大白菜叶色相关性状的QTL定位与分析

 应用已构建了AFLP遗传图谱的大白菜DH群体, 采用多模型QTL作图的方法, 通过色差计法、叶色素测定法和人为目测法3种方法7个指标对叶色相关性状进行QTL定位和分析。结果表明, 在7个连锁群上共检测到18个QTL, 其中色差计法检测到9个QTL, 叶色素测定法检测到8个QTL, 人为目测法仅检测到1个QTL。另外, 估算了单个QTL的贡献率和加性效应, 发现各QTL的加性效应各不相等, 各位点的贡献率在5.5%～15.6%之间。     

关联分析及其在玉米中的研究进展

阐述关联分析的概念、特点、方法、统计学原理以及第3代分子标记进行关硖分析的基础一单核苷酸多态性和连锁不平衡。     

玉米F2群体分子标记偏分离的遗传分析

以优良玉米(Zea mays L.)自交系抗感杂交组合（R15×掖478）的F2群体为材料,构建了239个分子标记(包括151个SSR标记和88个AFLP标记)的玉米分子连锁图,覆盖全基因组3 463.5 cM,相邻标记间的平均间距为14.5 cM。在239个标记中,16个SSR标记和9个AFLP标记表现偏分离(P<0.05)。在4条不同的染色体上发现5个偏分离的     

水稻4种农艺性状QTL的初步定位分析

本研究以粳稻品种＂藤坂5号＂与籼稻品种＂江西丝苗＂为亲本杂交构建的F2分离群体（137个单株）作为作图群体,对控制水稻株高、剑叶宽、剑叶长和剑叶长宽比4种农艺性状的QTL进行定位分析。分别在第1、3、4和7染色体上检测到7个QTLs,其中qPH-3、qFLLW-4和qFLW-3在其所控制的相应性状（株高,剑叶宽和剑叶长宽比）所定位到的QTL中的贡献率是最大的,是主效QTL。然而,在本研究中并未检测到控制剑叶长的QTL。这些分析结果为进一步的分析和精细定位奠定基础,为育种和种质创新提供理论依据。     

Comparative genetic analysis and molecular mapping of fertility restoration genes for WA,Dissi, and Gambiaca cytoplasmic male sterility systems in rice

The genetic relationship among three cytoplasmic male sterility (CMS) systems, consisting of WA, Dissi, and Gambiaca, was studied. The results showed that the maintainers of one CMS system can also maintain sterility in other cytoplasmic backgrounds. The F₁ plants derived from crosses involving A and R lines of the respective cytoplasm and their cross-combination with other CMS systems showed similar pollen and spikelet fertility values, indicating that similar biological processes govern fertility restoration in these three CMS systems. The results from an inheritance study showed that the pollen fertility restoration in all three CMS systems was governed by two independent and dominant genes with classical duplicate gene action. Three F₂ populations, generated from the crosses between the parents of good-performing rice hybrids, that possess WA, Dissi, and Gambiaca CMS cytoplasm, were used to map the Rf genes. For the WA-CMS system, Rf3 was located at a distance of 2.8 cM from RM490 on chromosome 1 and Rf4 was located at 1.6 cM from RM1108 on chromosome 10. For the Dissi-CMS system, Rf3 was located on chromosome 1 at 1.9 cM from RM7466 and Rf4 on chromosome 10 was located at 2.3 cM from RM6100. The effect of Rf3 on pollen fertility appeared to be stronger than the effect of Rf4. In the Gambiaca-CMS system, only one major locus was mapped on chromosome 1 at 2.1 cM from RM576. These studies have led to the development of marker-assisted selection (MAS) for selecting putative restorer lines, new approaches to alloplasmic line breeding, and the transfer of Rf genes into adapted cultivars through a backcrossing program in an active hybrid rice breeding program.     

The development of a genetic linkage map of blackcurrant (Ribes nigrum L.) and the identification of regions associated with key fruit quality and agronomic traits

The first genetic linkage map of blackcurrant (Ribes nigrum L.) was constructed using AFLP, SSR (genomic and EST-derived) and SNP markers, in a mapping population derived from two diverse breeding clones of blackcurrant from the SCRI breeding programme. Cluster analysis of the population revealed that the individuals within the population formed two distinct sub-populations, with segregation ratios consistent with one sub-population having the two intended parents, and the other being selfed segregants. The latter sub-population improves the map by providing a more informative estimate of recombination frequency than the crossed sub-population for some marker configurations, and also revealed the presence of two unlinked loci affecting viability. Several important phenological, agronomic and fruit quality traits were evaluated in the mapping population, and QTLs affecting these are located on the linkage map. This provides a framework for the development of marker-assisted breeding strategies for blackcurrant, to improve breeding efficiency and time to cultivar.     

Molecular characterization of the recombinant inbred line population derived from a japonica-indica rice cross

Recombinant inbred line (RIL) populations of rice are useful genetic sources for map-based cloning of agronomically important genes. Zhe733 is a high-yielding indica cultivar from China conferring resistance to rice blast (RB), rice water weevil (RWW) and straighthead; whereas Kaybonnet low-phytic acid 1-1 (KBNTlpa) is a mutant of a tropical japonica cultivar from the US containing low-phytic acid with average yield, and is susceptible to some RB races, RWW, and straighthead. A 355 RIL F₁₀₋₁₁ population derived from the cross of KBNTlpa × Zhe733 was recently released. Simple sequence repeat (SSR) markers were used to evaluate 269 RILs of this population. A total of 107 polymorphic markers were mapped on all rice chromosomes representing a total of 1,016.3 cM of genetic distance. Two hundred and thirty-five KBNTlpa × Zhe733 RILs (KZRILs) were clustered into seven groups based on allele frequencies of SSR markers. Twenty-three markers (21.1%) on chromosomes 3, 6, 7, 9, and 11 were found to favor Zhe733 (χ ² = 16.8−189.7 and P < 0.01) and five markers (4.6%) on chromosome 1 and 6 were found to favor KBNTlpa (χ ² = 18.5−46.6 and P < 0.01). Marker segregations were observed to be normal for both parents except 26 (10.2%) KZRILs were found to skew toward Zhe733 (χ ² > 15.7 and P < 0.01). Furthermore, the average frequencies of heterozygosity and non-parental alleles per KZRIL were 1.3% (0.0−38.9%) and 0.4% (0.0−15.0%), respectively. Thirteen heterozygous KZRILs were found at more than five markers loci and nine KZRILs were found with more than five non-parental alleles representing 5.1 and 3.5% of 255 KZRILs. Overall, this KZRIL population is a good population with relatively low frequencies of heterozygosity and non-parental alleles, and with relatively low percentages of skewed markers and skewed KZRILs. The profiles of these SSR markers should facilitate molecular tagging critical genes controlling yield, RB, RWW, and straighthead resistance.     

Association analysis using SSR markers to find QTL for seed protein content in soybean

Association analysis studies can be used to test for associations between molecular markers and quantitative trait loci (QTL). In this study, a genome-wide scan was performed using 150 simple sequence repeat (SSR) markers to identify QTL associated with seed protein content in soybean. The initial mapping population consisted of two subpopulations of 48 germplasm accessions each, with high or low protein levels based on data from the USDA’s Germplasm Resources Information Network website. Intrachromosomal LD extended up to 50 cM with r ² > 0.1 and 10 cM with r ² > 0.2 across the accessions. An association map consisting of 150 markers was constructed on the basis of differences in allele frequency distributions between the two subpopulations. Eleven putative QTL were identified on the basis of highly significant markers. Nine of these are in regions where protein QTL have been mapped, but the genomic regions containing Satt431 on LG J and Satt551 on LG M have not been reported in previous linkage mapping studies. Furthermore, these new putative protein QTL do not map near any QTL known to affect maturity. Since biased population structure was known to exist in the original association analysis population, association analyses were also conducted on two similar but independent confirmation populations. Satt431 and Satt551 were also significant in those analyses. These results suggest that our association analysis approach could be a useful alternative to linkage mapping for the identification of unreported regions of the soybean genome containing putative QTL.     

京海黄鸡IGF1R基因Alu Ⅰ、Hin1 Ⅰ多态位点的发现及其与生产性状的相关性

根据GenBank发表的鸡IGF1R基因序列针对外显子2和3设计2对引物,采用池DNA测序和PCR-R FLP技术,对京海黄鸡IGF1R基因的AluⅠ、Hin1Ⅰ位点进行多态性检测,并与京海黄鸡的生产性状进行相关性分析。结果表明:AluⅠ位点AA基因型个体在8周龄体重显著低于BB型个体(P<0.05),AA和AB基因型个体在12周龄体重显著低于BB型个体(P<0.05)。Hin1Ⅰ位点CC、CD基因型个体的初生重显著低于DD基因型(P<0.05),CC基因型个体的300日龄体重显著低于DD基因型(P<0.05)。研究结果初步显示,IGF1R基因可能是影响京海黄鸡生长性状的一个主效基因或是与之存在紧密遗传连锁的一个标记。     

Investigation and genome-wide association study of grain copper content in Chinese common wheat

Copper is a necessary trace mineral for the human body, and its deficiency threatens human health. Here, a panel of 243 Chinese wheat cultivars from five replications was used to measure the grain copper content (GCC) by atomic absorption spectrometry. Phenotypic analysis results revealed that the averaged GCC of surveyed cultivars ranged from 6.81 to 11.36 mg/kg with an average of 9.23 mg/kg. A genome-wide association study (GWAS) indicated that a total of 489 single-nucleotide polymorphisms (SNPs) were significant, explaining 10.1%–32.6% of the phenotypic variation and were mainly distributed on chromosomes 2A and 5A. Further analysis indicated that GCC_Hap_2A1, GCC_Hap_3B1, and GCC_Hap_5A1 may be important genetic loci that regulate GCC in wheat. Linkage mapping using a bi-parental population detected four QTLs on 1D, 6A, 6B, and 7D, explaining 8.66%, 7.55%, 8.21%, and 4.71% of the phenotypic variation, respectively. Additionally, two of the significant SNPs were located on 1D, as detected by GWAS, and were within the interval of QGCC.hau-1D, suggesting that this locus plays an important role in regulating wheat GCC. This study dissected the genetic mechanism of GCC in wheat and provides useful information for the utilization of high-GCC wheat germplasm by marker-assisted selection in wheat quality breeding.