秀水134为背景的染色体片段代换系的构建

染色体片段代换系作为发掘和鉴定有利基因的有力工具得到了广泛的应用。本研究以秀水134为背景亲本,以扬稻6号为供体亲本,构建了一套染色体片段代换系。该代换系包含53个株系,其代换片段长度在7.4～182.15 cM之间,占水稻全基因组的0.49%～12.15%,平均占水稻全基因组的5.0%。这套代换系的代换片段总长度为1 995 cM,覆盖水稻基因组的1.33倍。本文还对染色体片段代换系的构建策略和应用进行了讨论。     

以广东高州普通野生稻为供体亲本的水稻单片段代换系构建

以栽培稻品种粤香占为受体亲本,利用杂交、回交和微卫星标记辅助选择相结合的方法,构建了以高州普通野生稻为供体亲本的水稻单片段代换系群体。该群体由20个编号的9个单片段代换系构成。这9个单片段代换系分别分布在水稻的第1、2、3、10和11染色体上,代换片段长度为8.1～23.8cM,总长度为152.7cM,平均长度为17.0cM,代换片段对水稻基因组的覆盖总长度为136.1cM,覆盖率为7.5%。构建以高州普通野生稻为供体亲本的水稻单片段代换系,为发掘和利用高州普通野生稻的有利基因提供了理想的试验材料,为进一步开展高州普通野生稻的遗传研究提供了一条新途径。     

玉米优良自交系单片段代换系的构建

以优良自交系昌7-2为供体亲本、自交系9801为受体亲本,通过杂交、回交和供体染色体片段的SSR标记跟踪,构建以9801为遗传背景的昌7-2染色体单片段代换系群体,分析供体基因组成分在单片段代换系构建过程中的变化趋势。结果表明,共获得了74个以9801为背景的供体单片段代换系,片段长度为2.38～181.46 cM,平均长度为33.39 cM,导入片段总长为2 470.53 cM,染色体覆盖率为29%。     

水稻亚种间单片段代换系的建立

利用微卫星标记辅助选择,建立了29个以台中65为受体、低脚乌尖或窄叶青为供体的单片段代换系,该代换系群体的代换片段分布于9条染色体上,总长度为643.65 cM,平均长度为22.19 cM,覆盖全基因组427.55 cM,覆盖率为23.47%。     

基于基因组重测序信息构建玉米第5染色体的片段代换系

利用玉米自交系齐319与郑58杂交衍生的重组自交系群体,通过筛选剩余杂合体(RHL)以达到快速构建CSSLs的目的。在接近纯合的重组自交系群体中,结合基因组重测序信息扫描玉米第5染色体上的In Del位点,定点开发分子标记,筛选剩余杂合体进行自交快速获得了多个位点的染色体片段代换系。在玉米5号染色体的19 130 718 bp~214 379 898 bp区间内,共获得41个染色体片段代换系。两个染色体片段代换系位点间的间距为0.2~26.4 Mb,平均为2.5 Mb。其中8个染色体片段代换系群体中只含有1个多态位点,为单片段代换系。本研究所建立的CSSLs可为玉米第5染色体上QTL的精细定位及功能分析提供支撑,并为玉米育种提供中间材料。     

基于玉米87-1综3单片段代换系的穗长QTL分析

以优良玉米自交系综3为供体、87-1为受体,利用回交和SSR标记辅助选择相结合的方法,获得了51份纯合的染色体单片段代换系(Single Segment Substitution Line,SSSL),每个SSSL内只含有一个来源于供体的染色体片段。51个代换片段不均匀分布在玉米10条染色体上,代换片段长度在1.75～172.45 cM之间,平均长度为24.44cM。覆盖玉米基因组的总长度为933.90 cM,覆盖率为40.20%。2008年在郑州利用17份SSSL材料及在三亚利用39份SSSL材料对玉米穗长进行了1年2点的表型鉴定,共检测到20个穗长QTL,加性效率百分率在-12.10%～19.18%之间。结果表明,这些单片段代换系存在较大的遗传变异,是用于玉米复杂性状的QTL鉴定、基因克隆及功能分析的理想材料。     

小麦重要农艺性状QTL近等基因导入系的选育

为了给小麦重要农艺性状的QTL精细定位及克隆奠定基础,对14个从Am3/莱州953(轮回亲本)BC4F4代选出的性状表现与莱州953有明显差异的导入系的8个农艺性状进行了分析,结果表明,每个导入系有2～7个性状与莱州953差异显著,在每一个性状上都有对农艺性状具有正向效应的位点.利用143对在亲本之间具有多态性的SSR标记对导入系含有的供体片段进行了检测,其中54对引物在14个导入系中检测到了供体片段,每一个导入系中检测到3～15个纯合供体片段及0～4个杂合片段,占受体基因组的1.7%～14.2%,平均为7.48%.利用其中10个导入系与轮回亲本莱州953杂交的F2群体进行了单片段代换系的选择,从10个导入系的F2中检测到40个供体片段,并从F2群体中选出了22个单片段代换系.这些导入系及其单片段代换系可用于有益的QTL的发掘、QTL精细定位与作图等研究.     

栽培稻与普通野生稻BC2F2群体产量相关性状的QTL分析

以广陆矮4号(Oryza sativa ssp. indica)为母本及轮回亲本,普通野生稻（Oryza rufipogon）为父本,分单株连续回交2次,构建BC2F2群体。首先用241对具有双亲多态性的SSR标记对BC2F1单株进行代换片段分析,在此基础上,根据BC2F1的表型选产量较优的单株自交获得BC2F2群体,用代换片段上具有双亲杂合型基因型的24对SSR标记进行QTL定位。在所选的BC2F1单株上,共检测到分布于7条染色体上的20个野生稻的代换片段,平均每条染色体上有2.86个;代换片段长度最小为0.55 cM,最大为33.00 cM,平均长度为12.36 cM,总覆盖长度为247.20 cM,覆盖率为16.21%。利用BC2F2群体对14个产量相关性状进行QTL定位,共检测到控制8个性状的20个QTL。对性状表型值起增效作用的有11个,占总检出数的55%。控制产量相关性状的QTL存在簇状分布现象,这与表型相关分析结果相符合。     

作物染色体片段代换系的研究进展

染色体片段代换系是用亲本杂交、回交和分子标记辅助选择技术建立的一系列近等基因系,可以提高对复杂农艺性状QTL或基因定位的精确性,尤其是具有遗传效应的较小的数量性状基因位点,并进行遗传效应分析。目前,已在多种作物中构建了染色体片段代换系。本文对染色体片段代换系的特性及其在主要作物中的应用进行了综述,以期对今后研究染色体片段代换系起到促进作用。     

利用单片段代换系鉴定水稻株高及其构成因素的QTL

 通过t测验比较了单片段代换系与受体亲本华粳籼74之间的表型差异，对以6个水稻品种为供体的52个单片段代换系代换片段上株高及其构成因素的QTL进行了鉴定。以P≤0.001为阈值，在14个代换片段上共鉴定出24个QTL，包括10个株高QTL、2个穗长QTL、4个倒1节间长QTL、5个倒2节间长QTL、3个倒3节间长QTL，这些QTL分布于水稻的9条染色体上。QTL加性效应值为-4.08～3.98 cm，加性效应百分率为-19.35%～10.43%。     

Functional roles of root plasticity and its contribution to water uptake and dry matter production of CSSLs with the genetic background of KDML105 under soil moisture fluctuation

Soil moisture fluctuation (SMF) stress due to erratic rainfall in rainfed lowland (RFL) rice ecosystems negatively affect production. Under such condition, root plasticity is one of the key traits that play important roles for plant adaptation. This study aimed to evaluate root plasticity expression and its functional roles in water uptake, dry matter production and yield under SMF using three chromosome segment substitution lines (CSSLs) with major genetic background of KDML105 and a common substituted segment in chromosome 8. The CSSLs showed greater shoot dry matter production than KDML105 under SMF, which was attributed to the maintenance of stomatal conductance resulting in higher grain yield. The root system development based on total root length of the CSSLs were significantly higher than that of KDML105 due to the promoted production of nodal and lateral roots. These results implied that the common substituted segments in chromosome 8 of the 3 CSSLs may be responsible for the expression of their root plasticity under SMF and contributed to the increase in water uptake and consequently dry matter production and yield. These CSSLs could be used as a good source of genetic material for drought resistance breeding programs targeting rainfed lowland condition with fluctuating soil moisture environments and for further genetic studies to elucidate mechanisms underlying root plasticity.     

Identification of QTLs for Improvement of Plant Type in Rice (Oryza sativa L.) Using Koshihikari / Kasalath Chromosome Segment Substitution Lines and Backcross Progeny F2 Population

Abstract

Thirty-nine chromosome segment substitution lines (CSSLs) population derived from a Koshihikari / Kasalath cross was used for quantitative trait locus (QTL) analysis of plant type in rice (Oryza sativa L.). Putative rough QTLs (26.2～60.3cM of Kasalath chromosomal segments) for culm length, plant height, panicle number, chlorophyll content of flag leaf blade at heading and specific leaf weight, were mapped on the several chromosomal segments based on the comparison of CSSLs with Koshihikari in the field experiment for 3 years. In order to verify and narrow QTLs detected in CSSLs, we conducted QTL analyses using F₂ populations derived from a cross between Koshihikari and target CSSL holding a putative rough QTL. The qPN-2, QTL for panicle number was mapped on chromosome 2. In traits of flag leaf, the qCHL-4-1 and qCHL-4-2 for chlorophyll content was mapped on chromosome 4, and the qSLW-7 for specific leaf weight on chromosome 7. All QTLs were detected in narrow marker intervals, compared with rough QTLs in CSSLs. The qPN-2, qCHL-4-1 and qCHL-4-2 had only additive effect. On the other hand, the qSLW-7 showed over-dominance. It could be emphasized that QTL analysis in the present study with the combination of CSSLs and backcross progeny F₂ population can not only verify the rough QTLs detected in CSSLs but also estimate allelic effects on the QTL.     

利用染色体片段置换系群体检测水稻叶片形态QTL

 水稻叶片的形态改良是水稻株型育种和产量育种的重要目标之一。以9311/日本晴染色体片段置换系（CSSLs）群体为材料,定位了上3叶叶片长、宽、叶面积共9个性状QTL,分析了叶片性状与产量性状之间的相关性,同时定位了主穗重及产量构成因素（颖花数、千粒重、结实率）相关QTL。结果表明,CSSLs群体的叶片性状之间存在显著或极显著相关性;叶片性状与主穗重呈显著或极显著正相关,与主穗颖花数呈极显著正相关;叶片形态多数性状与结实率、千粒重没有显著相关性。两年共定位到20个叶片性状QTL,分布于第1、3、4、5、6、9、11共7条染色体的10个区间,贡献率为3.82%~14.61%,其中贡献率大于10%有6个,多个QTL成簇分布在相同区间,3个QTL在两年间重复检测到,8个QTL为前人未报道的新位点。两年共检测到16个与控制主穗产量相关的QTL,分布于第1、2、3、5、7、8、10共7条染色体13个区间,其中有7个主穗产量相关QTL所在5个区间与叶片形态14个QTL所在区间一致。     

Chromosome Segment Substitution Lines: A Powerful Tool for the Introgression of Valuable Genes from Oryza Wild Species into Cultivated Rice (O. sativa)

Wild species of rice (genus Oryza) contain many useful genes but a vast majority of these genes remain untapped to date because it is often difficult to transfer these genes into cultivated rice (Oryza sativa L.). Chromosome segment substitution lines (CSSLs) and backcross inbred lines (BILs) are powerful tools for identifying these naturally occurring, favorable alleles in unadapted germplasm. In this paper, we present an overview of the research involving CSSLs and BILs in the introgression of quantitative trait loci (QTLs) associated with the improved performance of rice including resistance to various biotic and abiotic stresses, and even high yield from wild relatives of rice and other unadapted germplasm into the genetic background of adapted rice cultivars. The CSSLs can be used to dissect quantitative traits into the component genetic factors and evaluate gene action as single factors (monogenic loci). CSSLs have the potential to uncover new alleles from the unadapted, non-productive wild rice accessions, develop genome-wide genetic stocks, and clone genes identified in QTL studies for functional genomics research. Recent development of high-density single-nucleotide polymorphism (SNP) arrays in rice and availability of custom-designed medium- and low-density SNP arrays will enhance the CSSL development process with smaller marker-defined segment introgressions from unadapted germplasm.     

利用染色体片段置换系定位水稻赖氨酸含量的QTL

 以籼稻品种9311为受体、粳稻品种日本晴为供体构建95个染色体片段置换系, 对水稻控制赖氨酸含量的QTL进行了定位。结果显示, 共有7个染色体片段置换系（chromosome segment substitution line, CSSL）的稻米赖氨酸含量与亲本9311差异显著。利用代换作图法共鉴定了4个与赖氨酸含量相关的QTL, 分别位于水稻第8、9和12染色体上。其中qHLY8和qHLY9.2来自高赖氨酸含量籼稻品种9311, 正向加性效应百分率分别为9.6%和8.5%;而qHLY9.1和qHLY12则来自低赖氨酸含量粳稻品种日本晴, 负向加性效应百分率分别为-16.0%和-21.3%。     

Detection of QTL for Cold Tolerance at Bud Bursting Stage Using Chromosome Segment Substitution Lines in Rice (Oryza sativa)

The cold tolerance at the bud bursting stage (CTB) was evaluated at 5°C by using a set of 95 chromosome segment substitution lines (CSSLs) derived from an indica rice 9311 and a japonica rice Nipponbare with a genetic background of 9311. The result showed that six CSSLs had slightly stronger effect on CTB than 9311. Total four quantitative trait loci (QTLs) for CTB were preliminary mapped on chromosomes 5 and 7 by substitution mapping. qCTB-5-1, qCTB-5-2 and qCTB-5-3 were mapped in the region of RM267-RM1237, RM2422-RM6054 and RM3321-RM1054, which were 21.3 cM, 27.4 cM and 12.7 cM in genetic distance on rice chromosome 5, respectively. qCTB-7 was mapped in a 6.8-cM region of RM11-RM2752 on rice chromosome 7.     

Assessment of Genetic Diversity of Drought Tolerant and Susceptible Rice Genotypes Using Microsatellite Markers

The introgression of wild chromosomal segments into popular rice varieties is one of the potential approaches for developing varieties for drought stress condition. Sixteen genotypes, including nine indica, two tropical japonica and five chromosome segments substitution lines(CSSLs) with different levels of tolerance/susceptibility to drought stress, were selected for diversity study. Sixty-three microsatellite markers were utilized for assessing genetic diversity. A total of 95 alleles were amplified, and out of them, 60 were polymorphic. Six unique alleles, amplified by the microsatellite loci RM276, RM472,RM488, RM537, RM541 and RM28089, were identified in six genotypes, namely FR13A, Brahamanakhi,RUF44, Swarna-sub1, Brahamanakhi and Satyabhama. The highest genetic similarity was found among CSSLs. Polymorphism information content(PIC) value varied from 0 to 1.00 with an average of 0.66 per locus. Twenty-eight microsatellites were found to be polymorphic, which could be used in marker-assisted selection programme. All the sixteen genotypes were grouped into two major clusters at genetic similarity of 0.64. In the cluster I, five CSSLs identified as diverse genotypes had wild ancestor segments responsible for drought tolerance, and hence they could be utilized as potential donors. The popular Indian varieties, Swarna-sub1 and IR64-sub1, could be used as recurrent parents in the future breeding program for developing varieties for abiotic stresses such as submergence and drought.     

QTL analysis of cold tolerance at seedling stage in rice (Oryza sativa L.) using recombination inbred lines

Cold tolerance at seedling stage of rice (Oryza sativa L.) is a favorable trait for the stable establishment in temperate and high-elevation areas. In the present study, 71 recombinant inbred lines (RIL) derived from the cross of Asominori (Japonica) and IR24 (Indica) were used to identify quantitative trait loci (QTL) affecting cold tolerance at seedling stage. The putative QTL was further confirmed using some chromosome segment substitution lines (CSSLs), in which IR24 was used as the donor parent and Asominori as the recurrent parent. The average seedling mortality was used as cold tolerance after cold treatment with 6 °C for 7 days and recovery culture with 25 °C for 4 days at three-leaf seedling stage. Three QTL affecting cold tolerance at seedling stage were detected on chromosomes 1, 5 and 6 with LOD scores ranging from 2.2 to 4.1 using composite interval mapping (CIM). Among them, qSCT-1 located in the region of XNpb87-2-C955 on chromosome 1 was a major QTL which explained 24.51% of total phenotypic variance and favorable allele came from japonica parent, Asominori. In addition, IR24 alleles at the other two loci (qSCT-5 and qSCT-6) increased cold tolerance. And these three QTL were confirmed by four lines from the IR24 CSSLs. Transferring favorable allele from japonica variety to indica background or pyramiding different QTL identified from indica is an effective way to improve cold tolerance of rice.     

不同环境下稻米品质性状QTL的检测及稳定性分析

【目的】挖掘新的稻米品质性状QTL并利用分子育种技术改良稻米品质。【方法】利用构建的一套以籼稻香型恢复系昌恢121为背景亲本,以优质粳稻越光为供体亲本的染色体片段代换系（CSSLs）为材料,在4个环境下对稻米品质性状进行QTL检测及稳定性分析。【结果】在4个环境下共检测到44个QTL,其中6个QTL能在多个环境下被检测到;第2、3、5、6和10染色体上存在多效QTL簇,对稻米品质性状具有明显的调控作用;第1、6和12染色体上7个QTL能在不同环境下稳定表达。【结论】第1染色体RM3143-RM1117区间qPGWC1和第12染色体RM3331-RM5479区间qPaT12是两个新的稳定表达QTL。     

不同环境下稻米品质性状QTL的检测及稳定性分析

【目的】挖掘新的稻米品质性状QTL并利用分子育种技术改良稻米品质。【方法】利用构建的一套以籼稻香型恢复系昌恢121为背景亲本，以优质粳稻越光为供体亲本的染色体片段代换系（CSSLs）为材料，在4个环境下对稻米品质性状进行QTL检测及稳定性分析。【结果】在4个环境下共检测到44个QTL，其中6个QTL能在多个环境下被检测到；第2、3、5、6和10染色体上存在多效QTL簇，对稻米品质性状具有明显的调控作用；第1、6和12染色体上7个QTL能在不同环境下稳定表达。【结论】第1染色体RM3143−RM1117区间qPGWC1和第12染色体RM3331−RM5479区间qPaT12是两个新的稳定表达QTL。