Quantitative Trait Loci For Protein Content Research Articles

Identification of Quantitative Trait Loci (QTL) for Sucrose and Protein Content in Soybean Seed.

Protein and sugar content are important seed quality traits in soybean because they improve the value and sustainability of soy food and feed products. Thus, identifying Quantitative Trait Loci (QTL) for soybean seed protein and sugar content can benefit plant breeders and the soybean market by accelerating the breeding process via marker-assisted selection. For this study, a population of recombinant inbred lines (RILs) was developed from a cross between R08-3221 (high protein and low sucrose) and R07-2000 (high sucrose and low protein). Phenotypic data for protein content were taken from the F2:4 and F2:5 generations. The DA7250 NIR analyzer and HPLC instruments were used to analyze total seed protein and sucrose content. Genotypic data were generated using analysis via the SoySNP6k chip. A total of four QTLs were identified in this study. Two QTLs for protein content were located on chromosomes 11 and 20, and two QTLs associated with sucrose content were located on chromosomes 14 and. 11, the latter of which co-localized with detected QTLs for protein, explaining 10% of the phenotypic variation for protein and sucrose content in soybean seed within the study population. Soybean breeding programs can use the results to improve soybean seed quality.

Genetic mapping high protein content QTL from soybean \u2018Nanxiadou 25\u2019 and candidate gene analysis

BackgroundSoybean is a globally important legume crop that provides a primary source of high-quality vegetable protein and oil. Seed protein content (SPC) is a valuable quality trait controlled by multiple genes in soybean.ResultsIn this study, we performed quantitative trait loci (QTL) mapping, QTL-seq, and RNA sequencing (RNA-seq) to reveal the genes controlling protein content in the soybean by using the high protein content variety Nanxiadou 25. A total of 50 QTL for SPC distributed on 14 chromosomes except chromosomes 4, 12, 14, 17, 18, and 19 were identified by QTL mapping using 178 recombinant inbred lines (RILs). Among these QTL, the major QTL qSPC_20–1 and qSPC_20–2 on chromosome 20 were repeatedly detected across six tested environments, corresponding to the location of the major QTL detected using whole-genome sequencing-based QTL-seq. 329 candidate DEGs were obtained within the QTL region of qSPC_20–1 and qSPC_20–2 via gene expression profile analysis. Nine of which were associated with SPC, potentially representing candidate genes. Clone sequencing results showed that different single nucleotide polymorphisms (SNPs) and indels between high and low protein genotypes in Glyma.20G088000 and Glyma.16G066600 may be the cause of changes in this trait.ConclusionsThese results provide the basis for research on candidate genes and marker-assisted selection (MAS) in soybean breeding for seed protein content.

Genome-Wide Characterization and Analysis of CIPK Gene Family in Two Cultivated Allopolyploid Cotton Species: Sequence Variation, Association with Seed Oil Content, and the Role of GhCIPK6.

Calcineurin B-like protein-interacting protein kinases (CIPKs), as key regulators, play an important role in plant growth and development and the response to various stresses. In the present study, we identified 80 and 78 CIPK genes in the Gossypium hirsutum and G. barbadense, respectively. The phylogenetic and gene structure analysis divided the cotton CIPK genes into five groups which were classified into an exon-rich clade and an exon-poor clade. A synteny analysis showed that segmental duplication contributed to the expansion of Gossypium CIPK gene family, and purifying selection played a major role in the evolution of the gene family in cotton. Analyses of expression profiles showed that GhCIPK genes had temporal and spatial specificity and could be induced by various abiotic stresses. Fourteen GhCIPK genes were found to contain 17 non-synonymous single nucleotide polymorphisms (SNPs) and co-localized with oil or protein content quantitative trait loci (QTLs). Additionally, five SNPs from four GhCIPKs were found to be significantly associated with oil content in one of the three field tests. Although most GhCIPK genes were not associated with natural variations in cotton oil content, the overexpression of the GhCIPK6 gene reduced the oil content and increased C18:1 and C18:1+C18:1d6 in transgenic cotton as compared to wild-type plants. In addition, we predicted the potential molecular regulatory mechanisms of the GhCIPK genes. In brief, these results enhance our understanding of the roles of CIPK genes in oil synthesis and stress responses.

Genome-wide association analysis in tetraploid potato reveals four QTLs for protein content

Valorisation of tuber protein is relevant for the potato starch industry to create added-value and reduce impact on the environment. Hence, protein content has emerged as a key quality trait for innovative potato breeders. In this study, we estimated trait heritability, explored the relationship between protein content and tuber under-water weight (UWW), inferred haplotypes underlying quantitative trait loci (QTLs) and pinpointed candidate genes. We used a panel of varieties (N = 277) that was genotyped using the SolSTW 20 K Infinium single-nucleotide polymorphism (SNP) marker array. Protein content data were collected from multiple environments and years. Our genome-wide association study (GWAS) identified QTLs on chromosomes 3, 5, 7 and 12. Alleles of StCDF1 (maturity) were associated with QTLs found on chromosome 5. The QTLs on chromosomes 7 and 12 are presented here for the first time, whereas those on chromosomes 3 and 5 co-localized with loci reported in earlier studies. The candidate genes underlying the QTLs proposed here are relevant for functional studies. This study provides resources for genomics-enabled breeding for protein content in potato.

Identification of QTLs for seed quality traits in rapeseed (Brassica napus L.) using recombinant inbred lines (RILs)

Rapeseed (Brassica napus L.) is the most important edible oilseed crop in China and the second most important globally after soybean. It provides edible vegetable oil for human consumption and proteins for the feed industry, and has recently gained increasing interest as a source of biodiesel. The improvement of seed quality traits for high protein, oil and oleic acid, and low erucic acid and glucosinolate content remains the most important breeding goal in B. napus. Mapping of quantitative trait loci (QTLs) underlying seed quality traits will allow us to enrich knowledge on these traits and improve the efficiency and precision of conventional rapeseed breeding via marker-assisted selection (MAS). In this study, a genetic linkage map comprising 181 markers (143 sequence-related amplified polymorphisms (SRAPs) and 38 simple-sequence repeats (SSRs)) and 19 linkage groups covering 1307.99 cM was constructed with 94 F7–8 recombinant inbred lines (RILs) derived from a cross between a high oil content line ‘827R’ and a low oil content line ‘Darmor_Sin’. A total of nine QTLs were identified (LOD > 2.5) on four chromosomal regions (LG1, LG10, LG11 and LG12) for seed quality traits: four for oil content (qOC-1, 2, 3, 4), two for protein content (qPC-1, 2), two for oleic acid content (qOAC-1, 2), and one for glucosinolate content (qGLC-1). The phenotypic variance explained by individual QTL was estimated as 7.70, 14.58, 16.00, and 23.11 % respectively for the four oil content QTLs; 13.16 and 14.81 % for the two protein content QTLs; 12.52 and 25.48 % for the two oleic acid content QTLs; and 47.71 % for the glucosinolate content QTL. The overall phenotypic variation explained by the identified QTLs was 61.39 % for oil content, 27.97 % for protein content, 38.00 % for oleic acid content and 47.71 % for glucosinolate content. Of the two QTLs identified for seed protein content, one (qPC-1) was tightly linked to a QTL for oil content (qOC-1) on LG1 and another one (qPC-2) was co-localized with a second QTL for seed oil content (qOC-2) on LG11. The two pairs of QTLs affected both traits with opposite additive effects confirming the negative correlation between oil and protein content in rapeseed. The present results will be of value for ongoing efforts to dissect the molecular basis of seed quality traits and practicing MAS in B. napus breeding programs.

Identification and mapping of stable QTL for protein content in soybean seeds

Protein and oil are two primary traits in soybean, which affect the quality of soyfood, feed, and oil products. The objectives of this research were to identify and validate quantitative trait loci (QTL) for seed protein. Crosses were made between two high-protein and two low-protein lines, R05-1415 × R05-638 designated as Population 1, and V97-1346 × R05-4256 as Population 2. A total of 242 and 214 recombinant inbred lines were developed for QTL mapping in populations 1 and 2, respectively. The F2 plants from the mapping populations were genotyped with simple sequence repeat (SSR) and/or single nucleotide polymorphism (SNP) markers. Seeds from F2:3, F2:4, and F2:5 lines were evaluated for seed protein content at three locations for 3 years accounting for five environments. A total of 120 polymorphic SSR markers and 526 polymorphic SNP markers were used to construct linkage maps. One major protein QTL on chromosome 20 was identified in both populations across all five environments and accounted for 20–42 % of protein content variation. Four protein QTL were identified on chromosome 1, 5, and 14, which accounted for 10–16 % of the total variation in protein content. These identified QTL along with linked SSR/SNP markers in this study would be of great value in facilitating marker-assisted selection for seed protein content in soybean breeding programs.

Dynamic QTL analysis of protein content and glutamine synthetase activity in recombinant inbred wheat lines.

Protein content (PC) is a crucial factor that determines the end-use and nutritional quality of wheat (Triticum aestivum). Glutamine synthetase (GS), which is a major participant in nitrogen metabolism, can convert inorganic nitrogen into organic nitrogen. Although many studies have been conducted on PC and GS, a dynamic analysis of all of the filling stages has not been conducted. Therefore, 115 F9-10 recombinant inbred wheat lines of 'R131/R142' were used to analyze PC and GS activity during different developmental stages, using the conditional quantitative trait loci (QTL) mapping method. Twenty-two and six conditional QTL were detected for PC and GS activily, respectively. More QTL in leaf PC were detected during the early filling stages than in the later filling stages. Grain PC QTL displayed different dynamic variations to leaf PC QTL during the entire grain-filling stages. All of the QTL were expressed differently over time, and nine conditional QTL were detected across two filling stages. QTL with similar functions may have tended to group in specific locales. This study provides dynamic genetic information on protein accumulation during grain-filling stages.

Identification of QTL/segments related to seed-quality traits in G. soja using chromosome segment substitution lines

Annual wild soybean characterized by low 100-seed weight (100SW), high protein content (PRC) and low oil content (OIC) may have favourable exotic genes/alleles for broadening the genetic base of the cultivated soybean. To evaluate the wild alleles/segments, a chromosome segment substitution line population comprising 151 lines with N24852 (wild) as the donor and NN1138-2 (cultivated) as the recurrent parent was analysed using single-marker analysis, interval mapping, inclusive composite interval mapping and mixed linear composite interval mapping. On 14 segments of ten chromosomes, 17 quantitative trait loci (QTL) were identified, with two segments each containing two QTL for 100SW and OIC and one segment containing two QTL for PRC and OIC, respectively. All the seven wild alleles/segments for 100SW were associated with negative effects and three were associated with positive effects, but one was associated with a negative effect for PRC, and five were associated with negative effects, but one was associated with a positive effect for OIC. Except Satt216 and Sat_224 for 100SW, the identified QTL/segments have been reported from cultivated soybean mapping populations. The detected wild segments may provide materials for further characterization, cloning and pyramiding of the alleles conferring the seed-quality traits.

Identification and validation of quantitative trait loci for seed yield, oil and protein contents in two recombinant inbred line populations of soybean.

Soybean seeds contain high levels of oil and protein, and are the important sources of vegetable oil and plant protein for human consumption and livestock feed. Increased seed yield, oil and protein contents are the main objectives of soybean breeding. The objectives of this study were to identify and validate quantitative trait loci (QTLs) associated with seed yield, oil and protein contents in two recombinant inbred line populations, and to evaluate the consistency of QTLs across different environments, studies and genetic backgrounds. Both the mapping population (SD02-4-59×A02-381100) and validation population (SD02-911×SD00-1501) were phenotyped for the three traits in multiple environments. Genetic analysis indicated that oil and protein contents showed high heritabilities while yield exhibited a lower heritability in both populations. Based on a linkage map constructed previously with the mapping population and using composite interval mapping and/or interval mapping analysis, 12 QTLs for seed yield, 16 QTLs for oil content and 11 QTLs for protein content were consistently detected in multiple environments and/or the average data over all environments. Of the QTLs detected in the mapping population, five QTLs for seed yield, eight QTLs for oil content and five QTLs for protein content were confirmed in the validation population by single marker analysis in at least one environment and the average data and by ANOVA over all environments. Eight of these validated QTLs were newly identified. Compared with the other studies, seven QTLs for seed yield, eight QTLs for oil content and nine QTLs for protein content further verified the previously reported QTLs. These QTLs will be useful for breeding higher yield and better quality cultivars, and help effectively and efficiently improve yield potential and nutritional quality in soybean.

Identification of germplasm with stacked QTL underlying seed traits in an inbred soybean population from cultivars Essex and Forrest

Soybean (Glycine max (L.) Merr.) seed provides valuable oil (~200 g/kg) and protein (~400 g/kg) co-products. Seed composition variations result from several quantitative trait loci (QTL) that act through development. The objectives here were to identify loci underlying seed traits in the Essex × Forrest (EF94)-derived recombinant inbred line (RIL) population which has low frequencies of marker polymorphisms. Seed weight, protein, and oil were measured over 3 years: 2001, 2003, and 2005. Essex’s seeds were larger (141 mg/seed), higher in protein (406 g/kg), and lower in oil (190 g/kg) than Forrest’s (115 mg/seed, 395 g protein/kg, and 203 g oil/kg). Marker analysis included 413 markers for trait associations used for ANOVA, interval mapping, and composite interval mapping. Eleven QTL in nine genomic regions were associated (LOD >2; P < 0.0077) with seed traits. Two QTL, for mean protein and seed size, were clustered on linkage group (LG) E (chromosome Gm16). QTL for protein content alone were found on LG C2 (Gm6), LG D1b (Gm2), LG H (Gm12), and LG I (Gm20). The alleles from Essex, the high-protein parent, underlay higher protein (4–10 g/kg) at four of five loci. A QTL for mean oil was found on LG A2 (Gm18) and on LG I (Gm 20). The alleles from Forrest underlay higher oil (3–4 g/kg). Five separate QTL for mean seed weight were found on LG A1 (Gm05), LG N (Gm15), two on LG B1 (Gm11) and one on LG N (Gm3). The alleles from Essex underlay greater seed weight (0.4–0.66 g/100 seeds). The QTL positions were consistent with reported loci. Germplasm that contained all five beneficial alleles at the QTL underlying protein was significantly higher in protein and yield than Essex (409.7–412.3 g/kg) and included RILs 49 and 62. The germplasm identified can be useful for further breeding of the many traits and QTL measured in each line.

Conditional QTL mapping of protein content in wheat with respect to grain yield and its components

Grain protein content in wheat (Triticum aestivum L.) is generally considered a highly heritable character that is negatively correlated with grain yield and yield-related traits. Quantitative trait loci (QTL) for protein content was mapped using data on protein content and protein content conditioned on the putatively interrelated traits to evaluate possible genetic interrelationships between protein content and yield, as well as yield-related traits. Phenotypic data were evaluated in a recombinant inbred line population with 302 lines derived from a cross between the Chinese cultivar Weimai 8 and Luohan 2. Inclusive composite interval mapping using IciMapping 3.0 was employed for mapping unconditional and conditional QTL with additives. A strong genetic relationship was found between protein content and grain yield, and yield-related traits. Unconditional QTL mapping analysis detected seven additive QTL for protein content, with additive effects ranging in absolute size from 0.1898% to 0.3407% protein content, jointly accounting for 43.45% of the trait variance. Conditional QTL mapping analysis indicated two QTL independent from yield, which can be used in marker-assisted selection for increasing yield without affecting grain protein content. Three additional QTL with minor effects were identified in the conditional mapping. Of the three QTLs, two were identified when protein content was conditioned on yield, which had pleiotropic effects on those two traits. Conditional QTL mapping can be used to dissect the genetic interrelationship between two traits at the individual QTL level for closely correlated traits. Further, conditional QTL mapping can reveal additional QTL with minor effects that are undetectable in unconditional mapping.

QTL analysis for gossypol and protein contents in upland cottonseeds with two different genetic systems across environments

Genetically improved cottonseed with high protein content and low or no gossypol content could be suitably processed for human and animal consumption. In the present study, quantitative trait loci (QTL) associated with the genetic effects including QTL main effects and QTL × environment interaction effects from tetroploid maternal plant genome and tetroploid embryo genome were simultaneously identified for protein and gossypol contents of cottonseeds. This is to help understand the QTL and QTL × environment interactions from embryo and maternal genomes for these two traits, and provide more effective information for their improvement in cottonseed through maker-assisted selection. The experiment was carried out on an immortal F2 population comprising 376 lines obtained among 188 recombinant inbred lines (RILs) derived from a cross between parents HS46 and MARKCBUCAG8US-1-88, grown in 2009 and 2010. Twelve QTL for protein content (PC) and ten for gossypol content (GC) were detected using a genetic linkage map comprising 388 molecular markers. Among them, five QTL for gossypol content and six QTL for protein content were found in two different environments, explaining 62.95 and 58.52 % of phenotypic variances, respectively. A total of nine QTL were associated with these two traits, which were subsequently mapped to chromosome 3, 5, 6, 15, 18, 22 and 25. Six of these QTL were also found to have environmental interaction effects. The results from this study could be very useful in adopting effect strategies for protein improvement and gossypol elimination in cottonseeds.

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 F 13 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.

QTL mapping of protein content in rice using single chromosome segment substitution lines

Protein content (PC) is an important component of rice nutritional quality. In order to better understand the genetic basis of this trait and increase related breeding efficiency, 21 single chromosome segment substitution (SCSS) lines grown in four sites over two growing seasons (regarded as eight environments) were used to associate PC with particular chromosome segments. Segments from 15 chromosomes were found to contain quantitative trait loci (QTLs) for PC in at least one environment. These included segments from chromosome 3 and 8, in which QTLs for PC had not previously been identified. The segment of chromosome 8 in CSSL-48 had the largest positive effect across all environments. The interaction between substitution and environment was highly significant. Some substitutions had large effects in one environment, but no effect in another (i.e. CSSL-08 and CSSL-17), while some substitutions significantly increased PC in one environment but decreased it in another (i.e. CSSL-41 and CSSL-43). By biplot and clustering analysis, the eight environments were grouped into two contrasting environment types, that is, Hainan and Jiangsu. The segment of chromosome 8 in CSSL-48 had PC-enhancing QTLs in both of the environment types. The segments in CSSL-34 had QTLs which increase PC in the Jiangsu environment but have no effect in the Hainan environment. For enhancing PC, CSSL-48 could be explored in breeding for wide adaptation across all environments, while CSSL-12, CSSL-14, CSSL-17, CSSL-41 and CSSL-43, and that in CSSL-34 could be explored in breeding for specific adaptation to the Hainan and Jiangsu environments, respectively. Near isogenic lines are under development to validate the QTLs with large effects in a range of genetic backgrounds relevant to Jiangsu and Hainan breeding programs. Secondary mapping populations are also being developed for further localising the responsible QTLs in CSSL-14, CSSL-34 and CSSL-48.

A comparison of grain protein content QTLs and flour protein content QTLs across environments in cultivated wheat

The protein content of cultivated wheat (Triticum aestivum L.) is an important determinant factor of the nutritional value of the grain and the technological properties and rheological properties of flour. In order to examine the genetic basis of protein content, we searched for grain protein content quantitative trait loci (QTLs) and flour protein content QTLs in a newly developed doubled haploid (DH) line and identified the genetic correlation between grain protein content and flour protein content in the same DH population. Both the DH population and its parental lines were evaluated for grain protein content and flour protein content in three field trials. Four additive effect QTLs, two pairs of epistatic QTLs, and two QTLs × environment (QE) interaction for grain protein content were identified. The model explained 51.52% of the phenotypic variation (PVE), with epistatic effects being better explained by the higher PVE than additive effects. Four additive effect QTLs, five pairs of epistatic QTLs, and one QE were detected for flour protein content. The model explained 45.8% of the PVE. Of the 15 QTLs identified, three additive QTLs and one pair of epistatic QTLs were determined for both grain protein content and flour protein content; of these, the QTLs for protein content were considered to be more 'stable' than those detected for only grain protein content or for only flour protein content. The data reported here may be useful for manipulating the QTLs for protein content by marker-assisted selection in future wheat breeding programs.

Development of PCR-based SCAR and CAPS markers linked to β-glucan and protein content QTL regions in oat

A key breeding objective in oat (Avena sativa L.) is cultivars with high and low beta-glucan content. In a targeted strategy to develop PCR-based markers linked to published beta-glucan content quantitative trait loci (QTLs) regions, 15 random amplified polymorphic DNA (RAPD) fragments were cloned and their sequences used to design sequence-characterized amplified region (SCAR) and cleaved amplified polymorphic sequence (CAPS) primers. The 13 derived SCAR markers and 2 derived CAPS markers were mapped on either the 'Kanota' x 'Ogle' (KO) or the 'Terra' x 'Marion' (TM) oat reference map. In addition, 3 previously reported SCAR markers were characterized further. Ten SCAR markers and one CAPS marker were associated with beta-glucan QTL regions and many of these are also associated with QTLs for protein content or other traits. These markers have the potential to help define homologous and homologous relationships in oat and investigate the complex genetics of beta-glucan and protein content.

QTL mapping of nutrient components in maize kernels under low nitrogen conditions

AbstractA set of 213 F2:3 families were used to investigate the effects of nitrogen (N) on grain yield and the concentrations of three nutrient components in maize (Zea mays L.) kernels. A genetic linkage map was constructed using 189 SSR (simple sequence repeat) markers, spanning a total of 2003 cM, including 11 linkages, and the families were evaluated under high N and low N conditions at two farm locations. The results indicate that low N conditions may induce an increase in starch concentration, but a decrease in protein levels. Twenty‐six quantitative trait loci (QTL) were detected for four measured traits in the two N treatments at both locations, including eight QTL for grain yield, seven QTL for oil content, six QTL for protein content and five QTL for starch content. The total number of QTL detected for the four measured traits under high N levels was greater than the QTL detected under low N conditions, and several QTL were identified that specifically expressed under different N conditions. These particular QTL could help provide greater understanding of the genetic basis of N‐usage efficiency.

콩에서 종실의 무게와 oil 및 단백질 함량을 조절하는 양적 형질 유전자좌와 연관된 simple sequence repeat marker

콩은 전 세계 시장의 48%를 차지하는 중요한 유료작물이다. 콩 종자를 구성하는 양적인 부분과 질적인 부분의 개선은 콩 육종 목표의 중요한 부분이다. 단백질함량과 종실의 크기는 두부와 콩나물의 질을 평가하는 중요한 특성이다. 따라서 본 연구는 콩에서 종실의 크기와 단백질 및 oil 함량을 조절하는 양적형질유전자좌(QTLs)를 확인하기 위하여 실시하였다. 시험재료로는 큰올콩과 신팔달콩을 교배한 후 <TEX>$F_2$</TEX>유래 <TEX>$F_10$</TEX>세대의 RIL을 이용하였으며, 이를 바탕으로 종실의 무게와 oil 및 단백질 함량과 관련된 QTLs를 탐색하였다. 종실의 무게와 단백질 및 oil 함량의 협의의 유전력은 각각 0.8과 0.78 및 0.71을 나타내었다. 종실의 무게와 관련된 QTLs는 연관군 F, I와 K의 세 개의 독립적인 QTLs를 확인하였다. 단백질함량과 관련된 QTLs는 연관군 D1b, E, H, I와 L의 다섯 개의 독립적인 QTLs를 확인하였다. 그리고 oil 함량과 관련된 QTLs는 연관군 D1b, E, G, I, J와 N의 여섯 개의 독립적인 QTLs를 확인하였다. oil 및 단백질 함량과 관련된 QTLs는 연관군 D1b, E와 I에서 공통적으로 나타났다. 따라서 이들 주요 QTL은 콩 품종 육성과정에서 품질의 개선하기 위한 선발 마커로서 활용가치가 높은 것으로 판단된다. Soybean [Glycine max (L.) Merr.] is an important crop, accounting for 48% of the world market in oil crops. Improvement of the quality and quantity of soybean seed constituents is one of the most important objectives in soybean breeding. Protein content and seed size are important properties to determine the quality of tofu and soy sprouts respectively. The objective of this study was to identify quantitative trait loci (QTLs) that control seed weight, protein and oil content in soybean. The 117 <TEX>$F_{2:10}$</TEX> recombinant inbred lines (RlL) developed from a cross of 'Keunolkong' and 'Shinpaldalkong' were used. Narrow-sense heritability estimates based on a plot mean on seed weight, protein and oil content were 0.8, 0.78 and 0.71, respectively. Four independent QTLs for seed weight were identified from linkage group (LG) F, I and K. Five QTL for protein content were located on LG D1b, E, H, I and L. Oil content was related with six QTLs located on LG D1b, E, G, I, J and N. Protein and oil content have three common QTLs on LG D1b, E and I. Thus, we identified major loci improving soybean seed quality.

Detection of grain protein content QTLs across environments in tetraploid wheats.

Grain protein content (GPC) is an important quality factor in both durum and bread wheats. GPC is considered to be a polygenic trait influenced by environmental factors and management practice. The objectives of this study were both to compare the quantitative trait loci (QTL) for GPC in a population of 65 recombinant inbred lines of tetraploid wheats evaluated in three locations for several years (eight data sets), and to investigate the genetic relationship among GPC and grain yield. QTLs were determined based on the Messapia x dicoccoides linkage map which covers 217 linked loci on the 14 chromosomes with 42 additional loci as yet unassigned to linkage groups. The map extends to 1352 cM; the average distance between adjacent markers was 6.3 cM. Seven QTLs for GPC, located on the chromosome arms 4BS, 5AL, 6AS (two loci), 6BS, 7AS and 7BS, were detected that were significant in at least one environment at P<0.001 or in at least two environments at P<0.01. One QTL was significant in all but one environment, two were significant in four or five environments, and four were significant in two out of eight environments. Six out of seven protein content QTLs had pleiotropic effects or were associated to QTLs for grain yield and explained the negative correlation among GPC and yield components. The present results support the concept that studies conducted in a single environment are likely to underestimate the number of QTLs that can influence a trait and that the phenotypic data for a quantitative trait should be collected over a range of locations to identify putative QTLs and determine their phenotypic effects.