Comparative genetic maps reveal extreme crossover localization in the Aegilops speltoides chromosomes

A total of 137 loci were mapped in Aegilops speltoides, the closest extant relative of the wheat B genome, using two F₂ mapping populations and a set of wheat-Ae. speltoides disomic addition (DA) lines. Comparisons of Ae. speltoides genetic maps with those of Triticum monococcum indicated that Ae. speltoides conserved the gross chromosome structure observed across the tribe Triticeae. A putative inversion involving the short arm of chromosome 2 was detected in Ae. speltoides. A translocation between chromosomes 2 and 6, present in the wheat B genome, was absent. The ligustica/aucheri spike dimorphism behaved as allelic variation at a single locus, which was mapped in the centromeric region of chromosome 3. The genetic length of each chromosome arm was about 50 cM, irrespective of its physical length. Compared to T. monococcum genetic maps, recombination was virtually eliminated from the proximal 50–100 cM and was localized in short distal regions, which were often expanded compared to the T. monococcum maps. The wheat B genome and the genome of Ae. longissima, a close relative of Ae. speltoides, do not show the extreme localization of crossovers observed in Ae. speltoides.     

Homoeologous relationships of Aegilops speltoides chromosomes to bread wheat

 Homoeologous pairing at metaphase I was analysed in the standard-type, ph2b and ph1b hybrids of Triticum aestivum (AABBDD) and Aegilops speltoides (SS). Data from relative pairing affinities were used to predict homoeologous relationships of Ae. speltoides chromosomes to wheat. Chromosomes of both species, and their arms, were identified by C-banding. The Ae. speltoides genotype carried genes that induced a high level of homoeologous pairing in the three types of hybrids analyzed. All arms of the seven chromosomes of the S genome showed normal homoeologous pairing, which implies that no apparent chromosome rearrangements occurred in the evolution of Ae. speltoides relative to wheat. A pattern of preferential pairing of two types, A-D and B-S, confirmed that the S genome is very closely related to the B genome of wheat. Although this pairing pattern was also reported in hybrids of wheat with Ae. longissima and Ae. sharonensis, a different behaviour was found in group 5 chromosomes. In the hybrids of Ae. speltoides, chromosome 5B-5S pairing was much more frequent than 5D-5S, while these chromosome associations reached similar frequencies in the hybrids of Ae. longissima and Ae. sharonensis. These results are in agreement with the hypothesis that the B genome of wheat is derived from Ae. speltoides. Received: 8 January 1998 / Accepted: 4 February 1998     

Construction and study of leaf rust-resistant common wheat lines with translocations of <Emphasis Type="Italic">Aegilops speltoides</Emphasis> Tausch. Genetic material

Genotyping was performed for the leaf rust-resistant line 73/00i (Triticum aestivum × Aegilops speltoides). Fluorescence in situ hybridization (FISH) with probes Spelt1 and pSc119.2 in combination with microsatellite analysis were used to determine the locations and sizes of the Ae. speltoides genetic fragments integrated into the line genome. Translocations were identified in the long arms of chromosomes 5B and 6B and in the short arm of chromosome 1B. The Spelt1 and pSc119.2 molecular cytological markers made it possible to rapidly establish lines with single translocation in the long arms of chromosomes 5B and 6B. The line carrying the T5BS · 5BL-5SL translocation was highly resistant to leaf rust, and the lines carrying the T6BS · 6BL-6SL translocation displayed moderate resistance. The translocations differed in chromosomal location from known leaf resistance genes transferred into common wheat from Ae. speltoides. Hence, it was assumed that new genes were introduced into the common wheat genome from Ae. speltoides. The locus that determined high resistance to leaf rust and was transferred into the common wheat genome from the long arm of Ae. speltoides chromosome 5S by the T5BS · 5BL-5SL translocation was preliminarily designated as LrAsp5.     

Characterization of Aegilops uniaristata chromosomes by comparative DNA marker analysis and repetitive DNA sequence in situ hybridization

RFLP analyses were performed on wheat-Aegilops uniaristata Vis. addition and translocation lines to confirm the identity of added N-genome chromosomes. Complete 1N, 3N, 4N, 5N and 7N chromosome additions were identified, while the complete long arm and only part of the short arm was identified for chromosome 2N. There were no wheat-like 4/5 and 4/7 translocations in the Ae. uniaristata chromosomes. Chromosome 3N carried an asymmetric pericentric inversion, and the translocation line was a product of centric fusion between the long arms of chromosomes 3B and 3N. Chromosome-specific RAPD and microsatellite markers were also identified for all the added Ae. uniaristata chromosomes available in this set of addition lines. A new genomic in situ hybridization protocol combining pre-annealing of probe and blocking DNA and prehybridization with blocking DNA was developed to differentiate the very closely related genomes of Ae. uniaristata and wheat. Hybridization sites for the repetitive DNA sequences pAs1, pSc119.2 and pTa71 were identified on the N-genome chromosomes of Ae. uniaristata using the fluorescent in situ hybridization technique. Results showed deviation from the previously published ideogram of this species. A new ideogram, which shows the hybridization sites for the above sequences, was produced in which the chromosomes are arranged according to their homoeologous group. Received: 23 April 1999 / Accepted: 6 August 1999     

Comparative genetic analysis of the Aegilops longissima and Ae. sharonensis genomes with common wheat

Aegilops longissima Schw. et Musch. (2n= 2x=14, S^lS^l) and Aegilops sharonensis Eig. (2n=2x=14, S^lS^l) are diploid species belonging to the section Sitopsis in the tribe Triticeae and potential donors of useful genes for wheat breeding. A comparative genetic map was constructed of the Ae. longissima genome, using RFLP probes with known location in wheat. A high degree of conserved colinearity was observed between the wild diploid and basic wheat genome, represented by the D genome of cultivated wheat. Chromosomes 1S^l, 2S^l, 3S^l, 5S^l and 6S^l are colinear with wheat chromosomes 1D, 2D, 3D, 5D and 6D, respectively. The analysis confirmed that chromosomes 4S^l and 7S^l are translocated relative to wheat. The short arms and major part of the long arms are homoeologous to most of wheat chromosomes 4D and 7D respectively, but the region corresponding to the distal segment of 7D was translocated from 7S^lL to the distal region of 4S^lL. The map and RFLP markers were then used to analyse the genomes and added chromosomes in a set of ’Chinese Spring’ (CS)/Ae. longissima chromosome additions. The study confirmed the availability of disomic CS/Ae. longissima addition lines for chromosomes 1S^l, 2S^l, 3S^l, 4S^l and 5S^l. An as yet unpublished set of Ae. sharonensis chromosome addition lines were also available for analysis. Due to the gametocidal nature of Ae. sharonensis chromosomes 2S^l and 4S^l, additions 1S^l, 3S^l, 5S^l, 6S^l and 7S^l were produced in a (4D)4S^l background, and 2S^l and 4S^l in a euploid wheat background. The analysis also confirmed that the 4/7 translocation found in Ae. longissima was not present in Ae. sharonensis although the two wild relatives of wheat are considered to be closely related. The phenotypes of the Ae. sharonensis addition lines are described in an Appendix. Received: 28 September 2000 / Accepted: 19 January 2001     

Microsatellite mapping of <Emphasis Type="Italic">Ae. speltoides</Emphasis> and map-based comparative analysis of the S,G, and B genomes of Triticeae species

The first microsatellite linkage map of Ae. speltoides Tausch (2n = 2x = 14, SS), which is a wild species with a genome closely related to the B and G genomes of polyploid wheats, was developed based on two F₂ mapping populations using microsatellite (SSR) markers from Ae. speltoides, wheat genomic SSRs (g-SSRs) and EST-derived SSRs. A total of 144 different microsatellite loci were mapped in the Ae. speltoides genome. The transferability of the SSRs markers between the related S, B, and G genomes allowed possible integration of new markers into the T. timopheevii G genome chromosomal maps and map-based comparisons. Thirty-one new microsatellite loci assigned to the genetic framework of the T. timopheevii G genome maps were composed of wheat g-SSR (genomic SSR) markers. Most of the used Ae. speltoides SSRs were mapped onto chromosomes of the G genome supporting a close relationship between the G and S genomes. Comparative microsatellite mapping of the S, B, and G genomes demonstrated colinearity between the chromosomes within homoeologous groups, except for intergenomic T6A^tS.1G, T4AL.5AL.7BS translocations. A translocation between chromosomes 2 and 6 that is present in the T. aestivum B genome was found in neither Ae. speltoides nor in T. timopheevii. Although the marker order was generally conserved among the B, S, and G genomes, the total length of the Ae. speltoides chromosomal maps and the genetic distances between homoeologous loci located in the proximal regions of the S genome chromosomes were reduced compared with the B, and G genome chromosomes.     

Investigation of a preferentially transmitted Aegilops sharonensis chromosome in wheat

Summary An attempt to produce a set of addition lines of Aegilops sharonensis to the wheat variety Chinese Spring produced only one addition line. This was due to preferential transmission of one chromosome from Ae. sharonensis. This chromosome was studied in detail by established cytological methods of chromosome observation and by the newer techniques of C-banding and in situ hybridization of a cloned DNA sequence. The chromosome was found to be partially homologous to an Ae. sharonensis chromosome of similar behaviour in another wheat addition line. The incomplete homology of the two Ae. sharonensis chromosomes was due to the presence of a translocated segment of a wheat chromosome. — Substitution lines of the Ae. sharonensis chromosome for wheat homoeologous group 4 were produced and the Ae. sharonensis chromosome thereby designated 4 S ^l .     

Molecular cytogenetic and genomic analyses reveal new insights into the origin of the wheat B genome

Key message

This work pinpointed the goatgrass chromosomal segment in the wheat B genome using modern cytogenetic and genomic technologies, and provided novel insights into the origin of the wheat B genome.

Abstract

Wheat is a typical allopolyploid with three homoeologous subgenomes (A, B, and D). The donors of the subgenomes A and D had been identified, but not for the subgenome B. The goatgrass Aegilops speltoides (genome SS) has been controversially considered a possible candidate for the donor of the wheat B genome. However, the relationship of the Ae. speltoides S genome with the wheat B genome remains largely obscure. The present study assessed the homology of the B and S genomes using an integrative cytogenetic and genomic approach, and revealed the contribution of Ae. speltoides to the origin of the wheat B genome. We discovered noticeable homology between wheat chromosome 1B and Ae. speltoides chromosome 1S, but not between other chromosomes in the B and S genomes. An Ae. speltoides-originated segment spanning a genomic region of approximately 10.46 Mb was detected on the long arm of wheat chromosome 1B (1BL). The Ae. speltoides-originated segment on 1BL was found to co-evolve with the rest of the B genome. Evidently, Ae. speltoides had been involved in the origin of the wheat B genome, but should not be considered an exclusive donor of this genome. The wheat B genome might have a polyphyletic origin with multiple ancestors involved, including Ae. speltoides. These novel findings will facilitate genome studies in wheat and other polyploids.

     

Development of commercially valuable traits in hexaploid triticale lines with <Emphasis Type="Italic">Aegilops</Emphasis> 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 Aurora: Aurolata (AABBUU), Aurodes (AABBSS), and Aurotika (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 Aurolata. 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 Spelt1 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 Aurodes 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 Aurolata and in a line resulting from crosses with Aurotika. 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.     

The application of wheat microsatellites to identify disomic Triticum aestivum-Aegilops markgrafii addition lines

 We describe the use of wheat microsatellites for the discrimination of Aegilops markgrafii chromosomes. Twenty out of eighty eight wheat microsatellites (WMS) tested were able to distinguish Triticum aestivum-Ae. markgrafii addition lines. Six, three, three, one and six of 18 WMS can be used as markers for single Ae. markgrafii chromosomes B, C, D, F and G, respectively. Addition line A is not available but additional bands, appearing only in Ae. markgrafii and the T. aestivum-Ae. markgrafii amphiploid and not in any of the available addition lines, indicate that three WMS detect markers for Ae. markgrafii chromosomes A. Addition line E could not be detected by any of the WMS markers applied, although the 20 WMS represented all the homologous groups of wheat. All three WMS located on the short arm of group-2 chromosomes were located on Ae. markgrafii chromosome B; three of four WMS, located on the long arm of wheat group-2 chromosomes, were specific to Ae. markgrafii chromosome G and three of four WMS, specific to group-5 chromosomes, were markers for Ae. markgrafii chromosome C, indicating the homoeology of these wheat chromosome arms with the respective Ae. markgrafii chromosomes. Received: 29 May 1997 / Accepted: 10 September 1997     

Development of wheat lines carrying stem rust resistance gene <Emphasis Type="Italic">Sr39</Emphasis> with reduced <Emphasis Type="Italic">Aegilops speltoides</Emphasis> chromatin and simple PCR markers for marker-assisted selection

The use of major resistance genes is a cost-effective strategy for preventing stem rust epidemics in wheat crops. The stem rust resistance gene Sr39 provides resistance to all currently known pathotypes of Puccinia graminis f. sp. tritici (Pgt) including Ug99 (TTKSK) and was introgressed together with leaf rust resistance gene Lr35 conferring adult plant resistance to P. triticina (Pt), into wheat from Aegilops speltoides. It has not been used extensively in wheat breeding because of the presumed but as yet undocumented negative agronomic effects associated with Ae. speltoides chromatin. This investigation reports the production of a set of recombinants with shortened Ae. speltoides segments through induction of homoeologous recombination between the wheat and the Ae. speltoides chromosome. Simple PCR-based DNA markers were developed for resistant and susceptible genotypes (Sr39#22r and Sr39#50s) and validated across a set of recombinant lines and wheat cultivars. These markers will facilitate the pyramiding of ameliorated sources of Sr39 with other stem rust resistance genes that are effective against the Pgt pathotype TTKSK and its variants.     

Molecular cytogenetic characterization of Aegilops biuncialis and its use for the identification of 5 derived wheat-Aegilops biuncialis disomic addition lines.

The aim of the experiments was to produce and identify different Triticum aestivum-Aegilops biuncialis disomic addition lines. To facilitate the exact identification of the Ae. biuncialis chromosomes in these Triticum aestivum-Ae. biuncialis disomic additions, it was necessary to analyze the fluorescence in situ hybridization (FISH) pattern of Ae. biuncialis (2n = 4x = 28, U(b)U(b)M(b)M(b)), comparing it with the diploid progenitors (Aegilops umbellulata, 2n = 2x = 14, UU and Aegilops comosa, 2n = 2x = 14, MM). To identify the Ae. biuncialis chromosomes, FISH was carried out using 2 DNA clones (pSc119.2 and pAs1) on Ae. biuncialis and its 2 diploid progenitor species. Differences in the hybridization patterns of all chromosomes were observed among the 4 Ae. umbellulata accessions, the 4 Ae. comosa accessions, and the 3 Ae. biuncialis accessions analyzed. The hybridization pattern of the M genome was more variable than that of the U genome. Five different wheat-Ae. biuncialis addition lines were produced from the wheat-Ae. biuncialis amphiploids produced earlier in Martonvásár. The 2M, 3M, 7M, 3U, and 5U chromosome pairs were identified with FISH using 3 repetitive DNA clones (pSc119.2, pAs1, and pTa71) in the disomic chromosome additions produced. Genomic in situ hybridization (GISH) was used to differentiate the Ae. biuncialis chromosomes from wheat, but no chromosome rearrangements between wheat and Ae. biuncialis were detected in the addition lines.     

Identification of alien chromatin specifying resistance to wheat streak mosaic and greenbug in wheat germ plasm by C-banding and in situ hybridization

Summary The chromosome constitutions of eight wheat streak mosaic virus (WSMV)-resistant lines, three of which are also greenbug resistant, derived from wheat/ Agropyron intermedium/Aegilops speltoides crosses were analyzed by C-banding and in situ hybridization. All lines could be traced back to CI15092 in which chromosome 4A is substituted for by an Ag. intermedium chromosome designated 4Ai-2, and the derived lines carry either 4Ai-2 or a part of it. Two (CI17881, CI17886) were 4Ai-2 addition lines. CI17882 and CI17885 were 4Ai-2-(4D) substitution lines. CI17883 was a translocation substitution line with a pair of 6AL.4Ai-2S and a pair of 6AS.4Ai-2L chromosomes substituting for chromosome pairs 4D and 6A of wheat. CI17884 carried a 4DL.4Ai-2S translocation which substituted for chromosome 4D. CI17766 carried a 4AL.4Ai-2S translocation substituting for chromosome 4A. The results show that the 4Ai-2 chromosome is related to homoeologous group 4 and that the resistance gene(s) against WSMV is located on the short arm of 4Ai-2. In addition, CI17882, CI17884, and CI17885 contained Ae. speltoides chromosome 7S substituting for chromosome 7A of wheat. The greenbug resistance gene Gb5 was located on chromosome 7S.Contribution No. 90-515-J from the Kansas Agricultural Experiment Station, Kansas State University, Manhattan, Kan., USA     

The effect of B chromosomes on meiotic and pre-meiotic spindles and chromosome pairing in Triticum/Aegilops hybrids

Diploid populations of Aegilops mutica and Aegilops speltoides containing B chromosomes have been used as male parents in crosses with aneuploid genotypes of Triticum aestivum to investigate the effect of B chromosomes on meiotic homologous and homoeologous chromosome pairing. F₁ hybrids of T. aestivum/Ae. mutica and T. aestivum/Ae. speltoides segregated into four classes with regard to the degree of meiotic chromosome pairing, irrespective of the presence of B chromosomes. The B chromosomes do not introduce factors altering the level of pairing other than that due to the natural allelic and gene variation occurring in the diploids. Similarly no reduction in pairing of homologous chromosomes was observed in genotypes in which pairs of homologues co-existed with B chromosomes. However, a significant drop in chiasma frequency was observed in F₁ hybrids of T. aestivum × Ae. mutica with B chromosomes and T. aestivum × Ae. mutica nullisomic for wheat chromosome 5D with B chromosomes, in temperature regimes of 12° C. No asynapsis occurred in similar hybrids in the absence of Mutica B chromosomes at low temperatures. The low-temperature sensitive phase lies early in the pre-meiotic interphase. In this instance the Mutica B chromosomes are interacting with specific gene loci of the A chromosomes. Synaptic pairing has been observed between A and B chromosomes in Ae. mutica. A high frequency of pollen mother cells with twice the number of chromosomes was observed in hybrids in the presence of Mutica B chromosomes due to failure of spindle formation at the last pre-meiotic mitosis. Meiotic spindle irregularities occurred in hybrids containing Speltoides B chromosomes. Hybrids of Ae. speltoides + B's X Ae. mutica + B's displayed the mitotic and meiotic spindle abnormalities introduced by the presence of the B chromosomes of each parent.     

Development of Triticum aestivum-Leymus racemosus translocation lines using gametocidal chromosomes

Specific chromosomes of certain Aegilops species introduced into wheat genome background may often facilitate chromosome breakage and refusion, and finally result in a variety of chromosome restructuring. Such a phenomenon is commonly called gametocidal effect of the chromosomes. The chromosome 2C of Ae. cylindrica is one of such chromosomes. In the present study, scab resistant wheat-L. racemosus addition lines involving chromosomes Lr.2 and Lr.7 were crossed to wheat-Ae. cylindrica disomic addition line Add2C. Then F₁ hybrids were subsequently backcrossed with wheat cv “Chinese Spring”. BC₁ plants with chromosome structural aberration were identified by C-banding. In the self-pollinated progenies of these plants, three translocation lines were developed and characterized by mitotic and meiotic analysis combined with C-banding and fluorescent in situ hybridization (FISH) using biotin-labeled genomic DNA of L. racemosus as probe. Some other putative translocation lines to be further characterized were also found. The practicability and efficiency of the translocation between wheat and alien chromosomes induced by gametocidal chromosomes, as well as the potential use of the developed alien translocation lines were also discussed.     

Relationships between the chromosomes of Aegilops umbellulata and wheat

 A comparative genetic map of Aegilops umbellulata with wheat was constructed using RFLP probes that detect homoeoloci previously mapped in hexaploid bread wheat. All seven Ae. umbellulata chromosomes display one or more rearrangements relative to wheat. These structural changes are consistent with the sub-terminal morphology of chromosomes 2 U, 3 U, 6 U and 7 U. Comparison of the chromosomal locations assigned by mapping and those obtained by hybridization to wheat/Ae. umbellulata single chromosome addition lines verified the composition of the added Ae. umbellulata chromosomes and indicated that no further cytological rearrangements had taken place during the production of the alien-wheat aneuploid lines. Relationships between Ae. umbellulata and wheat chromosomes were confirmed, based on homoeology of the centromeric regions, for 1 U, 2 U, 3 U, 5 U and 7 U. However, homoeology of the centromeric regions of 4 U with wheat group-6 chromosomes and of 6 U with wheat group-4 chromosomes was also confirmed, suggesting that a re-naming of these chromosomes may be pertinent. The consequences of the rearrangements of the Ae. umbellulata genome relative to wheat for gene introgression are discussed. Received: 10 July 1997 / Accepted: 19 September 1997     

Development of <Emphasis Type="Italic">Triticum aestivum-Leymus racemosus</Emphasis> translocation lines using gametocidal chromosomes

Specific chromosomes of certain Aegilops species introduced into wheat genome background may often facilitate chromosome breakage and refusion, and finally result in a variety of chromosome restructuring. Such a phenomenon is commonly called gametocidal effect of the chromosomes. The chromosome 2C of Ae. cylindrica is one of such chromosomes. In the present study, scab resistant wheat-L. racemosus addition lines involving chromosomes Lr.2 and Lr.7 were crossed to wheat-Ae. cylindrica disomic addition line Add2C. Then F₁ hybrids were subsequently backcrossed with wheat cv “Chinese Spring”. BC₁ plants with chromosome structural aberration were identified by C-banding. In the self-pollinated progenies of these plants, three translocation lines were developed and characterized by mitotic and meiotic analysis combined with C-banding and fluorescent in situ hybridization (FISH) using biotin-labeled genomic DNA of L. racemosus as probe. Some other putative translocation lines to be further characterized were also found. The practicability and efficiency of the translocation between wheat and alien chromosomes induced by gametocidal chromosomes, as well as the potential use of the developed alien translocation lines were also discussed.     

RFLP-based maps of the homoeologous group-6 chromosomes of wheat and their application in the tagging of Pm12, a powdery mildew resistance gene transferred from Aegilops speltoides to wheat

Genetic maps of the homoeologous group-6 chromosomes of bread wheat, Triticum aestivum, have been constructed spanning 103 cM on 6A, 90 cM on 6B and 124 cM on 6D. These maps were transferred to a Chinese Spring (CS) x line #31 cross to locate a dominant powdery mildew resistance gene, Pm12, introgressed into line #31 from Aegilops speltoides. Pm12 was shown to lie on the short arm of translocation chromosome 6BS-6SS.6SL in line #31, but could not be mapped more precisely due to the lack of recombination between the 6S Ae. speltoides segment and chromosome 6B. Possible strategies to reduce the size of the alien segment, which probably encompasses the complete long arm and more than 82% of the short arm of chromosome 6B, are discussed.     

C-banding pattern and polymorphism of Aegilops caudata and chromosomal constitutions of the amphiploid T. aestivum — Ae. caudata and six derived chromosome addition lines

Summary C-banding patterns were analysed in 19 different accessions of Aegilops caudata (= Ae. markgrafii, = Triticum dichasians) (2n = 14, genomically CC) from Turkey, Greece and the USSR, and a generalized C-banded karyotype was established. Chromosome specific C-bands are present in all C-genome chromosomes, allowing the identification of each of the seven chromosome pairs. While only minor variations in the C-banding pattern was observed within the accessions, a large amount of polymorphic variation was found between different accessions. C-banding analysis was carried out to identify Ae. caudata chromosomes in the amphiploid Triticum aestivum cv Alcedo — Ae. caudata and in six derived chromosome addition lines. The results show that the amphiploid carries the complete Ae. Caudate chromosome complement and that the addition lines I, II, III, IV, V and VIII carry the Ae. caudata chromosome pairs B, C, D, F, E and G, respectively. One of the two SAT chromosome pairs (A) is missing from the set. C-banding patterns of the added Ae. caudata chromosomes are identical to those present in the ancestor species, indicating that these chromosomes are not structurally rearranged. The results are discussed with respect to the homoeologous relationships of the Ae. caudata chromosomes.     

Effect of translocations from <Emphasis Type="Italic">Aegilops speltoides</Emphasis> Tausch on resistance to fungal diseases and productivity in common wheat

The effect of alien genetic material on resistance to fungal diseases and productivity traits was studied in the T. aestivum/Ae. speltoides common wheat introgression lines. The analysis of genomic composition of the lines by means of cytological Spelt1, pSc119.2, and pAs1 markers detected the presence of translocations in the chromosomes 5BL, 6BL, and 7D. The assessment of lines on susceptibility to the leaf rust and powdery mildew during three field seasons demonstrated that the lines containing the translocation fragments in the chromosomes 5B and 7D are completely resistant to the leaf rust population specific to the West Siberian region. The presence of the Ae. speltoides genetic material in the chromosome 7D provided a high level of resistance to powdery mildew. A positive effect of the translocation in the chromosome 5BL on such traits as the number of spikelets and grains per ear was demonstrated. A decrease in the thousand-grain weight was registered in all introgression lines independently of the chromosomal localization of alien chromatin. No negative effect on the studied traits was detected in lines with the translocation in the chromosome 7D except for thousand-grain weight, allowing them to be used as a source of disease resistance genes.