Genetic map of triticale compiling DArT, SSR, and AFLP markers

A set of 90 doubled haploid (DH) lines derived from F(1) plants that originated from a cross between × Triticosecale Wittm. 'Saka3006' and ×Triticosecale Wittm. 'Modus', via wide crossing with maize, were used to create a genetic linkage map of triticale. The map has 21 linkage groups assigned to the A, B, and R genomes including 155 simple sequence repeat (SSR), 1385 diversity array technology (DArT), and 28 amplified fragment length polymorphism (AFLP) markers covering 2397 cM with a mean distance between two markers of 4.1 cM. Comparative analysis with wheat consensus maps revealed that triticale chromosomes of the A and B genomes were represented by 15 chromosomes, including combinations of 2AS.2AL#, 2AL#2BL, 6AS.6AL#, and 2BS.6AL# instead of 2A, 2B, and 6A. In respect to published maps of rye, substantial rearrangements were found also for chromosomes 1R, 2R, and 3R of the rye genome. Chromosomes 1R and 2R were truncated and the latter was linked with 3R. A nonhomogeneous distribution of markers across the triticale genome was observed with evident bias (48%) towards the rye genome. This genetic map may serve as a reference linkage map of triticale for efficient studies of structural rearrangements, gene mapping, and marker-assisted selection.     

Influence of epistatic segregation distortion loci on genetic marker linkages in Japanese flounder

For genetic linkage analysis of Japanese flounder, 160 doubled haploids (DH) were artificially produced using mitotic gynogenesis and were genotyped for 458 simple sequence repeat (SSR) markers, 101 of which show distortional segregation. The genetic linkage map was constructed by modifying recombination fractions between the distorted markers. Between the corrected and uncorrected genetic maps, there were considerable differences in genetic distance, but not in relative locations among markers. Using a liability model, a segregation distortion locus (SDL), with an additive genetic effect of 1.772, was mapped between markers BDHYP387 and Poli56TUF of chromosome 24 in the corrected genetic map. Additionally, six pairs of epistatic SDLs were identified on chromosomes 1, 5, 8, 9, 23, and 24. Changes in genetic distances between markers did not occur on chromosome regions with main effect SDLs. However, most chromosome regions where genetic distances changed covered the detected epistatic SDLs. This study concluded that epistatic SDLs decrease linkages between markers and lengthen genetic distances in Japanese flounder. This finding has been partially validated in other DH populations derived from three female Japanese flounders.     

Unlocking the Genetic Diversity of Maize Landraces with Doubled Haploids Opens New Avenues for Breeding

Landraces are valuable genetic resources for broadening the genetic base of elite germplasm in maize. Extensive exploitation of landraces has been hampered by their genetic heterogeneity and heavy genetic load. These limitations may be overcome by the in-vivo doubled haploid (DH) technique. A set of 132 DH lines derived from three European landraces and 106 elite flint (EF) lines were genotyped for 56,110 single nucleotide polymorphism (SNP) markers and evaluated in field trials at five locations in Germany in 2010 for several agronomic traits. In addition, the landraces were compared with synthetic populations produced by intermating DH lines derived from the respective landrace. Our objectives were to (1) evaluate the phenotypic and molecular diversity captured within DH lines derived from European landraces, (2) assess the breeding potential (usefulness) of DH lines derived from landraces to broaden the genetic base of the EF germplasm, and (3) compare the performance of each landrace with the synthetic population produced from the respective DH lines. Large genotypic variances among DH lines derived from landraces allowed the identification of DH lines with grain yields comparable to those of EF lines. Selected DH lines may thus be introgressed into elite germplasm without impairing its yield level. Large genetic distances of the DH lines to the EF lines demonstrated the potential of DH lines derived from landraces to broaden the genetic base of the EF germplasm. The comparison of landraces with their respective synthetic population showed no yield improvement and no reduction of phenotypic diversity. Owing to the low population structure and rapid decrease of linkage disequilibrium within populations of DH lines derived from landraces, these would be an ideal tool for association mapping. Altogether, the DH technology opens new opportunities for characterizing and utilizing the genetic diversity present in gene bank accessions of maize.     

Quantitative trait loci controlling barley powdery mildew and scald resistances in two different barley doubled haploid populations

Powdery mildew and scald can cause significant yield loss in barley. In order to identify new resistance genes for powdery mildew and scald in barley, two barley doubled haploid (DH) populations were screened for adult plant resistance in the field and glasshouse under natural infection. The mapping populations included 92 DH lines from the cross of TX9425 × Franklin and 177 DH lines from the cross of Yerong × Franklin. Two quantitative trait loci (QTL) for resistance to powdery mildew were identified in the TX9425 × Franklin population. These QTL were mapped to chromosomes 7H and 5H, respectively. The phenotypic variation explained by the two QTL detected in this population was 22 and 17%, respectively. Three significant QTL were identified from the Yerong × Franklin population for the resistance to powdery mildew; the major one, detected on the short arm of chromosome 1H, explained 66% of phenotypic variation. The major QTL for scald resistance, identified from two different populations which shared a common parent, Franklin, were mapped in the similar position on 3H. However, the Franklin allele provided resistance to one population but susceptibility to the other population. The Yerong allele on 3H showed much better resistance to scald than the Franklin allele, which has not been reported before. Using high-density maps for both populations, some markers which were very close to the resistance genes were identified. Transgression beyond the parents in disease resistances of the DH populations indicates that both small-effect QTLs and genetic background may also have significant contributions towards the resistance.     

Comparison of genetic and cytogenetic maps of hexaploid wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) using SSR and DArT markers

A number of technologies are available to increase the abundance of DNA markers and contribute to developing high resolution genetic maps suitable for genetic analysis. The aim of this study was to expand the number of Diversity Array Technology (DArT) markers on the wheat array that can be mapped in the wheat genome, and to determine their chromosomal location with respect to simple sequence repeat (SSR) markers and their position on the cytogenetic map. A total of 749 and 512 individual DArT and SSR markers, respectively, were identified on at least one of four genetic maps derived from recombinant inbred line (RIL) or doubled haploid (DH) populations. A number of clustered DArT markers were observed in each genetic map, in which 20–34% of markers were redundant. Segregation distortion of DArT and SSR markers was also observed in each mapping population. Only 14% of markers on the Version 2.0 wheat array were assigned to chromosomal bins by deletion mapping using aneuploid lines. In this regard, methylation effects need to be considered when applying DArT marker in genetic mapping. However, deletion mapping of DArT markers provides a reference to align genetic and cytogenetic maps and estimate the coverage of DNA markers across the wheat genome. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Homology of AFLP products in three mapping populations of barley

Segregation of 850 polymorphic AFLP (amplified fragment length polymorphism) fragments was followed in three different doubled haploid (DH) barley populations, Dicktoo × Morex (DM), Igri × Franka (IF) and Blenheim × E224/3 (BE), which had previously been used to construct linkage maps using other molecular markers. The final maps consisted of 310, 655 and 474 markers, of which 234, 194 and 376, respectively, were AFLPs. A comparison of profiles from the parental lines identified 51 similar-sized AFLPs segregating in both DM and IF populations, 20 in the DM and BE populations and 18 in the IF and BE populations. Eight segregated in all three. Analysis of the complete datasets for each of the populations using Joinmap V.2. indicated that in general terms each of the AFLPs which were polymorphic in more than one population mapped to the same genetic locus. The number of co-dominant markers segregating in a single population ranged from 6% for DM to 12.6% for IF. These results are discussed in the context of using AFLP in genetic linkage and diversity studies. Received: 5 November 1996 / Accepted: 10 March 1997     

Mapping of QTLs for androgenetic response based on a molecular genetic map of x Triticosecale Wittmack.

Quantitative trait loci (QTLs) for androgenetic response were mapped in a doubled haploid (DH) population derived from the F1 hybrid of 2 unrelated varieties of triticale, 'Torote' and 'Presto'. A molecular marker linkage map of this cross was previously constructed using 73 DH lines. This map contains 356 markers (18 random amplified 5 polymorphic DNA, 40 random amplified microsatellite polymorphics, 276 amplified fragment length polymorphisms, and 22 simple sequence repeats) and was used for QTL analysis. The genome was well covered, and of the markers analysed, 336 were located in 21 linkage groups (81.9%) identified using SSR markers. The map covered a total length of 2465.4 cM with an average of 1 marker for each 6.9 cM. The distribution of the markers was not homogeneous across the 3 genomes, with 50.7% detected in the R genome. Several QTLs were found for the following variables related to the androgenetic response: number of embryos/100 anthers; plants regenerated from 100 embryos; number of green plants/total number of plants; and number of green plants/1000 anthers. Two were detected on chromosome 6B and 4R, which together had a 30% total influence on the induction of embryos. Another was found on 6B and on the unidentified LG1; these influenced the production of total plants from haploid embryo cultures. One QTL on chromosome 3R determined the photosynthetic viability of the haploid plantlets regenerated from microspores. Other QTLs were found on chromosomes 1B, 1R, 4R, and 7R, which helped the control of the final androgenetic response (the number of plantlets obtained for every 1000 anthers cultured).     

Quantitative trait loci associated with androgenic responsiveness in triticale (×Triticosecale Wittm.) anther culture

Quantitative trait loci (QTLs) associated with androgenic responsiveness in triticale were analyzed using a population of 90 DH lines derived from the F1 cross between inbred line ‘Saka 3006’ and cv. ‘Modus’, which was used in a number of earlier studies on molecular mapping in this crop. Using Windows QTL Cartographer and MapQTL 5.0, composite interval mapping (CIM) and association studies (Kruskal–Wallis test; K–W) for five androgenesis parameters (androgenic embryo induction, total regeneration and green plant regeneration ability, and two characteristics describing final androgenesis efficiency) were conducted. For the studied components of androgenic response, CIM detected in total 28 QTLs which were localized on 5 chromosomes from A and R genomes. Effects of all QTLs that were identified at 2.0 or above of the LOD score explained 5.1–21.7?% of the phenotypic variation. Androgenesis induction was associated with seven QTLs (LOD between 2.0 and 5.8) detected on chromosomes 5A, 4R, 5R and 7R, all of them confirmed by K–W test as regions containing the markers significantly linked to the studied trait. What is more, K–W test revealed additional markers on chromosomes: 5A, 2BL, 7B and 5R. Both total and green regeneration ability were controlled by genes localized on chromosome 4A. Some of the QTLs that affected final androgenesis efficiency were identical with those associated with androgenic embryo induction efficiency, suggesting that the observed correlation may be either due to tight linkage or to pleiotropy. Key message Five regions of the triticale genome were indicated as revealing significant marker/trait association. Markers located in these regions are potentially useful for triticale breeding through marker-assisted selection.     

The genetic and molecular characterization of pollen-derived plant lines from octoploid triticale x wheat hybrids

Six doubled-haploid (DH) lines, derived by anther culture from octoploid triticale x wheat hybrids, were characterized using cytological, biochemical and molecular techniques. Lines varied in their wheat and rye genome composition, and were either wheat-rye chromosome multiple addition lines or had spontaneous substitutions and/or wheat-rye translocations. Most of the lines contained a pair of 4R chromosomes, whereas 1R or 7R were present in others. The results are similar to those previously obtained with hexaploid triticale x wheat crosses and indicate that it is possible to produce alien (wheat/rye) addition, substitution, and translocation lines directly from the anther culture of intergeneric hybrids.     

Development of public immortal mapping populations,molecular markers and linkage maps for rapid cycling <Emphasis Type="Italic">Brassica rapa</Emphasis> and <Emphasis Type="Italic">B. oleracea</Emphasis>

Publicly available genomic tools help researchers integrate information and make new discoveries. In this paper, we describe the development of immortal mapping populations of rapid cycling, self-compatible lines, molecular markers, and linkage maps for Brassica rapa and B. oleracea and make the data and germplasm available to the Brassica research community. The B. rapa population consists of 160 recombinant inbred (RI) lines derived from the cross of highly inbred lines of rapid cycling and yellow sarson B. rapa. The B. oleracea population consists of 155 double haploid (DH) lines derived from an F1 cross between two DH lines, rapid cycling and broccoli. A total of 120 RFLP probes, 146 SSR markers, and one phenotypic trait (flower color) were used to construct genetic linkage maps for both species. The B. rapa map consists of 224 molecular markers distributed along 10 linkage groups (A1–A10) with a total distance of 1125.3 cM and a marker density of 5.7 cM/marker. The B. oleracea genetic map consists of 279 molecular markers and one phenotypic marker distributed along nine linkage groups (C1–C9) with a total distance of 891.4 cM and a marker density of 3.2 cM/marker. A syntenic analysis with Arabidopsis thaliana identified collinear genomic blocks that are in agreement with previous studies, reinforcing the idea of conserved chromosomal regions across the Brassicaceae.     

Segregation distortion and linkage analysis in eggplant (Solanum melongena L.)

An anther-derived doubled haploid (DH) population and an F2 mapping population were developed from an intraspecific hybrid between the eggplant breeding lines 305E40 and 67/3. The former incorporates an introgressed segment from Solanum aethiopicum Gilo Group carrying the gene Rfo-sa1, which confers resistance to Fusarium oxysporum; the latter is a selection from an intraspecific cross involving two conventional eggplant varieties and lacks Rfo-sa1. Initially, 28 AFLP primer combinations (PCs) were applied to a sample of 93 F2 individuals and 93 DH individuals, from which 170 polymorphic AFLP fragments were identified. In the DH population, the segregation of 117 of these AFLPs as well as markers closely linked to Rfo-sa1 was substantially distorted, while in the F2 population, segregation distortion was restricted to just 10 markers, and thus the latter was chosen for map development. A set of 141 F2 individuals was genotyped with 73 AFLP PCs (generating 406 informative markers), 32 SSRs, 4 tomato RFLPs, and 3 CAPS markers linked to Rfo-sa1. This resulted in the assignment of 348 markers to 12 major linkage groups. The framework map covered 718.7?cM, comprising 238 markers (212 AFLPs, 22 SSRs, 1 RFLP, and the Rfo-sa1 CAPS). Marker order and inter-marker distances in this eggplant map were largely consistent with those reported in a recently published SSR-based map. From an eggplant breeding perspective, DH populations produced by anther culture appear to be subject to massive segregation distortion and thus may not be very efficient in capturing the full range of genetic variation present in the parental lines.     

Evaluation of genetic diversity and uniformity of head cabbage DH lines by the use of RAPD markers

DH lines derived from cabbage cvs. Kamienna G?owa, S?awa z Enkhuizen and Langendijker, representing R1 generation, were analysed by the use of RAPD markers for their diversity and uniformity. For the evaluation of genetic diversity, eight primers yielding informative bands were used. Of the total of 83 RAPD bands scored in this study, 16.9% were polymorphic between a set of 13 DH lines. The similarity of the DH lines, estimated by Jaccard's coefficient, was depicted in the UPGMA dendrogram. Fourteen generated informative RAPD bands allowed the identification of DH lines developed from each cultivar. The evaluation of the uniformity for six closely related DH lines was possible by the use of three primers which generate one or two polymorphic bands. The lack of differences among ten plants of the five investigated DH lines manifested their uniformity. One line showed intraline polymorphism with two RAPD primers. The occurrence of the differences at the molecular level among ten plants indicated that their parental R0 plant was probably obtained from somatic cells, not by androgenesis.     

Quantitative trait loci for glucosinolate accumulation in Brassica rapa leaves

Glucosinolates and their breakdown products have been recognized for their effects on plant defense, human health, flavor and taste of cruciferous vegetables. Despite this importance, little is known about the regulation of the biosynthesis and degradation in Brassica rapa. Here, the identification of quantitative trait loci (QTL) for glucosinolate accumulation in B. rapa leaves in two novel segregating double haploid (DH) populations is reported: DH38, derived from a cross between yellow sarson R500 and pak choi variety HK Naibaicai; and DH30, from a cross between yellow sarson R500 and Kairyou Hakata, a Japanese vegetable turnip variety. An integrated map of 1068 cM with 10 linkage groups, assigned to the international agreed nomenclature, is developed based on the two individual DH maps with the common parent using amplified fragment length polymorphism (AFLP) and single sequence repeat (SSR) markers. Eight different glucosinolate compounds were detected in parents and F(1)s of the DH populations and found to segregate quantitatively in the DH populations. QTL analysis identified 16 loci controlling aliphatic glucosinolate accumulation, three loci controlling total indolic glucosinolate concentration and three loci regulating aromatic glucosinolate concentrations. Both comparative genomic analyses based on Arabidopsis-Brassica rapa synteny and mapping of candidate orthologous genes in B. rapa allowed the selection of genes involved in the glucosinolate biosynthesis pathway that may account for the identified QTL.     

The complex quantitative barley–<Emphasis Type="Italic">Rhynchosporium secalis</Emphasis> interaction: newly identified QTL may represent already known resistance genes

Two barley populations, i.e. 135 doubled haploid (DH) lines of the cross 'Igri' (rrs1) x 'Triton' (Rrs1) (I x T) and 76 DH lines of the cross 'Post' x 'Vixen' (both rrs1) (P x V), were analysed to identify QTL for Rhynchosporium secalis resistance independent of the Rrs1 locus by using the single spore R. secalis isolate 271 (Rrs1-virulent). A major QTL with its positive allele derived from cv. 'Triton' was detected in the I x T population on chromosome 2HS explaining almost 80% of the phenotypic variance. Thus, it can be considered as an R-gene corresponding to the already described Rrs15(CI8288) on chromosome 2HS. In addition, two minor QTL were identified, one in the centromeric region of 6H in a highly polymorphic region with already several mapped R-genes and a second one at the end of the short arm of chromosome 7H which may be an allele of Rrs2 because of its chromosomal position. Regarding the DH population P x V different minor QTL were identified on chromosomes 6H and 7H. The first one is corresponding to the genomic region of the Rrs13 gene whereas the QTL on chromosome 7H maps in a genomic region where several R-genes against different pathogens have been localized. A comparison of both QTL analyses reveals no R. secalis isolate 271-specific resistance locus but leads to the hypothesis that two of the identified QTL may be alleles of the R-genes Rrs15(CI8288) and Rrs2.     

Development of commercially valuable traits in hexaploid triticale lines with Aegilops introgressions as dependent on the genome composition

Introgressive hybridization is an efficient means to improve the genetic diversity of cultivated cereals, including triticale. To identify the triticale lines with Aegilops introgressions, genotyping was carried out with ten lines obtained by crossing hexaploid triticale with genome-substitution forms of the common wheat cultivar Avrora: Avrolata (AABBUU), Avrodes (AABBSS), and Avrotika (AABBTT). The genome composition of the triticale lines was studied by in situ hybridization, and recombination events involving Aegilops and/or common wheat chromosomes were assumed for nine out of the ten lines. Translocations involving rye chromosomes were not observed. Substitutions for rye chromosomes were detected in two lines resulting from crosses with Avrolata. Genomic in situ hybridization (GISH) with Ae. umbellulata DNA and molecular genetic analysis showed that chromosome 1R was substituted with Ae. umbellulata chromosome 1U in one of the lines and that 2R(2U) substitution took place in the other line. Fluorescence in situ hybridization (FISH) with the Spelt 1 and pSc119.2 probes revealed a translocation from Ae. speltoides to the long arm of chromosome 1B in one of the two lines resulting from crosses with Avrodes and a translocation in the long arm of chromosome 7B in the other line. In addition, the pSc119.2 probe revealed chromosome 1B rearrangements in four lines resulting from crosses with Avrolata and in a line resulting from crosses with Avrotika. The lines were tested for main productivity parameters. A negative effect on all productivity parameters was demonstrated for Ae. umbellulata chromosome 2U. The overwinter survival in all of the lines was similar to or even higher than in the original triticale cultivars. A substantial increase in winter resistance as compared with the parental cultivar was observed for the line carrying the T7BS-7SL translocation. The line with the 1R(1U) chromosome substitution seemed promising for the baking properties of triticale.     

Genetic mapping of a major gene in triticale conferring resistance to bacterial leaf streak

Key message

A major gene conferring resistance to bacterial leaf streak was mapped to chromosome 5R in triticale.

Abstract

Bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa (Xtu), is an important disease of wheat and triticale around the world. Although resistance to BLS is limited in wheat, several triticale accessions have high levels of resistance. To characterize the genetic basis of this resistance, we developed triticale mapping populations using a resistant accession (Siskiyou) and two susceptible accessions (UC38 and Villax St. Jose). Bulked segregant analysis in an F₂ population derived from the cross of Siskiyou × UC38 led to the identification of a simple sequence repeat (SSR) marker (XSCM138) on chromosome 5R that co-segregated with the resistance gene. The cross of Siskiyou × Villax St. Jose was advanced into an F_2:5 recombinant inbred line population and evaluated for BLS reaction. Genetic linkage maps on this population were assembled with markers generated using genotyping-by-sequencing as well as several SSR markers previously identified on 5R. Quantitative trait locus (QTL) mapping revealed a single major QTL on chromosome 5R, underlined by the same SSR marker as in the Siskiyou × UC38 population. The F₁ hybrids of the two crosses were highly resistant to BLS, indicating that resistance is largely dominant. This work will facilitate introgression of this rye-derived BLS resistance gene into the wheat genome by molecular marker-mediated chromosome engineering.

     

The effect of selection for phenotypical characters on the chromosome constitution in spring triticale

A set of spring triticale selection forms was studied with the use of microsatellite markers specific for D-genome chromosomes and genomic in situ hybridization. 2R/2D substitutions were found in six of twelve forms. Two lines displayed segregation for the substitution: plants with the substitution and without it, and plants heterozygous for the substitution were revealed. Segregation of the lines and the presence in them of telocentric chromosomes of wheat and rye in the monosomic state suggest that the process of formation is still in progress. The data obtained also demonstrate that triticale is under selection for the 2R/2D substitution as controlling the spectrum of adaptively and selectively valuable traits.     

Identification of QTLs Associated with Oil Content in a High-Oil Brassica napus Cultivar and Construction of a High-Density Consensus Map for QTLs Comparison in B. napus

Increasing seed oil content is one of the most important goals in breeding of rapeseed (B. napus L.). To dissect the genetic basis of oil content in B. napus, a large and new double haploid (DH) population containing 348 lines was obtained from a cross between ‘KenC-8’ and ‘N53-2’, two varieties with >10% difference in seed oil content, and this population was named the KN DH population. A genetic linkage map consisting of 403 markers was constructed, which covered a total length of 1783.9 cM with an average marker interval of 4.4 cM. The KN DH population was phenotyped in eight natural environments and subjected to quantitative trait loci (QTL) analysis for oil content. A total of 63 identified QTLs explaining 2.64–17.88% of the phenotypic variation were identified, and these QTLs were further integrated into 24 consensus QTLs located on 11 chromosomes using meta-analysis. A high-density consensus map with 1335 marker loci was constructed by combining the KN DH map with seven other published maps based on the common markers. Of the 24 consensus QTLs in the KN DH population, 14 were new QTLs including five new QTLs in A genome and nine in C genome. The analysis revealed that a larger population with significant differences in oil content gave a higher power detecting new QTLs for oil content, and the construction of the consensus map provided a new clue for comparing the QTLs detected in different populations. These findings enriched our knowledge of QTLs for oil content and should be a potential in marker-assisted breeding of B. napus.     

Loss of chromosomes 2R and 5RS in octoploid triticale selected for agronomic traits

The advanced lines of octoploid triticale which have been bred for nearly a half century in China show significant improvements in agronomic traits such as plant height, fertility, threshability, maturity and seed plumpness, although no intentional cytological selection had been performed. In this study, eight primary and six advanced lines were analyzed by fluorescence and genomic in situ hybridization to elucidate their chromosome constitutions. In the advanced lines, about 70% of the plants examined had 2n = 56 chromosomes (range: 50 to 58). Almost all advanced lines, however, had lost rye chromosome 2R and the short arm of 5R (5RS). The exceptions were lines Y1005 and Y4683: The former had lost only the 2R chromosome and the latter only 5RS. The reduction of rye chromosomes was compensated by an extra pair of 2D or A-genome (possibly 2A) chromosomes in plants with 2n = 56. This suggests that the loss of 2R and 5RS chromosomes contributes to the improvement of octoploid triticale. Since the plants with chromosome 2R are non-free threshing and chromosome 2D of synthetic wheat is known to carry the Tg (tenacious glumes) gene, it is possible that chromosome 2R carries a gene affecting the threshability, and we carried out selection to remove it. We also discuss the possible relationshipbetween 5RS and the genetic stability of octoploid triticale.     

Physical mapping and molecular-cytogenetic analysis of substitutions and translocations involving chromosome 1D in synthetic hexaploid triticale

 Chromosome 1D, which carries the advantageous alleles of glutenin and gliadin, attracts major interest with respect to improving the bread-making quality of triticale. Eighty-one BC₁F₄ lines from different primary and secondary hexaploid triticale crosses were selected for 1D chromatin analysis using SDS-PAGE and C-banding. In situ hybridization and RFLP-based comparative physical mapping of group 1 chromosomes revealed 20 lines with complete 1D (1A) substitutions. Nine 1D (1B) substitutions, six 1D (1R) substitutions and one 1D addition line were also selected. Three lines were pure AABBRR hexaploids without any D-genome chromosomes. For the remaining 42 lines (51.8%), a wide spectrum of 20 different recombinations between chromosomes 1A and 1D was uncovered. Altogether, they were generated without any earlier irradiation, tissue culture or genetic induction of chromosome pairing. In addition, 14 translocations between 1B/1D, 1A/1R, 1B/1R, 1D/1R and 1A/1B were detected. Considerable variability for sedimentation values was found, with the highest sedimentation values among lines with complete 1D chromosomes. The implications of using triticale as a model for generating compensating chromosome rearrangements in defined homoeologous groups and the breeding potential of D-genome chromatin introgressed into triticale with improved sedimentation values are discussed. Received: 27 July 1998 / Accepted: 5 August 1998