It has frequently been suggested to use the resynthesis of rapeseed (Brassica napus) from B. campestris and B. oleracea to broaden its genetic base. The objective of the present study is twofold: (1) to compare the genetic variation within resynthesized rapeseed with a world-wide collection of oilseed rape cultivars, and (2) to compare genetic distances estimated from RFLP markers with distances estimated from a relatively small number of allozyme markers. We investigated 17 resynthesized lines and 24 rapeseed cultivars. Genetic distances were estimated either based on the electrophoresis of seven allozymes, with a total of 38 different bands, or based on RFLP data of 51 probe/enzyme combinations, with a total of 355 different bands. The results of allozyme and RFLP analyses agreed reasonably well. Genetic distances, estimated from two independent sets of RFLP data with 25 and 26 probe/enzyme combinations respectively, were highly correlated; hence about 50 RFLP markers are sufficient to characterize rapeseed material with a large genetic diversity. The cultivars were clustered into three groups: (1) spring rapeseed of European and Northern American origin, (2) winter rapeseed of European and Northern American origin, and (3) rapeseed of Asian origin. Several of the resynthesized rapeseed lines were similar to European winter rapeseed cultivars, whereas others had quite unique patterns. It is concluded, that resynthesized rapeseed is a valuable source for broadening the genetic variation in present breeding material of Brassica napus. However, different lines differ widely in their suitability for this purpose.

Bioactive compounds were investigated in genotypes (cauliflower 10, white cabbage 10, curly kale 1) and plant parts of the three crops. The content of most of the major glucosinolates glucobrassicin, sinigrin and glucoiberin differed significantly between cultivars. Samples harvested in 2000 had higher amounts of several glucosinolates than samples from 1999. Within cauliflower the buds of the floret had 1.5 to 2.5-fold higher concentration of glucobrassicin and 4-methoxyglucobrassicin than the stalk. In white cabbage several glucosinolates had their highest content in the outer leaves (up to 2-fold higher). Upper leaves of curly kale contained 5-fold more of total glucosinolates than lower leaves. Chlorogenic acid was the dominating hydroxycinnamate in curly kale, which also contained at least ten times more of carotenoids (mainly lutein) than white cabbage. Total antioxidant capacity (TAC) assayed with the FRAP method was 0.76 (0.06) µmol/g fw (mean (SD)) in water-soluble and 0.32 (0.04) in water-insoluble extracts of cauliflower which was 62-68% higher than in white cabbage. Curly kale contained 6.4 and 6.1 µmol/g fw TAC in water-soluble and water-insoluble extracts. TAC did not differ between plant parts. Progoitrin and 4-hydroxyglucobrassicin were correlated to water-soluble TAC in white cabbage, probably reflecting a variation in other compounds. Cauliflower contained less glucose, fructose and sorbitol but more sucrose than white cabbage. Curly kale had lower contents of glucose (∼2 times), fructose (∼4-5 times) and sucrose (20 and 36 times, respectively) than cauliflower and white cabbage, while inositol was only found in curly kale. Storage of white cabbage reduced the amount of sorbitol and sucrose. The study shows that cultivar, plant part and storage affect the content of bioactive compounds in Brassica vegetables. The variation between years, as in cauliflower, is due to environmental factors. Since the cultivar ranking order was rather stable for several components the data could provide a basis for the selection of cultivars optimised for valuable health components for fresh market consumption.

Knowledge of the extent and type of relationship between agronomic characters in oilseed rape is of relevance to plant breeders, in order to avoid selecting against an agronomically important character while performing early generation selection of another character. Genetic and phenotypic correlations for ten agronomic characters were calculated across and within four summer oilseed rape crosses. From each cross 32 F3 families were tested in the first year and 12 F3 families in the second year. The genetic correlations with yield in every cross were generally low. There is a consistency of high positive correlation of oil content in the seed with protein content in the meal in all crosses. The genetic correlations sometimes displayed differences between the four crosses. This largely influenced the predictions for the proportion of lines that are superior for two characters simultaneously.

The effect of harvest time and storage on dietary fibre content and composition was investigated in six cultivars of white cabbage (Brassica oleracea var capitata). Three cultivars were of early maturity type (SW Nordpol, Rolly and Balbro) and three of late maturity type (Predikant, Hanna and Lion). The average total dietary fibre (TDF) content was 241 g kg À1 dry matter (DM) (CV = 13), of which approximately 25% was soluble (CV = 15). The main dietary fibre components were glucose (37%), uronic acid (32%), arabinose (12%) and galactose (8%) residues. Early cultivars generally had a lower TDF content than late maturity types, due to a lower amount of both insoluble (arabinose, galactose and glucose) and soluble (arabinose) polymers. An early cultivar, Rolly, had the highest solubility, 33%, versus 25 AE 4% for the other cultivars. The early cultivar SW Nordpol had a similar TDF content and proportion of soluble dietary fibre (SDF) to the late cultivar Hanna, but the dietary fibre composition was different, with the early cultivar having a lower proportion of arabinose residues. Storage for 6 weeks had minor effects on the dietary fibre. After further storage of the late maturity cultivars, there was an increase in insoluble dietary fibre (IDF) (glucose and uronic acid residues) and a decrease in SDF (arabinose and galactose residues). As a consequence the solubility of TDF decreased from 29 to 19% on average. Harvesting before physiological maturity was reached resulted in a somewhat lower content of TDF and IDF for two cultivars (Predikant and Hanna), while SDF was more or less unaffected for all cultivars. Long-term storage had fewer effects on cabbage harvested prior to maturity than when harvested at the right physiological maturity. It is concluded that the observed differences between cultivars and after long term storage are of such magnitude that they may affect nutritional properties of the dietary fibre.

Heterosis and epistasis in spring oilseed rape (Brassica napus L.) was analysed by comparing generation means for ten agronomic traits. Parents, F2, F3 and F 6 generations of four crosses with Swedish and French material were investigated. The F2 was 11% higher in yield, earlier in flowering time, and slightly later in maturation when compared with the parents. Randomly derived single seed descent lines had an 8% lower yield, were later flowering and maturing than the parents in F 6. This poorer average performance of recombinant lines is explained by the loss of favourable epistatic interactions present in the parents.