水稻幼苗耐Al3+胁迫的QTL定位分析

用珍汕97B/密阳46构建RIL群体及其遗传图谱,对其种子采用纸培法育苗和培养,并设2个Al³⁺浓度（20 mg/L和30 mg/L）胁迫处理,以处理20 d后的幼苗相对根长（%）和相对苗高（%）为耐Al3+胁迫指标,用于QTL定位分析。结果表明,以相对根长为指标,检测到2个耐Al³⁺胁迫的主效应QTL,即qRAC(r)2和qRAC(r)11,其中qRAC(r)2在2个胁迫处理下均被检测到,有效基因来自于珍汕97B,贡献率较大（12.92%和16.15%）,表现出较强的耐Al³⁺胁迫功能。以相对苗高为指标,还检测到qRAC(s)11-2（20 mg/L Al³⁺）和qRAC(s)11-1（30 mg/L Al³⁺）2个主效应QTL,它们均位于第11染色体。耐Al³⁺胁迫的QTL上位性分析还表明,总的QTL上位性互作效应比主效应QTL的作用更大,且显示出相当的复杂性,在不同胁迫浓度下,基因间可以通过不同的互作方式,表现出对高Al³⁺胁迫的耐性。以相对根长为指标,检测到8对上位性互作,涉及1、2、3、5、6、10等6条染色体的15个QTL位点;以相对苗高为指标,共检测到6对上位性互作,涉及第1、2、3、5、6、7、8、9、12等9条染色体;且几乎所有互作均发生在背景因子的QTL位点间。     

大田环境下玉米抗旱相关性状QTL定位

干旱是世界范围内导致玉米产量损失的主要因素。为了阐明玉米抗旱性的遗传基础并定位相关的数量性状位点,利用抗旱自交系临1和敏感的湘97-7组配160个F2:3家系定位群体,于2011年在湖南省作物研究所和长沙县高桥镇,分别在大田干旱胁迫和正常水分条件下进行表型鉴定。所考察性状包括抽雄至吐丝间隔、株高、千粒重和产量,用抗旱系数来衡量抗旱性。结果表明,110个SSR标记构建连锁图,图谱总长1246.1 cM,标记间平均距离11.33 cM。抗旱相关性状定位的QTL介于8～14个,共检测到43个QTL。单个QTL解释的表型变异为6.27%～18.27%。不同水分条件下定位到的QTL大多数不相同,表明对干旱胁迫的适应存在不同机制。抗旱性相关性状定位到的QTL,除第2和10染色体外,在其它染色体上都有分布,主要集中在第1染色体1.02-03区域和1.06-07区域,以及第3染色体3.04-05区域。第1染色体标记umc2224和bnlg176区间同时检测到与株高、千粒重和产量有关的QTL簇;标记bnlg1556和umc1128区间检测到与抽雄至吐丝间隔和产量有关的QTL簇。第3染色体标记umc1773和umc1311区间同时检测到与株高、千粒重和产量有关的QTL簇。这些QTL簇可能有助于通过分子标记辅助选择的方法提高干旱地区玉米的抗旱性。     

模拟干旱条件下水稻苗期形态性状的QTL定位

以抗旱性差异较大的亲本小白粳子和空育131以及其后代180个F2∶3家系群体为试验材料,构建了包含99个SSR分子标记的遗传连锁图谱,利用浓度为15％PEG-6000模拟干旱胁迫条件.在两种条件下,共检测到影响胚芽鞘长、苗高、主根长和根数的QTL 26个,分别位于水稻的第1、2、3、4、5、6、7、8、12条染色体上,贡献率变幅在4.53％～37.22％之间.其中控制苗高的QTL11个,控制胚芽鞘长的QTL 5个,控制主根长的QTL 5个,控制根数的QTL 5个.在第2条染色体的RM1358-RM1347区间和第6条染色体上的RM461-RM162区间发现了控制多个性状的QTL,在第2条染色体的RM1358-RM1347区间和第8条染色体的RM1384-RM547区间还检测到了在两种条件下同时控制胚芽鞘长和主根长的QTL.     

灌溉与自然降雨条件下水稻高代回交导入系产量QTL的定位

利用254个Lemont导入到特青背景的高代回交导入系定位了灌溉（对照）与自然降雨（干旱胁迫）环境下影响单株籽粒产量及其穗部相关性状的QTL。在两种环境下共检测到32个影响单株粒籽产量、千粒重和每穗实粒数的主效QTL,根据不同环境下表达的情况将其分成3类,第1类10个QTL,在两种环境下均被检测到;第2类14个QTL,只在对照条件下检测到;第3类8个QTL,受干旱胁迫诱导,只在胁迫条件下被检测到。此外还检测到9个影响胁迫与对照条件下性状差值的QTL。认为在两种条件下均检测到的相对稳定的3个QTL（QGn11b、QGn12和QGn11b）及影响两种条件下性状差值（即性状稳定性）的9个QTL可能对耐旱性有直接贡献。在所有12个耐旱QTL中,除在QGn5和QGy1的Lemont等位基因减小性状差值（即增强耐旱性）外,其余位点上增强耐旱性的等位基因均来自特青。另外通过与源自相同亲本的不同定位群体在不同环境下定位结果的比较,鉴别出一些受遗传背景和环境影响较小的QTL如QGn3b、QGw1、QGw5、QGy1、QGy5、QGy8和QGy10。对应用QTL定位结果进行标记辅助选择培育耐旱品种进行了探讨。     

水稻幼苗耐Al3+胁迫的QTL定位分析

用珍汕97B/密阳46构建RIL群体及其遗传图谱，对其种子采用纸培法育苗和培养，并设2个Al³⁺浓度（20 mg/L和30 mg/L）胁迫处理，以处理20 d后的幼苗相对根长（%）和相对苗高（%）为耐Al3+胁迫指标，用于QTL定位分析。结果表明，以相对根长为指标，检测到2个耐Al³⁺胁迫的主效应QTL，即qRAC(r)2和qRAC(r)11，其中qRAC(r)2在2个胁迫处理下均被检测到，有效基因来自于珍汕97B，贡献率较大（12.92%和16.15%），表现出较强的耐Al³⁺胁迫功能。以相对苗高为指标，还检测到qRAC(s)11-2（20 mg/L Al³⁺）和qRAC(s)11-1（30 mg/L Al³⁺）2个主效应QTL，它们均位于第11染色体。耐Al³⁺胁迫的QTL上位性分析还表明，总的QTL上位性互作效应比主效应QTL的作用更大，且显示出相当的复杂性，在不同胁迫浓度下，基因间可以通过不同的互作方式，表现出对高Al³⁺胁迫的耐性。以相对根长为指标，检测到8对上位性互作，涉及1、2、3、5、6、10等6条染色体的15个QTL位点；以相对苗高为指标，共检测到6对上位性互作，涉及第1、2、3、5、6、7、8、9、12等9条染色体；且几乎所有互作均发生在背景因子的QTL位点间。     

盐、碱胁迫下水稻苗期根数和根长的QTL分析

在盐、碱胁迫条件下,分析水稻苗期的根数和根长并定位其QTL位点,为水稻的耐盐性和耐碱性的遗传机制及分子标记辅助育种提供理论基础。以盐碱敏感水稻品种东农425与强耐盐碱水稻品种长白10为亲本构建的重组自交系(RIL)为作图群体,在盐胁迫140 mmol/L的NaCl和碱胁迫0. 15%Na_2CO_3的处理条件下,以正常浇灌为对照,进行水稻苗期时根数和根长的测定,利用QTL IciMapping v3. 3软件的完备区间作图法(ICIM)分别对盐、碱胁迫和对照条件下水稻的根数和根长进行QTL分析。检测到18个加性效应QTL,在第1,2,3,4,5,7,8,9和10染色体上,LOD值为2. 01～3. 35,表型变异的贡献率为6. 02%～20. 06%。自然条件下,检测到4个与根数相关的QTL,qNRN7-2贡献率最大,为12. 46%,未检测到根长相关的QTL。在盐胁迫下,共检测到5个与根长、根数相关的QTL,qSRN3的贡献率最大,为20. 06%。在碱胁迫下,共检测到与根数和根长相关的3个QTL,qARN2的贡献率为12. 99%; qARL3和qARL5的贡献率分别为7. 04%和8. 88%。共检测到4个自然条件与盐胁迫差值的根数和根长相关的QTL,其中,qNSRN8-2和qN-SRL1贡献率较大,分别为14. 01%和14. 12%。在自然条件与碱胁迫的差值条件下,共检测到2个与根长、根数相关的QTL,分布在3,10号染色体上;检测到1个与根数相关的QTL,位于3号染色体上的qN-ARN3,贡献率为6. 02%;检测到1个与根长相关的QTL,位于10号染色体上的qN-ARL10,贡献率为7. 45%。在盐胁迫和碱胁迫条件下,水稻苗期的根数和根长都受到明显影响,相对于盐胁迫,水稻对碱胁迫更为敏感。     

水稻第2染色体上抗旱相关性状QTL的精细定位

水资源危机使得水稻抗旱性的遗传与育种研究成为当今的研究热点之一。鉴定与水稻抗旱性直接相关的性状和产量的QTL,可为通过标记辅助选择培育抗旱水稻品种提供标记信息。以从供体IRAT109渗入到珍汕97B背景的269个高代回交渗入系中筛选出覆盖第2染色体目标区段的87个近等基因系为材料,在抗旱鉴定大棚中采用控制式供水,精细定位了水处理(对照)与干旱胁迫条件下影响水稻水分生理及产量相关性状的QTL。共检测到20个影响叶水势(LWP)、冠层温度(CT)、茎基粗(BCT)等性状相关QTL和百粒重(HGW)、每穗颖花数(SN)、着粒密度(SPD)等产量相关QTL。根据在不同环境下的表达情况,将其分为3类,第1类7个QTL,在两种环境下均被检测到;第2类4个,只在对照条件下检测到;第3类2个,分别控制叶水势和颈基粗,受干旱胁迫诱导,只在胁迫条件下被检测到,其中,叶水势定位在RIO02037-RIO02038约8.2 kb的区段上, 其加性效应和贡献率分别为-1.0361和13.03%,增效等位基因来自IRAT109;茎基粗定位在RIO02017-RIO02022约37.7 kb的区段内,加性效应和贡献率分别为0.2682和49.20%,增效等位基因来自珍汕97B。在水、旱2种条件下均检测到的相对稳定的7个QTL及干旱胁迫条件下的2个QTL可能对抗旱性有直接贡献。     

甘蓝型油菜耐盐和耐旱相关性状的QTL分析

盐胁迫和干旱胁迫是非生物胁迫中影响作物产量的重要因素,检测与耐盐和耐旱相关的QTL,可为抗逆油菜品种的选育提供理论依据。本研究利用德国冬性甘蓝型油菜Express和中国半冬性甘蓝型油菜SWU07为亲本构建的包含261个株系的双单倍体(doubled haploid,DH)群体,分别以1.2%NaCl溶液和20%PEG-6000溶液作为培养液模拟盐胁迫和干旱胁迫,去离子水为对照,对2个亲本和DH群体进行发芽试验。播种后7 d测定幼苗根长、鲜重及发芽率,计算各性状在盐胁迫和干旱胁迫下的相对值,并作为评价耐盐和耐旱的指标。根据已构建的遗传连锁图谱进行QTL定位。盐胁迫下,在3次重复中共检测到与盐胁迫相关的QTL 12个,分布在A02、A03、A05、A09、C01和C09染色体上,单个QTL可解释的表型变异为3.61%~10.59%,其中5个QTL在不同的重复中被检测到。干旱胁迫下,共检测到与干旱胁迫相关的QTL 9个,分布在A01、A02、A03、A05、A09、A10和C03染色体上,单个QTL可解释的表型变异为3.94%~12.90%,其中2个QTL在不同的重复中被检测到。此外,在A02和A03染色体上检测到与2种胁迫都相关的相互交叠的QTL。这些结果可为油菜耐盐和耐旱性改良提供更多遗传信息。     

太湖流域粳稻两类群体种子活力性状有利等位变异的发掘

发掘粳稻种子活力性状的优异等位变异和携带优异等位变异的载体材料可为培育适于直播的高活力粳稻品种提供遗传信息和育种材料。以太湖流域粳稻94个品种构成的自然群体和粳稻品种秀水79与粳稻恢复系C堡衍生的247个重组自交家系(RIL)群体为试验材料,利用斜板发芽法发芽,调查生长7d的幼苗根长、苗高和干重3个种子活力性状,采用Tassel软件中的GLM方法和Win QTL Cartographer2.5软件中的CIM方法进行种子活力性状的QTL分析,发掘有利等位变异和相应载体品种。结果表明:(1)在太湖流域粳稻自然群体中共检测到11个与种子活力性状相关联的SSR标记位点,共发掘出42个控制种子活力性状的优异等位变异,其中控制根长的17个,控制苗高的13个,控制幼苗干重的12个。携带种子活力性状优异等位变异且效应值较大的载体材料有滇屯502选早、扬稻6号、开青、籼恢429和C堡等。(2)在RIL群体中共检测到9个与种子活力性状相关的QTL,其中2个控制根长,4个控制苗高,3个控制幼苗干重。除控制幼苗干重的qDW-2a的有利等位变异RM525-143bp来自秀水79以外,其余8个位点的有利等位变异均来自C堡。(3)两类群体均在第1染色体上检测到与根长关联的SSR标记位点,均在第2、第8和第11染色体上检测到与苗高关联的位点,均在第2染色体上检测到与幼苗干重关联的位点,且在自然群体中检测到优于和多于家系群体的等位变异。     

基于SNP遗传图谱定位盐、旱胁迫下甘蓝型油菜种子发芽率的QTL

研究盐胁迫、干旱胁迫下甘蓝型油菜的发芽率,寻找与发芽率相关联的分子标记,可为油菜逆境胁迫下种子萌发的分子标记辅助育种提供理论依据。本研究以甘蓝型黄籽油菜GH06和甘蓝型黑籽油菜P174为亲本,通过单粒传法(single seed descent, SSD)连续自交9代构建重组自交系群体。采用16 g L^–1的NaCl溶液进行盐胁迫,20% (W/W)的PEG-6000溶液模拟干旱胁迫,处理重组自交系种子并统计其发芽率。实验室构建的SNP遗传图谱,包含2795个SNP多态性标记位点,总长1832.9 cM,相邻标记间平均距离为0.66 cM,利用该图谱并采用复合区间作图法(CIM)分析两种胁迫条件下第3天、第4天及累计4 d后发芽率的QTL。共检测到19个QTL,分布于A01、A03、A06、A07、A09和C06染色体上。其中,11个盐胁迫相关的QTL可解释的变异为4.9%~10.9%,8个干旱胁迫相关的QTL可解释的变异为3.8%~6.9%;并且在A03和A09染色体上,盐胁迫和干旱胁迫下检测到的QTL有相近区段。研究结果表明油菜种子发芽率属于典型的数量性状,受环境影响较大;且随着胁迫时间的延长,油菜种子启动了不同的基因来响应环境胁迫。     

Mapping QTLs for seedling root traits in a doubled haploid wheat population under different water regimes

A deep and thick root system has a positive effect on wheat yield, particularly in drought environments. A doubled haploid (DH) population of 150 lines derived from the cross Hanxuan 10?×?Lumai 14 was used to map QTLs for seedling root characteristics. The DH lines were cultivated in an agarose gel-chamber under well-watered (WW) and water-stressed (WS) regimes. Water stress was simulated by adding mannitol to the agarose gel. The seminal root traits, including maximum root length (MRL), seminal root number, total root length, project root area, root surface area, and seminal root angle were measured after 6?days of seedling development. Grain yields (GY) were measured in a field experiment. A total of 29 QTLs were identified for seedlings cultured under WW regimes, and 23 QTLs under WS regimes. Individual QTL accounted for phenotypic variations ranging from 4.98 to 24.31?%. The QTLs were distributed on 17 chromosomes, except 1D, 4D, 6B and 6D. Seven consistently expressed QTLs were detected for all the traits tested except MRL under both water regimes. The QTLs for root traits were unevenly distributed among chromosomes, and clustered in eight loci on seven chromosomes, showing pleiotropic effects on target traits. One region in the interval Xgwm644.2?CP6901.2 on chromosome 3B contained 9 QTLs affecting most root traits. The present data provide an insight into the genetic basis of seedling root development under different water regimes and may benefit breeding programs using marker-assisted selection (MAS) for root traits.     

Molecular marker assisted tagging of morphological and physiological traits under two contrasting moisture regimes at peak vegetative stage in rice (Oryza sativa L.)

Root morphology under well-watered conditions sampled on two occasions and under low-moisture stress was studied in a randomly chosen subset of 56 doubled haploid lines derived from a cross between IR64 and Azucena at two growth stages during the vegetative stage. A molecular map of the same population served as the basis for locating QTLs controlling root morphology and associated traits. The region flanking the RFLP markers RZ730 and RZ801 on chromosome 1 were associated with plant height in all three sampling environments. This position corresponds to sd-1 a semi-dwarfing gene. A total of 15 QTL were detected at the two developmental stages, of which only three QTL were common. Region flanked by RG157 and RZ318 (chromosome 2) contained QTL for root thickness under two different developmental stages. In total, 21 QTL for different traits were detected under low-moisture stress condition. While two QTL for plant height on chromosomes 1 and 3 were common, none of the loci for root morphological traits was common between the two different moisture regimes. The chromosomal segment between RG171 and RG157 contained QTL controlling tiller number per plant, total root length, root volume and total root number per plant. Absence of common QTL for root traits between two developmental stages and two moisture regimes suggests the existence of parallel genetic pathways operating at different growth stages and moisture regimes. Root volume and total root number per plant decreased significantly under stress, whereas maximum root length and plant height exhibited non-significant increases under stress. This revised version was published online in July 2006 with corrections to the Cover Date.     

Detection of quantitative trait loci (QTLs) for seedling traits and drought tolerance in wheat using three related recombinant inbred line (RIL) populations

In order to detect quantitative trait loci (QTLs) for drought tolerance in wheat during seed germination conditional and unconditional QTL analyses of eight seedling traits were conducted under two water regimes using three related F₉ recombinant inbred line populations with a common female parent. A total of 87 QTLs for the eight seedlings traits and 34 specific QTLs related to drought tolerance were detected. Seventy-one of these QTLs were major QTLs with contributions to phenotypic variance of >10 %. Of the 34 QTLs related to drought tolerance only eight were also detected by unconditional analysis of seedling traits under osmotic stress conditions indicating that most of the QTLs related to drought tolerance could not be detected by unconditional QTL analysis. Therefore, conditional QTL analysis of stress-tolerance traits such as drought tolerance was feasible and effective. Of 11 important QTL clusters located on chromosomes 1BL, 1D, 2A, 2B, 2D, 4A, 6B, and 7B, nine were detected in multiple populations and eight were detected by both unconditional and conditional analyses.     

冷水胁迫下水稻幼苗期根系性状的QTL分析

本研究以籼粳交“密阳23/吉冷1号”的F_2∶3 代200个家系作为作图群体，在自然和12℃冷水胁迫下，进行水稻幼苗期根系性状的鉴定，并以利用SSR标记构建的分子连锁图谱为基础，对水稻幼苗期的根数、最大的根长、最大根的根径、根干重、根/苗比等根系性状进行了数量性状位点（QTLs）分析。结果表明，上述根系性状在F₃代家系群均表现为连续分布，认为是由多基因所控制的数量性状。冷水胁迫下，在第1、2、6、11和12染色体上共检测到与根系性状相关的QTL 17个，对表型变异的解释率为5.8%～15.2%，其中与最大根的根径相关，位于第2染色体RM263-RM6区间的qCRD2和位于第11染色体RM21-RM206区间的qCRD11，以及与根干重相关，位于第2染色体RM262-RM263区间的qCRWT2和位于第11染色体RM229-RM21区间的qCRWT11贡献率较大，分别为15.0%、15.2%、10.6%和12.2%。这些基因的作用方式为部分显性或显性或超显性。     

水稻苗期耐淹相关性状QTL分析

以相同淹水条件下存活率差异较大的籼稻TN1与粳稻春江06(CJ06)为亲本构建的DH群体为试材,考察了DH群体及其双亲与苗期耐淹相关的5个性状,各性状均表现为连续分布,且都存在一定数量的双向超亲遗传类型,受多基因控制。使用分子连锁图谱进行QTL分析,共检测到16个与苗期耐淹有关的QTL,包括4个中胚轴长度QTL、3个株高QTL、3     

Quantitative trait loci and candidate genes for yield and related traits in Madhukar x Swarna RIL population of rice

Yield of popular rice varieties such as Swarna grown in rainfed lowlands and Madhukar grown in flood prone areas needs to be continuously improved. Recombinant inbred lines (RILs) were developed from the cross between two indica cultivars Madhukar and Swarna. QTLs were mapped using 110 markers in 168 RILs. In all, 26 QTLs were mapped for yield and five related traits on chromosomes 1, 2, 3, 6, 7, 8, 10, 11, and 12. QTL for plant height and days to flowering were co-located between RM23147 — RM337 on chromosome 8. RM251, RM314, and RM1135 were significantly associated with plant height and OsYSL17 was significantly linked with grain yield. Epistatic interaction was detected for plant height and number of tillers. Several candidate genes reported for yield and related traits underlie the QTL regions.     

QTL mapping for seedling traits associated with low‐nitrogen tolerance using a set of advanced backcross introgression lines of rice

Nitrogen (N) deficiency is a major yield‐limiting factor in rice production. The objective of this study was to identify putative QTLs for low‐N stress tolerance of rice, using an advanced backcross population derived from crosses between an indica cultivar ‘93‐11’ and a japonica cultivar ‘Nipponbare’ and genotyped at 250 marker loci. Plant height, maximum root length, root dry weight, shoot dry weight and plant dry weight under two N conditions and their relative traits were used to evaluate low‐N tolerance at the seedling stage. A total of 44 QTLs were identified on chromosomes 1, 2, 3, 4, 5, 6, 8 and 9. Eight intervals on five chromosomes were identified to harbour multiple QTLs, suggesting pleiotropism or multigenic effects according to the contributor of alleles. Some QTL clusters were found in the nearby regions of genes associated with N recycling in rice, indicating that the key N metabolism genes might have effects on the expression of QTLs. Several unique QTLs for relative traits were detected, which suggested the specific genetic basis of relative performance.     

Mapping QTLs for potassium-deficiency tolerance at the seedling stage in wheat (Triticum aestivum L.)

Potassium (K) deficiency is a major factor limiting crop development and yield. In this study, 20 traits were investigated at the seedling stage using a doubled-haploid population subjected to normal K and K deprivation treatments. Evaluation of phenotypes expressed under the two K supply conditions revealed that K deprivation was able to decrease values of ten measured traits, whereas values of the other ten traits increased. A total of 65 QTLs were detected across all 21 chromosomes, except for chromosomes 2B, 5A, and 7B. Individual QTLs in the two K supply treatments explained between 5.35 and 39.64 % of the phenotypic variation. Nine QTL clusters (C1–C9) involving 34 QTLs under the different K supply treatments were mapped to chromosomes 1A, 1B, 1D, 3B, 4A, 5B, 6A, and 7B. Our results are helpful for understanding the genetic basis of K deficiency in wheat, and provide useful information for genetic improvement of K deficiency in wheat by marker-assisted selection.     

水稻株型相关性状的QTL分析

以南方籼型杂交稻恢复系泸恢99和北方粳型超级稻沈农265杂交衍生的重组自交系群体(recombinant inbred lines, RILs)为试验材料, 对株型性状(株高、穗长、分蘖和叶片性状)进行不同环境下的数量性状基因位点(quantitative trait locus, QTL)分析。共检测到39个相关QTL, 分布在水稻第1、第2、第3、第6、第7、第8和第9染色体上, LOD值介于2.50~16.90之间, 有11个QTL能在两年中被检测到。株型相关的QTL在染色体上成簇分布, 主要分布于第1、第6和第9染色体上, 这可能与株型性状间显著或极显著相关有关。其中, 在第9染色体上RM3700B–RM7424区间存在1个QTL簇, 含4个QTL, 即qPH9、qPL9、qFLL9和qSLL9, 这4个QTL在两年中均被检测到。此外, 进一步鉴定出5个能稳定表达的QTL, 其中, qPH8、qFLW6和qSLW6效应较大。这些信息综合反映了株型相关性状遗传的复杂性, 有助于我们更全面地了解和掌握株型性状的遗传基础。