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Here we present a study on the genetic effects of agronomic and seed quality traits in double haploid (DH) populations, which were developed by microspore culture from reciprocal F1 hybrids produced between cultivar Californium and DH W-15. Each of the populations consisted of 25 DH lines. The field experiments were conducted in a randomized complete block design with three replications during three growing seasons. Field observations were recorded on seed yield and its structure: the number of branches and pods per plant, the number of seeds per pod, the 1000-seed weight, the content of fat in the seeds, and three unsaturated fatty acids (oleic, linoleic, linolenic) in the seed oil. In order to investigate the influence of cross direction on the studied traits, parental effects were evaluated on the basis of differences between reciprocal DH populations. The maternal effect was revealed on the number of seeds per pod and the effect of the paternal form on linolenic acid content. The occurrence of transgression effects also depended on the direction of crossing and this was particularly noticeable in terms of the number of seeds per pod. The use of multivariate statistical methods allowed for the simultaneous characterization and grouping of tested lines in terms of several traits. Graphic images of the distribution of DH lines in the space of the two first canonical variates showed a great variation between the two reciprocal populations, both in terms of yield and its components, as well as fat and those unsaturated fatty acids.

The genetic diversity of two winter oilseed rape (Brassica napus L.) collections was investigated using amplified fragment length polymorphism marker technology. The first collection of 78 genotypes was analyzed using 11 primer-enzyme combinations and PCR products were resolved by 13.35% denaturing polyacrylamide gels. The second collection was investigated using seven fluorescent-labeled AFLP primer combinations and PCR products were separated using capillary electrophoresis. A total of 262 polymorphic AFLP markers were obtained for the first collection and 423 polymorphic markers for the second. On the basis of all markers, principal component analysis was performed for both collections separately. The unweighted pair group method with arithmetic method based on the coefficient of dissimilarity separated the genotypes in collection 1 into two clusters and those in the second collection into three distinct clusters. Resynthesized lines formed a cluster that was clearly distinct from 42 winter oilseed rape parental lines in the cytoplasmic male sterility ogura system. Analysis of molecular variance showed that 79% and 81% of the detected variation was found to be within the groups (in the two collections, respectively), while the variation between groups contributed, respectively, to only 21% and 19% of the variance. Our results indicate that AFLP technology can be useful for the creation of a gene pool of parental components of winter oilseed rape hybrid cultivars. Additionally, de novo resynthesized Brassica napus lines provide a significant opportunity for enrichment of the gene pool of winter rapeseed.

In this report we characterized the ArabidopsisABI1 gene orthologue and Brassica napus gene paralogues encoding protein phosphatase 2C (PP2C, group A), which is known to be a negative regulator of the ABA signaling pathway. Six homologous B. napus sequences were identified and characterized as putative PP2C group A members. To gain insight into the conservation of ABI1 function in Brassicaceae, and understand better its regulatory effects in the drought stress response, we generated transgenic B. napus plants overexpressing A. thalianaABI1. Transgenic plants subjected to drought showed a decrease in relative water content, photosynthetic pigments content and expression level of RAB18- and RD19A-drought-responsive marker genes relative to WT plants. We present the characterization of the drought response of B. napus with the participation of ABI1-like paralogues. The expression pattern of two evolutionarily distant paralogues, BnaA01.ABI1.a and BnaC07.ABI1.b in B. napus and their promoter activity in A. thaliana showed differences in the induction of the paralogues under dehydration stress. Comparative sequence analysis of both BnaABI1 promoters showed variation in positions of cis-acting elements that are especially important for ABA- and stress-inducible expression. Together, these data reveal that subfunctionalization following gene duplication may be important in the maintenance and functional divergence of the BnaABI1 paralogues. Our results provide a framework for a better understanding of (1) the role of ABI1 as a hub protein regulator of the drought response, and (2) the differential involvement of the duplicated BnaABI1 genes in the response of B. napus to dehydration-related stresses. Electronic supplementary material The online version of this article (doi:10.1007/s11103-015-0334-x) contains supplementary material, which is available to authorized users.

Resynthesized (RS) Brassica napus can be used to increase the genetic diversity of this important crop plant and to develop the heterotic gene pool required for successful hybrid breeding programmes. The level of heterosis in F1 hybrids depends on the individual performance of the parents and on the degree of genetic difference between them. However, RS forms obtained from crosses of B. rapa ssp. with B. oleracea ssp. possess many undesirable agronomic traits, such as low quality of seeds, low yield and seed oil content, high erucic acid level in the oil and high glucosinolate content in seed meal. Therefore, RS oilseed rape needs to be improved by crossing with natural double-low oilseed rape, leading to selected double-low quality semi-RS lines that can be used for breeding. In this study, we evaluated the seed yield potential of F1 hybrids derived from crosses between Ogura cytoplasmic male-sterility (CMS) lines and doubled haploid (DH) semi-RS lines with restorer gene in three locations in Poland. The genotype by environment interaction (GE interaction) and general combining ability (GCA) of the restorer and CMS line effects, as well as the effects of heterosis, were also assessed. The results of the study provide the first insights into the use of semi-RS lines as components for the development of new hybrid cultivars. Even the introduction of 50% of the RS oilseed rape genotype to natural restorer lines resulted in a marked heterosis effect, with seed yield ranging from 4.56% to 90.17% more than that of the better parent. The yield of the best hybrid amounted to 108.6% of the seed yield of the open-pollinated cultivar Monolit and 94.4% of that of the hybrid cultivar Arsenal. The best DH semi-RS line S1, which had a significantly positive GCA for seed yield, can be recommended as a possible parent for inclusion in breeding programmes aimed at developing new hybrid cultivars.

This study presents the results of experiments concerning: (1) interspecific hybridization of Brassica oleracea × Brassica rapa via application of in vitro placental pollination and (2) embryological analysis of the process of resynthesis of Brassica napus. In order to overcome certain stigma/style barriers, B. rapa pollen was placed in vitro on an opened B. oleracea ovary (with style removed). Pollinated ovaries were cultured on Murashige and Skoog (MS) medium. After 24-d culture, the developing embryos were isolated from immature seeds and transferred onto MS medium supplemented with 0.47 μM kinetin, 0.49 μM 1-naphthaleneacetic acid, and 10% (v/v) coconut water. When the embryos had turned green, they were immediately placed onto MS medium with 100 μM kinetin. After development of the seedling, plantlets were transferred to soil. Chromosome doubling was achieved after another week. Cytometric analysis of nuclear DNA confirmed the hybrid nature of the plants. Resynthesis of B. napus can be performed through interspecific hybridization of B. oleracea × B. rapa followed by embryo rescue and genome doubling.

Traditional breeding methods based on inbreeding are difficult to implement in the case of Sinapis alba (white mustard) because this plant displays high levels of self-incompatibility. More rapid progress in breeding could be possible if biotechnological methods and in vitro cultures were used. However, white mustard is not readily amenable to biotechnological treatment. Seeds of traditional S. alba cultivars (e.g., Nakielska) are characterized by high levels of glucosinolates and erucic acid. However, a new Polish variety of white mustard (Bamberka) possesses low erucic acid content in the oil. The main goal of the study was elaboration of a plant regeneration system via in vitro culture of hypocotyl and cotyledon explants from low and high erucic acid-containing white mustard cultivars. In these experiments, a simple system for in vitro regeneration of white mustard was developed, with the aim to promote maximum formation of shoots within a short period of time. Traditional and improved cultivars of S. alba showed comparable capacity for shoot development from hypocotyl-derived and cotyledon-derived explants. The two types of cultivars were characterized by essentially equivalent shoot regeneration responses, being slightly higher in hypocotyl than the cotyledonary explants. A greater influence on shoot regeneration from hypocotyl explants was observed on medium supplemented with 4.4 μmol 6-benzylaminopurine, 0.57 μmol indole-3-acetic acid, and a low concentration of kinetin (4.6 μmol). This technique will allow for rapid generation of sufficient plant material for further use in a variety of white mustard breeding projects.

Oilseed rape (rapeseed, Brassica napus L.) is one of the most important crop plants, taking the third place after palm oil and soybean among oil plants and the fifth among economically important crops, following rice, wheat, maize and cotton (Snowdon et al., 2007). Oilseed rape is cultivated primarily in temperate regions, where climatic conditions prevent growth of most other oilseed crops. Spring cultivars of oilseed rape dominate in the USA, Canada, Australia and China, while winter varieties are cultivated mainly in northern European countries (Great Britain, France, Germany, Poland, Scandinavia, etc.).

Haploid microspore-derived embryos (MDEs) constitute a unique material for the introduction of new traits into winter oilseed rape (Brassica napus). MDEs have been transformed by using Agrobacterium tumefaciens strains EHA105 and LBA4404, both carrying the binary vector pKGIB containing the uidA gene encoding beta-glucuronidase (GUS) and the bar gene as a marker of resistance to phosphinotricin. Transformed embryos expressed GUS and regenerated plants that were resistant to herbicide Basta, as confirmed by a leaf-painting test. Progeny plants of the transformant T-39 were all transgenic, as they inherited T-DNA from their doubled haploid parental plant. Southern-blot analysis confirmed the integration and transmission of T-DNA into T1 plants. Transformation of MDEs facilitates the obtaining of winter oilseed rape homozygous for the introduced genes.