应用剩余杂合体衍生的近等基因系定位水稻株高QTL

为挖掘有育种利用价值的水稻株高新基因,以来源于‘Katy’/‘湘743’且在第1染色体RM11383-RM1198区间杂合的一个剩余杂合体RHL1030 (F₁₀)为材料,遗传分析RHL1030衍生群体,显示在该区间鉴定到控制株高QTL,增效等位基因来自于‘湘743’。应用SSR标记检测,从RHL1030衍生群体筛选杂合区间分别为RM3411-RM11782和RM6703-RM1198的两个单株,自交一代形成2个F₂群体,验证并界定株高QTL在RM6703-RM1198区间。从RM6703-RM1198区间分离群体筛选RM6703-RM8085区间杂合的3个单株和RM5389-RM1198区间杂合的1个单株,自交一代形成4个F₂群体,从群体中分别筛选母本纯合型、父本纯合型和杂合型单株各40株构成近等基因系进行方差分析,最终界定株高QTL在RM11782-RM5389区间,物理位置34.17M~35.73 Mb。本研究定位到一个新的控制株高QTL,为改良水稻株型提供资源。     

利用4个姊妹近等基因群体定位水稻粒重和粒形QTL

粒重是决定水稻产量的三要素之一。利用世界上粒重最大的品种之一SLG-1(供体亲本)与小粒品种日本晴(Nipponbare,轮回亲本)杂交,在各回交世代选择粒重较大单株与日本晴回交,构建水稻粒重和粒形的姊妹近等基因系(SNILs)。对获得的73 株BC₄F₁单株进行粒重频率分布统计,选择粒重频率分布在4个峰值处的代表性单株,自交获得4个BC₄F₂ SNILs群体。利用BSA法(分离群体分组混合分析法),从均匀分布在水稻染色体上的1 513对SSR标记中筛选出与粒重和粒形相关的多态性标记19对,以LOD≥2.5作为选择阈值,对粒重、粒长、粒宽和粒厚进行QTL扫描,共检测到6个区域的12个QTL,贡献率从7.22%到53.38%。这些QTL所在区域包含已克隆的粒长GS3和粒宽GW2,也包含没有精细定位的第2染色体的RM6318-RM1367、第3染色体的RM5477–RM6417和第6染色体的RM3370–RM1161等3个区域控制粒重和粒形的5个QTL。其中第3染色体上RM5477–RM6417区间存在粒形贡献率较大的新的QTL。构建含有这些粒重QTL的姊妹近等基因系,为进一步精细定位或克隆新的粒重或粒形QTL奠定了基础。     

利用染色体片段代换系定位陆地棉株高QTL

以陆地棉中棉所36为轮回亲本和海岛棉海1为供体亲本, 构建染色体片段代换系。为了能检测到稳定的株高QTL,将三个代换系群体(BC₅F₃, BC₅F_3:4和BC₅F_3:5)在5个环境中种植,2009年和2010年分别在河南安阳种植BC₅F₃单株、BC₅F_3:4株行, 2011年分别在河南安阳、辽宁辽阳和新疆石河子种植BC₅F_3:4株系。结果表明,在不同群体环境中株高的超亲比例为53.43%~88.97%。从早期构建的总图距为5088.28 cM, 含有2280个SSR标记位点,覆盖26条染色体的遗传连锁图谱中筛选标记,对408个单株进行的SSR鉴定,结果检测到16个株高QTL,分布在10条染色体上。单个QTL解释的表型变异为7.35%~13.17%。有7个QTL在2个以上环境被检测到。与标记MUSS563紧密连锁的qPH-15-19在一个环境中被检测到,在前人的研究中也有报道。这些结果为进一步精细定位QTL、基因克隆、分子辅助选择等研究奠定基础。     

大豆脂肪酸主要组分含量QTL定位

以中黄13×中黄20的100个BC₂F₂家系为作图群体,构建了一张包含131个SSR分子标记的遗传连锁图谱,图谱总长为2157.3 cM,平均遗传距离为16.5 cM,涵盖了大豆的20个连锁群。利用气相色谱技术测定BC₂F₂、BC₂F₃和BC₂F₄回交群体的脂肪酸主要组分含量,采用IciMapping 3.3完备区间作图法定位QTL,共检测到5种脂肪酸组分相关的QTL 26个,与棕榈酸、硬脂酸、油酸、亚油酸和亚麻酸相关的QTL分别为5、5、7、5和4个;3个区间在不同年份被检测到与同一脂肪酸组分相关,sat_294~satt228连续3年被检测到与棕榈酸含量相关,sat_253~satt323和sat_292~satt397连续2年被检测到与油酸含量相关;4个区间被检测到与2种脂肪酸组分相关,其中sat_294~satt228与棕榈酸、油酸相关,satt308~sat_422与硬脂酸、亚油酸相关,sat_292~satt397与油酸、亚油酸相关,satt374~satt269与油酸、亚麻酸相关。     

蓖麻有效穗数QTL定位及候选基因鉴定

有效穗数是蓖麻产量的重要构成因子。为揭示蓖麻有效穗数的遗传基础及挖掘其候选基因，利用表型差异显著的2个亲本杂交构建F₂和BC₁(F₁×P₂)群体，通过SSR引物基因分型以及CIM和ICIM-ADD 2种检测方法对单株有效穗数和一级分枝有效穗数进行QTL定位，并以相同方法在S₁群体进一步验证QTL重复性。在F₂群体中共检测到9/5(CIM/ICIM-ADD,下同)个QTL,其中，单株有效穗数和一级分枝有效穗数QTL分别为3/2,6/3个，分别解释了6.70%/11.87%和25.15%/13.87%的表型变异。BC₁群体的定位结果与F₂群体基本一致。其中，qESNPP3.1和qEPBSN3.1为稳定QTL,贡献率都接近10%,后者在S₁群体中再次检测到，贡献率为13.27%;它们在RCM915～RCM950标记区间内重叠分布，共同构成1个调控蓖麻有效穗数的主效QTL簇。从RCM915～RCM9...     

基于MAS技术对水稻保持系软华B稻瘟病抗性的分子改良

为选育优质抗稻瘟病保持系软华B,以携带稻瘟病抗性基因Pi46和Pi2的优质籼稻H281作为供体亲本、以软华B为轮回亲本,利用分子标记辅助选择(MAS)技术结合系谱选育法,聚合2个外源基因以改良保持系软华B。对性状稳定的改良株系进行稻瘟病抗性鉴定、稻米品质分析等。通过回交及多代自交,并结合分子标记检测,获得以软华B为遗传背景且含有2个纯合目标基因的BC₁F₆群体2个、BC₂F₅群体2个、BC₃F₄群体2个。田间自然诱发鉴定结果表明,不同回交世代改良材料在自然病圃均抗稻瘟病;育性鉴定结果显示,回交世代对不育系的不育度为52.7%～100.0%;农艺性状考查及米质分析表明,改良株系基本保留了软华B的主要农艺性状和稻米品质特性。SNP基因芯片分析结果显示,BC₁F₆的背景回复率为74.42%～77.77%,BC₂F₅的背景回复率为86.42%～87.75%,BC₃     

应用明恢86和佳辐占的F2群体定位水稻部分重要农艺性状和产量构成的QTL

应用籼稻品种明恢86和佳辐占为亲本建立的F2群体及相应的SSR分子标记连锁图,用区间定位法的Additive和Free两种模型分别对水稻部分重要农艺性状和产量构成性状的QTL进行了定位分析.结果Additive模型共检测到3个QTL,均位于第1号染色体的RM1-RM283区间,分别控制水稻生育期、株高和每穗粒数,基因成簇分布.Free模型共检测到5个QTL,其中控制水稻生育期、株高和每穗粒数的3个QTL的位置和效应大小与Additive模型基本相同;另外还检测到2个影响结实率和千粒重的QTL分别位于第7号染色体的RM180-RM214和第2号染色体的RM279-RM154区间,其贡献率均较小.同时,分析比较了研究结果与前人不同的原因.     

大豆质核互作雄性不育系NJCMS3A双亲雄性育性基因的SSR标记

利用大豆质核互作雄性不育系NJMCS3A的质、核供体亲本N21566和N21249构建F₂和BC₁F₁育性分离群体进行雄性育性的遗传分析与基因定位。结果表明, F₁正反交可育,F₂和BC₁F₁的可育株与不育株分离比例经χ²测验分别符合3∶1和1∶1,表明NJCMS3A供体亲本雄性育性由一对基因控制,可育等位基因为显性。该基因可能是NJCMS3A的一个恢复基因。选用793对SSR引物对F₂和BC₁F₁群体分别进行育性基因定位,发现该育性基因位于O连锁群上,在Satt331和Satt477标记之间,与Satt331、CSSR133和Satt477标记距离的次序一致,分别为8.1~10.4 cM、11.4~16.4 cM、13.3~19.2 cM。     

水稻高抗性淀粉含量基因sbe3-rs的KASP分子标记开发与利用

含有sbe3-rs基因型的高抗性淀粉含量水稻品种(系)具有调节餐后血糖、改善血脂和增强饱腹感等功效。以‘降糖稻1号’为sbe3-rs基因供体亲本通过杂交育种和回交转育方法培育优质高产高抗性淀粉水稻新品种具有重要意义。sbe3-rs基因第16个外显子的第105位处有T→C的碱基突变,基于该突变位点开发高通量KASP分子标记,利用该分子标记对杂交F₁后代50个单株和回交BC₁F₁后代44个单株共94份材料进行基因分型检测,结果显示50份F₁样品中有47个单株基因型为C/T杂合基因型,44份BC₁F₁群体材料中共有28个单株基因型为C/T杂合基因型。利用已开发的成熟的sbe3-rs的CAPS分子标记检测验证结果完全一致。同时利用开发的KASP分子标记对杂交F₂分离群体进行基因分型鉴定,对应高抗性淀粉基因型单株成熟期收获进行抗性淀粉含量测定,结果完全符合。结果表明针对sbe3-rs的突变位点开发KASP分子标记应用杂交回交群体,克服了前期开发...     

利用极端材料定位水稻粒形性状数量基因位点

利用极端大粒材料GSL156(千粒重71.9 g)与特小粒材料川七(千粒重12.1 g,轮回亲本)杂交、回交获得的BC₂F₂ 216个个体为作图群体,在北京进行稻谷粒长、粒宽、粒厚、长宽比、千粒重等粒形性状的鉴定。采用单标记分析和复合区间作图法,利用SSR标记对粒形性状进行数量性状基因座检测。结果表明,上述粒形性状在BC₂F₂群体均呈正态连续分布,表现为由多基因控制的数量性状;共检测到与粒形性状相关的QTL 28个,分布于第1、2、3、4、5、6和12染色体上。其中qGL3-2、qGL3-3、qGT12-1、qGT2-1、qGT5-1、qGW1-1、qGW12-1、qGW2-1、qGW5-1、qRLW3-1、qTGW12-1、qTGW2-1、qTGW3-3和qTGW5-1对表型变异的贡献率分别为13.70%、52.51%、21.13%、18.79%、20.92%、14.59%、18.33%、30.03%、20.05%、24.53%、13.47%、11.43%、21.30%和15.68%,为主效QTL。其中,第3染色体上检测出来的QTL最多。在所有检测到的28个QTL中,6个QTL的增效等位基因来源于小粒亲本川七,而其余QTL的增效等位基因均来源于大粒亲本GSL156,基因作用方式主要表现为加性或部分显性。第3染色体RM7580~RM8208区间是分别与粒宽、长宽比和千粒重相关的3个主效QTL的共同标记区间,第2染色体的RM7636~RM5812区间、第5染色体的RM3351~RM26区间和第12号染色体的RM1103~RM17区间是分别与粒宽、粒厚和千粒重相关的3个主效QTL的共同标记区间,这些区间对粒形贡献率较大,为进一步精细定位或克隆这些新的粒重或粒形QTL奠定了基础。同时大粒亲本对稻谷粒长、粒宽、粒厚和千粒重等性状的增效作用显著。     

Identification and validation of a yield-enhancing QTL cluster in rice (Oryza sativa L.)

Improvement of rice grain yield (YD) is an important goal in rice breeding. YD is determined by its related traits such as spikelet fertility (SF), 1,000-grain weight (TGW), and the number of spikelets per panicle (SPP). We previously mapped quantitative trait loci (QTLs) for SPP and TGW using the recombinant inbred lines (RILs) derived from the crosses between Minghui 63 and Teqing. In this study, four QTLs for SF and four QTLs for YD were detected in the RILs. Comparison of the locations of QTLs for these three yield-related traits identified one QTL cluster in the interval between RM3400 and RM3646 on chromosome 3. The QTL cluster contained three QTLs, SPP3a, SF3 and TGW3a, but no YD QTL was located there. To validate the QTL cluster, a BC₄F₂ population was obtained, in which SPP3a, SF3 and TGW3a were simultaneously mapped to the same region. SPP3a, SF3 and TGW3a explained 36.3, 29.5 and 59.0 % of phenotype variance with additive effect of 16.4 spikelets, 6 % SF and 1.8 g grain weight, respectively. In the BC₄F₂ population, though the region has opposite effects on TGW and SPP/SF, a YD QTL YD3 identified in this cluster region can increase 4.6 g grains per plant, which suggests this QTL cluster is a yield-enhancing QTL cluster and can be targeted to improve rice yield by marker aided selection.     

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.     

Mapping quantitative trait loci for awnness and yield component traits in isogenic lines derived from an Oryza sativa / O. rufipogon cross

An advanced backcross line, HR9118, was produced from a single plant of BC₂F₃ families derived from a cross between Oryza rufipogon Griff. (IRGC 105491) as a donor parent and the O. sativa subsp. japonica cv. Hwaseongbyeo as a recurrent parent. Although HR9118 resembled Hwaseongbyeo, several traits were different from those of Hwasoengbyeo, including days to heading, plant height, and awn. These differences between Hwasongbyeo and HR9118 could be attributed to introgressed O. rufipogon chromosome segments into HR9118. Introgression analysis using 460 SSR markers revealed that three O. rufipogon-specific chromosome segments were detected in HR9118 genome. F_2:3 populations derived from the cross between Hwaseongbyo and HR9118, consisting of 340 F₂ plants and 137 F₃ lines, were used to map and characterize QTLs for 12 traits. QTL analysis identified a total of 17 QTLs in the F_2:3 populations. Of these, seven QTLs were shared by the F₂ and F₃ populations, whereas the other ten QTLs were identified only in the F₃ population. In seven (41.2%) QTLs identified in this study, the O. rufipogon-derived alleles contributed desirable agronomic effects despite the overall undesirable characteristics of the wild phenotype. Each of three O. rufipogon introgressed segments contained multiple QTLs, indicating linkage and/or pleotropic effects. A cluster of eight QTLs was detected on chromosome 8 including a major QTL for awn. Substitution mapping using F₂ population indicated that awn8 was located within an interval between two SSR makers RM23326 and RM23356 which are 590 kb apart. SSR markers tightly linked to QTLs for yield components detected in this study will facilitate cloning of the gene underlying this QTL as well as marker-assisted selection for variation in grain weight in an applied breeding program.     

Identification of qRL7, a major quantitative trait locus associated with rice root length in hydroponic conditions

Root system development is an important target for improving yield in rice. Active roots that can take up nutrients more efficiently are essential for improving grain yield. In this study, we performed quantitative trait locus (QTL) analyses using 215 recombinant inbred lines derived from a cross between Xieqingzao B (XB), a maintainer line with short roots and R9308, a restorer line with long roots. Only a QTLs associated with root length were mapped on chromosomes 7. The QTL, named qRL7, was located between markers RM3859 and RM214 on chromosome 7 and explained 18.14–18.36% of the total phenotypic variance evaluated across two years. Fine mapping of qRL7 using eight BC₃F₃ recombinant lines mapped the QTL to between markers InDel11 and InDel17, which delimit a 657.35 kb interval in the reference cultivar Nipponbare. To determine the genotype classes for the target QTL in these BC₃F₃ recombinants, the root lengths of their BC₃F₄ progeny were investigated, and the result showed that qRL7 plays a crucial role in root length. The results of this study will increase our understanding of the genetic factors controlling root architecture, which will help rice breeders to breed varieties with deep, strong and vigorous root systems.     

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。     

Validation of molecular markers linked to fertility restorer gene(s) for WA-CMS lines of rice

The present study was carried out with the objective to validate the molecular markers, which have been previously reported to be linked to fertility restorer (Rf) gene(s) for WA-CMS lines of rice. Two mapping populations involving fertility restorer lines for WA-cytoplasm, viz., (i) an F₂ population derived from the cross IR58025A/KMR3R consisting of 347 plants and (ii) a BC₁F₁ population derived from the cross IR62829A/IR10198R//IR62829A consisting of 130 plants were analyzed. Nine SSR and three CAPS markers reported to be linked to Rf genes along with two previously unreported SSR markers were analyzed in the mapping populations. In both the populations studied, the trait of fertility restoration was observed to be under digenic control. Eight SSR markers (RM6100, RM228, RM171, RM216, RM474, RM311, MRG4456 and pRf1&2) showed polymorphism between the parents of the F₂ population, while the SSR markers RM6100 and RM474 showed polymorphism between the parents of both the F₂ and BC₁F₁ populations. Only one CAPS marker, RG146FL/RL was polymorphic between the parents of the BC₁F₁ population. RM6100 was observed to be closely segregating with fertility restoration in both the mapping populations and was located at a distance of ~1.2 cM. The largest phenotypic variation was accounted for the region located between RM311 and RM6100. Using the marker-trait segregation data derived from analysis of both the mapping populations, a local linkage map of the genomic region around Rf-4, a major fertility restoration locus on Chromosome 10 was constructed, and RM6100 was observed to be very close to the gene at a distance of 1.2 cM. The accuracy of the marker RM6100 in predicting fertility restoration was validated in 21 restorers and 18 maintainers. RM6100 amplified the Rf-4 linked allele in a majority of the restorers with a selection accuracy of 94.87%. Through the present study, we have established the usefulness of the marker RM6100 in marker-assisted selection for fertility restoration in segregating populations and identification of restorers while screening rice germplasm for their fertility restoration ability.     

Fine mapping of grain weight QTLs using near isogenic lines from a Cross between <Emphasis Type="Italic">Oryza sativa</Emphasis> and <Emphasis Type="Italic">O. grandiglumis</Emphasis>

In a previous study, we reported the grain weight QTL, tgw2 in the 150 F2:3 lines derived from a cross between Oryza sativa subssp. Japonica cv. Hwaseongbyeo and HG101. This QTL was confirmed in F4 lines (CR1242) segregating for the target region. For fine mapping of tgw2, one F₅ plant homozygous for the O. grandiglumis DNA in the target region was selected from CR1242 and crossed with Hwaseongbyeo to produce the F₂ and F₃ populations. QTL analysis using 490 F₂ plants confirmed the existence of tgw2 with an R ² value of 28.0%. This QTL explained 61.3% of the phenotypic variance for 1,000-grain weight in 64 F₃ lines. Substitution mapping with 47 F₃ lines and 74 F₄ plants with informative recombination breakpoints in the target region was carried out to narrow down the position of the tgw2. The result indicated that tgw2 was located in the 384-kb interval between two SSR markers, RM12813 and RM12836. Annotation data of BACs in this 384-kb region revealed that forty-five putative genes exist in this interval including the GW2 gene responsible for grain weight and width. Considering the position of the QTL tgw2, it appears that tgw2 is functionally related to the gene GW2. However, the possibility that another unknown mechanism might be responsible for regulation of grain weight at tgw2 cannot be ruled out. Four QTLs for grain length, grain width, and grain thickness were also located in the same interval suggesting that a single gene is involved in controlling these four traits. Substitution mapping also indicated that two QTLs for grain weight and culm length, tgw2 and cl2, were tightly linked.     

Novel quantitative trait loci for yield and yield related traits identified in Basmati rice (Oryza sativa)

Increasing crop productivity is one of the prime goals of crop breeding research. Rice grain yield is a complex quantitative trait governed by polygenes. Although several QTLs governing grain yield traits have been reported and limited attempts have been made to map QTLs for grain yield parameters in Basmati rice. A population from the cross Sonasal and Pusa Basmati 1121 comprising 352 RILs was generated through the single seed descent method. A total of 12 QTLs governing yield and yield-related traits were mapped on six chromosomes, namely, 1, 2, 3, 7, 8 and 9, of which five QTLs were novel. We identified a novel and robust epistatic QTL (qPH1.1 and qPL1.1) governing plant height and panicle length, flanked by the markers RM5336-RM1 on chromosome 1. The gene encoding brassinosteroid insensitive 1-associated receptor kinase 1 precursor is the putative candidate gene underlying this epistatic QTL. Another novel QTL, qNT3.1, governing tiller number was bracketed to a region of .77 Mb between the markers RM15247 and RM15281 on chromosome 3. Of the 57 annotated gene models, Os03g0437600 encoding alpha/beta-fold hydrolase, a homologous to AtKai2 is a putative candidate gene underlying the novel QTL qNT3.1. The other QTLs such as qDFF1.1 governing days to 50% flowering co-localizes with the gene Ghd7, QTL for plant height qPH1.2 co-localizes with the gene sd1, the QTLs for panicle length co-localizes with FUWA and DEP2, the QTL for tiller number co-localizes with OsRLCK57 and QTLs for thousand-grain weight co-localize with the major gene GS3. The QTLs identified in the current study can be effectively used in marker-assisted selection for developing Basmati rice varieties with a higher yield.     

Identification of four genes for stable hybrid sterility and an epistatic QTL from a cross between Oryza sativa and Oryza glaberrima

To further understand the nature of hybrid sterility between Oryza sativa and Oryza glaberrima, quantitative trait loci (QTL) controlling hybrid sterility between the two cultivated rice species were detected in BC₁F₁ and advanced backcross populations. A genetic map was constructed using the BC₁F₁ population derived from a cross between WAB450-16, an O. sativa cultivar, and CG14, an O. glaberrima cultivar. Seven main-effect QTLs for pollen and spikelet sterility were detected in the BC₁F₁. Forty-four sterility NILs (BC₆F₁) were developed via successive backcrosses using pollen sterility plants as female and WAB450-16 as the recurrent parent. Seven NILs, in which the target QTL regions were heterozygous while the other QTL regions as well as most of the reminder of the genome were homozygous for the WAB450-16 allele, were selected as the QTL identification materials. BC₇F₁ for the seven NILs showed a continuous variation in pollen and spikelet fertility. The four identified pollen sterility QTLs were located one each on chromosomes 1, 3, 7 and 7. Pollen sterility loci qSS-3 and qSS-7a were on chromosomes 3 and 7, respectively, which coincides with the previously identified S19, and S20, while loci qSS-1 and qSS-7b on chromosomes 1 and 7L appear distinct from all previously reported loci. An epistatic interaction controlling the hybrid sterility was detected between qSS-1 and qSS-7a.