Sunflower mutant containing high levels of palmitic acid in high oleic background

A new sunflower mutant, CAS-12, was obtained, which has both high palmitic (≈30%) and high oleic acid contents, and also a substantial amount of palmitoleic acid (≈7%). The mutant was selected after X-ray irradiation of dry seeds of the inbred line BSD-2-423, which had normal palmitic (≈3%) and high oleic (≈88%) acid levels. The increase of palmitic and palmitoleic acids occurred at the expense of the oleic acid content, which decreased to around 55% in respect to the original line. Linoleic acid content is always under 5%. Palmitic and palmitoleic acid levels were similar to those of the high palmitic mutant CAS-5 obtained in a previous programme from a low oleic line isogenic to BSD-2-423 using a similar mutagenic treatment. In that previous programme we also selected three high stearic acid mutants using chemical mutagenic treatment on the same sunflower line (RDF-1-532). We attempted to obtain mutants in other lines but were unsuccessful. The isolation of similar mutants in isogenic parental lines illustrates the importance of the genetic background in the development of specific mutants with an altered seed oil fatty acid composition. The oil of this mutant will increase the range of potential uses of sunflower oil. This revised version was published online in July 2006 with corrections to the Cover Date.     

Phenotypic variation for saturated fatty acid content in soybean

Summary Concern over high saturates in human diets has prompted the development of soybean [Glycine max (L.) Merr.] lines producing oil with reduced saturated fatty acid concentration. To better understand those factors that influence phenotypic expression for palmitic and stearic acid content in soybean, thirty soybean lines random for saturated fatty acid content were grown in eight field environments contrasting for mean temperature during seed-filling. Palmitic and stearic acid content varied significantly (P<0.01) both among genotypes and across environments, while genotype x environment interactions were reflected in changes in line variance and ranking for both traits. Therefore selection of a superior genotype for saturated fatty acid composition may not correlate well from one environment to another. In general, early-maturing lines were less sensitive than later-maturing lines in their response to changes in mean daily temperature for palmitic concentration. However, factors in addition to temperature appeared to influence genotype response for stearic acid content. It appears that genetic systems conditioning palmitic and stearic acids are independent, and that separate breeding strategies need be adopted to make simultaneous improvement for these two oil traits. In summary, development of soybean lines with low or high saturated fatty acid content may be accomplished through evaluation and selection in a few environments contrasting for temperature.Cooperative investigations of the USDA-ARS, and North Carolina Agric. Res. Serv., Raleigh, NC, U.S.A.     

Effects of Agrobacterium tumefaciens-mediated transformation and tissue culture on storage lipids in Brassica napus

The variation obtained in storage fatty acids induced by the procedures of tissue culture and transformation with Agrobacterium tumefaciens was investigated and compared in rapeseed, Brassica napus, cv. Hanna. An increased variation in the fatty acid profiles was noted after tissue culture and transformation compared with plants derived directly from seeds. In the second generation of rapeseed transformants, T₂, the content of oleic acid ranged from 39–72%, 12–31% for linoleic acid and 7–16% for linolenic acid. This could be compared with the oleic acid content in the T₂ generation of tissue culture-derived plants which ranged between 47–76% and in seed-derived material where oleic acid ranged between 55–69%.In the T₃ generation the ranges in transgenic seeds were decreased but still larger than in the seed derived plants. The range in transgenic plants was 49–64% for oleic acid, 20–28% for linoleic acid and 9–18% for linolenic acid. The most extreme individuals, both highest and lowest in the common fatty acids, were found in the group of transformed plants independent of generation. The total lipid content was also affected by the two treatments and seeds with the lowest and highest lipid content were both found among the transformed plants. In conclusion, care should be taken to use proper controls when performing transformation experiments in order to distinguish variation in the fatty acid profiles induced by the transformation procedure and tissue culture treatments from the changes due to transgenic expression. This revised version was published online in July 2006 with corrections to the Cover Date.     

野生花生脂肪酸组成的遗传变异及远缘杂交创造高油酸低棕榈酸花生新种质

以花生属19个近缘野生物种87份种质和113份栽野远缘杂交后代为材料, 系统分析野生花生脂肪酸组成的遗传变异及其在栽培种花生脂肪酸改良中的潜力。结果表明, 野生花生的棕榈酸含量与栽培种花生相似, 硬脂酸和油酸含量略低于栽培种花生, 亚油酸含量略高于栽培种。不同物种间以及同一物种内不同资源间的脂肪酸组成存在较大差异。A. rigonii棕榈酸含量较低, A. pusilla和A. duranensis油酸含量较高, A. batizocoi亚油酸含量较高, A. rigonii和A. duranensis油酸和亚油酸含量变幅较大。发掘出油酸含量达60%以上的野生资源2份(19-6, A. duranensis和23-1, A. sp.), 亚油酸含量达40%以上的资源7份, 其中A. rigonii(编号为11-4)亚油酸含量高达48%, 是目前所发现的花生资源中亚油酸含量最高的种质。远缘杂交后代脂肪酸的变异远远超过亲本间的差异, 而且不同组合间的棕榈酸、硬脂酸、油酸和亚油酸含量差异达显著或极显著水平。通过远缘杂交获得了6份油酸含量达64.0%以上且棕榈酸含量在8.5%以下的新种质, 其中yz8913-8油酸含量达67.85%, 比其栽培种亲本提高近30个百分点, 且棕榈酸含量仅7.60%。SRAP检测表明, 这6份远缘杂交后代除整合了亲本的DNA片段外, 还产生了新的DNA片段, 有的还丢掉了亲本的某些片段。农艺性状分析表明, 其中4份种质的综合农艺性状较好, 具有重要育种利用价值。     

Effect of genetic background on the target fatty acids of acyl-ACP thioesterase transgenes in Brassica napus

Acyl‐acyl carrier protein (ACP) thioesterase (TE) is involved in the biosynthetic fatty acid pathway of plants. Conventional canola lines transformed individually with the bay‐TE (Uc FatB1), elm‐TE (Ua FatB1), nutmeg‐TE (Mf FatB1) or Cuphea‐TE transgene (Ch FatB1), produce seed oil with modified fatty acid compositions. This study assessed the effects of genetic background, cytoplasm, maternal parent, and interaction of different TE transgenes, on the target fatty acids using F1 seeds and double haploid (DH) lines. The F₁ seeds were produced by crossing four TE transgenic parental lines and three non‐transgenic cultivars with distinct fatty acid compositions. The DH lines were developed from microspores of F₁ plants. DH lines from different crosses showed that genetic background does not have an effect on the relative levels of the target fatty acids of the same TE, indicating the stability of the substrate specificity of the TE within canola. However, significant effects of genetic background on the content of the major target fatty acids, lauric acid (C12:0) or palmitic acid (C16:0) depending on the TE, were observed. Expression of the TE in low erucic acid (C22:1) genotypes resulted in higher target fatty acid levels than expression in high C22:1 genotypes. Reciprocal crosses showed maternal effects, but not cytoplasmic effects. In addition, co‐expression of two different TE transgenes in the same seeds was observed. These results indicate the importance of selection for appropriate genetic backgrounds in order to maximize the expression of the target fatty acids of TE transgenes, and also indicate potential uses of TE co‐expression in modifying canola seed oil.     

Survey of safflower (Carthamus tinctorius L.) germplasm for variants in fatty acid composition and other seed characters

Summary Two hundred safflower accessions, originated in 37 countries, and multiplied in two environments, were evaluated for fatty acid composition of the seed oil and other seed characters. Overall mean values of stearic and palmitic acids were similar in both environments but differed for seed weight and oil content. Oleic and linoleic acids showed also similar overall mean content in both environments but some entries with intermediate contents of these acids displayed significant variation among environments. Oleic and linoleic acids showed a tremendous range of variation, from 3.1 to 90.60% and from 3.9 to 88.8%, respectively. The ranges of variation observed for stearic, oleic and linoleic acids indicate that all the reccessive genes, already discovered, controlling high content of these acids, st, ol and li, are present in the collection. Moreover, the upper values of oleic, ten points higher than the published values for the high oleic genotype olol, suggest than other genes controlling such levels may be present.     

Production of mutants with high cold tolerance in spring canola (<Emphasis Type="Italic">Brassica napus</Emphasis>)

A major factor affecting spring canola (Brassica napus) production in Canada is killing frosts during seedling development in the spring and seed maturation in the fall. The objective of this study was to explore the possibility of producing spring canola lines with mutations that have altered biochemical pathways that increase cold tolerance. The approach was to generate UV point mutations in cultured microspores followed by chemical in vitro selection of individual mutant microspores or embryos resulting in measurable alterations to various biochemical pathways with elevated levels of key defense signaling molecules such as, salicylic acid (SA), p-Fluoro-d,l-Phenyl Alanine (FPA), and jasmonic acid (JA). In addition, since proline (Pro) is known to protect plant tissues in the cold-induced osmotic stress pathway, mutants that overproduce Pro were selected in vitro by using three Pro analogues: hydroxyproline (HP), azetidine-2-carboxylate (A2C); and, 3,4-dehydro-d,l-proline (DP). Of the 329 in vitro selected mutant embryos produced, 74 were identified with significant cold tolerance compared to their donor parents through indoor freezer tests at −6°C, and 19 had better winter field survival than winter canola checks. All chemically selected mutant doubled haploids with increased cold tolerance compared well with parent lines for all seed quality and agronomic parameters. Development of increased frost tolerant cultivars should allow for spring canola to be produced in western Canada without compromising seed quality.     

Modifier QTL for fatty acid composition in soybean oil

Soybean [Glycine max (L.) Merr.] is the principal oilseed crop in the world. Soybean oil has various industrial and food applications. The quality of soybean oil is determined by its fatty acid composition. Palmitic, stearic, oleic, linoleic and linolenic are the predominant fatty acids in soybean oil. The objective of this study was to determine the associations of simple sequence repeat (SSR) molecular markers with minor differences in fatty acids in soybean oil thereby detecting modifier quantitative trait loci (QTL) which could further improve soybean oil quality. To achieve this objective, 101 F₆-derived recombinant inbred lines (RIL) from a population whose parents did not contain major mutant fatty acid alleles were developed from a cross of N87-984-16 × TN93-99. Fatty acids were determined by gas chromatography. Heritability estimates on an entry mean basis for fatty acids ranged from 65.8 to 77.3% for palmitic and linoleic acids, respectively. Molecular marker Satt537 located on molecular linkage group (MLG) D1b was associated with palmitic acid and Satt168 and Satt249 located on MLG B2 and J, respectively were associated with stearic acid. Molecular markers Satt185 or Satt268 (which are within 0.6 cM of each other) located on MLG E were consistently associated with oleic and linoleic acid, and Satt263 and Satt235 located on MLG E and G, respectively were associated with linolenic acid. The lack of markers associated with multiple fatty acids suggests the possibility of independently changing fatty acid levels to achieve a desirable composition, except for regions common to all saturated fatty acids. Phenotypic variation explained by the fatty acids modifier QTL ranged from 10 to 22.5%. These modifier QTL may be useful in making minor improvements to further enhance the quality of soybean oil.     

Fatty Acid Composition of Oil from Erucic Acid-Free Summer Rape Seed (Brassica napus L.) in Relation to Nitrogen Nutrition and Raceme Position

A greenhouse study was conducted to determine the effect of nitrogen supply (30, 100 or 170 ppm N) and raceme position on the fatty acid composition of oil extracted from erucic acid-free summer rape seed ( Brassica napus cv. Callypso ). The seven fatty acids analyzed for include palmitic, palmitolcic, stearic, oleic, linoleic, linolemc, and eicosenoic acids; of which oleic (59.54–64.84 %) and palmitoleic (0.36–0.4 %) acids were the highest and lowest levels respectively. Generally, N nutrition influenced fatty acid pattern only to a little extent. Palmitic, palmitoleic and stearic acid levels were increased by 170 ppm N, depending on raceme position, but oleic and linolenic acids were unaffected. Similarly, 170 ppm N produced the highest fatty acid levels in seeds on the lower portions of racemes, with the exception of oleic acid. This was also true in the case of the upper portions of racemes, except that 30 ppm N produced the highest levels of oleic and linoleic acids in rape seeds. Under the optimum N supply level (i.e. 100 ppm N), position of raceme on the rape plant did not greatly influence the levels of different fatty acids in lipids.     

Opposite oleic acid responses to temperature in oils from the seed and mesocarp of the olive fruit

Olive oil is mostly extracted from the mesocarp (∼95%) of the fruit with the seed (endosperm and embryo, ∼5%) containing little oil. There are correlative and manipulative evidence that temperature modulates fruit oil content and fatty acid composition of the oil from the whole fruit (i.e., with no distinction being made between oils derived from each oil-bearing structure) of olive. Notably, oleic acid concentration of olive oil decreases as fruit mean growth temperature increases. This response in the olive fruit is opposite to that documented in annual oil-seed crops such as sunflower and soybean. The objectives of the present study were: i) to compare temperature effects on fatty acid composition of oil derived from seed and from mesocarp; ii) to compare temperature effects on seed and mesocarp dry weights and oil concentrations. To do this, fruiting branches were enclosed in transparent plastic chambers with individualized temperature control. Temperature was manipulated during the seed growth (Period A) and during the second half of mesocarp growth (Period B) subphases. In both periods, the oleic acid proportion in mesocarp oil decreased as temperature increased, and was accompanied by increases of palmitic acid, linoleic and linolenic acids. Mesocarp dry weight did not respond significantly to temperature, but mesocarp oil concentration fell significantly as temperature increased. Seed dry weight, oil concentration and fatty acid composition exhibited responses to temperature during Period A only, with seed dry weight increasing between 20 and 25 °C with a sharp decrease at higher temperature, and oil concentration linearly falling 1.2% per °C. In contrast, seed oil oleic acid percentage increased between 20 and 28 °C, and fell slightly with higher temperature. Palmitic and stearic acids in seed oil increased sigmoidally with temperature, while linoleic acid decreased sigmoidally. Oleic acid percentage showed opposite responses in oil from the seed and the mesocarp. The response of the seed to temperature was similar to those observed in oil from embryos of annual oil-seed crops, although the abrupt fall in palmitic and stearic acid with temperature >25 °C seems to be distinctive for olive seed oil.     

大豆脂肪酸组分的胚、细胞质和母体遗传效应分析

利用5个大豆品种配制20个杂交组合,采用广义种子遗传模型分析了大豆脂肪酸组分的胚、细胞质和母体植株等3套遗传体系的基因主效应和基因型×环境效应。棕榈酸含量、硬脂酸含量和亚油酸含量是以基因型×环境互作效应为主。亚麻酸和油酸的遗传主效应和基因型×环境互作效应相近。在脂肪酸组分的遗传主效应中,棕榈酸、硬脂酸和亚油酸含量是以胚主效应为主。油酸含量和亚麻酸含量以细胞质主效应为主。在基因型×环境互作方差中,脂肪酸组分以极显著的胚互作方差为主。亚麻酸含量是以基因的加性效应和加性×环境互作效应为主,棕榈酸含量、硬脂酸含量、油酸含量和亚油酸含量以基因的显性和显性×环境互作效应为主。棕榈酸含量和油酸含量是以普通狭义遗传率为主。硬脂酸、亚油酸含量和亚麻酸含量以互作狭义遗传率为主。在普通狭义遗传率中,棕榈酸含量、油酸含量和亚麻酸含量以细胞质普通遗传率和母体普通遗传率为主。在互作狭义遗传率中,油酸含量和亚麻酸含量以胚互作狭义遗传率为主,亚油酸含量以母体植株互作遗传率为主。棕榈酸含量、硬脂酸含量、油酸含量和亚油酸含量以细胞质及母体选择响应和互作选择响应为主,亚麻酸含量的胚普通选择响应和互作选择响应为主。     

Assessment of growth and seed oil composition of kenaf (Hibiscus cannabinus L.) germplasm

This study was conducted to evaluate the growth characteristics and fatty acid composition among 15 kenaf mutants derived from the kenaf germplasm C14 and 15 kenaf accessions originating from Russia, India, China, Iran, and Italy. The overall growth performance (plant height, stem diameter, flowering date, leaf, and flower size) of the stem color mutant lines derived from C14 are similar to those of the original variety. However, the flower color mutant lines derived from C14 showed flowering to occur 10 days later when compared with the original variety and showed smaller leaf sizes than the original variety. Late-ripened kenaf accessions (Jinju, Auxu, and Jnagdae) can yield more bio-mass compared with early or medium-maturing germplasm. The late maturity kenaf (Auxu, Jinju, and Jangdae) has a higher oil percentage than the early maturity germplasm. Linoleic, oleic, and palmitic acids were the predominant fatty acids in all kenaf seeds. The stem color mutant lines significantly surpassed the parental means of all saturated fatty acids. In addition, the flower color mutant lines showed broad ranges of variation in oleic acid. The 15 accessions showed a wide range of fatty acid compositions, spanning from 29.75 to 38.30% saturated fatty acids and 61.70 to 70.24% total unsaturated fatty acids, and the late maturity kenaf has a higher linoleic acid percentage than the early maturity germplasm. The flowering period was highly positively (P ≤ 0.01) correlated with the plant height, stem diameter, oil percent, and linolenic acid (C_18:3), and it was significantly negatively (P ≤ 0.01) correlated with stearic acid (C_18:0). These results will provide valuable information to assist the parental selection of kenaf breeding.     

西藏昌都市类乌齐牦牛肉中主要脂肪酸的差异分析

探讨西藏昌都市类乌齐县不同乡镇和不同部位牦牛肉中脂肪酸的差异,明确类乌齐牦牛肉脂肪酸的特征。采用气相色谱串联质谱法测定类乌齐牦牛肉中脂肪酸的含量,用SPSS方法分析不同乡镇和不同部位牦牛肉脂肪酸的差异。结果表明：类乌齐牦牛肉主要含有11种饱和脂肪酸(SFA)、7种单不饱和脂肪酸(MUFA)和9种多不饱和脂肪酸(PUFA),平均含量分别为42.53%、53.27%和4.21%。类乌齐牦牛肉中脂肪酸的主要组成为油酸(C18:1n9c,44.47%)、硬脂酸(C18:0,21.08%)和棕榈酸(C16:0,14.78%)。饱和脂肪酸和单不饱和脂肪酸总量在各乡镇之间差异不显著,多不饱和脂肪酸总量在各乡镇之间存在显著差异。多不饱和脂肪酸主要为亚油酸(2.74%)、花生四烯酸(0.66%)、亚麻酸(0.39%)、二十碳五烯酸(0.11%)和二十二碳六烯酸(0.07%)等。类乌齐牦牛肉中n-6/n-3均值为4.85,其臀部肉和腱子肉的n-6/n-3均值分别为3.20和3.35。类乌齐牦牛肉中油酸和硬脂酸含量较高,不同乡镇的牦牛肉中多不饱和脂肪酸差异显著,其臀部肉和腱子肉具有较高的营养价值。     

In vitro selection for oleic and linoleic acid content in segregating populations of microspore derived embryos of Brassica napus

Microspore derived embryos (MDEs) in Brassica napuscontain large amounts of storage lipids which show a genotype specific fatty acid composition (FAC). One cotyledon of regenerating emblyos can be dissected at an early stage during the in vitro culture and used for fatty acid analysis. Thus, in breeding programmes to modify oil quality, only MDEs having the desired FAC need to be regenerated to plantlets and transferred to the greenhouse. In the present study the applicability of this method for the selection of a high oleic acid content and a low linoleic acid content in the seed oil has been tested by crossing a Brassica napus mutant line having a high oleic acid (C18:1) content in the seed oil (75%) with a wild type doubled haploid line with 62% C18:1 in the seed oil. Microspore culture was applied to the F1 plants. In total 59 MDEs were obtained, from which 31 were cultured with and 28 without 15μM abscisic acid for 3 weeksin vitro. One cotyledon was dissected under aspetic conditions and used for fatty acid analysis. The remaining part of the embryos were further regenerated to plantlets and transferred to the greenhouse to obtain seeds after self pollination. Seeds harvested from the doubled haploid lines in the greenhouse were used for fatty acid analysis and also for growing in the field. The abscisic acid treatment of the MDEs generally improved the correlations for linoleic and oleic acid between the MDEs and the seeds harvested in the greenhouse and the field. The correlations ranged from 0.68** to 0.81**.This indicates that selection for high oleic acid can be started already during an early stage of the in vitro culture. This revised version was published online in July 2006 with corrections to the Cover Date.     

Embryonic heterosis in the linolenic acid content of Matthiola incana seed oil

Summary The fatty acid composition of seed-oil of breeding lines and F₁ hybrids of Matthiola incana was analyzed, using direct esterification and gas chromatography. The breeding lines tested differed significantly with respect to the levels of palmitic, oleic, linoleic and linolenic acids. Embryonic-stage heterosis in linolenic acid concentration was demonstrated by F₁ hybrid seeds, derived from mating horticulturally different lines of M. incana. Linolenic acid content was negatively correlated with both oleic acid content (r=–0.85) and linoleic acid content (r=–0.66). None of the breeding lines or the F₁ hybrids significantly passed the limit of 67% linolenic acid. Possible genetic and biochemical explanations for the above phenotypic data are discussed.     

Isolation of induced mutants in linseed (Linum usitatissimum) having reduced linolenic acid content

Summary Seeds of Linum usitatissimum cv. Glenelg were treated with either gamma-rays or EMS in an attempt to induce mutations with a lower level of linolenic acid in linseed oil. Two mutant lines were identified in which linolenic acid constituted approximately 29% of the total fatty acid content compared with 43% in seed oil from untreated Glenelg plants. The reduced level of linolenic acid in the mutants is accompanied by an increase in the level of linoleic acid to 30% compared with 18% in Glenelg, but there was no change in the proportions of other fatty acids. These proportions of linolenic acid and linolenic acid are respectively the highest and lowest yet reported in stable genotypes of L. usitatissimum. The strong inverse relationship between these two fatty acids in these genotypes suggests that linolenic acid is synthesised by desaturation of linolenic acid and indicates that it may be possible to breed an edible linseed oil having both low levels of linolenic acid and high levels of linolenic acid.     

Genetic structure composed of additive QTL,epistatic QTL pairs and collective unmapped minor QTL conferring oil content and fatty acid components of soybeans

The relative importance of various types of quantitative trait locus (QTL) conferring oil content and its fatty acid components in soybean seeds was assessed through testing a recombinant inbred line (RIL) population (derived from KF1 × NN1138-2) in randomized blocks experiments in 2004–2006. The contents of oil and oleic, linoleic, linolenic, palmitic and stearic acids were determined with automatic Soxhlet extraction system and gas chromatography, respectively. Based on the established genetic linkage map with 834 markers, QTLNetwork2.0 was used to detect QTL under the genetic model composed of additive, additive × additive (epistasis), additive × year and epistasis × year effects. The contributions to the phenotypic variances of additive QTL and epistatic QTL pairs were 15.7% (3 QTL) and 10.8% (2 pairs) for oil content, 10.4% (3 QTL) and 10.3% (3 pairs) for oleic acid, 11.6% (3 QTL) and 8.5% (2 pairs) for linoleic acid, 28.5% (7 QTL) and 7.6% (3 pairs) for linolenic acid, 27.0% (6 QTL) and 16.6% (7 pairs) for palmitic acid and 29.7% (5 QTL) and 4.3% (1 pair) for stearic acid, respectively. Those of additive QTL by year interaction were small and no epistatic QTL pair by year interaction was found. Among the 27 additive QTL and 36 epistatic QTL (18 pairs), three are duplicated between the two QTL types. A large difference was found between the genotypic variance among RILs and the total variance of mapped QTL, which accounted for 52.9–74.8% of the genotypic variation, much larger than those of additive QTL and epistatic QTL pairs. This part of variance was recognized as that due to a collection of unmapped minor QTL, like polygenes in biometrical genetics, and was designated as collective unmapped minor QTL. The results challenge the breeders for how to pyramid different types of QTL. In addition, the present study supports the mapping strategy of a full model scanning followed by verification with other procedures corresponding to the first results.     

我国玉米籽粒脂肪酸含量研究

用甲酯化—气相色谱法测定了我国20个省(区)608份玉米品种籽粒的脂肪酸含量。统计结果表明:我国玉米6种主要脂肪酸的含量平均亚油酸为46.67%,油酸为34.18%,棕榈酸为15.02%,硬脂酸为2.25%,亚蔴酸为1.31%,花生酸为0.33%。不饱和脂肪酸之和为82.16%。用聚类分析法对脂肪酸含量以省(区)为单位作分区统计,统计结果表明:我国玉米亚     

Pure-lining of flax (<Emphasis Type="Italic">Linum usitatissimum</Emphasis> L.) genebank accessions for efficiently exploiting and assessing seed character diversity

Genetic heterogeneity within genebank accessions of a self-pollinating crop has great implications for their preservation, diversity assessment, utilization and exploitation. This study investigated the intra-accession diversity of 38 flax (Linum usitatissimum L.) genebank accessions preserved by Plant Gene Resources of Canada. Seven quantitative seed characters were studied: 1000 seed weight, seed oil concentration and fatty acid proportion of palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2) and α-linolenic acid (18:3). Ten additional morphological characters of high heritability were also recorded. In 13 accessions the intra-accession diversity was assessed based on 4 years of observation of 7–12 pure lines selected randomly from the original accessions. From these 13 accessions, seven showed significant variation among the pure lines for all seven seed characters. In five accessions most seed characters showed significant variation and only in one accession the homogeneity of seed characters dominated. Variation was found in landraces, breeding material and cultivars. In 40 cases an attempt was made to identify pure lines within an accession that significantly exceeded the mean value of the original accession in a seed character, for which the original accession had shown high or low values. In 25 cases and for all seven seed characters such pure lines could be detected. In six cases, the most extreme performing pure lines were not from the same accession, that had the highest or lowest accession mean for the considered character. There was no association of morphological variation with variation of the quantitative seed characters. For genebanks, separation of mixed accessions based on obvious phenotypic diversity and in particular based on characters that create a selective pressure is probably the most efficient way to ensure preservation of a wide range of diversity at reasonable cost. For exploitation of diversity in breeding programmes, pure-lining is very useful. J. Philip Raney—Deceased.