利用置换系检测棉花第22染色体短臂的产量相关性状QTLs

CSB22sh为以陆地棉(Gossypium.hirsutum L.)遗传标准系TM-1为背景的第22染色体短臂被海岛棉(Gossypium.barbadense L.)Pima3-79置换的海陆置换系。TM-1与CSB22sh杂交,构建了104个F2单株的作图群体,应用6748对SSR引物对亲本进行分子标记筛选,获得90个多态性标记位点。其中85个标记位点构建了总长85.24 cM的遗传图谱,标记间平均距离1.0 cM,覆盖棉花基因组的1.8%。通过复合区间作图法对F2:3和F2:4家系的7个产量相关性状(衣分、铃重、子指、株高、第一果枝节位、单株铃数、单株果枝数)进行QTL检测,共检出28个不同QTLs,解释性状表型变异的3.5%～44.8%。仅在一个环境中检测到的QTLs有17个,2个环境同时检测到的QTLs有8个,3个环境同时检测到的QTLs有3个。不同的QTL在相同区段的成簇分布表明,控制不同性状的基因可能紧密连锁或一因多效。检测到的稳定的QTL可以用于相应性状的分子标记辅助选择。     

玉米籽粒生理成熟后自然脱水速率QTL的初步定位

以吉846(脱水快,1.18%d-1)和掖3189(脱水慢,0.39%d-1)为亲本衍生出的232个重组自交系(F7)为作图群体,构建了具有101个SSR标记位点的玉米遗传连锁图谱,覆盖玉米基因组1941.7cM,标记间平均距离为19.22cM。通过1年2点试验(双城和哈尔滨,2007年)评价了232个重组自交系籽粒生理成熟后的自然脱水速率。采用WinQTL2.5对该性状数量性状位点(QTL)进行了初步定位和遗传效应分析,结果共检测出9个显著影响玉米籽粒生理成熟后自然脱水速率的QTL,分别位于第2、第3、第4、第5和第6染色体上,加性增效作用均来源于亲本吉846。其中在第2和第6染色体上的2个QTL(qKdr-2-1和qKdr-6-1)在2个环境下均稳定表达,分别位于SSR标记bnlg198～umc1516之间和phi126～phi077之间,其累积表型贡献率为15.49%。具有较快脱水速率的等位基因均来自吉846。所检测到的QTL将在分子辅助选育具有较快脱水速率的材料中具有较大的应用潜力。     

不同遗传背景下陆地棉衣分和子指性状QTL定位

为陆地棉产量性状有关的分子标记辅助育种奠定理论基础,以高品质中长绒棉品种‘新陆早24号’为父本,转基因抗虫棉常规品种‘鲁棉研28号’和高产、优质棉花新品种‘冀棉516’为母本,构建F2和F2:3分离群体;利用7638对SSR引物对‘鲁棉研28号’和‘新陆早24号’进行多态性进行筛选,共获得225对多态性引物,对238个F2单株DNA扩增获得238个多态性标记位点,其中185个构建了包括44个连锁群,总长为1509.38 cM的遗传连锁图谱,标记间的平均距离为8.16 cM,覆盖棉花总基因组的33.91%。根据已有图谱的定位结果,40个连锁群与染色体建立联系。利用复合区间作图法定位‘鲁棉研28号’与‘新陆早24号’分离群体F2单株和F2:3家系的衣分和子指性状QTL,其中得到3个衣分和5个子指的QTL;根据定位结果,选择了14对SSR引物,分析‘冀棉516’与‘新陆早24号’的多态性,其中6个标记构建了两个连锁群。1个衣分和1个子指的QTL在两个群体中均检测到,这些共同QTLs为分子标记辅助育种奠定了基础。     

2个抗虫棉的外源Bt基因分子鉴定及其染色体定位

以中美2个抗虫棉品种GK19与33B为试验材料,利用检测中美Bt基因的特异性引物,分别对抗虫棉亲本GK19和33B进行PCR扩增,并通过SSR分子标记技术对其Bt基因进行分子鉴定与染色体定位,旨在从外源基因转化事件的视角探究中美转基因抗虫棉差异的分子基础。结果表明, GK19为中国转Bt基因抗虫棉, 33B为美国转Bt基因抗虫棉; GK19的Bt基因被定位在棉花Chr.20上,共16对SSR多态性标记与其Bt基因连锁,两侧的分子标记为NAU3907和NAU2579,其遗传距离分别为2.4 cM和1.5 cM; 33B的Bt基因被定位在棉花Chr.26上,共20对SSR多态性标记与Bt基因连锁,目标Bt基因位于标记NAU460和dc40260之间,其遗传距离分别为3.6 cM和2.0 cM。以上结果表明GK19和33B属于不同的遗传转化事件。     

陆地棉背景下海岛棉第18染色体片段置换系的培育及相关农艺性状QTL定位

Sub18是以陆地棉遗传标准系TM-1为背景, 含海岛棉3-79第18染色体的置换系材料。本研究以TM-1为受体亲本, 置换系Sub18为供体亲本, 借助分子标记辅助选择技术培育了一套以TM-1为背景, 含海岛棉3-79第18染色体不同长度片段的置换系。这套置换系由45个株系构成, 共78个置换片段。其中27个株系导入单片段, 占总株系的60%; 9个株系导入2个片段, 占20%; 9个株系导入3个及以上片段, 占20%。导入片段总长度为467.6 cM, 约为该染色体遗传长度的4倍, 每个株系内被替换的染色体片段长度不完全相同, 平均遗传长度为5.99 cM, 最短的为0.9 cM, 最长的20.35 cM。其中13个株系表现开放花蕾性状, 涉及的最短导入片段长5.05 cM。对TM-1、Sub18以及培育的45个导入系进行农艺性状调查和QTL联合定位分析, 鉴定出纤维强度(qFS-C18-1)、整齐度(qFU-C18-1)、马克隆值(qFMi-C18-1)、成熟度(qFMa-C18-1)、皮棉重(qLW-C18-1)、籽指 (qSI-C18-1)和衣分 (qLP-C18-1) 7个加性QTL和5个上位性效应QTL。研究结果为进一步精细定位目标QTL、克隆QTL以及重要性状分子设计育种奠定了基础。     

棉花抗黄萎病QTL初步定位

本研究以高抗黄萎病的海岛棉品种海7124和高感黄萎病的陆地棉品种邯郸14组配的F2群体184个株系,构建了一个分子标记遗传连锁图,包括了142个位点和30个连锁群,标记间的平均距离为8.24cM,全长1169.6cM,覆盖棉花总基因组约23.4%。用复合区间作图分析共检测到12个抗黄萎病相关QTL,其中田间抗病性检测到不同时期7个病情指数相关QTL,1个病株率相关QTL,温室苗期抗病性定位4个病株率相关QTL。从绝对量上看,各QTL加性效应从2.20到42.39,显性效应从1.65到32.25,解释表型变异1.09%～22.73%,且田间抗病性获得的QTL与温室苗期抗病性得到的QTL基本相同,其中qFDI711-30-0.01位点距MUSS294仅为0.01cM,加性效应较高解释表型变异22.32%,这对于培育优质抗病材料用于标记辅助育种具有一定的参考价值。     

基于陆地棉背景的海岛棉染色体片段导入系产量性状QTL定位

棉花产量分为籽棉产量和皮棉产量,其中高皮棉产量总是育种的首要目标。皮棉产量由单株铃数、衣分、单铃重等因素组成。其中衣分在各因素中的遗传率最高,同时也是产量育种中重要的选择指标。育种中利用分离群体对单株铃数、铃重等产量性状选择受环境影响较大。利用染色体片段导入系进行铃数、铃重等产量性状的定位,定向改良产量性状,是棉花分子设计育种的有效方法。本研究利用陆地棉TM-1为轮回亲本和海岛棉海7124为非轮回亲本构建了一套陆地棉背景的染色体片段导入系,并在7个环境的田间试验下,鉴定了它们的产量表现,定位了28个与单株铃数、铃重、衣分和籽指相关的QTL。其中,在Dt亚组染色体上鉴定出的产量性状QTL多于在At亚组染色体上鉴定出的。28个QTL中,加性效应为正的16个,加性效应为负的12个,表明海岛棉不同的导入片段效应不同,有的片段可以提高陆地棉产量,有的则降低陆地棉产量。在6个环境下,导入系IL008(特征标记NAU2573和NAU3576)的衣分均显著高于轮回亲本TM-1,因此IL008可以应用于棉花分子育种,定向改良陆地棉的衣分。     

一个新矮生玉米种质资源矮生性状QTL的定位

用新发现的玉米矮生种质资源矮2003×冀257构建的255个F2:3家系为作图群体, 利用114个覆盖玉米全基因组的SSR标记构建连锁图谱, 图谱总长度2 852.1 cM, 标记间平均距离为27.42 cM。2006年在北京与海南进行随机区组试验, 鉴定了255个F2:3家系成株期株高。用复合区间作图法(composite interval mapping, CIM), 对控制玉米株高性状的遗传位点进行QTL检测。在两个不同环境下均检测到相同的控制玉米株高的QTL位点3个, 分别位于第1和第2条染色体。其中在第1染色体上的1.10~1.11区段存在一个控制株高的主效QTL, 与dwarf plant8 (d8)位置相近, 在北京和海南环境下分别能够解释株高表型变异的50.5%和37.5%, 作用方式表现为显性效应。深入的序列分析结果显示, 该基因/QTL位于已知的d8基因下游20~30 cM的染色体区间, 这可能是玉米中控制株高的一个新基因。     

利用陆海杂种BC1群体构建遗传连锁图谱并初步定位产量性状相关的QTL

摘要：本研究利用中棉所36和海1配制杂交组合,并用中棉所36为轮回亲本构建回交群体(BC1F1, BC2F1和 BC1S1)。用亲本和F1对新开发的2102对SSR引物进行多态性筛选,共筛选到317对含有海1显性带的引物,占筛选引物总数的15.08%;最终对其中的275对引物进行了BC1F1群体扩增,获得306个SSR标记差异位点。连锁分析表明（LOD=6.5）,有254个标记位点连锁,分布在42个连锁群中,覆盖2252.36cM,约占棉花基因组的50.05%;平均每个连锁群有6.08个标记,覆盖53.63 cM;标记间平均间距为8.87cM。利用BC1F1、BC2F1和BC1S1三个不同世代分离群体产量性状数据,共定位16个产量性状QTL,解释表型变异5.77%～19.86%。其中,衣分6个,铃重6个,籽指4个。有9个增效基因来自陆地棉亲本中棉所36,7个增效基因来自海岛棉亲本海1,说明了表型性状较差的品种同样可能含有可用于性状改良的增效基因。控制衣分的3个QTL可在不同的世代稳定检测到,效应稳定,增效基因均来自高值亲本陆地棉,为进一步分子标记辅助选择奠定了基础。     

利用陆海杂种BC1群体构建棉花遗传连锁图谱并初步定位产量性状相关的QTL

利用陆地棉推广品种中棉所36和海1配制杂交组合,并用中棉所36为轮回亲本构建回交群体(BC1F1,BC2F1和BC1S1).用亲本和F1对新开发的2102对SSR引物进行多态性筛选,共筛选到317对含有海1显性带的引物,占筛选引物总数的15.08%;最终对其中的275对引物进行了BC1F1群体扩增,获得306个SSR标记差异位点.连锁分析表明(LOD=6.5),有254个标记位点连锁,分布在42个连锁群中,覆盖2252.36 cM,约占棉花基因组的50.05%;平均每个连锁群有6.08个标记,覆盖53.63 cM;标记间平均间距为8.87 cM.利用BC1F1、BC2F1和BC1S1三个不同世代分离群体产量性状数据,共定位16个产量性状QTL,解释表型变异5.77%/～19.86%.其中,衣分6个,铃重6个,籽指4个.有9个增效基因来自陆地棉亲本中棉所36,7个增效基因来自海岛棉亲本海1,说明了表型性状较差的品种同样可能含有可用于性状改良的增效基因.控制衣分的3个QTL可在不同的世代稳定检测到,效应稳定,增效基因均来自高值亲本陆地棉,为进一步分子标记辅助选择奠定了基础.     

Fine‐mapping a fibre strength QTL QFS‐D11‐1 on cotton chromosome 21 using introgressed lines

An initial F₂ mapping population of 223 plants of the cross between TM‐1 (Gossypium hirsutum L.) × H102 (Gossypium barbadense L.) was used to map QTLs controlling fibre strength in cotton. A genetic linkage map with 408 SSR markers was constructed with a total length of 3872.6 cM. Multiple‐QTL model of the software MapQTL version 5.0 was used to map QTLs related to fibre strength of the F_2 : 3 population. QTL QFS‐D11‐1 conferring fibre strength was mapped between NAU2950 and NAU4855 on chromosome 21 (Chr. 21) which explained 23.4% of phenotypic variation. Introgressed lines (ILs), that is, IL‐D11‐1, IL‐D11‐2 and IL‐D11‐3 were obtained through marker‐assisted backcrossing in TM‐1 background. An F₂ population of 758 plants derived from cross IL‐D11‐2 × TM‐1 was used for fine‐mapping QTL QFS‐D11‐1. QFS‐D11‐1 was mapped between markers NAU2110 and NAU2950, adjacent to its initial interval NAU2950–NAU4855 with phenotypic variation explaining 35.8%. QFS‐D11‐1 was further mapped to 0.6 cM from the flanking marker NAU2950. The results will give a basis for marker‐assisted selection of QFS‐D11‐1 in cotton breeding and to lay the foundation for cloning QFS‐D11‐1.     

陆地棉衣分差异群体产量及产量构成因素

 以衣分差异较大的陆地棉品种为材料,构建了包含188个F₂单株的作图群体,应用6111对SSR引物对亲本进行了分子标记筛选,结果仅获得了123个多态性位点,其中88个位点构建了总长为666.7 cM、平均距离为7.57 cM的遗传图谱,覆盖棉花基因组的14.9%。通过复合区间作图法对F₂单株和F_2∶3家系进行QTL检测,共鉴定出了18个控制产量及产量构成因素变异的QTLs,包括2个衣分QTLs、4个子棉产量QTLs、4个皮棉产量QTLs、2个衣指QTLs、3个单株铃数QTLs、2个铃重QTLs和1个子指QTL。 解释的表型变异分别为\{6.9%\}～16.9%、5.6%～16.2%、4.8%～15.6%、7.7%～13.3%、8.2%～11.6%、6.1%～7%和6.6%。不同QTLs在相同染色体区段上的成簇分布表明与产量性状相关的基因可能紧密连锁或一因多效。产量及产量构成因素QTLs的遗传方式主要以显性和超显性效应为主。检测到的主效QTLs可以用于棉花产量及产量构成因素的分子标记辅助选择。     

转基因抗虫棉产量相关性状QTL的分子标记及定位

 采用亚洲棉渐渗的纤维强度突出的陆地棉优质新品系0-153与陆地棉转基因抗虫新品系sGK9708为亲本,构建了F₂及F_2∶3分离群体。利用3869对SSR引物筛选亲本,得到125对多态性引物。进一步对183个F₂群体单株分析得到150个多态性标记位点,其中100个标记位点连锁,构建20个连锁群,共覆盖660 cM,占棉花总基因组的14.67%,每个连锁群平均包含5个标记位点,标记间平均相距6.6 cM,其中13个连锁群确定了对应的染色体。利用F₂和F_2:3数据,通过复合区间作图,共检测到28个产量及相关因素的QTLs。这些控制产量性状的QTLs只存在于5个连锁群上,成簇分布。与皮棉产量性状有关的2个QTLs,均与其它多个产量相关性状的QTLs在同一个连锁区段内,增效基因遗传效应方向一致,有必要研究其在标记辅助选择中的效果。本研究没有检测到在多世代表现稳定的QTL。因此,需要培育重组自交系,进一步明确产量性状有关QTL的遗传效应。     

Marker-assisted selection of Verticillium wilt resistance in progeny populations of upland cotton derived from mass selection-mass crossing

Two progeny populations of upland cotton derived from mass selection-mass crossing, M₃S₂F₅ and its family lines M₃S₂F_5:6, were generated from 17 hybrid cotton lines derived from regional trials conducted in the Yellow River basin and Yangtze River basin in China. These populations were used to verify 39 reported molecular markers that were related to quantitative trait loci (QTLs) for Verticillium wilt resistance of cotton. Only 12 of 39 markers were polymorphic; 19 had no polymorphisms, and amplification failed for eight markers. The differences in disease grades of aa/AA genotype individuals for five markers, BNL3241, NAU1225, NAU1230, JESPR153, and BNL3031, reached either significant or highly significant levels in at least one population. These markers can thus be effectively used for marker-assisted selection (MAS) of the target trait. Especially for JESPR153 and BNL3031, the differences in disease grades of aa/AA genotype individuals both reached either significant or highly significant levels in the two populations. These two markers should be given preferential consideration when undertaking MAS. The two flanking markers were more effective than the single flanking marker for MAS of single-loci QTL. The selection effect will be greatly enhanced through a reasonable allocation of marker combinations for multi-locus QTL polymerization. When using multi-locus markers for multi-locus QTL-assisted polymerization breeding, the selection effect can be improved progressively by increasing the number of polymerization markers. The possible interaction of different QTLs or genetic backgrounds does not influence the selection effect. A combination of resistant genotypes and disease grade performance enabled final selection of three individuals resistant to Verticillium wilt.     

Construction of a genetic linkage map and QTL analysis of fiber-related traits in upland cotton (Gossypium hirsutum L.)

A genetic linkage map with 70 loci (55 SSR, 12 AFLP and 3 morphological loci) was constructed using 117 F₂ plants obtained from a cross between two upland cotton cultivars Yumian 1 and T586, which have relatively high levels of DNA marker polymorphism and differ remarkably in fiber-related traits. The linkage map comprised of 20 linkage groups, covering 525 cM with an average distance of 7.5 cM between two markers, or approximately 11.8% of the recombination length of the cotton genome. The present genetic linkage map was used to identify and map the quantitative trait loci (QTLs) affecting lint percentage and fiber quality traits in 117 F_2:3 family lines. Sixteen QTLs for lint percentage and fiber quality traits were identified in six linkage groups by multiple interval mapping: four QTLs for lint percentage, two QTLs for fiber 2.5% span length, three QTLs for fiber length uniformity, three QTLs for fiber strength, two QTLs for fiber elongation and two QTLs for micronaire reading. The QTL controlling fiber-related traits were mainly additive, and meanwhile including dominant and overdominant. Several QTLs affecting different fiber-related traits were detected within the same chromosome region, suggesting that genes controlling fiber traits may be linked or the result of pleiotropy.     

Using three selected overlapping RILs to fine-map the yield component QTL on Chro.D8 in Upland cotton

Cotton yield improvement is vital to fulfill rising global demands. The identification of major quantitative trait loci (QTL) for yield components was helpful in molecular marker-assisted selection (MAS) to improve cotton yield. We previously identified a densely populated QTL region for fiber qualities and yield components on chromosome D8 (Chro.D8) of Upland cotton from a (7235 × TM-1)RIL. In the present study, to fine-map yield component QTLs, we chose three overlapped recombinant inbred lines (RILs) with different intervals included the yield component QTLs, and backcrossed each line with TM-1 to develop three large sized mapping populations. Phenotypic data for yield components were collected in Nanjing (JES/NAU) and Xinjiang (BES/XJ) in 2006 and 2007. Three simple sequence repeat (SSR) genetic linkage maps on chro.D8 were constructed using 907 individuals in (7TR-133 × TM-1)F₂ (Pop A), 670 in (7TR-132 × TM-1)F₂ (Pop B), and 940 in (7TR-214 × TM-1)F₂ (Pop C). Three stable QTLs for boll size, two for lint percentage and one for boll number per plant,were detected on chro.D8 following analysis of three RIL backcrossed F₂/F_2:3 progeny at JES/NAU and BES/XJ although their cultivation practices differ greatly between these two cotton-growing regions. One QTL for boll number per plant exhibited a phenotypic variance (PV) of 5.6–10.1%, three QTLs for boll size exhibited 15.0–35.5% PV and two lint percentage QTLs exhibited 10.9–19.3% PV. Negative correlation between lint yield and fiber strength was confirmed.     

多环境下陆地棉(Gossypium hirsutum L.)重组自交系铃重与衣分性状的QTL分析

本研究利用以SGK9708为母本,0-153为父本构建的196个陆地棉重组自交系(F6:8)构建了包含186个标记,总长827.84 cM,标记间平均距离4.45 cM,覆盖棉花基因组18.6%的遗传连锁图谱,并对7个环境下的铃重和衣分性状进行QTL定位和上位性互作分析.利用两种分析软件(WinQTLcart2.5和Q...     

T1 locus in cotton is the candidate gene affecting lint percentage, fiber quality and spiny bollworm (Earias spp.) resistance

A genetic linkage map of chromosome 6 was constructed by using 270 recombinant inbred lines originated from an upland cotton cross (Yumian 1 × T586) F₂ population. The genetic map included one morphological (T₁) and 18 SSR loci, covering 96.2 cM with an average distance of 5.34 cM between two markers. Based on composite interval mapping (CIM), QTL(s) affecting lint percentage, fiber length, fiber length uniformity, fiber strength and spiny bollworm resistance (Earias spp.) were identified in the t₁ locus region on chromosome 6. The allele(s) originating from T586 of QTLs controlling lint percentage increased the trait phenotypic value while the alleles originating from Yumian 1 of QTLs affecting fiber length, fiber length uniformity, fiber strength and spiny bollworm resistance increased the trait phenotypic value.     

New QTLs for lint percentage and boll weight mined in introgression lines from two feral landraces into Gossypium hirsutum acc TM‐1

Overuse of a small number of Upland cotton cultivars has narrowed cotton's genetic base, leading to major difficulties in developing cotton cultivars with diverse genetic backgrounds that are able to adapt to adverse conditions. To effectively broaden the genetic base, chromosome introgression lines (ILs) were developed, where TM‐1, the genetic standard of Upland cotton, was used as the common recipient and its two feral landraces, TX‐256 and TX‐1046, were used as the donors. A total of 115 ILs, with an average segment length of 11.15 cM, were first developed via intraspecific hybridization by marker‐assisted selection (MAS) in BC₃F₂ generations, spanning 3887.75 cM of the cotton genome. Association analysis showed that 63 markers were found to be associated with boll weight (BW), lint percentage (LP) and seed index. The percent of phenotypic variance explained by 148 QTLs detected was 4.12% on average. Eleven and five new QTLs for BW and LP (one stable QTL identified for LP in all environments) were detected, respectively, which can be used for efficiently pyramiding favourable alleles into one cultivar by MAS.     

Mapping QTLs of traits contributing to yield and analysis of genetic effects in tetraploid cotton

Fiber yield and yield components – including lint index (LI), seed index (SI), lint yield (LY), seed cotton yield (SCY) and number of seeds per boll (NSPB) – were investigated on the farm of Huazhong Agricultural University in a population of 69 F₂ individuals and corresponding F_2:3 families derived from a cross between high-fiber-yield Gossypium hirsutum CV Handan 208 and a low-fiber-yield Gossypium barbadense CV Pima 90. On the basis of the genetic map constructed previously from the same population by Lin et al. (Plant Breed., 2005), quantitative trait locus (QTL) analysis was performed with the software QTL Cartographer V2.0 using composite interval mapping method (LOD ≥ 3.0). A total of 21 QTLs were identified, which were located in 15 linkage groups. The number of QTLs per trait ranged from one to seven. Of these QTLs detected, one affecting LI explained 24.3% of phenotypic variation (PV), five influencing SI explained 16.15–39.21% of PV, seven controlling LY explained 13.01–28.35% of PV, and two controlling SCY explained 22.76 and 39.97% of PV, respectively. Simultaneously, the detected six QTLs for NSPB were located on five linkage groups, which individually explained 28.01–38.32% of the total phenotypic variation. The results would give breeders further insight into the genetic basis of fiber yield.