The Identification of QTL Associated with Cotton Fruit Branch Length Suitable for Mechanized Harvest Utilizing BSA-seq

[Objective] This study aims to identify quantitative trait loci (QTLs) associated with cotton fruit branch length by using the combination of bulked-segregant analysis (BSA) and next-generation sequencing (NGS) method. [Method] In this study, the cotton F₂ segregating population was developed with the short branch line Sujimian 125 and long-branch variety Sikang 1 as cross parents. According to the average internode length of fruit branches in middle, extreme individuals in F₂ population were divided into two groups to generate the bulked DNA samples. The whole-genome resequencing of two DNA bulks was applied to analyze the single nucleotide polymorphism (SNP) and insertion-deletion (InDel) between two groups, and the fruit branch internode length related QTLs were detected using Euclidean distance (ED). [Result] With SNP data obtained from sequencing, a 0.8 Mbp range associated region on chromosome A3 was identified; with InDel data obtained from sequencing, a 1.09 Mbp range associated region on chromosome A3 was identified. Two regions overlapped, and the overlapped range was 0.77 Mbp. [Conclusion] This result suggested that the difference between I-type fruit branch and zero-type was due to different genetic locus and pattern rather than dosage effect of the same gene.     

越冬栽培稻产量性状相关QTL定位

越冬栽培稻是一类能越过自然冷冬季节并在第2年春季萌芽、正常开花结实、收获稻谷的水稻品种。本文通过对越冬栽培稻产量性状QTL分析,明确产量相关性状的遗传规律,旨在进一步解析越冬栽培稻产量性状的遗传机制,为育种创新利用提供理论依据。以3份越冬栽培稻构建的3个半同胞F2群体为材料。各考察15个产量相关性状,利用Excel 2003、GraphPad Prism 5.0和QTL IciMapping 4.10软件分析数据、绘制遗传图谱、定位QTL和联合分析。结果表明,产量性状表型值在3群体中呈连续正态分布,表现为数量性状遗传。共检测到37个QTL和26对上位性QTL,贡献率分别介于2.32%～36.31%和1.04%～2.05%;检测到9个同时影响2个及以上产量性状(一因多效)QTL标记区间;以联合分析检测到13个产量性状相关QTL,其中4个QTL区间与单群体检测QTL区间重叠;越冬栽培稻产量相关性状QTL以加–显性效应遗传为主、上位性遗传效应为辅。本研究将为越冬栽培稻产量相关基因挖掘及育种创新利用奠定基础。     

水稻黑条矮缩病抗性QTL定位

发掘水稻黑条矮缩病的抗性基因有助于抗病品种的选育,减少黑条矮缩病对水稻生产的危害。本研究构建了包含222个家系的L5494/IR36重组自交系群体。对该群体进行黑条矮缩病的田间诱发鉴定,抗性亲本IR36发病率为28.70%,感病亲本L5494发病率为84.26%,群体发病率范围为11.21%～89.81%。利用134对分子标记构建覆盖12条染色体的遗传连锁图谱,总遗传距离为1475.97 cM,平均标记间距为11.1 cM。利用QTL IciMapping 4.0对抗黑条矮缩病QTL进行分析,共检测到4个QTL,其中第1、第2、第9染色体上QTL的表型贡献率分别为12.64%、16.00%和8.43%,抗病等位基因来自抗病亲本IR36;第6染色体上QTL的表型贡献率为10.82%,抗病等位基因来自感病亲本L5494。在此基础上,利用93-11为供体、日本晴为背景的近等基因系材料,在qRBSDV-1定位区间内检测到来自93-11的抗性QTL。本研究结果为水稻黑条矮缩病抗性基因定位及分子标记辅助选择育种提供借鉴。     

基于侯选基因标记的四倍体马铃薯休眠QTL关联分析

休眠期是马铃薯(SolanumtuberosumL.)重要的块茎性状之一,寻找调控马铃薯块茎休眠的关键基因,揭示其分子机制以选育具有适宜休眠期长度的马铃薯品种,对于解决当前马铃薯产业中过长或过短休眠期带来的经济损失和食品安全隐患等问题十分关键。前期研究在二倍体马铃薯连锁群体中定位了6个加性休眠QTL,本研究拟在四倍体马铃薯育种材料中验证这些休眠QTL。基于休眠QTL连锁的候选基因标记,采用混合线性模型(MLM),模型中考虑群体结构和亲缘关系(Q+K),在四倍体马铃薯自然群体St-hzau中对马铃薯块茎休眠期进行了关联分析。5号染色体上休眠QTL DorB5.3连锁的候选基因标记S199_300和GWD (根据葡聚糖水双激酶α-glucan water dikinase基因设计)与马铃薯块茎休眠期具有显著的关联(P0.05),分别解释了休眠期表型变异的7.8%和3.2%,分别能增加休眠期7.1 d和4.5 d,即在二倍体马铃薯连锁群体中定位的稳定主效休眠QTL DorB5.3在四倍体马铃薯关联群体St-hzau中也表现显著, DorB5.3的稳定性在关联分析结果中得到了验证,表明候选基因标记策略在马铃薯块茎休眠QTL关联分析中是一种有效的策略。本研究所验证的主效休眠QTL DorB5.3及相应连锁标记可以直接用于马铃薯休眠育种。据此可以推测GWD可能在控制还原糖含量和块茎休眠2个方面均发挥作用,马铃薯块茎休眠机制与还原糖含量变化机制可能存在着部分交叉。     

春小麦抗旱耐热性QTL分析

为发掘控制小麦抗旱耐热基因位点,以小麦重组自交系(RILs)群体为材料,于2015-2017年小麦灌浆期进行干旱胁迫、热胁迫、旱热胁迫处理,并对抗旱耐热相关性状QTL进行分析。结果表明,在干旱胁迫、热胁迫、旱热胁迫下分别检测到22、36和30个QTL,其中控制旗叶叶绿素含量、旗叶含水量、穗粒重、千粒重的QTL数分别为26、21、22和19个。抗旱相关性状QTL位于2A、3B、4B、7B、3D、4D和7D染色体上,表型贡献率为9.38%～30.81%;耐热相关性状QTL位于2A、2B、3A、3B、4B、4D、5D、6D、7A和7B染色体上,表型贡献率为9.03%～34.97%。抗旱性共定位区间2个,分别位于2A(gwm294-wmc644)和7B(barc140-gwm297)染色体上;耐热性共定位区间2个,分别位于5D(cfd67-cfd40)和6D(barc196-barc54)染色体上;抗旱耐热性共定位区间3个,分别位于2A(gwm294-wmc644)、2B(wmc441-wmc317)和7B(wmc83-wmc276)染色体上,其中共定位区间gwm294-wmc644( Qcc-2A.2、 Qgw-2A.1)的贡献率超过10%,遗传距离较小(6.49 cM)。     

利用重组自交系高密度遗传图谱定位水稻芽期耐冷QTL

为定位水稻芽期耐冷QTL,本实验以双季超级稻品种‘五丰优T025’的双亲‘五丰B’和‘昌恢T025’杂交衍生的重组自交系(recombinant inbred lines, RILs)群体为材料,对10℃低温处理的水稻幼芽的存活率、根数、根长和芽长进行了测定。利用QTL Icimapping v4.2软件,共检测到3个控制芽期耐冷性QTL：qRL1、qRL2和qBL6,分别位于第1、2、6染色体上,LOD值分别为2.98,2.51和5.26,分别解释表型变异的10.54%,8.67%和14.04%,其增效等位基因均来自于亲本‘昌恢T025’。这些QTL定位在6.75k~40.05 kb染色体区间,为后续利用这些QTL进行分子标记辅助,选育芽期耐冷籼稻新品种奠定了基础。此外,检测到13对影响水稻芽期耐冷上位性互作QTL,分布在所有12条染色体,其中第3染色体与第8染色体之间互作位点可解释的表型变异率达到21.77%,表明上位性互作QTL在调控水稻芽期耐冷过程中也发挥了重要作用。     

水稻‘越光’品种的“前世今生”

‘越光’是一种短园粒水稻品种,自1953年在日本一开始推广种植,就是日本人最喜欢的大米。即使大面积推广种植50多年之后的现在,由于其米质优良和长期形成的消费口碑,也依然是日本水稻最大种植推广品种。为全面了解‘越光’品种育种过程和其特有的农艺性状以及控制有利性状基因组信息,我们以“Koshihikari: a premium short-grain ricecultivar - its expansion and breeding in Japan”文章为最主要参考文献并加以摘译,对其历史进行梳理,同时对当前中国优质稻育种提出了个人的思考。     

Construction of high-density linkage map and identification of QTLs associated with resistance to black rot in radish (Raphanus sativus) by RAD sequencing

High-density marker-based QTL mapping can serve as an effective strategy to identify novel genomic information to facilitate crop improvement. In this study, we genotyped an F₂ population (KB12-1 × PP12-1) using a RAD-seq approach and constructed a high-density linkage map for radish. After a series of filtering procedures were performed, 17,124 SNPs and 3,336 indels with aa × bb genotyping were retained to obtain bin markers. Then, a linkage map comprising a total of 1,221 bin markers in nine linkage groups spanning 1,467.3 cM with an average marker interval of 1.2 cM was constructed. We evaluated the resistance of the F₂ mapping population to black rot using F₃ progeny, and two major QTLs related to black rot resistance were identified based on this map. Among these QTLs, qBRR2 on Chr.2 explained 26.97% of the phenotypic variation with a LOD score of 11.93, and qBRR7 on Chr.7 accounted for 27.06% of the phenotypic variation with a LOD score of 11.83. The additive effect of qBRR2 was positive (14.97); however, qBRR7 had the opposite effect (−11.99). The high-density linkage map and the major QTLs qBRR2 and qBRR7 provide new important information for disease resistance gene discovery and utilization in genetic improvement.     

小麦株高QTL Qph.nau-5B的效应评价

株高直接影响小麦的产量潜力,也是植株抗倒伏性的重要组成部分。目前虽有大量株高相关QTL被鉴定到,但大多QTL的遗传效应仍不清楚。本研究前期利用小麦品种群体,通过关联分析鉴定到一个小麦株高主效QTL Qph.nau-5B。为了评价该QTL的效应,通过分子标记辅助选择分别构建了以南大2419、吉春1016和郑麦9023为供体亲本,中优9507为背景的3种等位变异的近等基因系,背景回复率均高于93%。在7个独立的试验环境中,所有近等基因系的株高较轮回亲本均显著降低,平均降幅为11.1 cm(10.3%)。Qph.nau-5B不同等位变异效应强弱不同,其中来源于吉春1016和郑麦9023的等位变异平均降秆效应相似(12.4 cm),显著大于南大2419的等位变异(8.6 cm),但各等位变异相对降秆效应大小受环境影响。此外,Qph.nau-5B对单株穗数、穗长、千粒重等农艺性状无明显负效应。本研究结果表明Qph.nau-5B具有重要的育种价值,可为小麦的株型分子设计育种提供基因资源。