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A yellow-seeded doubled haploid (DH) line no. 2127-17, derived from a resynthesizedBrassica napusL., was crossed with two black-seededBrassicacultivars‘Quantum’ and‘Sprint’ of spring type. The inheritance of seed colour was investigated in the F2, and BC1 populations of the two crosses and also in the DH population derived from the F1 of the cross‘Quantum’ × no. 2127-17. Seed colour analysis was performed with the colorimeter CR-300 (Minolta, Japan) together with a visual classification system. The immediate F1 seeds of the reciprocals in the two crosses had the same colour as the self-pollinated seeds of the respective black- and yellow-seeded female parents, indicating the maternal control of seed colour. The F1 plants produced yellow-brown seeds that were darker in colour than the seeds of no. 2127-17, indicating the partial dominance of yellow seed over black. In the segregating BC1 progenies of the two crosses, the frequencies of the black- and yellow-seeded plants fit well with a 1 : 1 ratio. In the cross with‘Quantum’, the frequencies of yellow-seeded and black-seeded plants fit with a 13 : 3 ratio in the F2 progeny, and with a 3 : 1 ratio in the DH progeny. However, a 49 : 15 segregation ratio was observed for the yellow-seeded and black-seeded plants in the F2 progeny of the cross with‘Sprint’. It was postulated from these results that seed colour was controlled by three pairs of genes. A dominant yellow-seeded gene (Y) was identified in no. 2127-17 that had epistatic effects on the two independent dominant black-seeded genes (B and C), thereby inhibiting the biosynthesis of seed coat pigments. [ABSTRACT FROM AUTHOR]

Five restorers of 'Polima' cytoplasmic male sterility (pol CMS) cannot restore the fertility in dominant genic male sterility (DGMS). A dominant male sterility gene from both, a DGMS line Rs1046AB and DGMS hybrid 'Zhongza No. 3', was successfully introduced into Polima cytoplasm. A random-mating population of pol CMS restorers was established by using many double-low pol CMS restorers as pollinators to cross continuously to the DGMS plants which had Polima cytoplasm. [ABSTRACT FROM AUTHOR]

A pentaploid hybrid plant (2n = 50, AACCO) between Brassica napus (AACC) and Orychophragmus violaceus (OO) showed matroclinous morphology and some patroclinous characters. Cloned progenies were mixoploid, consisting of various cells with 38-53 chromosomes, half of the cells with 50 chromosomes. The 50 chromosomes were mainly paired as 25 bivalents and segregated as 25 : 25 or 22 : 28; many other segregations were observed in some cells. Progenies produced by selfing had 38-47 chromosomes. Plants with 38 chromosomes were cytologically stable; in all other plants the chromosome number of individual cells varied between the genotype-specific maximum number and 38, indicating loss of chromosomes during mitosis. The mixoploid plants with 44 chromosomes mainly produced two kinds of mixoploid progenies with 44 and 41 chromosomes, respectively. All plants with 2n = 38 had the same morphology as the parental B. napus and were normal in fertility. These chromosome pairings and segregations in the pentaploid and its progeny support the hypothesis that O. violaceus is a natural polyploid species with a basic chromosome number of 3. [ABSTRACT FROM AUTHOR]

The male sterility (ms) of three recessive genic ms lines, 117AB, S45AB and 9012AB, was controlled in each case by two recessive male sterility genes. The genes responsible in 117AB and S45AB are the same, but they are genetically different from those in 9012AB. [ABSTRACT FROM AUTHOR]

The objective of this study was to dissect the genetic control of days to flowering (DTF) and photoperiod sensitivity (PS) into the various components including the main-effect quantitative trait loci (QTLs), epistatic QTLs and QTL-by-environment interactions (QEs). Doubled haploid (DH) fines were produced from an F1 between two spring Brassica napus cultivars Hyola 401 and Q2. DTF of the DH lines and parents were investigated in two locations, one location with a short and the other with a long photoperiod regime over two years. PS was calculated by the delay in DTF under long day as compared to that under short day. A genetic linkage map was constructed that comprised 248 marker loci including SSR, SRAP and AFLP markers. Further QTL analysis resolved the genetic components of flowering time and PS into the main-effect QTLs, epistatic QTLs and QEs. A total of 7 main-effect QTLs and 11 digenic interactions involving 21 loci located on 13 out of the 19 linkage groups were detected for the two traits. 3 main-effect QTLs and 4 pairs of epistatic QTLs were involved in QEs conferring DTF. One QTL on linkage group (LG) 18 was revealed to simultaneously affect DTF and PS and explain for the highest percentage of the phenotypic variation. The implications of the results for B. napus breeding have been discussed.

Bulked segregant analysis was used to identify RAPD markers linked to the Rfp of pol cms in rapeseed (Brassica napus L.) from the fertile and sterile DNA bulks. DNA bands amplified from 1040 random 10-mer primers were screened. Two polymorphic bands S1019(720) and S1036(810) were found linked to the Rfp locus at the same side with a map distance of 5.8 cM and 12.3 cM respectively. These polymorphic fragments were cloned and sequenced. Nucleotide sequence information was used to design 20-24-mer oligo nucleotide primers for PCR amplification. The SCAR markers that generated from the long primers showed the same pattern of segregation as the original RAPD markers in the backcross population. The SCAR markers would facilitate selection on the Pol CMS restorer lines in rapeseed.