QTL mapping of general combining abilities of four traits in maize using a high-density genetic map

General combining abilities(GCAs) are very important in utilization of heterosis in maize breeding. However, its genetic basis is unclear. In the present study, a set of 118 doubled haploid(DH) lines were induced from F_1 generations produced from the cross between the inbred line Zheng 58 and the inbred line W499 belonging to the Reid subgroup. Using the Maize SNP50 Bead Chip, a high-density genetic map was constructed based on the DH population which included 1 147 bin markers with an average interval length of 2.00 cM. Meanwhile, the DH population was crossed with three testers including W16-5, HD568, and W556, which belong to the Sipingtou subgroup. The GCAs of the ear height(EH), the kernel moisture content(KMC), the kernel ratio(KR), and the yield per plant(YPP) were estimated using these hybrids in three environments. Combining the high-density genetic map and the GCAs, a total of 14 QTLs were detected for the GCAs of the four traits. Especially, one pleiotropic QTL was identified on chromosome 1 between the SNP SYN16067 and the SNP PZE-101169244 which was simultaneously associated with the GCAs of the EH, the KR, and the YPP. These QTLs pave the way for further dissecting the genetic architecture underlying GCAs of the traits, and they may be used to enhance GCAs of inbred lines under the fixed heterotic pattern Reid×Sipingtou in China through a marker-assisted selection approach.     

水稻遗传图谱构建及粒形相关性状的QTL定位

[目的]构建水稻遗传连锁图谱,并对水稻粒形相关性状进行QTL分析,为水稻高效育种提供理论依据和育种材料.[方法]对具有极端粒形差异的两份水稻材料K1561和G1025进行杂交、自交获得F2分离群体,通过软件Map-maker/Exp 3.0构建水稻遗传连锁图谱,并利用软件QTLNetwork-2.0对2011年F2群体、2012年F2∶3家系群体的粒形相关性状数据进行相关性状的QTL定位.[结果]两个亲本的粒形性状指标差异明显,以千粒重相差最大;F2、F2∶3两个群体的相关粒形指标基本上呈连续分布状态且分布频率范围广.与F2单株相比,F2∶3家系的千粒重、粒长和粒宽的平均值更偏向于大粒亲本K1561.构建了含161对SSR标记的水稻遗传连锁图谱;共检测到18个粒形相关性状的QTL,分别分布于第1、2、3、7、9和12染色体上.其中,控制千粒重、粒长、粒宽和长宽比的QTL分别有7、5、5和1个,除qGL/GW12外,其他增效等位基因均来源于大粒亲本K1561.两个群体均能检测到的QTL有8个,分别为qTGW3、qTGW7、qTGW9.2、qTGW12、qG L1、qGL9、qGW12和qGL/GW12,其平均加性遗传力为6.04％、12.59％、6.29％、22.08％、4.86％、15.39％、22.12％和10.83％.[结论]定位获得3个效应值较大的新QTL位点qTGW12、qGL9和qGW12,为进一步定位并克隆这些粒形相关基因、阐明水稻产量和品质的控制机理提供了较好的遗传材料.     

QTL mapping of grain appearance quality traits and grain weight using a recombinant inbred population in rice(Oryza sativa L.)

Grain appearance quality traits,measured as grain length(GL),grain width(GW),length to width ratio(LWR),grain thickness(GT) and the percentage of grain with chalkiness(PGWC),as well as 1 000-grain weight(TGW),are very important factors that contribute to rice grain quality and yield.To detect quantitative trait loci(QTLs) affecting these traits,we developed a set of recombinant inbred lines(RILs) derived from Gang46B(G46B) and K1075,a G46 B introgression line with lower PGWC.Based on a linkage map containing 33 simple sequence repeat(SSR) markers,a total of 15 additive QTLs governing six measured traits were identified on 4 chromosomes across two environments.Of these,the five major QTLs which controlled GW,LWR,GT,PGWC,and TGW,each explaining up to 44.30,55.29,62.30,30.94,and 28.78%of the variation,respectively,were found in the same interval of RM18004-RM18068 on chromosome 5.The G46 B alleles contributed to the increase in GW,GT and PGWC at all loci,as well as the increase in TGW at its major QTL locus.Significant interactions between additive QTL and the environment were found at most loci,in which the largest,accounting for15.06%of variation,was observed between qPGWC-5 and the environment.A total of 15 epistasis QTLs were detected for all the traits,and GL,GW and PGWC had significant epistasis QTLs based on environment interactions with minor effects.These results are valuable for future map-based cloning of the QTLs and the collaborative improvement of G46 B in grain appearance quality and yield.     

邓小平思维方式特点浅析

邓小平思维方式是符合时代需要的科学的思维方式。文章从历史和现实、理论和实践结合的角度,对邓小平思维方式的形成及特点进行分析研究,这对我们形成科学的思维方法,迎接新世纪面临的挑战,具有积极的意义。     

六个玉米自交系数量性状配合力的分析

利用6个玉米自交系,按照双列杂交方法组配成15个组合,并对它们的株高、穗位高以及穗部性状进行了遗传学分析和配合力的估算,结果表明,自交系鲁原92和478的一般配合力较高,表现为综合性状较好,用它们作亲本组配杂交种,易得到较广泛的优势;而齐319和178自交系在穗重性状上的特殊配合力高,用它们作亲本会出现穗重突出的组合。     

棉花数量性状的连锁作图和关联作图最新进展

现代分子生物学技术和新的统计方法,大大促进了植物数量性状基因(QTL)的解析.连锁作图和关联作图是目前植物数量性状基因解析的重要方法,两者在QTL定位的精度和广度、提供的信息量、统计分析方法等方面具有明显的互补性.连锁作图可以初步对目标性状基因进行定位,而关联作图则可快速对目标基因进行验证和精细定位,并针对特定候选基因提供大量信息,验证候选基因的功能.综述了近10年来棉花数量性状的连锁作图和关联作图最新进展,并结合两种方法对棉花的QTL研究前景进行了展望.     

5个含热带血缘玉米骨干自交系产量性状的杂种优势与配合力效应分析

以不同杂优类群的4个玉米自交系为父本,5个舍热带血缘的自交系为母本,按NCⅡ遗传交配设计组配成20个杂交组合,2008-2009连续2 a采用裂区设计田间试验,对穗长、穗粗等8个性状进行杂种优势和配合力效应分析.结果表明:1)组合间除穗行数超亲优势差异不显著外,其它各个性状的中亲优势与超亲优势均存在极显著差异;2)除粒...     

普通荞麦重组自交系群体F4 代主要农艺性状分析

采用方差分析、相关分析和回归分析等方法对普通荞麦构建的包括两组重组自交系(RIL)群体F4代植株的株高、结实率、单株粒重等7个农艺性状进行了统计分析。结果表明,株高、单株种子粒数、结实率、花数在双亲间存在显著或极显著差异。RIL群体各性状变异范围较大,说明其选择性也大。7个农艺性状均呈连续变异,且大多符合偏正态分布,说明为多基因控制的数量性状。单株粒重与其他农艺性状间呈现显著或极显著的相关性,且与单株种子粒数相关性最大;除千粒重外,所有性状均与株高具有显著或极显著的相关性。多元回归分析表明,株高、主茎分枝数、单株种子粒数、千粒重是影响RIL群体单株粒重的主要因素,其中单株种子粒数贡献最大。     

A comparative study on segregation analysis and QTL mapping of quantitative traits in plants—with a case in soybean

Two approaches of genetic analysis of quantitative traits were compared with a case study on soybean. One approach was the segregation analysis developed by Gai et al. (2003), which utilized information from individuals of one or multiple segregation populations as well as that from parents based on the principles of the major-gene plus polygene inheritance model, mixture distribution, joint maximum-likelihood function, IECM (Iterated Expectation and Conditional Maximization) algorithm, and Akaike’s information criterion and goodness of fit tests. Another approach was quantitative trait locus (QTL) mapping with molecular markers. A recombinant inbred line (RIL) population with 201 families derived from (Kefeng No.1 × 1138-2) F_2:7:10 along with their parents were tested in a randomized block design experiment. The 171 RFLP, 60 SSR, and 79 AFLP molecular markers were used to mark the 201 families. The data of nine traits, i.e., number of days to flowering, number of days to maturity, plant height, number of nodes on main stem, number of pods per node, 100-seed weight, protein content, oil content, and plot yield, were analyzed with the segregation analysis procedure of RIL population with parents (Gai et al., 2003; Zhang and Gai, 2000; Zhang et al., 2001) to detect their genetic system, and those along with the molecular marker data were analyzed with WinQTL Cartographer (Basten et al., 1999; Zeng, 1993, 1994) to detect their QTL system. The results showed that both procedures could detect the main major genes or QTLs, and therefore, could be used as a mutual check and supplement. From the results that most of the traits were mainly controlled by three or four QTLs, it was impressed that the segregation analysis procedure of four major-gene plus polygene mixed inheritance model should be developed to fit the requirements. The results also showed that the QTLs of the involved traits concentrated on several linkage groups, such as C2, B1, F1, M, and N. Finally, the results showed that the experimental sample was not necessarily coincident with the theoretical population according to equality test, symmetry test, and representation test, and therefore, the sample should be checked, tested and then adjusted to fit the theoretical requirements through deleting the extra-biased families and markers.     

旱稻渗入系拔节期根系性状QTL定位

研究稻作抗旱的根系特征及其遗传机理,在作物育种程序上改良作物根系性状,提高作物抗旱性,为水旱稻杂交选育抗旱高产品种提供理论依据。本研究利用187个SSR标记和1套具有180个家系的旱稻渗入系群体BC3F7构建遗传连锁图,采用单标记分析法,对拔节期根系的6个性状(最长根长、粗根数、总根数、平均最粗根粗、根干重、总干重)进行QTL定位。拔节期检测到QTL共56个,其中影响上述6个性状的QTL数目分别是9、10、3、12、9和13,其总贡献率分别为43%、44%、19%、70%、39%和68%。另外,在检测到的QTL中除与总根数有关的有2个来自毫格劳的等位基因降低性状值以外,其位点毫格劳的等位基因均增加性状值。92.8%的渗入位点对以沈农265为遗传背景的渗入系的根系6个性状有促进作用;定位到的影响不同根系性状的QTL多数成簇排列;在RM1261附近定位到影响3个性状的QTL,推测是一个与根系抗旱性状密切相关的基因区域。     

From plant traits to plant communities: a statistical mechanistic approach to biodiversity

We developed a quantitative method, analogous to those used in statistical mechanics, to predict how biodiversity will vary across environments, which plant species from a species pool will be found in which relative abundances in a given environment, and which plant traits determine community assembly. This provides a scaling from plant traits to ecological communities while bypassing the complications of population dynamics. Our method treats community development as a sorting process involving species that are ecologically equivalent except with respect to particular functional traits, which leads to a constrained random assembly of species; the relative abundance of each species adheres to a general exponential distribution as a function of its traits. Using data for eight functional traits of 30 herbaceous species and community-aggregated values of these traits in 12 sites along a 42-year chronosequence of secondary succession, we predicted 94% of the variance in the relative abundances.     

Reaction of the antitumor antibiotic CC-1065 with DNA: structure of a DNA adduct with DNA sequence specificity

Sequence-dependent variations in DNA revealed by x-ray crystallographic studies have suggested that certain DNA-reactive drugs may react preferentially with defined sequences in DNA. Drugs that wind around the helix and reside within one of the grooves of DNA have perhaps the greatest chance of recognizing sequence-dependent features of DNA. The antitumor antibiotic CC-1065 covalently binds through N-3 of adenine and resides within the minor groove of DNA. This drug overlaps with five base pairs for which a high sequence specificity exists.     

Construction of a genetic linkage map and QTL analysis for some leaf traits in pear (Pyrus L.)

The major incompatibility barriers to specific inbred lines and the long generation duration in Pyrus L. may hinder the Pyrus breeding process. A genetic linkage map provides the foundation for quantitative trait loci (QTL) mapping and molecular marker-assisted breeding. In this study, we constructed a genetic map with 145 F₁ populations from a cross of two cultivars, Yali and Jingbaili, using AFLP and SSR markers. The map consisted of 18 linkage groups which included 402 genetic markers and covered 1395.9 cM, with an average genetic distance of 3.8 cM. The interval mapping was used to identify quantitative trait loci associated with four leaf agronomic traits in the F₁ population. The results indicated that four QTLs were associated with leaf length, two QTLs with leaf width, two with leaf length/leaf width, and three with petiole length. The eleven QTLs were associated with 9.9%–48.5% of the phenotypic variation in different traits. It is considered that the map covers almost the whole genome, and molecular markers will be greatly helpful to the related breeding.     

小梅山猪IGF2基因连锁的微卫星DNA标记与生长性状的关联分析

以IGF2基因作为控制猪生长性状主基因的候选基因,选用小梅山猪及其杂种作为试验猪群体,采用微卫星DNA标记技术,检测猪IGF2基因紧密连锁的3个微卫星DNA标记的多态性,同时对这3个微卫星DNA标记与生长性状进行关联分析。结果表明:SW 256等位基因D对180日龄体重性状有正效应,等位基因B有负效应;SWC9等位基因E对30日龄体重性状有正效应,等位基因F对180日龄体重性状有正效应。