水稻籼粳杂种F2群体中RFLP标记的异常分离及其染色体分布

利用水稻 Oryza sativa L.,2 n=2 4 1 2对染色体上的 5 4个 DNA限制性片段长度多态性 RFL P 标记 ,研究了它们在籼粳杂种 窄叶青 8号 / 京系 1 7 F2 群体中的分离 .结果表明 ,2 5 .9%的 RFLP标记的分离显著或极显著地偏离了预期的孟德尔比例 1∶ 2∶ 1 而表现为异常分离 .F2 群体中 3类 RFL P基因型中 窄叶青 8号 类型明显偏多 ,其基因频率为5 2 .1 % .同时还发现了 3个异常分离的染色体热点 ,即第 3染色体上的 RG2 2 7- RG369,第 7染色体上的 RG678- RG5 1 1 - RG5 2 8,以及第 1 2染色体上的 RG4 63- RG32 3,它们可能与导致异常分离的配子体基因座位有关 .     

陆地棉抗黄萎病基因的分子标记定位

棉花黄萎病是棉花生长过程中最具破坏力的病害之一,在世界范围内流行.棉花黄萎病已成为棉花生产中的主要障碍.减轻棉花黄萎病损失最为经济、安全、有效的办法就是培育和推广抗病品种.本研究利用抗黄萎病品系60182和感黄萎病品种军棉1号为亲本配制杂交组合,对陆地棉抗黄萎病性状进行遗传分析和抗病基因分子标记定位.用主基因＋多基因混合遗传模型和P1,P2,F1,B1,B2和F2六世代联合分析的方法对病叶比例性状进行遗传分析.结果表明,接种BP2,VD8,T9和三者等浓度混合病菌时,抗病性都受两对加性-显性-上位性主基因控制,陆地棉60182的抗病性在各个分离世代都以主基因遗传为主.运用F2为作图群体构建了一个含139个标记位点,31个连锁群,总长1165cM的分子标记连锁遗传图谱,标记平均距离为8.38cM,覆盖棉花全基因组的25.89%.调查229个F2：3家系各时期平均病级代表F2单株抗病性,结合连锁遗传图谱,复合区间作图检测QTL.结果显示,在60182上,接种BP2时检测到4个QTL位于D7染色体上,4个QTL位于D9染色体上;接种VD8时,有5个QTL位于D7染色体上,9个QTL位于D9染色体上;接种T9时,有4个QTL位于D7染色体上,5个QTL位于D9染色体上;接种混合病菌时,有3个QTL位于D7染色体上,7个QTL位于D9染色体上.60182在不同调查时期对4种黄萎病菌的抗性QTL都集中在D7、D9两条染色体上,形成两个明显的抗病QTL集中区.这一结果与两对主基因的遗传模式相吻合,充分表明陆地棉抗黄萎病品系60182兼具对落叶型,非落叶型黄萎病菌的广谱抗性.同时与陆地棉抗黄萎病QTL连锁的分子标记可加速抗黄萎病基因的应用,为培育稳定高抗黄萎病新材料提供有价值的理论依据.     

陆地棉超矮杆突变体基因的初步定位

陆地棉超矮杆是一种新发现的突变体材料。前期对其遗传规律的研究表明,超矮杆突变性状是受一对完全隐性基因du控制的质量性状。文章以"超矮1号"和"新陆早16"配置的F2为作图群体,通过对双亲以及近等基因池的筛选,在1 350对SSR引物中共获得70对多态性引物。而后检测F2作图群体每个单株的基因型,显示有36个标记可以连锁,分布在8个连锁群上,其中超矮杆突变性状位于连锁群LG01。与目标基因du连锁的分子标记有7个:NAU2679、NAU2749、NAU905、NAU2838、NAU5373、NAU2238和NAU4946,它们皆为共显性标记。依据现有的棉花遗传图谱,标记NAU4946、NAU2238、NAU905、NAU5373和NAU2679位于第6染色体上,而目标基因du位于NAU2238和NAU4946之间,遗传距离分别为3.3 cM和1.4 cM,由此推定du在第6条染色体上。     

亚洲棉种内群体异常偏分离的分子标记检测

利用3个形态标记、20个SSR和11个SRAP多态性标记,研究它们在“如东鸡脚桠果”与“美国中棉971”杂交的F2群体中的分离情况。结果表明,77.42%的分子标记表现为偏分离,所有的偏分离标记都偏向母本“如东鸡角桠果”;如此高的偏分离比例以及偏分离标记都偏向一个亲本,这种现象在棉花中是比较罕见的。3种类型的SSR标记和非物种特异性的SRAP标记都表现偏分离,而形态标记则表现为正常分离,这表明该异常偏分离现象是由材料本身的遗传特性所决定的。通过分析偏分离的共显性标记的等位基因频率(p=q)以及各种基因型频率(p2:2pq:q2)的F2分布,发现大多数标记的等位基因频率差异显著而F2基因型频率分布正常,表明这些标记产生偏分离可能是配子体选择的结果。     

水稻无内稃突变体的遗传分析和基因定位

花器官发育异常的突变体是研究植物花发育分子遗传机制的良好实验材料,以水稻无内稃突变体为父本,生47、N625和CDR22为母本配制杂交组合进行性状遗传分析,根据F2代表型及X^2测验结果表明,突变性状是由单隐性基因控制的,选用突变体为父本,生47为母本杂交的F2群体作定位群体,利用SSLP标记的和RFLP标记将与突变性状相关的基因定位在第6染色体短臂上RFLP标记C498和RZ450之间,暂定名为npa-1。为进一步的基因克隆及功能研究奠定了基础。     

小麦农家品种红麦(苏1661)中一个主效抗条锈病基因的微卫星标记定位

应用分离体分组混合分析法（bulked segregant analysis,BSA）和微卫星标记多态性分析方法,对红麦（保存单位编号：苏1661;统一编号：ZM008712）中的一个主效抗条锈病基因YrHm进行了分子标记和定位研究。共用512对微卫星引物对抗、感基因池进行了多态性分析,经用包括230个单株的F2分离群体进行遗传连锁性检测,发现4个与YrHm基因连锁的微卫星标记Xgwm904、Xbarcl73、Xcfdl3和Xcfd42,均位于小麦染色体6D短臂上。经Mapmaker3．0b软件计算,这4个标记与目的基因间的遗传距离分别为7．3、25．1、47．7和62．1cM,均位于YrHm基因远离染色体顶端的一侧。用全套中国春小麦缺体一四体材料进行检测,进一步确认了这4个标记均位于小麦6D染色体。因此,将YrHm基因定位于小麦染色体臂6DS上。     

印度南瓜果皮和果肉颜色遗传分析及基因定位

以印度南瓜‘98-2-351’与‘06820-1’杂交构建F2群体,对亲本及各世代群体成熟果实果皮和果肉颜色进行调查、统计分析。结果表明:F2群体中果皮桔红色和灰色的分离比呈3∶1,说明果皮灰色是由单隐性基因控制;F2群体中果肉黄色和白色的分离比呈3∶1,说明果肉白色也是由单隐性基因控制。利用群体分离分析法结合隐性群体分析法,采用SSR分子标记,找到了2个与控制灰色果皮基因位点CmRc紧密连锁的SSR标记(PU078072和PU013839),其连锁遗传距离分别为5.9cM和14.5cM;同时找到了1个与控制白色果肉基因位点CmFc紧密连锁的SSR标记PU132712,其连锁遗传距离为6.7cM。本研究为进一步筛选与控制印度南瓜果皮和果肉颜色基因更加紧密连锁的分子标记及相关基因的精确定位奠定了基础。     

水稻顶节间长度控制基因(EUI)的精细定位

通过对一水稻顶节间特异伸长突变体Mh-1进行经典遗传学和基因定位分析,认为该表型是一个核基因隐性突变所致。利用Mh-1与正常的T65-sd1杂交的F2群体对该位点定位研究分析,发现其与水稻第5条染色体长臂STS标记E30531和CAPS标记C903连锁,遗传距离分别为6．7cM和2．8cM。经进一步发展新的分子标记,将该基因精确定位在0．3cM的区域,为进一步克隆和研究该基因的分子机制奠定基础。     

小麦品系5R618抗叶锈基因的初步定位

5R618是高抗叶锈病小麦品系。为了确定该品系所携带的抗叶锈基因,以5R618与感病小麦品种郑州5389杂交获得F1,自交获得F2分离群体以及F2∶3家系,用叶锈菌生理小种THJP对亲本、F2分离群体以及F2∶3家系进行叶锈抗性鉴定,然后进行分子标记分析。结果显示,5R618对生理小种THJP的抗病性由1对显性基因控制,该基因暂命名为Lr5R。经过亲本和抗感池间分子标记筛选以及F2∶3家系的标记检测,Lr5R定位于染色体3DL上,barc71和STS24-16是Lr5R最近的2个标记,遗传距离分别为0.9 c M和2.1 c M。     

水稻粒簇生材料Cgr320的鉴定及遗传偏分离分析

籽粒簇生稻Cgr320为一类水稻突变材料,其性状表现为2~3朵颖花(籽粒)簇生在水稻主穗轴或枝梗顶部。为了进一步明确其簇生性状的遗传机制,本研究用Cgr320作父本分别与武运粳24和93-11配制了2个杂交组合,获得杂种F1、F2分离群体,对亲本、F1和F2群体的簇生性状进行了形态学观察和遗传连锁分析。结果表明,Cgr320其他农艺性状与普通栽培稻差异不显著。簇生性状在F1植株表现为野生型,在F2群体中出现严重偏离孟德尔(3∶1)遗传分离,卡方测验值X2(3∶1)为7.71和144.87。随机选取第1、2、3、4、5、6、7、8、9、10、11和12染色体上RM493、RM3762、RM1338、RM3217、RM249、RM20155、RM3325、RM22418、RM6797、RM1146、RM7557和RM27706等12对微卫星标记对武运粳24/Cgr320 22个F2隐性(簇生)单株进行遗传连锁分析,发现12个标记所扩增的22个F2隐性单株基因型都极显著偏向武运粳24,卡方检验值X2(1∶2∶1)大于X2(0.05,2)临界值5.991,控制cgr320簇生性状基因存在严重偏分离遗传,这种遗传现象必将误导我们判定控制籽粒簇生基因所在的连锁群。本研究结果将为水稻基因定位研究提供参考信息。     

Distorted Segregations of RFLP Markers and Their Distribution on Chromosomes in an indica/japonica F2 Population of Rice (Oryza sativa L.)

he segregation ratio of RFLP markers in an F2 population from indica "Zhaiyeqing 8” and japonica "Jingxi 17' of rice (Oryza sativa L., 2n= 24) was studied using 54 RFLP markers distributed on 12 chromosomes. Distorted segregation was found in 25.9% of the marker tested, which was indicated by significant deviation from the expected Mendelian segregation ratio ( I: 2: 1) at 5% or 1% level. Among the three RFLP genotypes of the F2 population “Zhaiyeqing” 8 genotype was significantly more than the expected, and its gene frequency was up to 52.1 %. Three positions for distorted segregation were found on chromosome 3 (RG227-RG369), 7 (RG678-RG511-RG528) and 12 (RG463-RG323). These positions could be related to gametophyte loci responsible for the distortion.     

水稻日本晴与广陆矮4号杂交F2群体SSR标记偏分离原因探析

以全基因组测序已经完成的材料粳稻日本晴和完成了第4染色体全序列测序的籼稻广陆矮4号的杂交F2作为构图群体,共90个单株,构建了一张含148个微卫星标记的水稻分子遗传图谱。该F2群体显著偏分离非常高,发现有49个分子标记表现偏分离（P〈0．05）,占总标记数的33．11％,这些偏分离标记中有36个偏向广陆4号,13个偏向杂合体,没有偏向日本晴的偏分离标记。讨论了配子体基因和孢子体基因导致偏分离的原因,通过已经定位的配子体基因和杂种不育基因分布在偏分离集中的区域来进一步说明配子体基因和杂种不育基因确实是导致偏分离形成的原因,而且还通过未定位的标记分析了偏分离的原因。     

籼粳杂种双单倍体的配子选择

对典型的灿与粳稻杂种,窄叶青８号／京系１７Ｆ１花药进行培养获得的１３２个双单倍体的形态特性、同工酶与ＲＦＬＰ标记的分离与重组进行了考察分析,研究是否存在配子选择问题。结果表明：（１）对４个重要数量性状和６个涉及籼、粳特征的形态指数进行考察所获数据均为连续分布,并呈正态曲线;（２）用８种同工酶对５２个ＤＨ系分析结果表明,只有２种同工酶显著偏离期望的１：１比率,而灿与粳的总基因型比率相近;（３）应用１６７个ＲＦＬＰ标记对１３２个ＤＨ系进行的分析发现,有３６％标记发生偏分离,但偏籼与偏粳的比率相近,两个亲本基因组在ＤＨ群体中所占比率相同（各５０％）,各种基因组成呈正态分布。综上所述,本研究虽观察到一些轻微偏分离现象,但籼粳基因基本上随机分离与重组,等位基因总频率未偏离１：１比率。     

Analysis of Segregation Distortion of Molecular Markers in F2 Population of Rice

A genetic linkage map comprising 148 SSR markers loci was constructed using an F₂ population consisting of 90 lines derived from a sub-specific cross between a japonica variety Nipponbare and an indica variety Guangluai-4. The F₂ population showed high significantly distorted segregations. Among these SSR markers, 49 markers (33.11%) showed the genetics distortion(P<0.05). Of them, 36 markers deviated toward male parent indica GuangLuAi-4 and 13 markers toward heterozygote, but none toward the female parent Nipponbare. It was found that the segregation distortion might be caused by gametophyte and zygote. Since most gametophyte loci and sterility loci were mapped in segregation distortion regions, it indicated that the segregation distortion may be caused by these gametophyte loci and sterility loci. Finally, this research also analyzed the skewed segregation of some markers, which had not been mapped on chromosome.     

Genetic segregation of microsatellite markers in Saccharum officinarum and S. spontaneum

Genetic mapping techniques can be used to study the interaction between two different genomes after hybridization. This study investigated a Saccharum officinarum (Green German or GG, 2n approximately 11x approximately 110) x S. spontaneum (IND 81-146 or IND, 2n approximately 7x approximately 56) interspecific cross. Segregation of 193 microsatellite (SSR) loci was evaluated in the F(1) progeny of 169 full-sibs of the cross. Following the two-way pseudo-testcross strategy and 'cross pollination' population type, linkage groups (LG) and phases were established for each parent map, using the criteria of LOD score > or = 3.0 and a maximum recombination frequency of 0.35. Of the 193 markers analyzed, 61 were IND-specific, 106 were GG-specific, and 26 were heterozygous in both parents. About 78% of the markers segregated in a Mendelian fashion and 22% were distorted (as evaluated by chi(2)-tests, P < or = 0.01). The GG map included 91 marker loci arranged into 25 LG covering 1180 cM of the officinarum genome. The IND map consisted of 46 marker loci assembled into 10 LG, which spanned 614 cM of the spontaneum genome. A specific chromosome associated with segregation distortion was detected in the female (GG) genome only, probably as a result of double reduction. The segregation patterns of the marker loci indicated a centromere-driven distortion process with the shared allelic markers (as putative centromeres) regulating the placement and association of markers with opposite phase (coupling vs repulsion) and dosage on either side. Although incomplete, the framework maps were informative with respect to segregation distortion, chromosome fusion, rearrangements, and translocations, observed in both parental genomes as a result of their merger.     

Detection of segregation distortions in an indica-japonica rice cross using a high-resolution molecular map

We have constructed a high-resolution rice genetic map containing 1383 DNA markers covering 1575 cM on the 12 linkage groups of rice using 186 F₂ progeny from a cross between a japonica variety, Nipponbare, and an indica variety, Kasalath. Using this high-resolution molecular linkage map, we detected segregation distortion in a single wide cross of rice. The frequencies of genotypes for 1181 markers with more than 176 genotype data were plotted along this map to detect segregation distortion. Several types of distorted segregation were observed on 6 of the chromosomes. We could detect 11 major segregation distortions at ten positions on chromosomes 1, 3, 6, 8, 9, and 10. The strongest segregation distortion was at 107.2 cM on chromosome 3 and may be the gametophyte gene 2 (ga-2). The Kasalath genotype at this position was transmitted to the progeny with about a 95% probability through the pollen gamete. At least 8 out of the 11 segregation distortions detected here are new. The use of the high-resolution molecular linkage map for improving our understanding of the genetic nature and cause of these segregation distortions is discussed.     

栽培大豆与半野生大豆杂种F_2群体中RFLP标记的偏分离及其形成原因的分析

本文研究了大豆５６个ＤＮＡ限制性片段长度多态性（ＲＦＬＰ）标记在一栽培大豆／半野生大豆杂种Ｆ２群体中的分离。结果表明,２５％的ＲＦＬＰ标记表现了偏分离,偏离的方向主要趋于栽培大豆亲本,其形成原因主要是存在着配子体选择。这对研究大豆的遗传及育种选择等有着重要的指导意义。     

Distorted segregation resulting from pea chromosome reconstructions with alien segments from Pisum fulvum

Pea (Pisum sativum L.) satellited chromosome reconstructions were analyzed by cytologic markers to identify segregation distortion events. The presence of modified chromosomes was evaluated on the basis of additional rDNA genes, an extra and a longer satellite, all derived from chromosome 5 and chromosome 7 from P. fulvum Sibth. & Sm. The segregation of modified satellited chromosome 5 was monitored through fluorescent in situ hybridization with rDNA probe; it fitted the expected 1:2:1 ratio after self-pollination of a heterozygous genotype for modified chromosome 5. In different genotypes, which were heterozygous for both modified chromosomes 5 and 7, the combined segregation of these chromosomes showed the occurrence of seven karyotype classes instead of the expected nine. The classes with modified chromosome 7 and without modified chromosome 5, whether heterozygous or homozygous, were absent. The hypothesis of gamete selection was rejected since the expected segregation ratio of 5:3:1 was significant by chi-square test. Based on the other hypothesis of postzygotic selection, the segregation ratio did not show a significant deviation from the expected 9:3:1 ratio, thereby indicating that embryo abortion caused the segregation distortion (SD). The hypothesis of the SD system involving two loci carried by the alien satellites of modified chromosomes 5 and 7 is discussed in relation to the evolution of the P. fulvum genome.     

Linkage analysis of anther-derived monoploids showing distorted segregation of molecular markers

Monoploids can be obtained from several diploid plant species by anther culture. Mapping of molecular markers using monoploids is greatly facilitated by the simple 1:1 segregation ratio expected from all heterozygous loci in the genome. Distorted segregation of molecular markers, however, appears to be a common phenomenon in many crop species and hinders the use of monoploids for mapping purposes. This report examines the segregation pattern of two marker genes linked together with one locus or separately with two independent loci which are responsible for the observed distortion. Each of the loci exhibiting distorted segregation has one of the two alleles which inhibits regeneration of the gametic cells in vitro and disrupts the expected segregation ratio of the linked markers. All possible situations in which linkage occurs between markers and distortion-causing genes are considered. Theoretical results outlining the segregation pattern among these linkage types indicate that the distinguishable distorted ratios can be used for mapping purposes. A protocol is given for the mapping of distorted gene markers based on existing gene mapping software. An example is presented of the mapping of distorted RAPD markers of monoploids obtained from a diploid potato genotype. Received: 18 October 1999 / Accepted: 24 November 1999<@head-com-p1a.lf>Communicated by G. Wenzel