Chromosomal Location of 46 New RAPD Markers in Rye (Secale Cereale L.)

The polymerase chain reaction (PCR) was used to locate RAPD markers using disomic wheat–rye addition lines in order to develop a set of molecular markers distributed on the seven rye chromosomes. We carried out RAPD amplifications on genomic DNA of wheat Chinese Spring (CS), rye Imperial (I), the amphiploid wheat–rye and the seven disomic wheat–rye addition lines (1R–7R) using 140 different 10-mer oligonucleotides. Forty six new RAPD markers were located on the seven rye chromosomes and all the disomic wheat–rye addition lines were identified on the basis of their amplification patterns. The number of RAPD bands located on 1R, 2R, 3R, 4R, 5R, 6R and 7R chromosomes were 5, 8, 11, 8, 8, 10 and 6, respectively. The seven wheat–rye addition lines can be distinguished using only the following three 10-mer oligonucleotides: OPA16, OPF19 and GEN3-605, the other RAPD primers being useful for this purpose. The use of these RAPDs as a source of molecular markers that could be linked to interesting genes or other important agronomic traits is discussed.     

Detection and mapping of SSRs in rye ESTs from aluminium-stressed roots

Aluminium toxicity is a major problem for crop production on acid soils. Rye (Secale cereale L.) has one of the most efficient group of genes for aluminium tolerance, at least, four independent and dominant loci, Alt1, Alt2, Alt3 and Alt4, located on chromosome arms 6RS, 3RS, 4RL and 7RS, have been described. The increasing availability of expressed sequence tags in rye and related cereals provides a valuable resource of non-anonymous DNA molecular markers. In order to obtain simple sequence repeat (SSR) markers related with Al tolerance more than 1,199 public accessible rye cDNA sequences from Al-stressed roots were exploited as a resource for SSR markers development. From a total of 21 S. cereale microsatellite (SCM) loci analysed, 12 were located on chromosomes 1R, 2R, 3R, 4R and 5R, using wheat–rye addition lines or mapped using a F₂ population segregating for Al tolerance. Seven SCM loci were included in a rye map with other SCIM and RAPD markers. Moreover, 14 SCM loci could be associated to proteins with known or unknown function. The possible implications of these sequences in aluminium tolerance mechanisms are discussed.     

A new aluminum tolerance gene located on rye chromosome arm 7RS

Rye has one of the most efficient groups of genes for aluminum tolerance (Alt) among cultivated species of Triticeae. This tolerance is controlled by, at least, three independent and dominant loci (Alt1, Alt2, and Alt3) located on chromosome arms 6RS, 3RS, and 4RL, respectively. The segregation of Alt genes and several random amplified polymorphic DNA (RAPD), Secale cereale inter-microsatellite (SCIM), and Secale cereale microsatellite (SCM) markers in three F(2) between a tolerant cultivar (Ailés) and a non-tolerant inbred line (Riodeva) were studied. The segregation ratio obtained for aluminum tolerance in the three F(2) populations analyzed was 3:1 (tolerant:non-tolerant), indicating that tolerance is controlled by one dominant locus. SCIM811(1376) was linked to an Alt gene in the three F(2) populations studied, and three different SCIMs and one RAPD (SCIM811(1376), SCIM812(626), SCIM812(1138), and OPQ4(725)) were linked to the Alt gene in two F(2) populations. This result indicated that the same Alt gene was segregating in the three crosses. SCIM819(1434) and OPQ4(578) linked to the tolerance gene in one F(2) population were located using wheat-rye ditelosomic addition lines on the 7RS chromosome arm. The Alt locus is mapped between SCIM819(1434) and the OPQ4(578) markers. Two microsatellite loci (SCM-40 and SCM-86), previously located on chromosome 7R, were also linked to the Alt gene. Therefore, the Alt gene segregating in these F(2) populations is new and probably could be orthologous to the Alt genes located on wheat chromosome arm 4DL, on barley chromosome arm 4HL, on rye chromosome arm 4RL, and rice chromosome 3. This new Alt gene located on rye chromosome arm 7RS was named Alt4. A map of rye chromosome 7R with the Alt4 gene, 16 SCIM and RAPD, markers and two SCM markers was obtained.     

Molecular markers linked to the aluminium tolerance gene Alt1 in rye (Secale cereale L.)

 Rye has one of the most efficient group of genes for aluminium (Al) tolerance among cultivated species of Triticeae. This tolerance is controlled by at least two independent and dominant loci (Alt1 and Alt3) located on chromosomes 6RS and 4R. We used two pooled DNA samples, one of Al-tolerant individuals and another of Al-sensitive plants from one F₂ that segregated for the Alt1 locus. We also used two pooled DNA samples, one with genotypes 11 and another with genotypes 22 for the Lap1 locus (leucin aminopeptidase) from another F₂ progeny that segregated for this locus, located on the 6RS chromosome arm. We identified several RAPD markers associated with the pooled Al-tolerant plants and also with one of the bulks for the Lap1 locus. The RAPD fragments linked to Alt1 and Lap1 genes were transformed into SCAR markers to confirm their chromosomal location and linkage data. Two SCARs (ScR01 ₆₀₀ and ScB15 ₇₉₀₀ ) were closely linked to the Alt1 locus, ScR01 ₆₀₀ located 2.1 cM from Alt1 and ScB15 ₇₉₀ located 5.5 cM from Alt1, on the 6RS chromosome arm. These SCAR markers can aid in the transfer of Al tolerance genes into Al-sensitive germplasms. Received: 9 December 1997 / Accepted: 12 May 1998     

New PCR based markers allowed to identify <Emphasis Type="Italic">Secale</Emphasis> chromatin in wheat-<Emphasis Type="Italic">Secale africanum</Emphasis> introgression lines

The genus of Secale has many agronomically important characters. In order to use the best of this species, markers tracking the rye chromatin incorporated into wheat must be developed. In this study, one rye genome-specific random amplified polymorphic DNA (RAPD) marker was isolated from Secale africanum (R^a genome). Two cloned markers, named OPP13₁₁₆₅ and OPP13₆₆₂, were 1165 bp and 662 bp, respectively. Sequence analysis revealed that OPP13₁₁₆₅ was highly homologous to a part of a new class of transposon-like gene called the Revolver family, and OPP13₆₆₂ was partially similar to LTR gypsy-like retrotransposon. Fluorescence in situ hybridization (FISH) showed only OPP13₁₁₆₅ localized within the whole arms of rye except their terminal regions and no signal was detected on wheat chromosomes, while OPP13₆₆₂ had no hybridization signal detected on wheat and rye genomes. Based on these sequences, two pairs of sequence-characterized amplified region (SCAR) primers were designed, and the resulted SCAR markers were able to target both cultivated and wild Secale species. The FISH patterns and the two SCAR markers should be able to identify and track all wheat-rye translocation lines, especially the S. africanum chromatin.     

Chromosomal location of alcohol dehydrogenase gene(s) in rye,using wheat-rye addition lines

Following disc electrophoresis on standard gels, rye seed extracts showed two bands (ADH-3 and 5) for alcohol dehydrogenase. The ADH-3 band was homologous to the ADH band observed in other diploid species of the Triticinae, and with the ADH-3 band of 4 × and 6 × wheat. It is proposed that the rye isoenzymes ADH-3 and 5 are governed respectively, by the genes Adh _R1 and Adh _R2. Using bread wheat (Holdfast) lines with disomic addition of individual rye (King II) chromosomes, we found that the ADH-5 band was associated with the addition of rye chromosome IV (after Riley), indicating thereby that Adh _R2 gene is located on this chromosome. The products of Adh _R1 and Adh _R2 do not form active heterodimers, among themselves, but do form active dimers with wheat ADH monomers. It is suggested that the use of chromosomal addition lines may provide a method for locating genes for those enzymes, where the rye and wheat isoenzymes are electrophoretically distinct.     

Introgression of Resistance to Powdery Mildew Conferred by Chromosome 2R by Crossing Wheat Nullisomic 2D with Rye

Using the nulUsomic back-cross procedure, four wheat-rye chromosome substitution 2R （2D） lines with different agronomic performance, designated WR02-145-1, WR01-145-2, WR02-145-3, and WR02-145-4, were produced from a cross between 2D nullisomic wheat （Triticum aestivum L. cv. ＂Xiaoyan 6＂） and rye （Secale cereale L. cv. ＂German White＂）. The chromosomal constitution of 2n=42=21 in WR02-145 lines was confirmed by cytological and molecular cytogenetic methods. Using genomic in situ hybridization on root tip chromosome preparations, a pair of intact rye chromosomes was detected in the WR02-145 lines. PCR using chromosome-specific primers confirmed the presence of 2R chromosomes of rye in these wheat-rye lines, indicating that WR02o145 lines are disomic chromosome substitution lines 2R （2D）. The WR02-145 lines are resistant to the powdery mildew （Erysiphe graminis DC. f. sp. tritici E. Marchal） isolates prevalent in northern China and may possess gene（s） for resistance to powdery mildew, which differ from the previously identified Pm7gene located on chromosome 2RL. The newly developed ＂Xiaoyan 6＂- ＂German White＂ 2R （2D） chromosome substitution lines are genetically stable, show desirable agronomic traits, and are expected to be useful in wheat improvement.     

From the rye Alt3 and Alt4 aluminum tolerance loci to orthologous genes in other cereals

The major limit to plant growth in acid soils is the presence of toxic aluminum (Al) cations, which limit growth by inhibiting root elongation. Aluminum tolerance in rye is controlled by (at least) four independent loci (Alt1, Alt2, Alt3 and Alt4) located on chromosome arms 6RS, 3RS, 4RL and 7RS, respectively. In this work, we analyzed several F₂ populations in which two different Alt loci were segregating. We constructed a map of chromosome 7R, which contains the Alt4 locus and microsatellite and PCR-markers (B1, B4, B11, B26 and BCD1230). These markers were mapped to the S arm of 7R using wheat-rye addition lines. Our results show that all these markers are linked to the Alt4 locus already known to be on 7RS. In addition, the OPS14 ₇₀₅ RAPD marker was linked to the Alt3 locus using bulked segregant analysis. This RAPD marker was transformed into a SCAR (ScOPS14 ₇₀₅ ) and was localized to arm 4RL using wheat-rye addition lines. Finally, this SCAR was linked to the Alt3 locus at a genetic distance of 23.4 cM. In light of the current findings, and taking into account the synteny relationships in cereals, we propose candidate Alt3 and Alt4 orthologues in other cereals.     

Production of wheat-rye substitution lines and identification of chromosome composition of karyotypes using C-banding, GISH, and SSR markers

Based on the cross (Triticum aestivum L. × Secale cereale L.) × T. aestivum L., wheat-rye substitution lines (2n = 42) were produced with karyotypes containing, instead of a pair of homologous wheat chromosomes, a homeologous pair of rye chromosomes. The chromosome composition of these lines was described by GISH and C-banding methods, and SSR analysis. The results of genomic in situ hybridization demonstrated that karyotype of these lines included one pair of rye chromosomes each and lacked wheat-rye translocations. C-banding and SSR markers were used to identify rye chromosomes and determine the wheat chromosomes at which the substitution occurred. The lines were designated 1R(1D), 2R(2D)₂, 2R(2D)₃, 3R(3B), 6R(6A)₂. The chromosome composition of lines 1R(1A), 2R(W)₁, 5R(W), 5R(5A), and 6R(W)₁, which were earlier obtained according to the same scheme for crossing, was characterized using methods of telocentric analysis, GISH, C-banding, and SSR analysis. These lines were identified as 1R(1A), 2R(2D)₁, 5R(5D), 5R(5A), and 6R(6A)₁, C-banding of chromosomes belonging to line 1R(1A) revealed the presence of two translocated chromosomes (3DS.3DL-del. and 4AL.W) during simultaneous amplification of SSR markers located on 3DL and 4AS arms. The “combined” long arm of the newly derived chromosome 4A is assumed to be formed from the long arm of chromosome 4AS itself and a deleted segment 3DL. All examined lines are cytologically stable, except for 3R(3B), which does not affect the stability of rye 3R chromosome transfer. Chromosome identification and classification of the lines will permit them to be models for genetic studies that can be used thereafter as promising “secondary gene pools” for the purpose of plant breeding.     

Identification and chromosomal organization of two rye genome-specific RAPD products useful as introgression markers in wheat.

Two rye genome-specific random amplified polymorphic DNA (RAPD) markers were identified for detection of rye introgression in wheat. Both markers were amplified in all of the tested materials that contained rye chromatin such as rye, hexaploid triticale, wheat-rye addition lines, and wheat varieties with 1BL.1RS translocation. Two cloned markers, designated pSc10C and pSc20H, were 1012 bp and 1494 bp, respectively. Sequence analysis showed that both pSc10C and pSc20H fragments were related to retrotransposons, ubiquitously distributed in plant genomes. Using fluorescence in situ hybridization (FISH), probe pSc10C was shown to hybridize predominantly to the pericentromeric regions of all rye chromosomes, whereas probe pSc20H was dispersed throughout the rye genome except at telomeric regions and nucleolar organizing regions. The FISH patterns showed that the two markers should be useful to select or track all wheat-rye translocation lines derived from the whole arms of rye chromosomes, as well as to characterize the positions of the translocation breakpoints generated in the proximal and distal regions of rye arms.     

Behaviour of rye univalents in hybrids of 6x-triticale with Triticum turgidum (L.) ssp. turgidum conv. durum (Desf.)

In a cytological analysis of the meiotic behaviour in PMCs of five hybrids between hexaploid triticale and durum wheat, Triticum turgidum L., chromosome association at meiotic first metaphase and the behaviour of rye univalents at first anaphase were analyzed. The chromosomes of the B genome, chromosomes 4A and 7A (disomic condition), and the seven rye chromosomes, could be distinguished by their C-banding pattern. No wheat-rye paring was detected at metaphase I. Rye univalents were observed as laggards which disjoined either predominantly equationaly (2R, 3R, 4R, 5R and 7R) or predominantly reductionaly (1R and 6R). Misdivision occurred in up to 3% of rye univalents.     

用Langdon二体代换系统建立小麦染色体RAPD标记

以一套Ｌａｎｇｄｏｎ硬粒小麦二体代换系及其亲本Ｌａｎｇｄｏｎ、中国春和中国春双端体为材料,研究适于硬粒小麦和普通小麦的理想ＲＡＰＤ分析条件,进行小麦Ａ、Ｂ和Ｄ染色体组各个染色体的ＲＡＰＤ分析。结果表明,ＡｍｐｌｉＴａｑＳｔｏｆｆｅｌｆｒａｇｍｅｎｔ比ＴａｑＤＮＡＰｏｌｙｍｅｒａｓｅ优越。所用１２个随机引物中,７个引物扩增出的１３个特异产物,可确定在硬粒小麦ＬａｎｇｄｏｎＡ、Ｂ染色体组和中国春Ｄ染色体组中的１０个个别染色体上。４个标记进一步定位在相应的４个染色体臂上。结果还表明,用Ｌａｎｇｄｏｎ二体代换系统、中国春双端体为材料,容易得到重复性高、特异性强的ＲＡＰＤ标记。     

Identification of the 1RS rye chromosomal segment in wheat by RAPD analysis

The introgression of rye DNA into the wheat genome was studied using random decamer and specific primers with the polymerase chain reaction (PCR). DNA from paired near-isolines in Chisholm and Arkan backgrounds differing with respect to the presence of a 1 RS.1 BL translocation was amplified with 120 arbitrary sequence primers. Two of the primers (OPR 19 and OPJ07) amplified rye-specific DNA fragments. The OPR19 primer amplified a 1.35-kb fragment that appeared to be specific to the 1 RS.1 BL translocation, based on its presence only in lines carrying the 1 RS. 1 BL translocation. A fragment of the same size was also amplified in 1 RS.1 AL translocation lines. This 1 RS. 1 BL marker locus was designated Ximc 1. The other primer, OPJ07, amplified a 1.2-kb DNA sequence, that was designated Ximc 2, specific to the wheat-rye translocation in various wheat backgrounds. The sequences of the two marker loci were found to be different from each other. The Ximc 1 locus was a low-copy sequence which was also present in Balboa rye genomic DNA. Through the use of specific primers, the presence of the rye-specific marker was confirmed in hexaploid as well as in tetraploid wheat backgrounds. The use of RAPDs for the study of smaller alien introgressions into wheat is discussed.     

AFLP markers tightly linked to the aluminum-tolerance gene Alt3 in rye (Secale cereale L.)

Rye (Secale cereale L.) is considered to be the most aluminum (Al)-tolerant species among the Triticeae. It has been suggested that aluminum tolerance in rye is controlled by three major genes (Alt genes) located on rye chromosome arms 3RL, 4RL, and 6RS, respectively. Screening of an F₆ rye recombinant inbred line (RIL) population derived from the cross between an Al-tolerant rye (M39A-1–6) and an Al-sensitive rye (M77A-1) showed that a single gene controls aluminum tolerance in the population analyzed. In order to identify molecular markers tightly linked to the gene, we used a combination of amplified fragment length polymorphism (AFLP) and bulked segregant analysis techniques to evaluate the F₆ rye RIL population. We analyzed approximately 22,500 selectively amplified DNA fragments using 204 primer combinations and identified three AFLP markers tightly linked to the Alt gene. Two of these markers flanked the Alt locus at distance of 0.4 and 0.7 cM. Chromosomal localization using cloned AFLP and a restriction fragment length polymorphism (RFLP) marker indicated that the gene was on the long arm of rye chromosome 4R. The RFLP marker (BCD1230) co-segregated with the Alt gene. Since the gene is on chromosome 4R, the gene was designated as Alt3. These markers are being used as a starting point in the construction of a high resolution map of the Alt3 region in rye. Received: 29 March 2000 / Accepted: 9 July 2001     

Controlled introgression to wheat of genes from rye chromosome arm 1RS by induction of allosyndesis

Summary Chromosome pairing between rye chromosome arm 1RS, present in two wheat-rye translocation stocks, and its wheat homoeologues was induced by introducing the translocations into either a ph1bph1b or a nullisomic 5B background. This rye arm carries a gene conferring resistance to wheat stem rust, but lines carrying the translocation produce a poor quality dough unsuitable for breadmaking. Storage protein markers were utilised along with stem rust reaction to screen for allosyndetic recombinants. From a 1DL-1RS translocation, three lines involving wheat-rye recombination were recovered, along with thirteen lines derived from wheat-wheat homoeologous recombination. From a 1BL-1RS translocation, an additional three allosyndetic recombinants were recovered. Nullisomy for chromosome 5B was as efficacious as the ph1b mutant for induction of allosyndesis, and the former stock is easier to manipulate due to the presence of a 5BL-encoded endosperm protein. The novel wheat-rye chromosomes present in the recombinant lines may enable the rye disease resistance to be exploited without the associated dough quality defect.     

Candidate gene identification of an aluminum-activated organic acid transporter gene at the Alt4 locus for aluminum tolerance in rye (Secale cereale L.)

Among cereal crops, rye is one of the most tolerant species to aluminum. A candidate gene approach was used to determine the likely molecular identity of an Al tolerance locus (Alt4). Using PCR primers designed from a wheat aluminum tolerance gene encoding an aluminum-activated malate transporter (TaALMT1), a rye gene (ScALMT1) was amplified, cloned and sequenced. Subsequently, the ScALMT1 gene of rye was found to be located on 7RS by PCR amplification using the wheat–rye addition lines. SNP polymorphisms for this gene were detected among the parents of three F₂ populations that segregate for the Alt4 locus. A map of the rye chromosome 7R, including the Alt4 locus ScALMT1 and several molecular markers, was constructed showing a complete co-segregation between Alt4 and ScALMT1. Furthermore, expression experiments were carried out to clarify the function of this candidate gene. Briefly, the ScALMT1 gene was found to be primarily expressed in the root apex and upregulated when aluminum was present in the medium. Five-fold differences in the expression were found between the Al tolerant and the Al non-tolerant genotypes. Additionally, much higher expression was detected in the rye genotypes than the moderately tolerant “Chinese Spring” wheat cultivar. These results suggest that the Alt4 locus encodes an aluminum-activated organic acid transporter gene that could be utilized to increase Al tolerance in Al sensitive plant species. Finally, TaALMT1 homologous sequences were identified in different grasses and in the dicotyledonous plant Phaseolus vulgaris. Our data support the hypothesis of the existence of a common mechanism of Al tolerance encoded by a gene located in the homoeologous group four of cereals. G. Fontecha and J. Silva-Navas contributed equally to this work.     

New wheat-rye 5DS-4RS·4RL and 4RS-5DS·5DL translocation lines with powdery mildew resistance

Powdery mildew is one of the serious diseases of wheat (Triticum aestivum L., 2n = 6 × = 42, genomes AABBDD). Rye (Secale cereale L., 2n = 2 × = 14, genome RR) offers a rich reservoir of powdery mildew resistant genes for wheat breeding program. However, extensive use of these resistant genes may render them susceptible to new pathogen races because of co-evolution of host and pathogen. Therefore, the continuous exploration of new powdery mildew resistant genes is important to wheat breeding program. In the present study, we identified several wheat-rye addition lines from the progeny of T. aestivum L. Mianyang11 × S. cereale L. Kustro, i.e., monosomic addition lines of the rye chromosomes 4R and 6R; a disomic addition line of 6R; and monotelosomic or ditelosomic addition lines of the long arms of rye chromosomes 4R (4RL) and 6R (6RL). All these lines displayed immunity to powdery mildew. Thus, we concluded that both the 4RL and 6RL arms of Kustro contain powdery mildew resistant genes. It is the first time to discover that 4RL arm carries powdery mildew resistant gene. Additionally, wheat lines containing new wheat-rye translocation chromosomes were also obtained: these lines retained a short arm of wheat chromosome 5D (5DS) on which rye chromosome 4R was fused through the short arm 4RS (designated 5DS-4RS·4RL; 4RL stands for the long arm of rye chromosome 4R); or they had an extra short arm of rye chromosome 4R (4RS) that was attached to the short arm of wheat chromosome 5D (5DS) (designated 4RS-5DS·5DL; 5DL stands for the long arm of wheat chromosome 5D). These two translocation chromosomes could be transmitted to next generation stably, and the wheat lines containing 5DS-4RS·4RL chromosome also displayed immunity to powdery mildew. The materials obtained in this study can be used for wheat powdery mildew resistant breeding program.     

Genetic structure and diversity of European flint maize populations determined with SSR analyses of individuals and bulks

Characterization and manipulation of aluminum (Al) tolerance genes offers a solution to Al toxicity problems in crop cultivation on acid soil, which composes approximately 40% of all arable land. By exploiting the rice (Oryza sativa L.)/rye (Secale cereale L.) syntenic relationship, the potential for map-based cloning of genes controlling Al tolerance in rye (the most Al-tolerant cereal) was explored. An attempt to clone an Al tolerance gene (Alt3) from rye was initiated by using DNA markers flanking the rye Alt3 gene, from many cereals. Two rice-derived, PCR-based markers flanking the Alt3 gene, B1 and B4, were used to screen 1,123 plants of a rye F₂ population segregating for Alt3. Fifteen recombinant plants were identified. Four additional RFLP markers developed from rice genes/putative genes, spanning 10 kb of a 160-kb rice BAC, were mapped to the Alt3 region. Two rice markers flanked the Alt3 locus at a distance of 0.05 cM, while two others co-segregated with it. The rice/rye micro-colinearity worked very well to delineate and map the Alt3 gene region in rye. A rye fragment suspected to be part of the Alt3 candidate gene was identified, but at this level, the rye/rice microsynteny relationship broke down. Because of sequence differences between rice and rye and the complexity of the rye sequence, we have been unable to clone a full-length candidate gene in rye. Further attempts to clone a full-length rye Alt3 candidate gene will necessitate the creation of a rye large-insert library.     

Generation of PCR-based markers for the detection of rye chromatin in a wheat background

Oligonucleotide primers were developed to detect the presence of four rye sequences using a PCR assay. These assays give a rye-specific signal from wheat DNA template which contains various rye chromosomes or chromosome segments. The sequences identified were associated with the nucleolar organiser region, the 5S-Rrna-R1 locus, the telomere, and a widely dispersed, rye-specific repetitive element Ris-1. The primers amplified from the well-established loci Nor-R1 and 5S-Rrna-R1 on rye chromosome arm 1RS, and also located a 5s-Rrna locus on chromosome 3R. The telomere-associated sequence was present on every rye chromosome, and was also present, at a low copy number, in both wheat and barley. These assays will be particularly useful for introgression programmes aimed at reducing the rye content of the 1BL.1RS wheat-rye translocation. When multiplexed, the primers will enable a rapid, simultaneous assay for a number of distinct rye loci, which can be derived from a small portion of mature endosperm tissue.     

A molecular linkage map of rye

A genetic map of six chromosomes of rye, (all of the rye chromosomes except for 2R), was constructed using 77 RFLP and 12 RAPD markers. The map was developed using an F₂ population of 54 plants from a cross between two inbred lines. A rye genomic library was constructed as a source of clones for RFLP mapping. Comparisons were made between the rye map and other rye and wheat maps by including additional probes previously mapped in those species. These comparisons allowed (1) chromosome arm orientation to the linkage groups to be given, (2) the corroboration of several evolutionary translocations between rye chromosomes and homoeologous chromosomes of wheat; (3) an increase in the number of available markers for target regions of rye that show colinearity with wheat. Inconsistencies in the location of markers between the wheat and rye maps were mostly detected by multi-copy probes.