Cattle chromosome 6 was scanned with 11 markers, ten microsatellites and the casein haplotype, to identify quantitative trait loci (QTLs) affecting the following milk production traits: milk yield, fat percentage, fat yield, protein percentage and protein yield. Twelve Finnish Ayrshire half-sib families with a total of 480 sons were genotyped and used in a grand-daughter design. Interval mapping was performed with a multiple-marker regression approach with a one-QTL and a two-QTL model, and the significance threshold values were determined empirically using a permutation test. Across-family analysis with the one-QTL model revealed an effect on protein percentage (P < 0.05) and on milk yield (P < 0.05). The analysis with the two-QTL model identified significant effects (P < 0.05) on protein percentage, milk yield, and fat yield. Comparing these two cases, the results suggest the existence of two QTLs on chromosome 6 with an effect on milk production traits. One of the QTLs was located around the casein genes. As the other QTL was similar in location and effect to a QTL found previously in Holstein-Friesians, an identity-by-descent approach could be applied to fine map this region.

Bulk segregant analysis was used to search for RAPD (random amplified polymorphic DNA) markers linked to gene(s) affecting oleic acid concentration in an F2 population from the Brassica rapa ssp. oleifera cross Jo4002 x a high oleic acid individual from line Jo4072. Eight primers (=8 markers) out of 104 discriminated the 'high' and 'low' bulks consisting of extreme individuals from the oleic acid distribution. These markers were analysed throughout the entire F2 population, and their association with oleic acid was studied using both interval mapping and ANOVA analysis. Six of the markers mapped to one linkage group. A quantitative trait locus (QTL) affecting oleic acid concentration was found to reside within this linkage group with a LOD score >15. The most suitable marker for oleic acid content is OPH-17, a codominant marker close (<4cM) to the QTL. The mean seed oleic acid content in the F2 individuals carrying the larger allele of this marker was 80.14±9.76%; in individuals with the smaller allele, 54.53±6.83%; in the heterozygotes, 65.47±8.15%. To increase reproducibility, the RAPD marker was converted into a SCAR (sequence characterized amplied region) marker with specific primers. Marker OPH-17 can be used to select spring turnip rape individuals with the desired oleic acid content.

A total of 453 bulls belonging to 11 half-sib families of Finnish Ayrshires were genotyped for six microsatellite markers on chromosome 9. The data were used in an attempt to map quantitative trait loci applying regression as a multimarker approach. For association analysis with a granddaughter design, the EBV for 12 traits were used: milk yield, protein yield, fat percentage, protein percentage, daughter weight, bull growth, calf mortality, days open, fertility treatments, nonreturn rate, SCC, and clinical mastitis. The empirical values of significance thresholds were determined using a permutation test on the experimental data. Although no significant effects were found, the results indicate some support for the existence of a locus on chromosome 9 that affects milk and protein yields.

The F2 progeny (64 individuals) from the cross between oilseed rape (Brassica napus L.) cultivar Topas and R4 (a low linolenic mutation line) was analyzed with 8 RFLPs and 34 RAPDs to discover a genetic tag for gene(s) affecting linolenic acid concentration. According to variance analysis (ANOVA), one RAPD marker (25a) was significantly associated with linolenic acid content; the linolenic acid concentration in the seeds of F2 individuals showing the marker (includes both homo- and hetero-zygotes) was 7.43 +/- 1.35% and in those lacking the marker was 5.70 +/- 1.52%. Marker 25a may be used to facilitate selection for fatty acid composition in future breeding programs of oilseed rape.

A linkage map of spring turnip rape (Brassica rapa ssp. oleifera) was conslructed from an F2 population of a cross Jo4002 x Sv3402. The map contained 22 RFLP loci, 144 RAPDs, one microsatellite, and one morphological marker (seed colour). All ten B.rapa linkage groups could be identified and the total map distance was 519 cM. A proportion of the markers (13%), most of which were located in two linkage groups, showed segregation distortion.