水稻条纹病毒和介体灰飞虱抗性的QTL分析

水稻品种Kasalath高抗条纹病毒和介体灰飞虱。为剖析不同抗性类型基因之间的关系，利用回交重组自交系群体Nipponbare/Kasalath//Nipponbare分析了对条纹病毒和介体灰飞虱抗性的数量性状基因座。结果在第11染色体S2260–G257标记区间检测到1个与条纹病毒抗性相关的QTL（qSTV11），LOD值为9.2, 贡献率为35.79%；在第3染色体R1618–C595 和R2170–C1135标记区间各检测到1个与介体灰飞虱抗性相关的QTL (qSBPH3-a, qSBPH3-b)，LOD值和贡献率分别为3.12和2.96, 11.69% 和11.36%,表明条纹病毒和介体灰飞虱抗性由不同基因所控制,而且两者之间不相关。此外，还分别检测到两对与条纹病毒和介体灰飞虱抗性相关的上位性QTL，暗示水稻对条纹病毒和介体灰飞虱的抗性受主效和上位性QTL的共同影响。进一步分析发现SSR标记BJ11-8与qSTV11紧密连锁, 为分子标记辅助选择高抗条纹叶枯病水稻品种提供了基础。     

籼稻品种9311抗白叶枯基因鉴定和定位

稻白叶枯病(bacterial blight,BB)是威胁中国水稻生产的最主要病害之一。本研究在田间观察材料时发现普通野生稻染色体片段代换系CSSL45高感白叶枯病,于是利用6个不同的白叶枯菌株对CSSL45及其受体亲本9311进行抗性鉴定,结果表明它们之间对不同菌株表现出明显的抗感病差异。随后利用GX0312菌株对9311/CSSL45的194个F2分离单株进行接种鉴定,遗传分析表明:籼稻品种9311的抗性由一个显性的抗白叶枯基因控制。最后进一步利用分子标记对472株感白叶枯病的单株进行重组单株检测,最终将Xa41(t)定位在水稻第11号染色体的SSR标记RM27320和RM27335之间,物理距离约为220 kb。本研究定位的Xa41(t)可能与此前报道的4个抗性基因Xa3/Xa26、Xa4和Xa40是互为等位基因。因此,合理利用Xa41(t)基因与其他不同抗性基因进行聚合,对广西水稻白叶枯病抗性育种具有重要的意义。     

多环境下稻米粒重的QTL定位

以粳稻Asominori为遗传背景的染色体片段置换系（CSSLs）群体为材料,利用基于性状-标记多元回归分析方法对稻谷粒重和精米粒重进行多环境的QTL定位。结果在5个环境共检测到6个粒重相关QTL,分布于第1、6、7和8染色体上,对表型变异的贡献率介于13%~35%;其中控制精米粒重的qMRW-1a和稻谷粒重的qPRW-1在不同环境中均能稳定表达,且均位于第1染色体RFLP标记XNpb113附近,该基因座还同时控制着粒宽。qMRW-1a和qPRW-1共同对应的置换系AIS8和AIS11与Asominori 的粒重差异在不同环境中均显著(P < 0.05),表明该QTL的等位基因在不同环境中效应显著。比较发现该QTL在不同遗传群体中均能被重复检测到,且与蔗糖磷酸合酶基因（SPS）位置一致,推测该QTL与淀粉合成代谢有关。qMRW-1a 和qPRW-1在不同环境条件和遗传背景中表达,因此可用于进一步的精细定位研究。     

水稻恢复系C224抗条纹叶枯病相关QTL的检测

在实验室采用人工接种方法鉴定了亲本及192个99B/C224杂交后代F2∶3家系对水稻条纹病毒的抗性,表型值用条纹叶枯病病情指数表示,利用QTL IciMapping软件,采用完备区间作图法分析水稻条纹叶枯病抗性基因,共检测到5个QTLs:分别为qstv1、qstv2、qstv3-1、qstv3-2和qstv11,位于...     

水稻抗条纹叶枯病基因Stv-bi的分子标记辅助选择

水稻条纹叶枯病是我国黄淮及长江流域粳稻区重要的病害。由于水稻条纹叶枯病的发病受外界条件影响较大,人工接种抗性鉴定比较困难,利用与抗病基因紧密连锁的分子标记进行标记辅助选择对提高抗性育种效率具有重要意义。来自籼稻抗源Modan的Stv-bⁱ是水稻育种中广泛应用的条纹叶枯病抗性基因。本研究设计了与Stv-bⁱ紧密连锁的SSR及STS分子标记,用3个抗条纹叶枯病混合群体F30718(圣稻13/镇稻88)、F50701(武优34/T022//圣稻806)、F60702 (V6/T022//镇稻88)进行分子标记检测和田间条纹叶枯病抗性鉴定,其结果的符合率分别为99.3%、87.7%和91.8%。表明这些分子标记可以用于条纹叶枯病抗性基因Stv-bⁱ分子标记辅助选择。     

利用高密度遗传图谱发掘水稻抽穗期新位点

水稻抽穗期是决定水稻种植地区及其季节适应性的关键因素,发掘控制水稻抽穗期相关的新主效QTL至关重要。利用包含527个bin标记的高密度遗传连锁图谱,通过靶向测序基因型检测技术对水稻“空育131/小白粳子”衍生的RIL群体进行抽穗期基因型分析。通过对双亲和RIL群体的基本统计分析发现,双亲抽穗期呈极显著差异,表型处于RIL群体范围内,RIL群体有明显的超亲分离现象,符合正态分布。利用IciMapping 4.2软件的完备区间作图法,在水稻第1、3和7号染色体上共检测到4个QTL,其中3个QTL区间内分别含有与抽穗期相关的已知基因OsGI、Hd6和Ghd7,而qHD-3-1是控制水稻抽穗期的新位点。     

利用CSSL群体研究稻米AC和PC相关QTL表达稳定性

利用以Asominori为遗传背景具IR24染色体片段的置换系（CSSL）群体，在“2年4点”8个环境对稻米直链淀粉含量（AC）和蛋白质含量（PC）进行QTL定位和表达稳定性分析。结果共检测到8个AC和PC相关QTL，其中2个QTL在8个环境中都能重复出现，即影响AC的qAC-8和控制PC的qPC-8，平均贡献率分别为21.0%和26.9%。qAC-8和qPC-8对应置换系与背景亲本Asominori在8个环境中相应性状的表现型都达到极显著差异(P<0.01)；都仅与8个环境中的2个环境之间存在显著的互作效应；说明qAC-8 和qPC-8的效应显著且稳定性较高。此外，qAC-8和qPC-8都被定位在第8染色体R727~G1149区间，IR24的等位基因可同时提高AC和PC，这为研究水稻籽粒直链淀粉和蛋白质形成途径之间的相互关系以及碳氮代谢协同调控的遗传机制提供了新的信息。     

水稻材料IR65482抗稻瘟病基因鉴定与定位

水稻材料IR65482对不同地区的稻瘟菌小种具有广谱抗性,已知其第6号染色体上具有一个抗稻瘟病病基因Pi40(t)。本研究应用极端分离混合池重测序策略,对IR65482抗稻瘟病基因进行鉴定,并在其第11号染色体上鉴定到另一个抗稻瘟病基因。进一步利用IR65482与日本晴配置的F2群体进行基因定位,将IR65482抗稻瘟病基因定位在水稻第11染色体末端InDel标记OSL3-2和OSL3-5之间约425 kb的区间。本研究结果对利用IR65482开展水稻抗稻瘟病育种具有指导意义,也为后续克隆IR65482的抗病基因提供了理论依据。     

水稻抗条纹叶枯病基因Stv-bi的分子标记辅助选择

水稻条纹叶枯病是我国黄淮及长江流域粳稻区重要的病害。由于水稻条纹叶枯病的发病受外界条件影响较大,人工接种抗性鉴定比较困难,利用与抗病基因紧密连锁的分子标记进行标记辅助选择对提高抗性育种效率具有重要意义。来自籼稻抗源Modan的Stv-bⁱ是水稻育种中广泛应用的条纹叶枯病抗性基因。本研究设计了与Stv-bⁱ紧密连锁的SSR及STS分子标记,用3个抗条纹叶枯病混合群体F30718(圣稻13/镇稻88)、F50701(武优34/T022//圣稻806)、F60702 (V6/T022//镇稻88)进行分子标记检测和田间条纹叶枯病抗性鉴定,其结果的符合率分别为99.3%、87.7%和91.8%。表明这些分子标记可以用于条纹叶枯病抗性基因Stv-bⁱ分子标记辅助选择。     

抗青枯病兼大果和高出仁率的花生新种质创制

青枯病是影响花生产量和品质的重要土传性细菌病害,百果重和出仁率是与花生产量相关的重要性状。本研究利用远杂9102和徐州68-4杂交构建的RIL群体,在B02染色体上定位到青枯病抗性主效QTL qBWRB02。结合前期对百果重和出仁率QTL的定位结果发现,所涉及的3个性状的主效QTL分布在不同的染色体上。以RIL群体基因型数据和多个环境的青枯病抗性、百果重和出仁率表型数据为基础,利用与主效QTL紧密连锁分子标记筛选出6份聚合抗青枯病、荚果大、出仁率高3种优良性状的新种质,可以作为育种中间材料或亲本培育高产抗病新品种。本研究利用分子标记辅助选择和表型鉴定相结合有效筛选抗病高产种质,为未来花生育种提供了新思路。     

Quantitative trait loci mapping and stability for low temperature germination ability of rice

A high rate of germination at low temperatures is necessary for economic yields to be maintained. In this paper, the genetic control of low temperature germination ability (LTG) was assessed by the measurement of germination rate (GR), germination rate index (GI) and mean germination time (MGT), and genetically mapped using a set of recombinant inbred lines, derived from a cross between the japonica cultivar 'Asominori' and the indica cultivar 'IR24'. Putative quantitative trait loci (QTL) were validated by testing in two related sets of chromosome segment substitution lines (CSSL). In this genetic background, LTG is under the control of a number of QTL, each of relatively small effect, and is spread over six chromosomes. The most stable of these QTL was for GR, mapping to a segment of chromosome 11 which also carries a QTL for GI. On chromosome 2, qGR-2 not only controlled GR, but also was associated with GI and MGT. Significant differences in LTG were detected between 'Asominori' and some CSSL harbouring qGR-2 or qGR-11 .     

Molecular mapping of a quantitative trait locus qSTV11Z harbouring rice stripe virus resistance gene,Stv‐b

Rice stripe virus (RSV) predominantly affects rice. In this study, we attempted to localize the quantitative trait locus (QTL) conferring RSV resistance in the ‘Zenith’ variety, which is known to harbour Stv‐a and Stv‐b. The resistant variety Zenith was crossed with the susceptible variety ‘Ilpum’ to generate a mapping population comprising 180 F_2:3 lines for QTL analysis. Contrary to previous findings, we could not detect Stv‐a‐specific QTLs on chromosome 6. Stv‐b‐specific QTL was detected on the long arm of chromosome 11; it was designated qSTV11^z. Six F_4:5 lines were selected from the F_3:4 population and fine‐mapped using insertion/deletion (InDel) markers. qSTV11^z was mapped to a 520‐kb region between the InDel markers Sid2 and Indel8. This region included OsSOT1 (candidate gene for STV11) and other previously reported RSV resistance QTLs. The OsSOT1 sequence in Ilpum and Zenith was identical to that of the susceptible variety ‘Koshihikari’, indicating that OsSOT1 is not the candidate gene of qSTV11^z. The localization of qSTV11^z should provide useful information for marker‐assisted selection and determination of genetic resources in rice breeding.     

Detection of quantitative trait loci (QTL) associated with resistance to whitebacked planthopper (Sogatella furcifera) in rice (Oryza sativa)

Whitebacked planthopper (WBPH) is an important insect pest of rice. In this study, we report quantitative trait loci (QTL) associated with resistance to WBPH using a doubled‐haploid (DH) mapping population derived from the cross IR64/Azucena. We evaluated a set of 91 DH lines using various screening tests which measure seedling resistance, antibiosis and tolerance to WBPH. QTL analysis involving a RFLP map of 175 markers detected a significant QTL on chromosome 7 (RG511‐RG477) associated with seedling resistance to WBPH. In addition, QTL analysis involving available defence related candidate genes as markers on a sub set of 60 DH lines showed significant association of genomic regions on chromosome 1 (W1‐pMRF1), 2 (XLRfrI7‐RG157) and 7 (RG711‐CDO418) with resistance to WBPH. Several suggestive QTL were detected on chromosomes 2, 3, 6, 7, 8 and 11 showing the possibility of their association with resistance to WBPH. The phenotypic contribution of the QTL ranged from 8.4% to 32.1%. Some of the WBPH resistance QTL detected in this study showed similar map positions with the QTL reported for resistance to brown planthopper (BPH) in the same mapping population. These results would be useful for attempts to trace the genes associated with resistance to planthoppers in rice.     

Mapping and validation of QTLs for rice sheath blight resistance

Sheath blight, caused by Rhizoctonia solani, is one of the most serious diseases of rice. Among 33 rice accessions, mainly from National Institute of Agrobiological Sciences (NIAS) Core Collection, we found three landraces from the Himalayas—Jarjan, Nepal 555 and Nepal 8—with resistance to sheath blight in 3 years’ field testing. Backcrossed inbred lines (BILs) derived from a cross between Jarjan and the leading Japanese cultivar Koshihikari were used in QTL analyses. Since later-heading lines show fewer lesions, we used only earlier-heading BILs to avoid association with heading date. We detected eight QTLs; the Jarjan allele of three of these increased resistance. Only one QTL, on chromosome 9 (between markers Nag08KK18184 and Nag08KK18871), was detected in all 3 years. Chromosome segment substitution lines (CSSLs) carrying it showed resistance in field tests. Thirty F₂ lines derived from a cross between Koshihikari and one CSSL supported the QTL.     

Identification and validation of a major QTL for salt tolerance in soybean

To identify quantitative trait loci (QTLs) conditioning salt tolerance in soybean (Glycine max (L.) Merr.), two recombinant inbred line (RIL) populations derived from crosses of FT-Abyara × C01 and Jin dou No. 6 × 0197 were used in this study. The FT-Abyara × C01 population consisted of 96 F₇ RILs, and the Jin dou No. 6 × 0197 population included 81 F₆ RILs. The salt tolerant parents FT-Abyara and Jin dou No. 6 were originally from Brazil and China, respectively. The QTL analysis identified a major salt-tolerant QTL in molecular linkage group N, which accounted for 44.0 and 47.1% of the total variation for salt tolerance, in the two populations. In the FT-Abyara × C01 population, three RILs were found to be heterozygous around the detected QTL region. By selfing the three residual heterozygous lines, three sets of near isogenic lines (NILs) for salt tolerance were developed. An evaluation of salt tolerance of the NILs revealed that all the lines with FT-Abyara chromosome segment at the QTL region showed significantly higher salt tolerance than the lines without the FT-Abyara chromosome segment. Results of the NILs validated the salt tolerance QTL detected in the RIL populations.     

Validating a segment on the short arm of chromosome 6 responsible for genetic variation in the hull silicon content and yield traits of rice

Rice is a typical silicon-accumulating plant and the beneficial effect of silicon on rice has long been recognized. In a previous study using 244 recombinant inbred lines (RILs) of an indica rice cross, Zhenshan 97B/Milyang 46 grown in 2003, four QTLs were detected for hull silicon content. QTL qHUS-6 had the largest effect among these, and the same interval also had significant effects on yield traits in the same population. The primary objective of this study was to validate the QTL effect in this region on HUS and yield traits. The same RIL population and another RIL population of lower heterogeneity were grown in 2004. QTL qHUS-6 was found to have significant additive effects on hull silicon content with a consistent direction in the two populations. From a residual heterozygous line selected from RILs of the same cross, 15 F_2:3 lines that differed only in a 2.15-Mb segment extending from RM587 to RM6119 on the short arm of chromosome 6 were derived. In these lines, qHUS-6 displayed a major effect, so did QTLs for yield traits previously detected in the same region. Two more QTLs for HUS detected in 2003, qHUS-1-1 and qHUS-1-2, also had consistent effects in the Zhenshan 97B/Milyang 46 RIL population in 2004. Thus this study verified three candidate regions for fine mapping HUS QTLs and determining the genetic relationship between silicon content and yield traits in rice.     

普通小麦‘Holdfast’条锈病成株抗性QTL定位

Holdfast是来自英国的小麦品种,多年来一直保持良好的条锈病持久抗性。本研究目的是发掘Holdfast的条锈病成株抗性基因及其紧密连锁的分子标记,为小麦持久抗性品种选育提供材料和方法。利用铭贤169和Holdfast杂交后代重组自交系(recombinant inbred lines, RIL)群体,于2014—2015和2015—2016年度在甘肃甘谷、甘肃中梁和四川成都进行条锈病成株抗性鉴定,并统计最大严重度(maximum disease severity, MDS)。基于小麦660K SNP芯片和BSA(bulkedsegregantanalysis)技术初步确定抗病基因所在的染色体后,将目标区域的SNP标记转化为KASP(KompetitiveallelespecificPCR)标记,检测整个RIL群体,进行基因型分析。最后进行RIL群体条锈病成株抗性的QTL分析,在5AL和7AL染色体上发现了2个成株抗性QTL。5A染色体长臂上1个条锈病成株抗性QTL QYr.gaas-5AL,在所有环境下均存在,可解释6.5%～9.3%的表型变异; QYr.gaas-5AL位于标记Ax-109948955和Ax-108798241之间,连锁距离分别为0.5 cM和1.1 cM。在7A染色体长臂上定位到1个条锈病成株抗性QTL QYr.gaas-7AL,在2015年和2016年甘谷环境中均稳定存在,分别解释6.2%和7.3%的表型变异;QYr.gaas-7AL位于标记Ax-110361069和Ax-108759561之间,连锁距离分别为0.5 cM和0.7 cM。携带QYr.gaas-5AL和QYr.gaas-7AL抗病等位基因家系的MDS显著低于感病等位基因家系的MDS,表明QYr.gaas-5AL和QYr.gaas-7AL可有效降低条锈病严重度,可应用于小麦抗条锈育种。     

三黄占2号稻瘟病抗性与稻米直链淀粉含量的关系研究

以高抗稻瘟病、直链淀粉含量（AC）较高的三黄占2号和高感稻瘟病、AC较低的丽江新团黑谷衍生的重组自交系群体为研究材料，从性状的相关性和控制两性状的基因在染色体上的位置关系剖析稻瘟病抗性和稻米AC的内在关系。结果表明，两性状间没有显著的相关性。3个与AC相关的QTL分别被定位在第5、6和7染色体上，其加性效应均来自丽江新团黑谷，起降低AC的作用。比较这些QTL与先前对同一群体鉴定的稻瘟病抗性基因（主效基因和QTL）在染色体上的位置，表明控制这两性状的基因上没有紧密连锁关系, 亦没有显著的基因间互作。据此认为，通过亲本的合理选择和分子标记辅助选择可以把三黄占2号稻瘟病持久抗性与理想AC整合到同一品系中，育成优质、抗病的优良品种。