Quantitative Trait Loci for Resistance to Stripe Disease in Rice(Oryza sativa)

In order to map the quantitative trait loci for rice stripe resistance, a molecular linkage map was constructed based on the F2 population derived from a cross between Zhaiyeqing 8 and Wuyujing 3. Reactions of the two parents, F1 individual and 129 F2：3 lines to, rice stripe were JnvestJgated by both artificial Jnoculation at laboratory and natural infection in the field, and the ratios of disease rating index were scored. The distribution of the ratios of disease rating index in Zhaiyeqing 8/Wuyujing 3 F2：3 population ranged from 0 to 134,08 and from 6.25 to 133.6 under artificial inoculation at laboratory and natural infection in the field, respectively, and showed a marked bias towards resistant parent （Zhaiyeqing 8）, indicating that the resistance to rice stripe was controlled by quantitative trait loci （QTL）. QTL analysis showed that the QTLs detected by the two inoculation methods were completely different. Only one QTL, qSTVT, was detected under artificial inoculation, at which the Zhaiyeqing 8 allele increased the resistance to rice stripe, while two QTLs, qSTV5 and qSTV1, were detected under natural infection, in which resistant alleles came from Zhaiyeqing 8 and Wuyujing 3, respectively. These results showed that resistant parent Zhaiyeqing 8 carried the alleles associated with the resistance to rice stripe virus and the small brown planthopper, and susceptible parent Wuyujing 3 also carried the resistant allele to rice stripe virus. In comparison with the results previously reported, QTLs detected in the study were new resistant genes to rice stripe disease. This will provide a new resistant resource for avoiding genetic vulnerability for single utilization of the resistant gene Stvb-i.

Quantitative trait loci detection of E dwardsiella tarda resistance in Japanese flounder Paralichthys olivaceus using bulked segregant analysis

In recent years, Edwardsiella tarda has become one of the most deadly pathogens of Japanese fl ounder( Paralichthys olivaceus), causing serious annual losses in commercial production. In contrast to the rapid advances in the aquaculture of P. o livaceus, the study of E. tarda resistance-related markers has lagged behind, hindering the development of a disease-resistant strain. Thus, a marker-trait association analysis was initiated, combining bulked segregant analysis(BSA) and quantitative trait loci(QTL) mapping. Based on 180 microsatellite loci across all chromosomes, 106 individuals from the F1333(♀: F0768 ×♂: F0915)(Nomenclature rule: F+year+family number) were used to detect simple sequence repeats(SSRs) and QTLs associated with E. tarda resistance. After a genomic scan, three markers(Scaffold 404-21589, Scaffold 404-21594 and Scaffold 270-13812) from the same linkage group(LG)-1 exhibited a signifi cant difference between DNA, pooled/bulked from the resistant and susceptible groups( P <0.001). Therefore, 106 individuals were genotyped using all the SSR markers in LG1 by single marker analysis. Two different analytical models were then employed to detect SSR markers with different levels of signifi cance in LG1, where 17 and 18 SSR markers were identifi ed, respectively. Each model found three resistance-related QTLs by composite interval mapping(CIM). These six QTLs, designated q E1–6, explained 16.0%–89.5% of the phenotypic variance. Two of the QTLs, q E-2 and q E-4, were located at the 66.7 c M region, which was considered a major candidate region for E. tarda resistance. This study will provide valuable data for further investigations of E. tarda resistance genes and facilitate the selective breeding of disease-resistant Japanese fl ounder in the future.

QTL Mapping for Partial Resistance to Southern Corn Rust Using RILs of Tropical Sweet Corn

Southern corn rust is one of destructive diseases in maize caused by Puccinia polysora Undrew. A mapping population of tropical sweet corn recombinant inbred lines (RILs) derived from a cross between hA9104 and hA9035 inbred lines were set up to detect quantitative trait loci (QTLs) involved in partial resistance to southern corn rust. Eighty nine RILs were used to evaluate resistance levels using nine-point relative scale (1-9) at Sweet Seeds, Suwan Farm, Thailand include combined analysis. A genetic linkage map was constructed with 157 SSR markers, with a total length of 2123.1 cM, covering 10 chromosomes. Broad-sense heritability of individual location ranged from 0.76 and 0.82 and combined across locations was 0.87. Multiple QTL mapping (MQM) was applied for the identification of the QTLs. Fifteen QTLs were detected on chromosome 1, 2, 5, 6, 9 and 10 in both locations and combined across locations. QTLs on chromosome 1, 5 and 6 were contributed by alleles of resistant parent hA9104 while others were contributed by alleles from the susceptible parent, hA9035. Phenotypic variance of each QTL explained ranged from 6.1% to 41.8% with a total of 69.8% - 81.9%. QTL on chromosome 1, 6 and 10 were stable QTLs detected in both locations.

Relationship Between Coleoptile Length and Drought Resistance and Their QTL Mapping in Rice

By using a set of recombinant inbred line （RIL） population involving in 195 lines derived from a cross of Zhenshan 97B （lowland variety） and IRAT109 （upland variety）, the correlation analysis between coleoptile length （CL） and drought resistance index （DRI） and their QTL identification were conducted. There existed a significantly positive relationship between CL and DRI with the correlation coefficient of 0.2206＊＊ under water stress conditions. Under normal and water stress conditions, a total of eleven and four QTLs for CL and DRI, respectively, were detected on chromosomes 1,2, 4, 5, 6, 7, 9, 11 and 12 by using a linkage map including 213 SSR markers, which explained 4.84% to 22.65% of phenotypic variance. Chromosomes 1 and 9 possessing the QTLs for DRI harbored simultaneously QTLs for CL, and qCL9 shared the same chromosome location with qDR19 （RM160-RM215）. Comparing the QTLs related to drought resistance in other studies, QTLs for CL and DRI were located in the same or adjacent marker interval as those related to root traits, such as number, dry weight, depth, and length of root. Moreover, sixteen and three pairs of epistatic loci for CL and DRI were found, which accounted for 56.17% and 11.93% of the total variation in CL and DRI, respectively.

Identification of QTL for adult-plant resistance to powdery mildew in Chinese wheat landrace Pingyuan 50

Powdery mildew caused by Blumeria graminis f. sp. tritici is one of the major wheat diseases worldwide. The Chinese wheat landrace Pingyuan 50 has shown adult-plant resistance(APR)to powdery mildew in the field for over 60 years. To dissect the genetic basis of APR to powdery mildew in this cultivar, a mapping population of 137 double haploid(DH) lines derived from Pingyuan 50/Mingxian 169 was evaluated in replicated field trials for two years in Beijing(2009–2010 and 2010–2011) and one year in Anyang(2009–2010). A total of 540 polymorphic SSR markers were genotyped on the entire population for construction of a linkage map and QTL analysis. Three QTL were mapped on chromosomes 2BS(QPm.caas-2BS.2), 3BS(QPm.caas-3BS),and 5AL(QPm.caas-5AL) with the resistance alleles contributed by Pingyuan 50 explaining 5.3%,10.2%, and 9.1% of the phenotypic variances, respectively, and one QTL on chromosome 3BL(QPm.caas-3BL) derived from Mingxian 169 accounting for 18.1% of the phenotypic variance.QPm.caas-3BS, QPm.caas-3BL, and QPm.caas-5AL appear to be new powdery mildew APR loci.QPm.caas-2BS.2 and QPm.caas-5AL are possibly pleiotropic or closely linked resistance loci to stripe rust resistance QTL. Pingyuan 50 could be a potential genetic resource to facilitate breeding for improved APR to both powdery mildew and stripe rust.

Molecular and Physical Mapping of Powdery Mildew Resistance Genes and QTLs in Wheat: A Review

Wheat powdery mildew （Pro） is a major disease of wheat worldwide. During the past years, numerous studies have been published on molecular mapping of Pm resistance gene（s） in wheat. We summarized the relevant findings of 89 major re- sistance gene mapping studies and 25 quantitative trait loci （QTL） mapping studies. Major Pm resistance genes and QTLs were found on all wheat chromosomes, but the Pm resistance genes/QTLs were not randomly distributed on each chromosome of wheat. The summarized data showed that the A or B genome has more major Pm resistance genes than the D genome and chromosomes 1A, 2A, 2B, 5B, 5D, 6B, 7A and 7B harbor more major Pm resistance genes than the other chromosomes. For adult plant resistance （APR） genes/QTLs, B genome of wheat harbors more APR genes than A and D genomes, and chromo- somes 2A, 4A, 5A, 1B, 2B, 3B, 5B, 6B, 7B, 2D, 5D and 7D harbor more Pm resistance QTLs than the other chromosomes, suggesting that A genome except 1A, 3A and 6A, B genome except 4B, D genome except 1D, 3D, 4D, and 6D play an impor- tant role in wheat combating against powdery mildew. Furthermore, Pm resistance genes are derived from wheat and its rela- tives, which suggested that the resistance sources are diverse and Pm resistance genes are diverse and useful in combating against the powdery mildew isolates. In this review, four APR genes, Pm38/Lr34/Yr18/Sr57, Pm46/Lr67/Yr46/Sr55, Pm？/Lr27/Yr30/ SY2 and Pm39/Lr46/Yr29, are not only resistant to powdery mildew but also effective for rust diseases in the field, indicating that such genes are stable and useful in wheat breeding programmes. The summarized data also provide chromosome locations or linked markers for Pm resistance genes/QTLs. Markers linked to these genes can also be utilized to pyramid diverse Pm resis- tance genes/QTLs more efficiently by marker-assisted selection.

辣椒疫病研究进展

因辣椒—疫霉菌互作的分子机制解析是抗性育种的基础,本文从辣椒疫霉菌的宿主和辣椒病害症状、疫霉菌致病因子及其致病机制、辣椒疫病抗性相关基因和抗性网络研究等3个方面综述了近年来辣椒—疫霉菌互作机制的研究进展,以期为进一步深入解析其分子机制提供理论参考。

基于黄褐棉导入系群体定位抗黄萎病QTL

【目的】黄萎病(Verticillium wilt)是棉花生产中的最主要病害,且棉花黄萎病的致病机理尚不清楚。通过构建黄褐棉导入系群体定位棉花黄萎病抗性相关的数量性状位点(quantitative trait loci,QTL),为抗黄萎病分子标记开发和辅助育种提供参考。【方法】以陆地棉(Gossypium hirsutum)B0011为轮回亲本、黄褐棉(G.mustelinum)为供体亲本,构建有71个株系的BC_(5)S_(5)群体。利用2 839个单核苷酸多态性(single nucleotide polymorphism,SNP)标记结合表型值进行黄萎病抗性相关QTL定位。【结果】共检测到15个与黄萎病抗性相关的QTL,可解释4.21%~26.77%的表型变异。加性效应分析表明:其中6个QTL的有利等位基因来源于黄褐棉,9个QTL有利等位基因来自B0011。同时,qVW-A01-1、q VW-A02-2和qVW-A07-2在2个及以上环境中被检测到,表型变异解释率分别为15.56%~16.56%、11.95%~24.62%和13.22%~16.73%。利用BC5S5群体黄萎病抗性的最佳线性无偏预测值(best linear unbiased prediction,BLUP)进行QTL定位,共检测到5个QTL,其中qVW-A01-1B、q VW-A02-1B分别与加性效应分析稳定检测到的qVW-A01-1、qVW-A02-2物理位置一致,分别解释23.67%和17.90%的表型变异。【结论】本研究发现2个稳定的QTL即qVW-A01-1和qVW-A02-2,可为抗黄萎病分子标记辅助选择育种及候选基因功能鉴定奠定基础。

Detecting quantitative trait loci for water use efficiency in rice using a recombinant inbred line population

Breeding rice with high water use efficiency (WUE) can ameliorate water shortage through water-saving irrigation.However,WUE is a complex quantitative trait and very few studies have been conducted to measure WUE directly.In this study,a recombined inbred line population derived from a cross between an indica lowland rice and upland japonica rice was used to dissect the genetic control of WUE by fine-monitored water supply experiments.Quantitative trait loci (QTL) were scanned for 10 traits including heading date (HD),water-consumption per day (water/d),shoot weight gain per day (shootw/d),root weight gain per day (rootw/d),kernel weight gain per day (kernelw/d),average WUE at whole plant level (WUEwhole/d),average WUE for up-ground biomass (WUEup/d),average WUE for grain yield (WUEyield/d),average economic index (econindex/d),and average root/shoot ratio per day (ratio/d).The results show that most of the traits were significantly correlated to each other.Twenty-four QTL (LOD ≥ 2.0) were detected for econindex,econindex/d,WUEyield,WUEyield/d,WUEup,WUEup/d,WUEwhole,WUEwhole/d,kernelw,kernelw/d,rootw,and water/d by composite interval mapping.These QTLs are located on chromosomes 1,2,4,6,7,8,and 12.Individual QTLs accounted for 4.97%-10.78% of the phenotypic variation explained.Some of these QTLs overlapped with previously reported drought resistance QTLs detected in this population.These results provide useful information for further dissection of the genetic basis and marker-assisted selection of WUE in rice.

水稻纹枯病抗性QTL分析

对籼稻窄叶青 8号 (ZYQ8)和粳稻京系 17(JX17)以及由它们构建的加倍单倍体 (DH)群体 ,分别在杭州和海南岛 ,采用注射器接种法进行纹枯病抗性鉴定 ,并使用该群体的分子连锁图谱进行数量性状座位 (QTL)分析。共检测到 4个抗纹枯病的QTL(qSBR 2、qSBR 3、qSBR 7和qSBR 11) ,分别位于第 2、第 3、第 7和第 11染色体。其中qSBR 2、qSBR 3、qSBR 7的抗性基因由抗病亲本ZYQ8贡献 ,而qSBR 11的抗性基因来自感病亲本JX17。qSBR 2、qSBR 3和qSBR 7在杭州和海南岛都能检测到 ,而qSBR 11只在杭州检测到。在杭州的实验中 ,纹枯病病级与秆长和抽穗期呈显著负相关 ;在控制秆长和抽穗期的QTL中 ,控制秆长的qCL 3与qSBR 3位于同一染色体区域 ,其余QTL与抗纹枯病的QTL之间无连锁关系。

冬小麦低温处理叶片细胞膜透性的QTL定位

为探索冬小麦抗寒性的分子机制,以168个花培3号×豫麦57的双单倍体株系为作图群体,利用已构建含有324个SSR标记的遗传图谱,对电导法测定低温(-18℃)处理后的叶片膜透性进行QTL定位。利用完全区间作图法,在3种环境下共检测到21个与叶片膜透性相关的加性QTLs,分布于1B、2A、3A、3B、5B、6A、6B、6D、7B和7D染色体上,其中4个位点(qCMP-1B-1、qCMP-3B-2、qCMP-5B-1和qCMP-5B-4)遗传贡献率大于10%,属主效基因,其余QTL的遗传贡献率较小,属微效基因。3种环境条件下在5B染色体的Xgwm213-Xswes861.2区间检测到共同位点,与Xswes861.2的遗传距离为0cM,其中qCMP-5B-1(环境1)和qCMP-5B-4(环境3)的贡献率高达17.5%和14.0%。研究结果对于小麦抗寒标记选择和抗寒育种具有应用价值。

玉米弯孢菌叶斑病抗性的QTL分析

通过利用AFLP和SSR标记 ,对丹 340×沈 135的F2∶3 群体 (113个家系 )进行玉米弯孢菌叶斑病抗性基因的遗传作图和QTL分析 ,得到如下结论 :(1)玉米弯孢菌叶斑病抗性是由多基因控制的 ;(2 )应用复合区间作图法 ,对 1999年的玉米全株抗病性 ,检测到 4个QTL ,分别位于第 6、6、8和 10染色体上 ,可解释表型变异的 4 9.9% ;对 2 0 0 0年的玉米全株抗病性 ,检测到 6个QTL ,2个位于第 6染色体上 ,3个位于第 7染色体上 ,1个位于第 10染色体上 ,可解释表型变异的 77.6 % ;第 10染色体上的QTL是 2年间共同的QTL ,来自抗病亲本沈 135 ;(3)对每个QTL(定量特征点位分析 ) ,均检测到加性和显性效应 ,但相对大小有不同 ,各QTL以部分显性、显性和超显性为主要遗传方式 ;(4)控制玉米弯孢菌叶斑病抗性的QTL之间存在上位性互作。

三个小麦赤霉病抗源的抗性QTL定位

为寻找小麦赤霉病抗性基因及可用于分子标记辅助育种的抗性连锁标记．对中国的三个小麦赤霉病抗源苏麦3号、望水白和宁894037进行了抗性QTL的定位研究。SSR、AFLP分析与QTL分析结果表明，尽管三个抗源的来源和遗传背景并不同，但均在3B染色体短臂上发现抗性主效QTL，不同遗传群体所获得的QTL位点所处的染色体区段略有差异，位于QTL两翼的SSR标记也有所不同。苏麦3号的赤霉病抗性主效QTL位于3B染色体上的标记区间Xgwm533～Xgwm493内；宁894037的抗性位点分布于3B和6B染色体上。分别定位于标记Xgwm493～Xbarcl33和Xgwm644-Xgwm518之间；望水白的抗性主效QTL也位于3B染色体上．定位于标记Xgwm493～Xbarc147之间。微效QTL由于遗传群体的不同，分别住于1B、3B和2A染色体上。研究还表明，寻找抗性QTL在3B染色体以外的新抗源十分必要。

植物数量抗病基因克隆及其抗性机理的研究进展

培育广谱、持久抗病的作物品种,不仅需要深入研究质量抗病性,而且需要更深入地洞悉数量抗病性的可能作用机理。而目前,人们对数量抗病基因的可能特征和数量抗病性的机理的认识还相当模糊,这在很大程度上限制了数量抗病基因在育种实践中的应用。本文首先综述数量性状座位(quantitativetraitloci,QTL)的克隆策略和精确获取数量抗病性状值的方法;其次根据数量抗性座位(quantitativeresistanceloci,QRL)的相关研究进展,对QRL的可能特征进行一定的综述,认为部分QRL的抗性机理直接对应于R基因、抗病基因类似物(resistancegeneanalogs,RGA)、防卫基因、防卫反应途径中的相关基因等在植物抗病性上的作用机理;最后,作者推测存在4种抗性特征的QRL,即小种特异性或非特异性QRL和“病原菌”特异性或广谱性QRL,并认为数量抗性持久性的遗传基础与这些不同特征的QRL间有着密切的联系。该综述将对QRL的候选基因分析和克隆、数量抗病机理研究和QRL的育种应用提供有益的参考。

水稻胚芽鞘长度与抗旱性的关系及QTL定位

对由水稻品种珍汕97B和早稻品种IRAT109构建的重组自交系195个株系的胚芽鞘长度及抗旱系数的研究表明，水分胁迫下水稻重组自交系群体的胚芽鞘长度与抗旱系数的相关系数为0．2206^＊＊。应用由213个SSR标记构建的遗传连锁图对控制胚芽鞘长度和抗旱系数的QTL进行了定位。检测到胚芽鞘长度和抗旱系数的主效QTL各为13个和5个，单个QTL对表型的贡献率为2．28％～22．65％；在第9染色体上两者的QTL出现在相同的分子标记区间（RM160-RM215）。检测到胚芽鞘长度和抗旱系数的互作位点分别为17对和3对，影响胚芽鞘长度的互作位点联合贡献率为58．35％；影响抗旱系数的互作位点联合贡献率为11．93％。控制胚芽鞘长度和抗旱系数的QTL分别与其他研究中控制根系性状（深根干质量、根深、根长、根数等）的QTL位于相同的标记区间。

玉米抗丝黑穗病QTL分析

以Mo17（抗）×黄早四（感）的F2分离群体（191个单株）为作图群体，构建了含有84个SSR位点和48个AFLP位点的遗传连锁图谱，全长1542．9cM，平均图距11．7cM。在吉林省公主岭和黑龙江省哈尔滨2个地点，通过人工接种方法对184个相应的F3家系（缺失7个）进行抗病鉴定。采用复合区间作图法对抗丝黑穗病数量性状位点（QTL）进行定位及遗传效应分析。在吉林公主岭地区检测到5个QTL，分别位于第1、2、3、8、9染色体上，解释的表型方差为10．0％。16．3％。在黑龙江哈尔滨地区也检测到5个QTL，分别位于第1、2、3、4、7染色体上，解释的表型方差为4．6％。13．4％。比较分析发现，两地一致在第2、3染色体上各检测到1个QTL，其中第2染色体上的表现为超显性效应，第3染色体上的表现为加性效应。研究结果为玉米抗丝黑穗病种质改良提供了重要信息。

高粱重要抗性性状的基因定位研究进展

抗病性是高粱遗传改良的主要目标,是高粱高产、优质的重要保证。近年来,随着分子生物技术的进步,高粱基因组研究得到迅速发展,大量重要的抗性性状基因被定位于相应的高粱遗传连锁图上,这为高粱抗性机制的生理研究、抗性基因的克隆、分子标记辅助选择、有利基因的定向转移及基因聚合奠定了基础。本文综述了高粱抗旱性QTL、抗病性基因、抗虫性基因、抗寄生草及耐寒性基因定位的研究进展,探讨抗性基因定位存在的问题及其有效利用,展望了高粱抗性基因定位在高粱遗传育种研究中的应用前景。

水稻籼粳交DH群体白叶枯病抗性的QTL定位

以中抗白叶枯病的粳稻品种春江06、感病品种TN1及其DH群体为材料,接种白叶枯病菌浙173后,考察了该DH群体的白叶枯病抗性,并进行了数量性状座位(QTL)分析。共检测到控制白叶枯病的3个QTL(qBBR1、qBBR3-1和qBBR7),分别位于第1、3和第7染色体上,其中第3染色体上的qBBR3-1和第7染色体上的qBBR7加性效应为正值;而位于第1染色体上的qBBR1为负值,3个QTL的总效应达54.4%。春江06中不存在白叶枯病抗性主基因,它的抗性由微效多基因控制,其中在第3和第7染色体上分别有1个QTL。

普通小麦白粉病成株抗性的QTL分析

以抗白粉病的日本小麦品种Fukuho-komugi和以色列小麦Oligoculm杂交F1的DH(doubled haploid)群体107个系为材料,利用313个SSR标记和37个RFLP标记,对Fukuho-komugi和Oligoculm的白粉病成株抗性进行QTL分析。试验材料于2003—2004年度种植在北京2、003—2004和2004—2005年度种植在安阳,调查白粉病发病情况。构建了由350个位点组成的遗传连锁图,覆盖小麦21个连锁群,全长3 101 cM。采用复合区间作图法进行白粉病成株抗性QTL分析,在1A、2B4、B和7D上发现4个抗白粉病QTL,分别解释13.6%、6.6%、8.9%和12.7%的表型变异。抗白粉病基因及其紧密连锁分子标记的发掘,将为小麦抗白粉病育种的分子标记辅助选择提供理论和技术支持。

水稻白叶枯病数量抗性座位定位及其小种专化性

用水稻白叶枯病3个毒力不同的菲律宾小种P2、P6和P9，对供体Lemont导入到特青背景的178个近等基因导入系群体，进行白叶枯病数量抗性座位（quantitative resistance loci，QRL）定位及其小种专化性研究。供试亲本Lemont感3个小种，特青中感P2和P9，感P6。导入系群体的病斑长度呈连续正态分布。共发现影响病斑长度的10个主效QRL和12对互作QRL，除第6染色体上的QBr6c外，所有位点上的Lemont等位基因均增加了病斑长度（即降低了抗病性）。在第11染色体RM144～RM123区间检测到1个主效QBr11，推测为Xa4基因，对P2和P9表现为主效QRL，但完全被P6克服，在该位点未能检测到任何抗性残余效应。主效和互作QRL对不同小种具有不同的抗性反应，存在明显的小种专化性，虽然有些QRL对不同小种的互作方向一致，但互作效应存在着数量差异。由于在感病亲本中检测到较多的主效和互作QRL，这些QRL之间的相互作用及其效应的累加，有利于寄主与病原菌小种之间的稳定化选择，共同增强寄主抗病性及稳定性效应。