The complex genetic architecture of quality traits has hindered efforts to modify seed nutrients in soybean. Genome-wide association studies were conducted for seed composition, including protein, oil, fatty acids, an...The complex genetic architecture of quality traits has hindered efforts to modify seed nutrients in soybean. Genome-wide association studies were conducted for seed composition, including protein, oil, fatty acids, and amino acids, using 313 diverse soybean germplasm accessions genotyped with a high-density SNP array. A total of 87 chromosomal regions were identified to be associated with seed composition, explain- ing 8%-89% of genetic variances. The candidate genes GmSAT1, AK-HSDH, SACPD-C, and FAD3A of known function, and putative MtN21 nodulin, FATB, and steroid-5-^-reductase involved in N2 fixation, amino acid biosynthesis, and fatty acid metabolism were found at the major-effect loci. Further analysis of additional germplasm accessions indicated that these major-effect loci had been subjected to domes- tication or modern breeding selection, and the allelic variants and distributions were relevant to geographic regions. We also revealed that amino acid concentrations related to seed weight and to total protein had a different genetic basis. This helps uncover the in-depth genetic mechanism of the intricate relationships among the seed compounds. Thus, our study not only provides valuable genes and markers for soybean nutrient improvement, both quantitatively and qualitatively, but also offers insights into the alteration of soybean quality during domestication and breeding.展开更多
Besides the natural selection, the crops cultivated today have experienced two episodes of strong artificial selection, domestic and modern breeding. Domestication led to giant genetic structure differentiation betwee...Besides the natural selection, the crops cultivated today have experienced two episodes of strong artificial selection, domestic and modern breeding. Domestication led to giant genetic structure differentiation between cultivars and their wild species, while modern breeding made further genetic structure differentiation between the modern varieties and the landraces. In a population, diversity of the loci under strong selection is significantly lower than that of other loci. At the same time, diversity in the genomic regions flanking these selected loci also declines in the process of selection. This phenomenon is called hitchhiking effects or selection sweep in genetics. Genomic regions with selection sweep （haplotype block） could be detected after draft genome scanning （genome typing） with molecular markers in a number of released varieties or natural populations. Marker/trait association analysis in these regions would detect the loci （or QTLs） even the favored alleles （genes） in breeding or natural adaptation. Fine scanning of these genomic regions would help to determine the sizes of haplotype blocks and to discover the key genes, thereby providing very valuable information for isolation of the key genes and molecular design of new varieties. Establishment of high density genetic linkage maps in the major crops and availability of high throughput genotyping platform make it possible to discover agronomic important genes through marker/trait association analysis. On the basis of available publications, we give a brief introduction of the hitchhiking effect mapping approach in this paper using plant height, 1 000-grain weight, and phosphorus-deficiency tolerance as examples in wheat.展开更多
文摘The complex genetic architecture of quality traits has hindered efforts to modify seed nutrients in soybean. Genome-wide association studies were conducted for seed composition, including protein, oil, fatty acids, and amino acids, using 313 diverse soybean germplasm accessions genotyped with a high-density SNP array. A total of 87 chromosomal regions were identified to be associated with seed composition, explain- ing 8%-89% of genetic variances. The candidate genes GmSAT1, AK-HSDH, SACPD-C, and FAD3A of known function, and putative MtN21 nodulin, FATB, and steroid-5-^-reductase involved in N2 fixation, amino acid biosynthesis, and fatty acid metabolism were found at the major-effect loci. Further analysis of additional germplasm accessions indicated that these major-effect loci had been subjected to domes- tication or modern breeding selection, and the allelic variants and distributions were relevant to geographic regions. We also revealed that amino acid concentrations related to seed weight and to total protein had a different genetic basis. This helps uncover the in-depth genetic mechanism of the intricate relationships among the seed compounds. Thus, our study not only provides valuable genes and markers for soybean nutrient improvement, both quantitatively and qualitatively, but also offers insights into the alteration of soybean quality during domestication and breeding.
文摘Besides the natural selection, the crops cultivated today have experienced two episodes of strong artificial selection, domestic and modern breeding. Domestication led to giant genetic structure differentiation between cultivars and their wild species, while modern breeding made further genetic structure differentiation between the modern varieties and the landraces. In a population, diversity of the loci under strong selection is significantly lower than that of other loci. At the same time, diversity in the genomic regions flanking these selected loci also declines in the process of selection. This phenomenon is called hitchhiking effects or selection sweep in genetics. Genomic regions with selection sweep （haplotype block） could be detected after draft genome scanning （genome typing） with molecular markers in a number of released varieties or natural populations. Marker/trait association analysis in these regions would detect the loci （or QTLs） even the favored alleles （genes） in breeding or natural adaptation. Fine scanning of these genomic regions would help to determine the sizes of haplotype blocks and to discover the key genes, thereby providing very valuable information for isolation of the key genes and molecular design of new varieties. Establishment of high density genetic linkage maps in the major crops and availability of high throughput genotyping platform make it possible to discover agronomic important genes through marker/trait association analysis. On the basis of available publications, we give a brief introduction of the hitchhiking effect mapping approach in this paper using plant height, 1 000-grain weight, and phosphorus-deficiency tolerance as examples in wheat.
