Intraspecific chromosomal polymorphism ofTriticum araraticum (Poaceae) detected by C-banding technique

DifferentTriticum araraticum lines were studied by C-banding method. The intraspecific divergence ofT. araraticum was shown to be caused mainly by large chromosomal rearrangements. Two main chromosomal types were distinguished among the studied lines: (1) a karyotype similar to that ofT. timopheevii and (2) different one. The first type includes some lines ofT. araraticum subspp.kurdistanicum andararaticum; the second comprises most lines ofT. araraticum subsp.araraticum. The lines of the first type can give fertile F₁ hybrids withT. timopheevii.     

中国甘蓝型油菜遗传多样性的RAPD分子标记

本文利用ＲＡＰＤ方法和统计学分析,对我国７省市和国外引进的总计４０份甘蓝型油菜品种的遗传多样性进行了研究。结果表明,４０个品种的甘蓝型油菜存在着广泛的遗传变异,根据ＲＡＰＤ指纹图谱,通过在ＤＮＡ分子水平上的聚类分析可以将它们分为３大类群,反映出这些品种之间的亲缘关系,并对如何引进甘蓝型油菜资源进行了初浅的讨论。     

Attributes of Individual Flowers of Brassica napus L. are Affected by Defoliation but not by Intraspecific Competition

To investigate the effect of intraspecific competition on floweringin Brassica napus‘Westar’, a series of 30 pots wasestablished that spanned a range of one–96 plants perpot. In each pot, the following attributes of individual flowerswere quantified: petal length; petal width; stamen length; pistillength; pollen production; diameter of pollen grains; and nectarproduction. Certain plants contained a transgenic marker thatenabled the vigour of their pollen to be quantified by screeningthe progeny from post-pollination trials against conventionalmale competitors. Plant size was strongly affected by plantdensity; plants in the lowest density pots comprised ten-timesmore dry biomass than individuals in the highest density pots.However, none of the attributes of individual flowers variedwith density. In contrast, the number of flowers per plant declinedrapidly with density. In the face of resource scarcity, theplants apparently conserved flower size rather than flower number.There was no difference in the response to density between transgenicand conventional plants, but transgenic plants obtained morefertilizations than expected in post-pollination competitionagainst conventional competitors. A separate experiment demonstratedthat B. napus is, nevertheless, capable of plasticity in certainflower attributes (petal size, stamen length) in response todefoliation. Explanations for the stability of flower size relativeto flower number are discussed. Copyright 2001 Annals of BotanyCompany Brassica napus, defoliation, density effects, flowers, flower size, intraspecific competition, nectar production, oilseed rape, pollination, transgenic plants     

Construction of an oilseed rape (Brassica napus L.) genetic map with SSR markers

We constructed a Brassica napus genetic map with 240 simple sequence repeats (SSR) primer pairs from private and public origins. SSR, or microsatellites, are highly polymorphic and efficient markers for the analysis of plant genomes. Our selection of primer pairs corresponded to 305 genetic loci that we were able to map. In addition, we also used 52 sequence-characterized amplified region primer pairs corresponding to 58 loci that were developed in our lab. Genotyping was performed on six F2 populations, corresponding to a total of 574 F2 individual plants, obtained according to an unbalanced diallel cross design involving six parental lines. The resulting consensus map presented 19 linkage groups ranging from 46.2 to 276.5 cM, which we were able to name after the B. napus map available at , thus enabling the identification of the A genome linkage groups originating from the B. rapa ancestor and the C genome linkage groups originating from the B. oleracea ancestor in the amphidiploid genome of B. napus. Some homoeologous regions were identified between the A and the C genomes. This map could be used to identify more markers, which would eventually be linked to genes controlling important agronomic characters in rapeseed. Furthermore, considering the good genome coverage we obtained, together with an observed homogenous distribution of the loci across the genome, this map is a powerful tool to be used in marker-assisted breeding. Electronic Supplementary Material Supplementary material is available for this article at     

Linkage analysis of molecular markers and quantitative trait loci in populations of inbred backcross lines of Brassica napus L.

Backcross populations are often used to study quantitative trait loci (QTL) after they are initially discovered in balanced populations, such as F(2), BC(1), or recombinant inbreds. While the latter are more powerful for mapping marker loci, the former have the reduced background genetic variation necessary for more precise estimation of QTL effects. Many populations of inbred backcross lines (IBLs) have been developed in plant and animal systems to permit simultaneous study and dissection of quantitative genetic variation introgressed from one source to another. Such populations have a genetic structure that can be used for linkage estimation and discovery of QTL. In this study, four populations of IBLs of oilseed Brassica napus were developed and analyzed to map genomic regions from the donor parent (a winter-type cultivar) that affect agronomic traits in spring-type inbreds and hybrids. Restriction fragment length polymorphisms (RFLPs) identified among the IBLs were used to calculate two-point recombination fractions and LOD scores through grid searches. This information allowed the enrichment of a composite genetic map of B. napus with 72 new RFLP loci. The selfed and hybrid progenies of the IBLs were evaluated during two growing seasons for several agronomic traits. Both pedigree structure and map information were incorporated into the QTL analysis by using a regression approach. The number of QTL detected for each trait and the number of effective factors calculated by using biometrical methods were of similar magnitude. Populations of IBLs were shown to be valuable for both marker mapping and QTL analysis.     

Identification of molecular markers associated with linoleic acid desaturation in Brassica napus

 Linolenic acid is a component of canola oil that is readily oxidized, which results in a reduced frying stability and shelf life of the oil. The reduction of linolenic acid in canola seed has therefore been an important breeding objective for many years. The inheritance of linolenic acid concentrations in seed oil is polygenic and is also strongly influenced by the environment. For these reasons, molecular markers are sought to assist in early and reliable selection of desired low linolenic acid genotypes in breeding programmes. Molecular markers associated with low linolenic acid loci were identified in a doubled-haploid population derived from a cross between the Brassica napus lines, ‘Apollo’ (low linolenic)×YN90-1016 (high linolenic) using RAPDs and bulked segregant analysis. A total of 16 markers were distributed over three linkage groups, which individually accounted for 32%, 14% and 5% of the phenotypic variation in linolenic acid content. The rapeseed fad3 gene was mapped near the locus controlling 14% of the variation. The mode of inheritance appeared to be additive, and a QTL analysis showed that collectively the three loci explained 51% of the phenotypic variation within this population. PCR fragments for low linolenic acid ‘Apollo’ alleles (3% linolenic acid) were identified at all three loci. Simultaneous selection for low linolenic acid ‘Apollo’ alleles at each locus resulted in a group of DH lines with 4.0% linolenic acid. The use of these makers in the breeding programme will enhance the breeding of low linolenic acid B. napus cultivars for production in Canada. Received: 23 September 1997 / Accepted: 21 October 1997     

Diversity array technology markers: genetic diversity analyses and linkage map construction in rapeseed (Brassica napus L.)

We developed Diversity Array Technology (DArT) markers for application in genetic studies of Brassica napus and other Brassica species with A or C genomes. Genomic representation from 107 diverse genotypes of B. napus L. var. oleifera (rapeseed, AACC genomes) and B. rapa (AA genome) was used to develop a DArT array comprising 11 520 clones generated using PstI/BanII and PstI/BstN1 complexity reduction methods. In total, 1547 polymorphic DArT markers of high technical quality were identified and used to assess molecular diversity among 89 accessions of B. napus, B. rapa, B. juncea, and B. carinata collected from different parts of the world. Hierarchical cluster and principal component analyses based on genetic distance matrices identified distinct populations clustering mainly according to their origin/pedigrees. DArT markers were also mapped in a new doubled haploid population comprising 131 lines from a cross between spring rapeseed lines 'Lynx-037DH' and 'Monty-028DH'. Linkage groups were assigned on the basis of previously mapped simple sequence repeat (SSRs), intron polymorphism (IP), and gene-based markers. The map consisted of 437 DArT, 135 SSR, 6 IP, and 6 gene-based markers and spanned 2288 cM. Our results demonstrate that DArT markers are suitable for genetic diversity analysis and linkage map construction in rapeseed.     

Comparison of somatic and sexual Brassica napus - Sinapis alba hybrids and their progeny by cytogenetic studies and molecular characterization.

Reciprocal crosses were performed between Brassica napus (AACC, 2n = 38) cv. Brutor and Sinapis alba (SalSal, 2n = 24) cv. Carine. Using fertilized ovary culture, 2.2 and 1.9% of interspecific hybrids were produced when white mustard was the female and the male parent, respectively. On S. alba cytoplasm, three plants with a BC1-like structure (SalSalAC, 2n = 43) were obtained and ACSal (2n = 31) and AACCSal (2n = 50) hybrids on reciprocal crosses. At the same ploidy level, no differences in meiotic behavior were observed. The amphidiploids (AACCSalSal, 2n = 62), produced after colchicine treatment of ACSal hybrids, were compared with the somatic hybrids previously obtained from the same parental varieties. Only two somatic hybrids differed and one of them lost Idh-2 rapeseed isozymes, whereas all the plants presented an hybrid pattern for all the other molecular markers. The plants with 50 chromosomes (AACCSal) from sexual hybrids were similar whatever their origins. Their comparison with back-cross progeny of somatic hybrids revealed that the latter one differed either by chromosome number, ranging from 42 to 54, or by the percentage of cells with less than 12 univalents and with multivalents. From our results, the efficiency of protoplast fusion compared with sexual crosses as a tool to introduce new traits in a crop is discussed.     

SSR标记对不同黄籽甘蓝型油菜亲本材料的遗传分析

杂交育种中,亲本选配是育种成败的关键。本研究以重庆市油菜工程技术研究中心提供的180份甘蓝型黄子油菜亲本种质为材料,应用分布于不同连锁群的60对SSR标记进行了分析,共检测出308个标记位点,每对引物在不同亲本材料之间的等位基因数在1～11个之间,平均位点为5.1个。其中多态性位点207个,多态率达67.2%。对SSR扩增结果进行UPGMA分析,在遗传距离0.566处,180个品种(系)分为3个类群,聚类结果与种质来源比较一致,本研究为甘蓝型油菜黄子杂交育种和优势组合的选配提供了理论依据。     

Development and genetic mapping of microsatellite markers from genome survey sequences in Brassica napus

Microsatellite or simple sequence repeat (SSR) markers are routinely used for tagging genes and assessing genetic diversity. In spite of their importance, there are limited numbers of SSR markers available for Brassica crops. A total of 627 new SSR markers (designated BnGMS) were developed based on publicly available genome survey sequences and used to survey polymorphisms among six B. napus cultivars that serve as parents for established populations. Among these SSR markers, 591 (94.3%) successfully amplified at least one fragment and 434 (73.4%) detected polymorphism among the six B. napus cultivars. No correlation was observed between SSR motifs, repeat number or repeat length with polymorphism levels. A linkage map was constructed using 163 newly developed BnGMS marker loci and anchored with 164 public SSRs in a doubled haploid population. These new markers are evenly distributed over all linkage groups (LGs). Given that the majority of these SSRs are derived from bacterial artificial chromosome (BAC) end sequences, they will be useful in the assignment of their cognate BACs to LGs and facilitate the integration of physical maps with genetic maps for genome sequencing in B. napus. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Genetic and molecular approaches to improve nutritional value of Brassica napus L. seed

Oilseed rape (Brassica napus L.) is a major oil crop that also supplies proteins for the feed industry. In order to reduce total cost production, the objective is to increase oil yield while reducing crop inputs (especially nitrogen and pesticides). Concomitantly, it is necessary to anticipate specific uses (e.g., fatty acid composition) and to ensure the valorisation of the by-products (rapeseed meal). By the past, improvement of seed quality focused on fatty acid balance and low seed glucosinolate content. Current goals include the breeding of yellow-seeded rapeseed lines with high content of seed oil. The use of molecular tools and the exploitation of Arabidopsis knowledge will be presented and discussed.     

Molecular markers for low-glucosinolate alleles in oilseed rape (Brassica napus L.)

Two recent studies have mapped QTLs associated with the level of seed glucosinolates in oilseed rape (Brassica napus L.). It was likely that the two most significant QTLs identified in each study were the same, as they were linked to RFLP alleles identified by common DNA probes. To investigate the utility of these probes in breeding programmes, they were used to study RFLPs in a range of low- and high-glucosinolate cultivars and breeding lines. It was shown that all low glucosinolate spring and winter cultivars possessed a specific RFLP fragment identified by probe wg3f7 which is linked to theGSL-1 QTL, and all high-glucosinolate cultivars possessed a specific RFLP fragment identified by probe wg7a8, which is linked to theGSL-2 QTL. Cultivar Ariana, which has intermediate levels of glucosinolates possessed the low-glucosinolate fragment atGSL-1 but the high-glucosinolate fragment atGSL-2. A similar result was found with the cvs. Martina and Bronowski which have intermediate and variable levels of glucosinolates. There were no other RFLP fragments identified by other DNA probes which were specific to either the low- or high-glucosinolate phenotypes. The use of probes wg3f7 and wg7a8 in selection of low-glucosinolate lines in breeding programmes is discussed.     

Immunocytochemical localization of myrosinase in Brassica napus L.

The cytological and intracellular localization of myrosinase (EC 3.2.3.1) has been studied by immunochemical techniques using paraffin-embedded sections of radicles and cotyledons from seeds of Brassica napus L. cv. Niklas. For immunolabelling, sections were sequentially incubated with a monoclonal anti-myrosinase antibody and with peroxidase-and fluorescein-isothiocyanate-conjugated secondary antibodies. Enzyme and fluorescence label was present in typical myrosin cells both in radicles and in cotyledons. With higher magnification, fluorescence label revealed that the intracellular localization of myrosinase was associated with the tonoplast-like membrane surrounding the myrosin grains in the myrosin cells. The results also indicate that a large proportion of the positive myrosin cells are located in the second-outermost cell layer of the peripheral cortex region of the radicles.Abbreviations FITC fluorescein isothiocyanate - PBS phosphate-buffered saline - PBS-T PBS with 0.5% (v/v) Tween-20 (polyoxyethylene sorbitane monolaurate) This work was supported by The Norwegian Research Council for Science and the Humanities. We wish to thank Professor Med. O.A. Haugen, Department of Pathology, University of Trondheim, Norway, for the skilful assistance provided regarding fixation and sectioning.     

Comparison of RAPD and RFLP genetic markers in determining genetic similarity among Brassica oleracea L. genotypes

Genetic similarity among 45 Brassica Oleracea genotypes was compared using two molecular markers, random amplified polymorphic DNA (RAPD) and restriction fragment length polymorphisms (RFLPs). The genotypes included 37 broccolis (var. italica), five cauliflowers (var. botrytis) and three cabbages (var. capitata) which represented a wide range of commercially-available germplasm, and included open-pollinated cultivars, commercial hybrids, and inbred parents of hybrid cultivars. Fifty-six polymorphic RFLP bands and 181 polymorphic RAPD bands were generated using 15 random cDNA probes and 62 10-mer primers, respectively. The objectives were to compare RFLP and RAPD markers with regard to their (1) sampling variance, (2) rank correlations of genetic distance among sub-samples, and (3) inheritance. A bootstrap procedure was used to generate 200 random samples of size n (n=2,3,5,... 55) independently from the RAPD and RFLP data sets. The coefficient of variance (CV) was estimated for each sample. Pooled regressions of the coefficient of variance on bootstrap sample size indicated that the rate of decrease in CV with increasing sample size was the same for RFLPs and RAPDs. The rank correlation between the Nei-Li genetic similarity values for all pairs of genotypes (990) based on RFLP and RAPD data was 0.745. Differences were observed between the RFLP and RAPD dendrograms of the 45 genotypes. Overlap in the distributions of rank correlations between independent sub-samples from the RAPD data set, compared to correlations between RFLP and RAPD sub-samples, suggest that observed differences in estimation of genetic similarity between RAPDs and RFLPs is largely due to sampling error rather than due to DNA-based differences in how RAPDs and RFLPs reveal polymorphisms. A crossing algorithm was used to generate hypothetical banding patterns of hybrids based on the genotypes of the parents. The results of this study indicate that RAPDs provide a level of resolution equivalent to RFLPs for detemination of the genetic relationships among genotypes.     

Selection of Brassica napus L. embryogenic microspores by flow sorting

Flow cytometry can be used to select and sort microspore subpopulations of Brassica napus cv. Topas. Data obtained from embryogenic microspore populations were used to identify potentially embryogenic microspores from developmentally heterogeneous microspore populations based on differences in forward light scatter and green autofluorescence. Culture enrichment for embryogenic microspores is possible. Frequencies of 8 and 14% microspore embryogenesis were obtained when selected 16 h and 72 h after culture initiation. This represents 5- and 13-fold increase in microspore embryogenesis compared to non-sorted controls.     

High-resolution mapping of the Brassica napus Rfp restorer locus using Arabidopsis-derived molecular markers

The two forms of cytoplasmic male sterility (CMS) native to the oilseed rape or canola species Brassica napus, nap and pol, have novel features that may provide insight into the molecular mechanisms through which CMS/nuclear restorer systems evolve. One such feature is the finding that the distinct nuclear restorer genes for the two systems represent different alleles or haplotypes of the same nuclear locus. Improved understanding of how these systems have evolved will require molecular cloning and characterization of this novel locus. We have employed an approach that exploits the regional co-linearity between the Arabidopsis and Brassica genomes to construct a high-resolution genetic map of the nuclear restorer for the pol system, Rfp. Specifically, Arabidopsis-derived sequences have been used as a set of ordered RFLP probes to localize Rfp to a region of the B. napus genome equivalent to a 115 kb interval on Arabidopsis chromosome 1. Based on the known relationship of physical distances between orthologous segments of Arabidopsis and Brassica chromosomes, it is anticipated that the B. napus restorer locus is now mapped to sufficient resolution to permit its isolation and characterization.     

Melliferous potential of Brassica napus L. subsp. napus (Cruciferae)

Morphophysiological characteristics of oilseed rape flowers, such as features of the nectaries, nectar production, and observations on honey bee visits and honey and seed yield were studied with the aim to evaluate the melliferous potential of this crop as well as its attractiveness to pollinators. Calculation of the theoretical maximal honey yield revealed that the actual amount of extracted honey was much lower than the potential yield, indicating that this bee pasture is underutilized. We found that honey bee pollination increased oilseed rape yield, i.e., seed production, by 12 % compared with the treatment in which pollinators were excluded.