Quantitative trait loci mapping of seed colour,hairy leaf,seedling anthocyanin,leaf chlorosis and days to flowering in F2 population of Brassica rapa L.

A diversity arrays technology (DArT) map was constructed to identify quantitative trait loci (QTL) affecting seed colour, hairy leaf, seedling anthocyanin, leaf chlorosis and days to flowering in Brassica rapa using a F₂ population from a cross between two parents with contrasting traits. Two genes with dominant epistatic interaction were responsible for seed colour. One major dominant gene controls the hairy leaf trait. Seedling anthocyanin was controlled by a major single dominant gene. The parents did not exhibit leaf chlorosis; however, 32% F₂ plants showed leaf chlorosis in the population. A distorted segregation was observed for days to flowering in the F₂ population. A linkage map was constructed with 376 DArT markers distributed over 12 linkage groups covering 579.7 cM. The DArT markers were assigned on different chromosomes of B. rapa using B. rapa genome sequences and DArT consensus map of B. napus. Two QTL (RSC1‐2 and RSC12‐56) located on chromosome A8 and chromosome A9 were identified for seed colour, which explained 19.4% and 18.2% of the phenotypic variation, respectively. The seed colour marker located in the ortholog to Arabidopsis thaliana Transparent Testa2 (AtTT2). Two QTL RLH6‐0 and RLH9‐16 were identified for hairy leaf, which explained 31.6% and 20.7% phenotypic variation, respectively. A single QTL (RSAn‐12‐157) on chromosome A7, which explained 12.8% of phenotypic variation was detected for seedling anthocyanin. The seedling anthocyanin marker is found within the A. thaliana Transparent Testa12 (AtTT12) ortholog. A QTL (RLC6‐04) for leaf chlorosis was identified, which explained 55.3% of phenotypic variation. QTL for hairy leaf and leaf chlorosis were located 0–4 cM apart on the same chromosome A1. A single QTL (RDF‐10‐0) for days to flowering was identified, which explained 21.4% phenotypic variation.     

Quantitative trait loci for early maturity and their potential in breeding for earliness in Brassica juncea

A doubled haploid population of Brassica juncea, developed from a cross between two parental lines differing for days to maturity, was used to study the efficiency of indirect selection for a primary trait through selection of secondary trait(s) over direct selection for the primary trait when quantitative trait loci information is available for both primary and secondary traits, and applied. Days to maturity was considered as primary trait, while days to first flowering, days to end of flowering, flowering period and plant height were considered as secondary traits. An RFLP linkage map was employed for QTL analysis of maturity and maturity-determinant traits, and a stable QTL B6 simultaneously affecting these two types of traits was identified. This linked QTL explained 11.7% phenotypic variation for days to maturity, 20.7% variation for days to first flowering, 24.3% variation for days to end of flowering and 14.4% variation for plant height. Phenotypic evaluation of maturity and/or maturity-determinant traits, viz. days to first flowering, days to end of flowering and plant height revealed that limited genetic advance for early maturity can be achieved through phenotypic selection of the primary and/or the secondary trait(s). However, the estimates of genetic advance for early maturity based on combined phenotypic evaluation and linked QTL data was found to be, at least, three times higher compared to genetic advance based on phenotypic evaluation only, demonstrating the potential of marker-assisted selection in breeding for early maturity in B. juncea.     

Quantitative trait analysis of flowering time in spring rapeseed (B. napus L.)

The inheritance of flowering time trait in spring-type rapeseed (Brassica napus L.) is poorly understood, and the investigations on mapping of quantitative trait loci (QTL) for the trait are only few. We identified QTL underlying variation for flowering time in a doubled haploid (DH) mapping population of nonvernalization-responsive canola (B. napus L.) cultivar 465 and line 86 containing introgressions from Houyou11, a Chinese early-flowering cultivar in Brassica rapa L. Significant genetic variation in flowering time and response to photoperiod were observed among the DH lines from 465/86. A molecular linkage map was generated comprising three types of markers loci. QTL analysis indicated that flowering time is a complex trait and is controlled by at least 4 major loci, localized on four different linkage groups A6, A7, C8 and C9. These loci each accounted for between 9.2 and 12.56 % of the total genotypic variation for first flowering. The published high-density maps for flowering time mapping used different marker systems, and the parents of our crosses have different genetic origins, with either spring-type B. napus or B. rapa. So we cannot determine whether the QTL on the same linkage groups were in the same region or not. There was evidence of additive × additive epistatic effects for flowering time in the DH population. Epistasis existed not only between main-effect QTLs, but also between QTLs with minor effects. Four pair of epistasis effects between minor QTLs explained about 20 % of the genetic variance observed in the DH population. The results indicated that minor QTLs for flowering time should not be ignored. Significant genotypes × environment interactions were also found for the quantitative traits, and with significant change in the ranking of the DH lines in different environments. The results implied that FQ3 was a non-environment-specific QTL and may control flowering time by autonomous pathway. FQ4 were winter-environment-specific QTL and may control flowering time by photoperiod-pathway. Identification of the chromosomal location and effect of the genes influencing flowering time may hasten the development of canola varieties having an optimal time for flowering in target environments such as for high altitude areas, via marker-assisted selection.     

A major QTL associated with preharvest sprouting in rapeseed (<Emphasis Type="Italic">Brassica napus</Emphasis> L.)

Preharvest sprouting (PHS) is one of the most important factors affecting the cereal production worldwide, in regions characterized by rainfall and high humidity during harvest season. It is sometimes a problem in rapeseed (Brassica napus L.), especially in production of commercial F₁ hybrids. To detect quantitative trait loci (QTL) controlling PHS, a F₂ population consisting of 269 F_2:3 lines was created from the cross between a PHS-tolerant line (117AB) and a PHS-susceptible line (7,605). A linkage map was constructed using 35 Simple Sequence Repeat markers and 242 Amplified Fragment Length Polymorphism markers. PHS was measured as a percentage of sprouted seeds on the mother plant, 7 days after physiological maturity. Five putative QTLs for PHS were detected and located on LG2 (N11) and LG7 (N3), respectively. Phenotypic variance explained by each QTL ranged from 4.11 to 50.78% and the five putative QTLs explained about 75.63% of the total phenotypic variance. A major QTL was identified on LG2 (N11) flanked by P3C4180 and C6C13160, which explained 50.78% of the total phenotypic variance. Meanwhile, we detected four significant epistatic interactions with a total contribution of 17.16% of the total phenotypic variance.     

Several stably expressed QTL for spike density of common wheat (Triticum aestivum) in multiple environments

Spike density (SD), an important spike morphological trait associated with wheat yield, is the spikelet number per spike (SNS) divided by spike length (SL). In this study, phenotypic data from eight environments were collected and a recombinant inbred line population (RIL) constructed by the wheat line 20828 and the cultivar 'Chuannong16' and a Wheat55K SNP array-based constructed genetic linkage map were used to identify SD quantitative trait locus (QTL). Correlation between SD and other agronomic traits was calculated. Genes associated with plant growth and development for major loci were predicted. The results showed that 24 QTLs associated with SD were detected in eight environments. Among them, three major QTL, namely QSd.sicau-5B.2, QSd.sicau-2D.3 and QSd.sicau-4B.1, explained up to 35.62%, 14.21% and 11.23% of phenotypic variation, respectively. The positive alleles of them were all derived from 'Chuannong16'. The significant relationships between SD and other agronomic traits were detected and discussed. Taken together, the stably expressed SD QTL under different environments identified in this study provided theoretical guidance for further fine mapping and germplasm improvement.     

Mapping of a gene that confers short lateral branching (slb) in melon (Cucumis melo L.)

Plant architecture plays an important role in the yield, product quality, and cultivation practices of many crops. Branching pattern is one of the most important components in the plant architecture of melon (Cucumis melo L.). ‘Melon Chukanbohon Nou 4 Go’ (Nou-4) has a short-lateral-branching trait derived from a weedy melon, LB-1. This trait is reported to be controlled by a single recessive or incompletely dominant major gene called short lateral branching (slb). To find molecular markers for marker-assisted selection of this gene, we first constructed a linkage map using 94 F₂ plants derived from a cross between Nou-4 and ‘Earl’s Favourite (Harukei-3)’, a cultivar with normal branching. We then conducted quantitative trait locus (QTL) analysis and identified two loci for short lateral branching. A major QTL in linkage group (LG) XI, at which the Nou-4 allele is associated with short lateral branching, explained 50.9 % of the phenotypic variance, with a LOD score of 12.5. We suggest that this QTL corresponds to slb because of the magnitude of its effect. Another minor QTL in LG III, at which the Harukei-3 allele is associated with short lateral branching, explained 9.9 % of the phenotypic variance, with a LOD score of 4.2. Using an independent population, we demonstrated that an SSR marker linked to the QTL in LG XI (slb) could be used to select for short lateral branching. This is the first report of mapping a gene regulating the plant architecture of melon.     

Molecular characterization of genetic basis of Sugarcane Yellow Leaf Virus (SCYLV) resistance in Saccharum spp. hybrid

Sugarcane (Saccharum Spp.) produces 80% of the world's sugar along with other by‐products. The production of sugarcane is vulnerable to infestation of sugarcane yellow leaf virus (SCYLV) worldwide. A study was conducted using an F₁ segregating population derived from CP95‐1039 × CP88‐1762 to identify the genetic factors underlying SCYLV resistance. The disease infection data were measured using tissue blot immunoassay after 6 years of exposure to the virus under natural field conditions. Genetic maps were created using genotyping by sequencing‐based markers for each parent separately following a pseudo‐testcross approach. Two quantitative trait loci (QTL) were detected for SCYLV resistance accounting for 28% of the phenotypic variation. A major QTL qSCYLR79 located on linkage group 79 and linked with marker 3PAV3154 appears to be unique for SCYLV resistance in sugarcane. Progeny having a combination of two major alleles had 31% less SCYLV incidence than progeny with a combination of major and minor alleles in the genomic region of qSCYLR79. Thus, selection against the minor allele may decrease the SCYLV incidence in sugarcane.     

Detection of loci controlling seed glucosinolate content and their association with Sclerotinia resistance in Brassica napus

A genetic linkage map of Brassica napus constructed from a cross between a low glucosinolate cultivar ‘H5200’ and a high glucosinolate line ‘NingRS‐1’ was used to identify loci associated with seed glucosinolate content and to understand the association between specific glucosinolate components and Sclerotinia resistance. Seed glucosinolate content was assessed by standard High pressure Liquid Chromatogram (HPLC) protocol. Seven components of seed glucosinolate, including four types of aliphatic glucosinolate, two types of indolyl glucosinolates and one aromatic glucosinolate were detected in the seeds. Three quantitative trait loci (QTLs) were identified for seed total glucosinolate content. From three to 15 loci were found to be responsible for different types of glucosinolates, and by comparing the overlapped intervals, eight genomic regions were defined. One of the nine loci associated with aliphatic glucosinolate content was found to be associated with Sclerotinia resistance on the leaf at the seedling stage, and one locus, responsible for 3‐indolyl‐methyl glucosinolate content, was probably linked with Sclerotinia resistance on the stem of the maturing plant. The association between seed glucosinolate content and Sclerotinia resistance is discussed.     

Mapping and validation of the quantitative trait loci for leaf stay‐green‐associated parameters in maize

Functional stay‐green is generally regarded as a desirable trait of varieties in major crops including maize. In this study, we used an F_3:4 recombinant inbred line population with 165 lines from a cross between a stay‐green inbred line (Zheng58) and a model inbred line (B73) using 211 polymorphic simple sequence repeat markers to map quantitative trait loci for three stay‐green‐associated parameters, chlorophyll content, photosystem II photochemical efficiency and stay‐green area, at maturity stage, detected a total of 23 quantitative trait loci (QTL) on nine chromosomes. Single QTL explained 3.7–13.5% of the phenotypic variance. Additionally, we validated some important stay‐green QTL using a heterogeneous inbred family approach and found that the stay‐green‐associated parameters were significantly correlated with the plant yield. This study may contribute to a better insight into the regulatory mechanism behind leaf stay‐green in maize and a novel development of elite maize varieties with delayed leaf senescence through molecular marker‐assisted selection.     

Detection of QTLs for bread‐making quality in wheat using a recombinant inbred line population

Whereas gluten fraction accounts for 30–60% of the variation in wheat bread‐making quality, there remains substantial variation determined by non‐gluten factors. The objective of this study was to detect new loci for wheat quality. The genetics of sodium dodecyl sulphate‐sedimentation volume (Ssd), grain hardness (GH), grain protein content, wet gluten content (WGC) and water absorption (Abs) in a set of 198 recombinant inbred lines derived from two commercial varieties was studied by quantitative trait loci (QTL) analysis. A genetic map based on 255 marker loci, consisting of 250 simple sequence repeat markers and five glutenin loci, Glu‐A1, Glu‐B1, Glu‐D1, Glu‐B3 and Glu‐D3, was constructed. A total of 73 QTLs were detected for all traits. A major QTL for GH was detected on chromosome 1B and its relative contribution to phenotypic variation was 27.7%. A major QTL for Abs on chromosome 5D explained more than 30% of the phenotypic variation. Variations in Ssd were explained by four kinds of genes. Some QTLs for correlated traits mapped to the same regions forming QTL clusters or indicated pleiotropic effects.     

Quantitative trait locus analysis of seed germination,seedling vigour and seedling‐regulated hormones in Brassica napus

Good germination and seedling vigour are major breeding targets in winter oilseed rape (Brassica napus), because seedling vigour and prewinter crop establishment are closely associated with postwinter growth and yield. Here, we identified quantitative trait loci (QTL) related to germination, seedling vigour and seedling‐regulated hormones in a doubled haploid (DH) mapping population from a cross between winter oilseed rape parents with high vigour (Express 617) and low vigour (1012‐98). By phenotyping in a climate‐controlled glasshouse, we identified a total of 13 QTL on nine chromosomes for germination and seedling‐related traits at 7 and 14 days after sowing (DAS), explaining up to 11.2% of the phenotypic variation for seedling vigour. Forty‐seven metabolic QTL on 15 chromosomes were identified for auxin, abscisic acid (ABA) and dihydrophaseic acid (DPA) at 5 and 12 DAS, explaining up to 49.4% of phenotypic variation in seedling hormone composition. Multitrait QTL hot spots contribute to our understanding of the genetics and metabolomics of germination and seeding vigour in B. napus, and represent potential targets to breed high‐vigour cultivars.     

Quantitative trait loci for leafhopper (Empoasca fabae and Empoasca kraemeri) resistance and seed weight in the common bean

A population of 108 common bean recombinant inbred lines (RILs) (F_5:6‐9), derived from a leafhopper (Empoasca fabae and E. kraemeri)‐susceptible cultivar (‘Berna’) and a leafhopper‐resistant line (EMP 419) was used to identify molecular markers genetically linked to leafhopper resistance and seed weight. Bulked segregant analysis and quantitative trait analysis identified eight markers that were associated with resistance to E. fabae, and four markers that were associated with E. kraemeri resistance. Three markers were associated with resistance to both species. A partial linkage map of the bean genome was constructed. Composite interval mapping identified quantitative trait loci (QTL) for resistance to both leaf hopper species on core‐map linkage groups B1, B3 and B7. QTL for seed weight were found close to the locus controlling testa colour and an α‐phaseolin gene.     

Quantitative trait locus mapping of floral and related traits using an F2 population of Aquilegia

The objective of this study was to determine quantitative trait loci (QTL) underlying ten floral and related traits in Aquilegia. The traits assessed were calyx diameter, corolla diameter, petal length, petal blade length, sepal length, sepal width, spur length, spur width, plant height and flower number. These are important traits for ornamental value and reproductive isolation of Aquilegia. QTL analysis of these traits was conducted using single‐marker analysis and composite interval mapping (CIM). We used an F₂ population consisting of 148 individuals derived from a cross between the Chinese wild species Aquilegia oxysepala and the cultivar Aquilegia flabellata ‘pumila’. Resulting CIM analysis identified 39 QTLs associated with these traits, which were mapped on seven linkage groups. These QTLs could explain 1.22–53.28% of the phenotypic variance. Thirty‐one QTLs, which explained more than 10% of the phenotypic variation, were classified as major QTLs. Graphical representations of the QTLs on seven linkage groups were made. Our research provides the potential for future molecular assisted selection breeding programmes and the cloning of target genes through fine mapping.     

Molecular and physical mapping of genes affecting awning in wheat

Quantitative trait loci (QTL) for three traits related to awning (awn length at the base, the middle and the top of the ear) in wheat were mapped in a doubled‐haploid line (DH) population derived from the cross between the cultivars ‘Courtot’ (awned) and ‘Chinese Spring’ (awnless) and grown in Clermont‐Ferrand, France, under natural field conditions. A molecular marker linkage map of this cross that was previously constructed based on 187 DH lines and 550 markers was used for the QTL mapping. The genome was well covered (more than 95%) and a set of anchor loci regularly spaced (one marker every 20.8 cM) was chosen for marker regression analysis. For each trait, only two consistent QTL were identified with individual effects ranging from 8.5 to 45.9% of the total phenotypic variation. These two QTL cosegregated with the genes Hd on chromosome 4A and B2 on chromosome 6B, which are known to inhibit awning. The results were confirmed using ‘Chinese Spring’ deletion lines of these two chromosomes, which have awned spikes, while ‘Chinese Spring’ is usually awnless. No quantitative trait locus was detected on chromosome 5A where the B1 awn‐inhibitor gene is located, suggesting that both ‘Courtot’ and ‘Chinese Spring’ have the same allelic constitution at this locus. The occurrence of awned speltoid spikes on the deletion lines of this chromosome suggests that ‘Chinese Spring’ and ‘Courtot’ have the dominant B1 allele, indicating that B1 alone has insufficient effect to induce complete awn inhibition.     

Relationships between water-use traits and photosynthesis in Brassica oleracea resolved by quantitative genetic analysis

The genetic control of water‐use and photosynthetic traits in Brassica oleracea is resolved by genetic analysis of quantitative trait loci (QTL). Variations in leaf conductance, photosynthetic assimilation rate, leaf thickness and leaf nitrogen content were assessed in a segregating population of F₁‐derived doubled haploid (DH) B. oleracea lines. In addition, stable carbon isotope ratios in leaf organic material were used as a surrogate measure of plant water‐use efficiency. Analysis of an existing linkage map for the population revealed significant QTL on seven linkage groups. Single significant QTL explained between 3.4% and 36.6% of the phenotypic variance in each of the traits measured. The locations of QTL for several traits were found to coincide in a physiologically meaningful way; stable carbon isotope discrimination had QTL co‐locating with leaf level water‐use efficiency, photosynthetic capacity with leaf thickness and nitrogen content and stomatal density with leaf thickness. Taken together, these results suggest that single genes or clusters of genes at these loci may have an influence on the expression of physiologically related traits controlling water‐use and photosynthesis.     

Co-location of seed oil content,seed hull content and seed coat color QTL in three different environments in <Emphasis Type="Italic">Brassica napus</Emphasis> L.

Increasing seed oil content is an important breeding goal for Brassica napus L. (B. napus). The identification of quantitative trait loci (QTL) for seed oil content and related traits is important for efficient selection of B. napus cultivars with high seed oil content. To get better knowledge on these traits, a molecular marker linkage map for B. napus was constructed with a recombinant inbred lines (RIL) population. The length of the map was 1,589 cM with 451 markers distributed over 25 linkage groups. QTL for seed oil content, seed hull content and seed coat color in three environments were detected by composite interval mapping (CIM) tests. Eleven QTL accounted for 5.19–13.57% of the variation for seed oil content. Twelve QTL associated with seed hull content were identified with contribution ranging from 5.80 to 22.71% and four QTL for seed coat color accounted for 5.23–15.99% of the variation. It is very interesting to found that co-localization between QTL for the three traits were found on N8. These results indicated the possibility to combine favorable alleles at different QTL to increase seed oil content, as well as to combine information about the relationship between seed oil content and other traits.     

Genetic detection of node of first fruiting branch in crosses of a cultivar with two exotic accessions of upland cotton

Flowering time has biological and agricultural significance for crops. In Upland cotton (Gossypium hirsutum L.), photoperiodic sensitivity is a major obstacle in the utilization of primitive accessions in breeding programs. Quantitative trait loci (QTLs) analysis was conducted in two F₂ populations from the crosses between a day-neutral cultivar Deltapine 61 (DPL61) and two photoperiod sensitive G. hirsutum accessions (T1107 and T1354). Node of first fruiting branch (NFB) was used to measure relative time of flowering. Different flowering time genetic patterns were observed in the two populations. Two QTLs were found across five scoring dates, accounting 28.5 (qNFB-c21-1) and 15.9% (qNFB-c25-1) of the phenotypic variation at the last scoring date in Pop. 1107 (DPL61 by T1107); whereas, one major QTL (qNFB-c25-1) can be detected across five scoring dates, explained 63.5% of the phenotypic variation at the last scoring date in Pop. 1354 (DPL61 by T1354). QTLs with minor effects appeared at various scoring date(s), indicating their roles in regulating flowering at a lower or higher node number. Genetic segregation analysis and QTL mapping results provide further information on the mechanisms of cotton photoperiodic sensitivity. Part of a Ph.D. dissertation by senior author submitted to the Department of Plant and Soil Sciences, Mississippi State University, December 2007. Contribution of USDA-ARS in cooperation with the Mississippi Agric. and Forestry Exp. Stn. Journal paper J. 11276 of Mississippi Agric. and Forestry Exp. Stn.     

Identification of QTL for oil content,seed yield,and flowering time in oilseed rape (<Emphasis Type="Italic">Brassica napus</Emphasis>)

A genetic map was constructed with 353 sequence-related amplified polymorphism and 34 simple sequence repeat markers in oilseed rape (Brassica napus L.). The map consists of 19 linkage groups and covers 1,868 cM of the rapeseed genome. A recombinant doubled haploid (DH) population consisting of 150 lines segregating for oil content and other agronomic traits was produced using standard microspore culture techniques. The DH lines were phenotyped for days to flowering, oil content in the seed, and seed yield at three locations for 3 years, generating nine environments. Data from each of the environments were analyzed separately to detect quantitative trait loci (QTL) for these three phenotypic traits. For oil content, 27 QTL were identified on 14 linkage groups; individual QTL for oil content explained 4.20–30.20% of the total phenotypic variance. For seed yield, 18 QTL on 11 linkage groups were identified, and the phenotypic variance for seed yield, as explained by a single locus, ranged from 4.61 to 24.44%. Twenty-two QTL were also detected for days to flowering, and individual loci explained 4.41–48.28% of the total phenotypic variance.     

Identification and mapping of a quantitative trait locus controlling extreme late bolting in Chinese cabbage (Brassica rapa L. ssp. pekinensis syn. campestris L.) using bulked segregant analysis

DNA markers linked to a locus controlling an extreme late bolting trait, which was originally found in a local cultivar of a non-heading leafy vegetable,‘Osaka Shirona Bansei’ (Brassica rapa L. ssp. pekinensis syn. campestris L.) were identified using bulked segregant analysis. A doubled haploid (DH) line, DH27, which is a progeny of ‘Osaka Shirona Bansei’, shows extreme late bolting, and bolts without vernalization. DH27 was crossed with a normal bolting DH line, G309. The plantlets of the parents, F₁ and F₂, were vernalized and then grown in a greenhouse. The bolting time of F₂ plants showed a continuous distribution from 19 to 231 days after vernalization (DAV), suggesting the effects of a few major genes and polygenes. Possible linkage markers for this trait were screened by modified bulked segregant analysis (BSA). The BSA using four bulks suggested that a 530-bp RAPD band RA1255C was linked to a locus controlling the bolting trait. The RAPD band was cloned and used as a probe to detect RFLP. The fragment detected a single locus, BN007-1,the segregation of which in the F₂ population matched that of RA1255C. Three other RAPDs were found to be linked to BN007-1. A quantitative trait locus(QTL) affecting the bolting time was detected around BN007-1 using MAPMAKER/QTL. Since the difference between bolting times of both the parental genotypes in the F₂ was 138 days, these markers may be useful for a marker-assisted selection (MAS) in the breeding program for late bolting or bolting-resistant cultivars in B. rapa crops. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development of yellow-seeded Brassica napus of double low quality

Two yellow‐seeded white‐petalled Brassica napus F₇ inbred lines, developed from interspecific crosses, containing 26–28% emcic acid and more than 40 μmol glucosinolates (GLS)/g seed were crossed with two black/dark brown seeded B. napus varieties of double low quality and 287 doubled haploid (DH) lines were produced. The segregation in the DH lines indicated that three to four gene loci are involved in the determination of seed colour, and yellow seeds are formed when all alleles in all loci are in the homozygous recessive state. A dominant gene governed white petal colour and is linked with an erucic acid allele that, in the homozygous condition, produces 26–28% erucic acid. Four gene loci are involved in the control of total GLS content where low GLS was due to the presence of recessive alleles in the homozygous condition in all loci. From the DH breeding population a yellow‐seeded, yellow‐petalled, zero erucic acid line was obtained. This line was further crossed with conventional B. napus varieties of double low quality and, following pedigree selection, a yellow seeded B. napus of double low quality was obtained. The yellow seeds had higher oil plus protein content and lower fibre content than black seeds. A reduction of the concentration of chromogenic substances was found in the transparent seed coat of the yellow‐seeded B. napus.