡萄抗霜霉病基因RAPD标记的序列分析

用WizardDNAClean upSystem纯化葡萄抗霜霉病基因RAPD遗传标记OPO 0 6 - 150 0片段 ,用T easyVector克隆RAPD标记 ,采用自动荧光DNA测序仪 (型号ABI 377DNASe quencer)测定了该DNA片段的核苷酸组成及其排列顺序 .来自中国野葡萄的RAPD标记OPO 0 6- 150 0从左右两端各测了 586bp和 4 52bp .对两端序列的酶切位点进行了分析 .根据两端序列可以设计专一PCR扩增引物作为合成抗霜霉病检测探针的基础 ,用于检测葡萄抗病育种和抗病品种的霜霉病抗性 .     

小麦染色体2DS雌性育性位点遗传多态性分析

小麦雌性不育系XND126属于生态遗传型不育系.通过SSR分子标记分析,在2DS染色体上定位了一个雌性育性主效QTL位点.为了构建高密度遗传图谱并精细定位该主效位点,用2DS参考遗传图谱上的14对SSR标记,研究了59个育性正常的普通小麦品种与XND126的DNA多态性,筛选到不同生态型多态性较高的品种共12个,每个品种多态性标记达12~13个,这些品种可以用作杂交亲本,构建新的QTL精细定位群体.在品种组成的群体中,与主效基因位点最近的标记,表现出有较多的品种与雌性不育系具有差异.     

利用分子标记研究小麦遗传群体的赤霉病抗性鉴定方法

针对小麦赤霉病抗源苏麦3号构建的两个小麦重组自交系遗传群体苏麦3号／Alondra和苏麦3号／安农8455，采用单花接种、表土接种及自然发病3种不同的接种方法进行小麦赤霉病抗性接种鉴定，并根据苏麦3号赤霉病抗性主效QTL的连锁分子标记Xgwm 493和Xgwm 533．1分别对群体进行抗性连锁分析．检测结果表明，在温室单花接种所获得的鉴定数据中，标记的赤霉病抗性连锁效应最高，P值分别小于0．0001，抗性鉴定结果最为准确．研究表明，对小麦赤霉病这种由数量性状控制，受外界环境影响较大的真菌病害进行抗扩展性的遗传研究，应采用控温控湿条件下的单花滴注接种鉴定方法最为合适．     

中国小麦周8425B/中国春RIL群体成株抗叶锈基因的QTL定位

为确定小麦叶锈病抗病基因的QTL检测及定位,找到能与抗病基因紧密连锁的分子标记,以小麦品种周8425B,中国春及其杂交获得的244个F_(2∶8) RIL群体为试验材料,分别于2014～2015年在河北保定和河南周口进行了田间叶锈病病害严重度调查,获得了群体的表型数据,利用SNP标记和SSR标记进行基因分型,得到了群体基因型数据,运用软件Joinmap和QTL Ici Mapping 3.1进行连锁作图和QTL定位。结果找到2个QTL位点,分别位于2B,7D染色体上。     

高效热不对称交互式PCR技术克隆地黄基因

利用高效热不对称交互式PCR(hiTAIL-PCR)技术从地黄基因组中扩增出3个DNA片段,经过电泳检测、回收、纯化和测序获得2个片段的碱基序列.其中一个由578个bp组成,包含一个453bp的开放阅读框(ORF),编码151个氨基酸,与一些已知纤维素合酶基因在DNA水平和氨基酸水平的同源性分别高达81%~91%和83%~99%,而且推测蛋白质具有纤维素合酶的结构域;另一个由385个bp组成,没有ORF,不编码蛋白质,但是,预测其包含启动子元件.这些结果表明使用hiTAIL-PCR技术可以克隆地黄基因,克隆的基因将为地黄基因分子作用机制和分子育种研究奠定基础.     

Linkage graph analysis: A linkage-group-based QTL synthesis analysis approach

Consensus quantitative trait loci (QTL) in meta-analysis of multiple independent QTL mapping experiments provides a strong foundation for marker-assisted selection and gene cloning. However, meta-analysis suffers from the lack of available genomic information and the results vary when different reference linkage maps are used. Here, to overcome these limitations, we propose a linkage-group-based QTL synthesis analysis approach that we have named linkage graph analysis. First, a graph model is constructed from derived linkage groups. Next, an unsupervised classification approach is used to obtain marker intervals with co-segregating patterns among multiple genomes. Finally, a frequent itemset mining technique is used to identify the markers (or intervals) closely linked to the QTL. The proposed method was validated by one Monte Carlo simulation study and by real data analysis of cotton genomes. Two major advantages of the new method are: (i) A reference linkage group is not required; (ii) the effect of the initial QTL is reduced because false QTLs can be detected and excluded from the dataset. The ability to reliably identify the markers associated with a true QTL is valuable in crop breeding.     

基于SLAF-seq玉米高密度遗传连锁图谱构建与株型性状QTL定位

 株型直接决定生物产量、种植密度与籽粒产量,利用玉米高密度遗传连锁图谱解析株型相关性状的遗传机制,对选育理想株型玉米新品种具有重要意义。本研究利用SLAF-seq技术,依据玉米黄早四参考基因组信息,对昌7-2与PHB1M及其138个F_2：3家系高通量测序,开发高密度SNP的遗传图谱,并进行株型相关性状QTL定位。研究结果构建了一张总图距为1354.81 cM,标记间的平均距离为0.32 cM,标记数为4220个SLAF标签（7876个SNP）的高密度遗传图谱。在E1与E2两种密度下,对株高、穗位、叶片数、节间数、平均节间长进行QTL定位,共检测到10个QTL位点,其中,有7个PVE超过了10%。叶片数、穗位、节间数为主效QTL,ADD为负值,叶片数与节间数的减效等位基因来源于PHB1M,穗位的减效等位基因来源于昌7-2。叶片数与节间数在2个密度下均定位在8号染色体上,说明二者之间有着共同的遗传机制。与QTL关联的SLAF标记共有61个,其中,SLFA7305498和SLFA6717271为qLC-2-LG8与qIC-2-LG8共有标记。该研究将为玉米株型相关性状的标记辅助选择提供支撑。     

Pre-selecting young bulls before progeny-testing with marker-assisted BLUP

Suppose that a QTL affecting milk production trait or dairy cattle has been identified,and the relative distances between the QTL and the markers are hnown without error.The relative efficiency of pre-selection of young bulls before progeny-testing with marker-assisted BLUP(MBLUP) over conventional progeny-testing(i.e.random selection before progeny-testing)for five generations was studied using Monte Carlo simulation.Different numbers of QTL alleles(two or infinite),initial frequencies of the favorable QTL allele(0.1 and 0.5,when the QTL has two alleles),distances between the adjacent markers(5 cM or 20 cM),and ratios of the QTL variance to the genetic variance(10%,25%,and 50%)were considered in the simulation.The results showed that the relative efficiency of MBLUP was higher when the marker distance was 5 cM than that when the distance was 20 cM.The larger the QTL alleic effect,the lower the MBLUP efficiency.The relative superiority of MBLUP was higher when the QTL had two alleles and the frequency of the favorable QTL allele was low in the base population.The relative superiority of MBLUP decreased with th progress of generation in all cases and the decreasing rate was getting higher with the increase of marker density and QTL effect.     

影响小麦加工品质数量性状位点的研究

以M5和M16为亲本构建的重组自交系为材料,对影响小麦加工品质性状的数量性状位点（QTL）进行了研究．检测了群体中籽粒硬度、蛋白质含量、SDS沉降值、拉伸面积等品质性状,它们在群体中呈近似正态的连续分布,为多基因控制的数量性状．利用43个SSR标记和42个AFLP标记构建了相关染色体的分子连锁图．在1A、5D、6D染色体上分别检测到与籽粒硬度相关的QTL各1个,其中位于染色体5D上的Xgwn190对表型变异的贡献率最大,达62．5％,为主效基因;在1B和6A染色体上分别检测到与蛋白质含量相关的QTL各1个,它们对表型变异的贡献率分别为13．2％和15．6％;在染色体1B和3B上分别检测到与SDS沉降值相关的QTL各1个,贡献率最大（10．2％）的一个QTL位于3B染色体上靠近E37M61—286的区域;在1A、3B、5D染色体上分别检测到与拉伸面积相关的QTL各1个,其中5D染色体上的Xgwn190对表型的贡献率最大,为11．5％．     

家畜育种中MAS的遗传标记与QTL

简要评述了在家畜育种中标记辅助选择（ＭＡＳ）所适用的遗传标记系统及对数量性状位点（ＱＴＬ）和标记的基本要求．对ＭＡＳ中遗传标记与ＱＴＬ的紧密连锁之意义进行了讨论，认为遗传标记与ＱＴＬ间的连锁程度是决定ＭＡＳ效能的关键因素．并简述了获得与ＱＴＬ紧密连锁之遗传标记的一般方法     

Advances on methods for mapping QTL in plant

Advances on methods for mapping quantitative trait loci (QTL) are firstly summarized. Then, some new methods, including mapping multiple QTL, fine mapping of QTL, and mapping QTL for dynamic traits, are mainly described. Finally, some future prospects are proposed, including how to dig novel genes in the germplasm resource, map expression QTL (eQTL) by the use of all markers, phenotypes and micro-array data, identify QTL using genetic mating designs and detect viability loci. The purpose is to direct plant geneticists to choose a suitable method in the inheritance analysis of quantitative trait and in search of novel genes in germplasm resource so that more potential genetic information can be uncovered.     

A genome scan for quantitative trait loci affecting grain yield and its components of maize both in single-and two-locus levels

Maize is one of the most important cereal crops in the world. The hybrid yield advantage is responsible for about 10 percent of the total global maize production of 550 Mt[1]. It is exigent to study the yield traits so as to improve the hybrids per se in …     

Identification of salt-tolerance QTL in rice (Oryza sativa L.)

Quantitative trait loci (QTLs) controlling salt-tolerance at the seedling stage in rice (Oryza sativa L.) were identified by interval mapping (SIM) and composite interval mapping (CIM) using a doubled haploid population ZJDH and its high resolution genetic linkage map. The population was derived from an inter-subspecific cross between an indica variety Zhaiyeqing8 (ZYQ8) and a japonica variety Jingxi17 (JX17). Analysis of survival days of seedlings treated with 0.7% NaCI revealed that a major salt-tolerance quantitative trait locus (QTL), Std, was present between markers RG612 and C131 on chromosome 1 when using both MAPMAKER/QTL 1.1 and PLABQTL 1.0 (SIM). Its allele which contributes to salt-tolerance was from ZYQ8. In addition, seven more QTLs which give additive effect on salt-tolerance are identified when using PLABQTL (CIM), and most of them were from JX17.     

Conditional and unconditional mapping of quantitative trait loci underlying plant height and tiller number in rice (Oryza sativa L.)grown at two nitrogen levels

In this study, we used 127 double haploid (DH) lines to analyze agricultural traits of rice. The DH lines, derived from a ZYQ8 (indica)/JX17 (japonica) cross by anther culture, contained 160 RFLP and 83 SSR markers. Unconditional and conditional quantitative trait loci (QTL) mapping was conducted to analyze plant height (PH) and tillers per plant (TP) at ?ve growth stages that were grown at two nitrogen levels. Fourteen PH and 13 TP unconditional QTL were identified in the di?erent growth stages, including 19 QTL from high-nitrogen (HN) and 14 QTL from low-nitrogen (LN) conditions. The conditional QTL for 14 genomic regions under LN/HN conditions showed that there was a significant effect on PH and TP across the different stages. Only one conditional QTL, ph2-3, was unable to be detected in unconditional mapping. More QTL were detected in the ?rst four rice growth stages than in the final stage. Furthermore, a line from the DH mapping population, DH78, was identified in extreme phenotypes of PH and TP that exhibited dwarfism and less-tiller (dft) characters. The gene dft1 was mapped to chromosome 2 using a backcrossed population of DH78/JX17 through a mapbased cloning strategy. The location of dft1 coincided with the mapping region of the small-LOD peak, QTL ph2 and tp2, which were identified in plants grown in low-nitrogen conditions. Further backcrossing and fine-mapping successfully delimited the dft1 locus to a 91 kb region.