Mapping of QTLs for Nitrogen Use Efficiency and Related Traits in Rice （ Oryza sativa L.）

Current rice production is usually guaranteed by applying large amount of chemical nitrogen fertilizers to paddy soils. The improvement of nitrogen use efficiency is of great importance not only in rice production itself but in environmental protection as well. In this study we performed a molecular marker-based genetic analysis of nitrogen use efficiency for biomass production （NUEp） and several other related traits in a recombinant inbred line （RIL） population, derived from a cross of the parents of Shanyou 63, the most widely cultivated indica hybrid in China. A total of 12 QTLs were detected using interval mapping with a LOD threshold of 2.0, among which one QTL controlling NUEp was located at the marker interval of Waxy-C1496 on chromosome 6, and the rest 11 QTLs associated nitrogen concentration and accumulation in rice plant were positioned on chromosomes 1, 2, 4 and 6, respectively. Correlation between NUEp and other traits was analyzed and the implications of the results with respect to the improvement of the hybrid rice were discussed.     

Advanced Backcross QTL Analysis for the Whole Plant Growth Duration Salt Tolerance in Rice（Oryza sativa L.）

Salinity is a major factor limiting rice yield in coastal areas of Asia. To facilitate breeding salt tolerant rice varieties, the wholeplant growth duration salt tolerance（ST） was genetically dissected by phenotyping two sets of BC2F5 introgression lines（ILs） for four yield traits under severe natural salt stress and non-stress filed conditions using SSR markers and the methods of advanced backcross QTL（AB-QTL） analysis and selective introgression. Many QTLs affecting four yield traits under salt stress and nonstress conditions were identified, most（〉90%） of which were clustered in 13 genomic regions of the rice genome and involved in complex epistasis. Most QTLs affecting yield traits were differentially expressed under salt stress and non-stress conditions. Our results suggested that genetics complementarily provides an adequate explanation for the hidden genetic diversity for ST observed in both IL populations. Some promising Huanghuazhan（HHZ） ILs with favorable donor alleles at multiple QTLs and significantly improved yield traits under salt stress and non-stress conditions were identified, providing excellent materials and relevant genetic information for improving rice ST by marker-assisted selection（MAS） or genome selection.     

Major Gene Identification and Quantitative Trait Locus Mapping for Yield- Related Traits in Upland Cotton （Gossypium hirsutum L.）

Segregation analysis of the mixed genetic model of major gene plus polygene was used to identify the major genes for cotton yield-related traits using six generations P1, P2, F1, B1, B2, and F2 generated from the cross of Baimian 1 x TM-1. In addition to boll size and seed index, the major genes for the other five traits were detected： one each for seed yield, lint percentage, boll number, lint index; and two for lint yield. Quantitative trait locus/loci （QTL） mapping was performed in the F2 and F2：3 populations of above cross through molecular marker technology, and a total of 50 QTL （26 suggestive and 24 significant） for yield-related traits were detected. Four common QTL were discovered： qLP-3b（F2）/qLP-3（F2：3） and qLP-19b （F2）/qLP-19（F2：3） for lint percentage, qBN-17（F2）/qBN-17（F2：3） for boll number, and qBS-26b（F2）/qBS-26（F2：3） for boll size. Especially, qLP- 3b（Fz）/qLP-3（F2：3）, not only had LOD scores 〉3 but also exceeded the permutation threshold （5.13 and 5.29, respectively）, correspondingly explaining 23.47 and 29.55% of phenotypic variation. This QTL should be considered preferentially in marker assisted selection （MAS）. Segregation analysis and QTL mapping could mutually complement and verify, which provides a theoretical basis for genetic improvement of cotton yield-related traits by using major genes （QTL）.     

QTLs for Sugar Content of Stalk in Sweet Sorghum （Sorghum bicolor L.Moench）

High sugar content of sorghum stalk is an important factor in the sorghum silage production. To identify the genomic regions controlling sugar content and to develop molecular markers linked to sugar content in sweet sorghum, we used an F2：3 segregating population consisting of 207 individuals derived from a cross between a high sugar content inbred line, Early Folger, and a normal inbred line, N32B, for genetic linkage mapping and quantitative trait locus （QTL） analysis. We constructed a genetic linkage map spanning 983.5 cM based on a total of 327 markers comprising 31 restriction fragment length polymorphism （RFLP） markers, 254 amplified fragment length polymorphism （AFLP） markers, and 42 simple sequence repeat （SSR） markers. In the 20 linkage groups detected, 98.2% of markers aligned to the 10 linkage groups of sorghum. Variations in sugar content at different growth stages and among internodes suggested that the sugar content of middle internodes is stable and suitable for measuring at early dough stage. The broad sense heritability （hB0 of sugar content was 0.64 and 0.62 estimated from the data of F3 families and each parent in 2003 and 2004. We identified one and two QTLs accounting for 22.2 to 25.0% of phenotypic variance using simple interval mapping method in 2003 and 2004, respectively. These two QTLs showed a negative additive effect, and over-dominance effect. A QTL on LG-D was detected in both two years. Above results will be help us to understand the genetic mechanism of sugar content in sorghum and the QTL detected in this study might be useful in the improvement of sugar content by marker-assisted selection.     

Analysis of Two-Dimensional Gel Electrophoresis Images of Protein from Posterior Silk Gland of Silkworm （Bombyx mort） on Day 1 and Day 4 in the 5th Instar Stage

The posterior silk gland （PSG） of silkworm is an important organ where fibroin is synthesized and secreted exclusively. Because fibroin constitutes 75-80% of the silk filament, the mechanism governing fibroin secretion, quality and yield of cocoon can be elucidated by the study on the PSG. Using two-dimensional gel electrophoresis （2-DE） and image analysis system, the changes in the protein composition in the PSG cell were investigated on the day 1 （D1） and day 4 （D4） in the 5th instar stage from five different strains of silkworm （Bombyx mori）. While differences at protein level between days and strains were far less than those observed at the gene level using EST analysis. The change trends in protein composition from D1 to D4 were diverse among the different strains. The results suggest that the secretion of fibroin is regulated by multiple proteins. The site of regulation and the proteins responsible for the regulation vary with the strain, which leads to differences between strains in the capacity of fibroin secretion in the PSG cell.     

Molecular Related Indexes Assessment and Traits Correlation Analysis of Turbot（Scophthalmus maximus L.） by Using SSR Marker Correlation Coefficient in Turbot

Five molecular related indexes： MOL, SIM, d2, H0and PIC of 15 turbot parent pairs were estimated by using 10 SSR loci, which were used in correlation analysis with growth traits, DIL and DIW, of family filial from those 15 parent pairs.DIL and DIW were regressed on the MOL, SIM, d2, H0and PIC. Results showed MOL of five SSR loci（12, 17, 24, 81 and 85） and SIM of five loci（17, 21, 24, 81and 85） all shared significant positive correlation with DIL（r=0.482, P=0.035 and r=0.479, P=0.035, respectively）; H0of six SSR loci（11, 17, 21, 24, 26 and 85） had significant positive correlation with DIW（r=0.551, P=0.017）; PIC of two SSR loci（9and 26） had significant positive（r=0.519, P=0.024） correlation with DIL, while that and of four loci（17, 24, 27 and 85） had significant negative correlation（r=-0.519,P=0.024）, with DIL. This present study suggested that filial growth expression could be predicted by using molecular related indexes in turbot breeding practice, and the accuracy of prediction depends on more SSR loci, especially associated with QTL.     

Bulked Segregant Analysis to Detect QTL Related to Heat Tolerance in Rice （Oryza sativa L.） Using SSR Markers

The study was undertaken to assess the genetic effect of quantitative trait loci （QTLs） conferring heat tolerance at flowering stage in rice. A population consisting of 279 F2 individuals from the cross between 996, a heat tolerant cultivar and 4628, a heat-sensitive cultivar, was analyzed for their segregation pattern of the difference of seed set rate under optimal temperature condition and high temperature condition. The difference of seed set rate under optimal temperature condition and high temperature condition showed normal distribution, indicating the polygenic control over the trait. To identify main effect of QTL for heat tolerance, the parents were surveyed with 200 primer pairs of simple sequence repeats （SSR）. The parental survey revealed 30% polymorphism between parents. In order to detect the main QTL association with heat tolerance, a strategy of combining the DNA pooling from selected segregants and genotyping was adopted. The association of putative markers identified based on DNA pooling from selected segregants was established by single marker analysis （SMA）. The results of SMA revealed that SSR markers, RM3735 on chromosome 4 and RM3586 on chromosome 3 showed significant association with heat tolerance respectively, accounted for 17 and 3% of the total variation respectively. The heat tolerance during flowering stage in rice was controlled by multiple gene. The SSR markers, RM3735 on chromosome 4 and RM3586 on chromosome 3 showed significant association with heat tolerance respectively, accounted for 17 and 3% of the total variation respectively. The two genetic loci, especially for RM3735 on chromosome 4, can be used in marker-assistant-selected method in heat tolerance breeding in rice.     

QTL Mapping of Isoflavone,Oil and Protein Contents in Soybean （Glycine max L. Merr.）

Soybean （Glycine max L. Merr.） is the world＇s foremost source of edible plant oil and proteins, meantime, the biologically active secondary metabolites such as saponins and isoflavones are benefit to human health. The objective of this study was to identify quantitative trait loci （QTL） and epistatic interactions associated with isoflavone, protein, and oil contents in soybean seeds. An F13 recombinant inbred line （RIL） comprising 474 lines was derived from a cross between Jindou 23 and Huibuzhi cultivars. SSR technique was employed for mapping of the QTLs. The QTLs for isoflavone, protein, and oil contents were analyzed and 23 QTLs were detected based on the constructed linkage map. Six QTLs for isoflavone content were localized in linkage groups J, N, D2, and G, eleven QTLs for oil content were localized in the linkage groups A1, A2, B2, C2, and D2, and six QTLs for protein content were localized in linkage groups B2, C2, G, and H1. The correlative analysis demonstrated that the isoflavone content had significant correlation with protein content, while significantly negative correlations was existed between oil and protein content, and significantly positive correlations was existed between protein and oil content. All these findings have laid an important basis for the marker assisted breeding in soybean. The phenotypic correlations of quantitative traits may be resulted from the correlation of the QTL controlling those traits.     

Identification of QTLs for Starch Content in Sweetpotato （Ipomoea batatas （L.） Lam.）

Sweetpotato （Ipomoea batatas （L.） Lam.） breeding is challenging due to its genetic complexity. In the present study, interval mapping （IM） and multiple quantitative trait locus （QTL） model （MQM） analysis were used to identify QTLs for starch content with a mapping population consisting of 202 F1 individuals of a cross between Xushu 18, a cultivar susceptible to stem nematodes, with high yield and moderate starch, and Xu 781, which is resistant to stem nematodes, has low yield and high starch content. Six QTLs for starch content were mapped on six linkage groups of the Xu 781 map, explaining 9.1-38.8% of the variation. Especially, one of them, DMFN 4, accounted for 38.8% of starch content variation, which is the QTL that explains the highest phenotypic variation detected to date in sweetpotato. All of the six QTLs had a positive effect on the variation of the starch content, which indicated the inheritance derived from the parent Xu 781. Two QTLs for starch content were detected on two linkage groups of the Xushu 18 map, explaining 14.3 and 16.1% of the variation, respectively. They had a negative effect on the variation, indicating the inheritance derived from Xu 781. Seven of eight QTLs were co-localized with a single marker. This is the first report on the development of QTLs co-localized with a single marker in sweetpotato. These QTLs and their co-localized markers may be used in marker-assisted breeding for the starch content of sweetpotato.     

Multiple Interval Mapping for Whole Cocoon Weight and Related Economically Important Traits QTL in Silkworm (Bombyx mori)

A backcrossed population (BCi) derived from a cross between C100 and Dazao was obtained. The quantitative trait loci (QTLs) of the economically important traits for whole cocoon weight, cocoon shell weight, ratio of cocoon shell and weight of pupae, etc., were analyzed for the first time using the multiple interval mapping software WinQTLCart2.0. In total 40 QTLs were detected and contributed to 21 groups based on the constructed linkage map. According to the mapping results, 2, 2, 3, and 2 major QTLs explained over 20% of total phenotypic variations, whereas four QTLs, namely qCW-19,qSW-2, qCSR-4, and qPW-23, explained more than 30% of total phenotypic variations for whole cocoon weight, cocoon shell weight, ratio of cocoon shell and weight of pupae, respectively. Correlated traits QTLs often share the same location.Furthermore, most of the detected QTLs were closed to one-side marker. By using the very closed markers, positive QTLs can be aggregated, which can form a basis for molecular marker-assisted selection and breeding.     

家蚕全茧量及重要相关经济性状的多重区间作图分析

 利用家蚕品系C100和大造的回交一代BC1群体，用WinQTLCart2.0软件对家蚕全茧量、茧层量、茧层率和蛹体重等4个重要经济性状在分子连锁图的基础上进行了多重区间作图分析。共检测到40个QTL，分布于21个连锁群，其中全茧量、茧层量、茧层率和蛹体重的QTL中，贡献率超过20%的主效QTL数分别为2、2、3、2个，贡献率超过30%的主效QTL有4个，分别是控制全茧量的qCW-19、茧层量的qSW-2、茧层率的qCSR-4和蛹体重的qPW-23。相关显著的经济性状的QTL具有集中分布的特点，并且检测到的QTL均与其单侧标记紧密连锁，利用紧密连锁的分子标记将不同的增效QTL进行聚合，为优质高产家蚕新品种的选育打下基础。     

家蚕蚕蛹黄酮类化合物的提取与测定

为推进家蚕蛹体的药用开发,研究家蚕蛹体黄酮类化合物的提取及其含量的测定方法。将蛹体用研钵研碎,选用80%乙醇溶剂在60℃下抽提4 h,1次即可,可有效提取家蚕蛹体黄酮类化合物;以1%AlCl3显色在TU-1800SPC紫外光分光光度计420 nm波长下比色,可测定出家蚕蛹体黄酮类化合物的含量。家蚕蛹体含黄酮类化合物,其质量比达到0.362 mg·g-1左右。     

陆地棉高密度遗传图谱的构建及产量相关性状的QTL定位

【目的】通过构建高密度SNP遗传图谱,开展棉花多群体产量相关性状的QTL定位,获得稳定性好、精确度高的QTL,为产量性状调控基因的挖掘和有效分子标记的开发提供依据。【方法】以高稳产冀丰1271为母本、优质自交系冀丰173为父本,构建包含200个单株的F₂群体,利用测序基因分型(genotyping by sequencing,GBS)技术开发群体的SNP标记并构建高密度遗传图谱,对F₂、F_2:3、F_2:4群体的衣分、子指和单铃重进行QTL定位,注释主效和稳定QTL位点内的基因并分析基因在不同组织的表达模式,筛选候选基因。【结果】通过简化基因组测序,共获得383.07 Gb数据,包括母本冀丰1271的26.93 Gb、父本冀丰173的27.30 Gb和F₂群体的328.84 Gb,Q30值分别为90.55%、89.95%和95.77%。在F₂群体中开发了1 305 642个SNP标记,其中,用于构建遗传图谱的aa?bb型SNP为410 726个。构建了一张包...     

基于高密度遗传图谱定位水稻籽粒大小相关性状QTL

【目的】通过对水稻籽粒大小相关性状进行QTL定位及候选基因的筛选,为水稻籽粒大小相关基因的精细定位、克隆及基因功能等研究奠定基础。【方法】以籼稻品种特华占搭载高空气球空间诱变后产生的特异矮秆突变体CHA-1为母本,以籼稻品种航恢7号搭载"神州八号"飞船经空间诱变后筛选出的突变体H335为父本杂交衍生出的275个RIL群体作为供试材料,利用GBS测序技术构建高密度遗传图谱,RIL群体及亲本分别于2017年早季和2017年晚季在华南农业大学实验教学基地种植。成熟收获后通过扫描仪获取水稻籽粒图像,利用SmartGrain软件获取籽粒大小相关性状表型数据。采用QTL IciMapping v 4.0软件基于完备复合区间作图法,对水稻籽粒大小相关性状进行QTL定位。【结果】构建的高密度遗传图谱包含2 498个Bin标记,总图距2 371.84cM,标记间平均遗传图距为0.95 cM。两季共检测到26个籽粒大小相关QTL,分布于第1、2、3、4、7和9染色体上,单一QTL贡献率为0.16%—14.41%。在第1、2、3、7染色体上检测到5个QTL簇(qGS1、qGS2、qGS3-1、qGS3-2和...     

水稻分蘖相关性状的QTL定位与分析

应用147个SSR标记,对水稻测序品种日本晴(Nipponbare以下简称Nipp)×广陆矮4号(部分 测序,以下简称GLA)的F2群体进行基因检测,构建了全长为1736．6cM、覆盖水稻基因组12条染色体 的连锁图,采用QTLCart1．7统计软件对水稻分蘖相关性状如分蘖数、穗数、有效分蘖数、分蘖率等4 个性状的基因座位进行定位分析,检测到5个主效果基因和17个微效基因,同时结合基因组研究的 最新成果,对7个与标记间遗传距离为0(QTL POS=0)的OTLs进行生物信息学的分析,尝试用OTL 定位预测基因的功能。     

Mapping of QTLs for Nitrogen Use Efficiency and Related Traits in Rice( Oryza sativa L.)

Current rice production is usually guaranteed by applying large amount of chemical nitrogen fertilizers to paddy soils. The improvement of nitrogen use efficiency is of great importance not only in rice production itself but in environmental protection as well. In this study we performed a molecular marker-based genetic analysis of nitrogen use efficiency for biomass production (NUEp) and several other related traits in a recombinant inbred line (RIL) population, derived from a cross of the parents of Shanyou 63, the most widely cultivated indica hybrid in China. A total of 12 QTLs were detected using interval mapping with a LOD threshold of 2.0, among which one QTL controlling NUEp was located at the marker interval of Waxy-C1496 on chromosome 6, and the rest 11 QTLs associated nitrogen concentration and accumulation in rice plant were positioned on chromosomes 1, 2, 4 and 6, respectively. Correlation between NUEp and other traits was analyzed and the implications of the results with respect to the improvement of the hybrid rice were discussed.     

四倍体小麦胚大小性状QTL定位与分析

【目的】挖掘小麦胚大小性状相关的数量性状位点,解析胚大小与其他重要农艺性状之间的相关性,为胚相关性状QTL的精细定位及育种利用奠定基础。【方法】以四倍体小麦矮兰麦（Ailanmai）和野生二粒小麦（LM001）构建的121份F8代重组自交系群体（AM群体）作为研究材料,将其分别种植于成都市崇州试验基地（2018、2019和2020年）、成都市温江区试验基地（2020年）和雅安市试验基地（2020年）,调查5个环境下的胚长、胚宽、胚长/胚宽、胚长/粒长、胚宽/粒宽以及胚面积6个性状,结合基于小麦55K SNP芯片构建的遗传连锁图谱对上述6个性状进行QTL定位。【结果】胚大小性状呈近似正态分布,符合数量性状的遗传特征。QTL定位共检测到27个胚大小相关性状的QTL,其中,7个分别控制胚长和胚宽的QTL可解释7.75%—21.74%和7.67%—33.29%的表型变异,共检测到5个在多环境稳定表达的主效QTL:QEL.sicau-AM-3B、QEW.sicau-AM-2B、QEW/KW.sicau-AM-2B、QEL/EW.sicau-AM-2B-1和QEA.sicau-AM-2B,其贡献率...     

辛硫磷对家蚕细胞周期蛋白家族基因转录活性的影响

【目的】探讨经辛硫磷诱导后,家蚕细胞周期蛋白家族基因(CyclinA、CyclinB、CyclinB3、CyclinE)在5龄幼虫各种组织中的转录活性,为进一步研究有机磷农药对家蚕的损伤机制提供参考。【方法】采用实时荧光定量PCR方法,以饲喂清水浸泡过的桑叶为对照,分析家蚕5龄3d幼虫喂食辛硫磷(4μg/mL)浸泡桑叶24h后,脑、脂肪体、中肠、丝腺、马氏管、精巢及卵巢等7种组织中4种细胞周期蛋白家族基因的转录水平。【结果】与对照组相比,辛硫磷诱导24h后,CyclinA、CyclinB、CyclinB3在各组织中均表达上调,CyclinE在中肠及脂肪体中表达显著下调,在精巢与马氏管中无明显变化,在其他组织中则表达上调。【结论】辛硫磷诱导24h后,家蚕组织中CyclinA、CyclinB及CyclinB3基因表达上调,这可能是家蚕对磷胁迫的响应;CyclinE在中肠及脂肪体中表达显著下调,这与这2种器官是家蚕重要的解毒代谢器官有关。