Chromosomal location of genes for resistance to powdery mildew in <Emphasis Type="Italic">Agropyron cristatum</Emphasis> and mapping of conserved orthologous set molecular markers

Agropyron cristatum exhibits resistance to Blumeria graminis f. sp. tritici. Disomic and ditelosomic chromosome addition lines of A. cristatum in ‘Chinese Spring’ wheat were utilized to determine which A. cristatum chromosomes carry resistance gene(s). Resistance is conferred by gene(s) on chromosome arms 2PL and 6PL. The availability of molecular markers capable of detecting these chromosome arms in a wheat background would be very useful for marker-assisted introgression of 2PL and 6PL chromatin into common wheat. With this aim, 170 wheat conserved orthologous set (COS) markers (92 and 78 from wheat homoeologous groups 2 and 6 respectively) were assessed for their utility in A. cristatum. A total of 116 (68.2%) COS markers successfully amplified product in A. cristatum and 46 (40.0%) of these markers were polymorphic between A. cristatum and common wheat. From marker loci mapping on wheat homoeologous group 2 chromosomes, 23 markers (34.9%) were polymorphic between A. cristatum and common wheat and from them 13 markers were assigned to chromosome arm 2PL and six markers were mapped to chromosome 4P of A. cristatum showing that this chromosome is related to wheat homoeologous group 2. From marker loci mapping on wheat homoeologous group 6 chromosomes, 23 (46.0%) markers were polymorphic between A. cristatum and common wheat and from them 17 markers were located on chromosome 6P, six of them were mapped to chromosome arm 6PS and five to chromosome arm 6PL, respectively. The specific COS markers allocated on the long arms of chromosomes 2P and 6P may have a role in marker-assisted screening in wheat breeding for powdery mildew disease resistance.     

Identification, characterisation, and chromosome locations of rye and wheat specific ISSR and SCAR markers useful for breeding purposes

Rye (Secale cereale L. and S. strictum) offers potential to increase the genetic variability and to introduce desirable characters for wheat improvements. Cytogenetic techniques have been used to screen wheat lines containing rye chromatin. These techniques are not adequate since they are highly technical and time consuming. They are not suitable for breeding programs that require rapid screening of large numbers of genotypes. The main objective of this study was to develop and characterize ISSR and SCAR markers that can distinguish wheat from rye genome. Total DNA from wheat, rye, and triticale accessions from different provenances were amplified with ISSR primers in PCR assays. Three wheat-diagnostic sequences were identified. In addition three rye-diagnostic ISSR markers of which, one marker specifically diagnostic for Secale strictum were characterized. Pairs of primers flanking these specific sequences were designed to produce SCAR markers. Two SCAR markers were rye genome-specific. One SCAR was present in all the seven rye chromosome, and another was specific to rye chromosomes two, three, four, and seven. These newly developed ISSR and SCAR markers should be useful to wheat breeders screening genotypes that may contain rye chromatins.     

Identification of SCAR markers linked to <Emphasis Type="Italic">or</Emphasis>, a gene inducing beta-carotene accumulation in Chinese cabbage

The or mutation in Chinese cabbage (Brassica rapa L. ssp. pekinensis) is a recessive, single-locus mutation that causes the head leaves of the plant to accumulate carotenoids and turn orange. In China, considerable attention has been focused in recent years on breeding the variety with orange head leaves. In this study, sequence-characterized amplified region (SCAR) markers linked to the or gene were identified based on random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) by performing a bulked segregant analysis (BSA) using a doubled haploid (DH) population derived from the F₁ cross between 91-112 (white head leaves) and T12-19 (orange head leaves) via microspore culture. Two RAPD markers—OPB01-845 and OPAX18-656—and 1 AFLP marker, namely, P67M54-172, were identified to be linked to the or gene, and they were successfully converted into the SCAR markers SCR-845, SCOR204, and SCOR127, respectively. In a linkage analysis, these 3 SCAR markers and 2 previously published simple sequence repeat markers, namely, BRMS-51 and Ni4D09 (located on R9 linkage group), were mapped to the same linkage group with the or gene at a LOD score of 6.0, indicating that the or gene should be located on the linkage group R9 of the A genome. In addition, accuracies of 92%, 90%, and 89.1% were obtained when 110 different inbred breeding lines of Chinese cabbage were used for investigation with these 3 SCAR markers, indicating that these makers could be used in marker-assisted selection in orange head leaf breeding programs for Chinese cabbage.     

Isolation of a new repetitive DNA sequence from Secale africanum enables targeting of Secale chromatin in wheat background

A genome specific DNA sequence that detects Secale africanum chromatin incorporated into wheat was developed in this study. Random amplified polymorphic DNA (RAPD) analysis was used to search for genome specific DNA sequences of S. africanum in lines, R111, “mianyang11” (MY11) and wheat-rye 1RS/1BL translocations R25 and R57. A high copy rye-specific DNA segment pSaD15₉₄₀ of the S. africanum genome was obtained. The sequence of pSaD15 did not show any significant homology to other reported sequences in databases and it is therefore a new repetitive sequence of Secale. PCR primers were designed for pSaD15₉₄₀, which amplify a clear 887 bp fragment in S. africanum but not in any wheat. The primers also amplified an 887 bp fragment in other accessions of rye, Chinese Spring-Imperial rye chromosome additions and a diverse range of material carrying different rye chromosomes or chromosomal segments. In situ hybridization showed that probe pSaD15₉₄₀ was specifically hybridized throughout all rye chromosomes arms except for the terminal regions. The advantage of the rye-specific probe developed herein compared to those of previous reports is that it has been shown to be widely applicable to other Secale species. The probe will be useful as a molecular marker for the introgression of S. africanum and other rye chromosome segments into the wheat genome.     

Development and Validation of SCAR Markers Co-Segregating with an Agropyron Elongatum Derived Leaf Rust Resistance Gene Lr24 in Wheat

Summary An Agropyron elongatum-derived leaf rust resistance gene Lr24 located on chromosome 3DL of wheat was tagged with six random amplified polymorphic DNA (RAPD) markers which co-segregated with the gene. The markers were identified in homozygous resistant F₂ plants taken from a population segregating for leaf rust resistance generated from a cross between two near-isogenic lines (NILs) differing only for Lr24. Phenotyping was done by inoculating the plants with pathotype 77-5 of Puccinia triticina. To enable gene-specific selection, three RAPD markers (S1302₆₀₉, S1326₆₁₅ and OPAB-1₃₈₈) were successfully converted to polymorphic sequence characterized amplified region (SCAR) markers, amplifying only the critical DNA fragments co-segregating with Lr24. The SCAR markers were validated for specificity to the gene Lr24 in wheat NILs possessing Lr24 in 10 additional genetic backgrounds including the Thatcher NIL, but not to 43 Thatcher NILs possessing designated leaf rust resistance genes other than Lr24. This indicated the potential usefulness of these SCAR markers in marker assisted selection (MAS) and for pyramiding leaf rust resistance genes in wheat.     

Reduction of <Emphasis Type="Italic">Aegilops sharonensis</Emphasis> chromatin associated with resistance genes <Emphasis Type="Italic">Lr56</Emphasis> and <Emphasis Type="Italic">Yr38</Emphasis> in wheat

The Lr56/Yr38 translocation consists primarily of alien-derived chromatin with only the 6AL telomeric region being of wheat origin. To improve its utility in wheat breeding, an attempt was made to exchange excess Ae. sharonensis chromatin for wheat chromatin through homoeologous crossover in the absence of Ph1. Translocation heterozygotes that lacked Ph1 were test-crossed with Chinese Spring nullisomic 6A tetrasomic 6B and nullisomic 6A-tetrasomic 6D plants and the resistant (hemizygous 6A) progeny were analyzed with four microsatellite markers. Genetic mapping suggested general homoeology between wheat chromosome 6A and the translocation chromosomes, and showed that Lr56 was located near the long arm telomere. Thirty of the 53 recombinants had breakpoints between Lr56 and the most distal marker Xgwm427. These were characterized with additional markers. The data suggested that recombinants #39, 157 and 175 were wheat chromosomes 6A with small intercalary inserts of foreign chromatin containing Lr56 and Yr38, located distally on the long arms. These three recombinants are being incorporated into adapted germplasm. Attempts to identify the single shortest translocation and to develop appropriate markers are being continued.     

Morphological and cytogenetic studies on the hybrid between bread wheat and <Emphasis Type="Italic">Psathyrostachys huashanica</Emphasis> Keng ex Kuo

Psathyrostachys huashanica Keng ex Kuo (2n = 2x = 14, NsNs), a source of wheat stripe rust, take-all fungus, and powdery mildew resistance with tolerance to salinity and drought, has been successfully hybridized as the pollen parent to bread wheat without using immature embryo rescuing culture for the first time. All of the CSph2b × P. huashanica hybrid seeds germinate well. Backcross derivatives were successfully obtained. F₁ hybrids were verified as intergeneric hybrids on the basis of morphological observation, cytological and molecular analyses. The results obviously showed the phenotypes of the hybrid plants were intermediate between bread wheat and P. huashanica. Chromosome pairing at MI of PMCs in the F₁ hybrid plants was low, and the meiotic configuration was 26.80 I + 0.60 II (rod). Cytological analysis of the hybrid plants revealed the ineffectiveness of the ph2b gene on chromosome association between the parents. Eight RAPD-specific markers for Ns genome were selected for RAPD analysis, and the results indicated that F₁ hybrids contained the Ns genome of P. huashanica. Furthermore, the significance of the finding for bread wheat improvement was discussed.     

Development and application of PCR markers specific to the 1Ns chromosome of Psathyrostachys huashanica Keng with leaf rust resistance

Wheat–Psathyrostachys huashanica Keng disomic addition line 12-3 was developed and characterized using genomic in situ hybridization (GISH), expressed sequence tag–sequence tagged site (EST–STS), and sequence characterized amplified region (SCAR) markers. Mitotic and meiotic GISH analyses indicated that it contained 42 wheat chromosomes and a pair of P. huashanica chromosomes. Eight EST–STS multiple-loci markers located on the homoeologous group 1 chromosomes of wheat amplified polymorphic bands in the 1Ns disomic addition line 12-3, which were unique to P. huashanica. These markers suggested that the introduced Ns chromosomes belonged to homoeologous group 1. Furthermore, diagnostic fragments of random amplified polymorphic DNA marker OPAG10₉₈₆ and simple sequence repeat marker Xgwm601 ₁₃₅ were cloned, sequenced, and converted into SCAR markers, i.e., RHS153 and SHS10, respectively, which were validated using a range of distinct plant species and a complete set of wheat–P. huashanica disomic addition lines (1Ns–7Ns, 2n = 44 = 22 II). The results demonstrated that the SCAR markers targeted the Ns genome of P. huashanica and they were linked to the 1Ns chromosome. In addition, 12-3 was evaluated to test its leaf rust resistance in the adult stages and its agronomic traits. These newly developed EST–STS and SCAR markers will be powerful tools for wheat breeders who want to screen for genotypes containing the 1Ns chromosome, with low costs and high throughput.     

High‐throughput development of SSR marker candidates and their chromosomal assignment in rye (Secale cereale L.)

Shotgun survey sequences of flow‐sorted individual rye chromosomes were data mined for the presence of simple sequence repeats (SSRs). For 787,850 putative SSR loci, a total of 358,660 PCR primer pairs could be designed and 51,138 nonredundant SSR marker candidates were evaluated by in silico PCR. Of the 51,138 SSR primer candidates, 1,277 were associated with 1,125 rye gene models. A total of 2,112 of the potential SSR markers were randomly selected to represent about equal numbers for each of the rye chromosomes, and 856 SSRs were assigned to individual rye chromosomes experimentally. Potential transferability of rye SSRs to wheat and barley was of low efficiency with 4.3% (2,189) and 0.4% (223) of rye SSRs predicted to be amplified in wheat and barley, respectively. This data set of rye chromosome‐specific SSR markers will be useful for the specific detection of rye chromatin introgressed into wheat as well as for low‐cost genetic and physical mapping in rye without the need for high‐tech equipment.     

Crossability and embryo rescue enhancement in wide crosses between wheat and three Agropyron species

Summary Soft winter wheat lines were crossed with Agropyron intermedium, A. elongatum and A. trichophorum using pollen from single plants of Agropyron spp. to pollinate wheat spikes. Not only species but also individual plants within varieties of Agropyron species differed in percent seed set with a wheat genotype. In two arrays of crosses between two phenotypically different plants of A. elongatum and nine wheat lines, one Agropyron plant gave higher seed set (overall=27.1%) than the other (overall=3.7%). The differences were significant in seven of the nine cross combinations. Results are consistent with the hypothesis that these two plants differ in their crossability as pollen parents with wheat, and suggest the possibility of occurrence of crossability genes in wheatgrasses. The success rate of hybrid embryo rescue was higher (87.5%) with cold treatment (4°C) than without cold treatment (75.0%) of excised embryos on culture media. Results underscore the significance of genotype of the alien species for crossing with low crossable wheats, and of the physical factors for improving embryo rescue in wide crosses.Contribution No. 11,825, Purdue Agric. Exp. Stn., West Lafayette, Indiana 47907, USA. The research was supported in part by Public Varieties of Indiana.     

Genome-specific markers of tetraploid wheats and their putative diploid progenitor species

The objective of this study was to isolate genome‐specific markers from the genomes of tetraploid wheats and the putative donor diploid species on the basis of random amplified polymorphic DNA analysis followed by cross‐hybridization. Twenty different Triticum and Aegilops species and accessions were analysed by polymerase chain reaction (PCR) using 30 random primers. The polymorphic PCR fragments were then isolated, labelled and used in cross‐hybridization screenings. The hybridization results established that one marker was specific to the Ae. speltoides S genome, two to the A genome, one to the B genome and five to the G genomes of polyploid species (and to the genomes of the corresponding progenitor species). Four markers were identified that were specific to both the B and G genomes. Analysis of the Triticum and Aegilops species and accessions supported the notion that Ae. speltoides is more closely related to the B and G genomes of polyploid wheat species than were other members of the Sitopsis section. The data also indicated that the B and G genomes had originated from different accessions of Ae. speltoides.     

Identifying AFLP and microsatellite markers for vernalization response gene Vrn-B1 in hexaploid wheat using reciprocal mapping populations

Marker‐assisted selection may be useful for combining specific vernalization response (Vrn) alleles into a single wheat genotype for yield enhancement; however, DNA markers are only available for two of the three genes identified to date. The objectives of this study were to investigate reciprocal effects on days to heading using F₂ populations generated by cross‐hybridizing near‐isogenic lines (NILs) carrying spring (Vrn‐B1; TDB) and winter (vrn‐B1; TDC) alleles, and to identify markers linked to Vrn‐B1 through genetic linkage analysis. Heading data were recorded for 91 and 89 progeny from reciprocal mapping populations TDB/TDC and TDC/TDB, respectively, and significant (P < 0.0001) reciprocal and dominance effects were detected. Among 207 amplified fragment length polymorphisms primer pairs and seven wheat microsatellite markers screened, two and one, respectively, were linked distally to Vrn‐B1 on wheat chromosome 5BL. Microsatellite Xgwm408 was most closely linked to Vrn‐B1 at 3.9 and 1.1 cM in the TDB/TDC and TDC/TDB map, respectively. Reciprocal differences in recombination distances emphasize the importance of female parent choice when generating mapping populations. Molecular markers are now available for three Vrn loci in wheat.     

Development and characterization of a new set of 164 polymorphic EST‐SSR markers for diversity and breeding studies in rubber tree (Hevea brasiliensis Müll. Arg.)

Despite its economic importance and recent genome release, the need for molecular tools for Hevea brasiliensis is high. In the frame of a disease resistance study, EST sequences were retrieved from public database or generated by sequencing SSH libraries. Sequences were trimmed and microsatellite motifs searched using an ad hoc bioinformatic pipeline, and pairs of primers for the amplification of candidate markers were generated. We found a total of 10 499 unigenes from both sources of sequences, and 673 microsatellites motifs were detected using the default parameters of the pipeline. Two hundred sixty‐four primer pairs were tested and 226 (85.6%) successfully amplified. Out of the amplified candidate markers, 164 exhibited polymorphism. Relationships based on dendrograms using simple matching index and diversity statistics based on EST‐SSRs were compared with Genomic SSRs, showing the potentialities of EST‐derived microsatellites for resistance studies but also for population genetics approaches.     

Promoter anchored amplified polymorphism based on random amplified polymorphic DNA (PAAP-RAPD) in cotton

Non-coding sequences account for a majority of the higher plant genome, some of which have important effects in gene regulation and plant development. In an effort to develop molecular marker systems to search for polymorphisms associated with high fiber yield and quality in cotton, we have developed a methodology that could specifically target the regulatory regions of the cotton genome. In this study we designed 10-nucleotide degenerate promoter primers based on conserved core promoter sequences and tested their applicability in PCR amplifications in combination with 10-mer random amplified polymorphic DNA (RAPD) primers. The amplified markers are called promoter anchored amplified polymorphism based on RAPD (PAAP-RAPD). Forty cotton genotypes with diverse genetic and geographical backgrounds were used to test the PAAP-RAPD system using polyacrylamide gel electrophoresis. Based on PAAP-RAPD markers amplified from 12 primer combinations, the 40 genotypes were classified into five distinctive groups: two Upland cotton (Gossypium hirsutum) groups from China, another two Upland cotton groups from the USA, and one group from American Pima cotton (G. barbadense). The groupings are in general consistent with their genetic and geographical origins. Thirty-six PAAP-RAPD and RAPD fragments were cloned and four of them were further subjected to sequence analysis. Signal scanning using software PLACE confirmed that they contained an array of cis-regulatory sequences in addition to the core promoter sequences. The results demonstrate the potential application of PAAP-RAPD as a new marker system specifically targeting regulatory regions of the plant genome.     

Efficient development of Haynaldia villosa chromosome 6VS‐specific DNA markers using a CISP‐IS strategy

Development of effective molecular markers linked to Pm21 deriving from Haynaldia villosa is critical for wheat breeding of powdery mildew resistance. In this study, we designed 12 pairs of conserved‐intron scanning primers (CISPs), using intron‐containing conserved genes located on the short arm of Brachypodium distachyon chromosome 3 (3BdS) aligned with cDNA or expressed sequence tags (ESTs) of Triticeae crops. Of 12 CISP primer pairs, 11 amplified DNA both in H. villosa and in wheat, and four displayed H. villosa chromosome 6VS‐specific polymorphisms. Six non‐polymorphic DNAs were further sequenced for designing internal primers, and five additional 6VS‐specific markers were obtained. Of the total nine 6VS‐specific co‐dominant markers, six could effectively trace Pm21 in F₂ population derived from the hybrid between the T6AL.6VS line and ‘Yangmai 158’. This study demonstrated that Brachypodium genomic information could be powerfully utilized to develop molecular markers in H. villosa or other Triticeae species.     

A physical map of chromosome 4Hch from H. chilense containing SSR, STS and EST-SSR molecular markers

The construction of a physical map of chromosome 4H^ch from Hordeum chilense containing molecular markers capable of detecting segments of this chromosome in a wheat background would be very useful for marker-assisted introgression of 4H^ch chromatin into both durum and common wheat. With this aim, the applicability of 106 barley chromosome 4H primers (62 SSRs and 44 STSs) to amplify markers showing polymorphism between H. chilense and both common or bread and durum wheat was investigated. Twenty-five SSR (40.3%) and six STS (13.6%) barley primer pairs consistently amplified H. chilense products. Eight SSR (12.9%) and four STS (9.1%) barley primers were polymorphic between H. chilense and both common and durum wheat, 10 of them (6 SSRs and 4 STSs) were located on chromosome 4H^ch using both the addition line of chromosome 4H^ch in Chinese Spring wheat and a tritordeum line (an amphiploid between H. chilense and T. turgidum) nullisomic for chromosome 4H^ch. Additionally, 18 EST-SSR barley markers previously located on chromosome 4H^ch were screened for polymorphism; 15 were polymorphic between H. chilense and both durum and common wheat. For physical mapping we used a ditelosomic tritordeum line for the short arm of chromosome 4H^ch and a tritordeum line homozygous for a 70% terminal deletion of the long arm of 4H^ch. A total of 25 markers (6 SSRs, 4 STSs and 15 EST-SSRs) were mapped to chromosome 4H^ch. Eight markers were allocated on the 4H^chS, eight were mapped in the 30% proximal region of 4H^chL and nine were on the 70% distal region of 4H^chL, respectively. Arm location on barley chromosome 4H was also carried out using both 4HS and 4HL ditelosomic addition lines in wheat. All markers mapped may have a role in marker-assisted introgression of chromatin segments of chromosome 4H^ch in both durum and common wheat backgrounds. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Development of a molecular marker for a bruchid (Callosobruchus chinensis L.) resistance gene in mungbean

Bruchid, Callosobruchus spp. (Coleoptera: Bruchidae), is a serious pest during storage of seeds of mungbean (Vigna radiata (L.) Wilczek) and other Vigna species. A source of resistance to this pest has been identified in Vigna sublobata (Roxb.) Bairig. accession TC1966. Two hundred recombinant inbred lines at the F₁₂ generation have been developed for molecular mapping of bruchid resistance (Br) gene in TC1966. Through bulked segregant analysis (BSA), ten randomly amplified polymorphic DNA (RAPD) markers associated with the bruchid resistance gene were successfully identified. A total of four closely linked RAPDs were cloned and transformed into sequence characterized amplified region (SCAR) and cleaved amplified polymorphism (CAP) markers. Seven CAPs developed from the identified RAPD markers showed tighter linkage with the Br gene than the original RAPD. Through transformation of RAPDs into CAPs, codominant markers for bruchid resistance were successfully obtained. Homozygous genotypes of these PCR-based markers were estimated to contribute 85% of the variance for seed damage when the insect assay was performed under favorable growth conditions for bruchid.     

Identification of molecular markers linked to adult plant leaf rust resistance gene <Emphasis Type="Italic">Lr48</Emphasis> in wheat and detection of <Emphasis Type="Italic">Lr48</Emphasis> in the Thatcher near-isogenic line with gene <Emphasis Type="Italic">Lr25</Emphasis>

The recessive adult plant resistance (APR) gene Lr48 in wheat was tagged with flanking random amplified polymorphic DNA (RAPD) markers. Markers S336₇₇₅ in coupling and S3₄₅₀ in repulsion with Lr48 were identified in wheat line CSP44. Tests of these markers on available Thatcher near-isogenic lines (NILs) detected the likely presence of Lr48 in TcLr25. A test of allelism of APR involving the cross TcLr25 × CSP44 indicated that Lr48 was present in both lines. A separate experiment on inheritance of resistance in an F₂ population of TcLr25 × Agra Local confirmed the presence of a dominant seedling resistance gene (Lr25) and a recessive APR gene (Lr48) in TcLr25. This study demonstrated the value of molecular markers in identifying the presence of masked genes in genetic stocks where direct phenotyping failed to detect their presence.     

Genetic maps of RAPD, AFLP and ISSR markers in Ananas bracteatus and A. comosus using the pseudo-testcross strategy

Genetic maps of random amplified polymorphic DNA (RAPD), amplified fragment length polymorphisms (AFLP) and inter simple sequence repeats (ISSR) markers in pineapple (2n = 2x = 50) are reported for the first time. On the basis of a segregating population of 46 F1 individuals from a cross Ananas comosus x A. bracteatus, genetic maps of these two species were constructed using the two‐way pseudo‐testcross approach. The A. bracteatus map consists of 335 markers (60 RAPDs, 264 AFLPs and 11 ISSRs) assembled into 50 linkage groups, 26 of them with at least four markers. The A. comosus map consists of 157 markers (33 RAPDs, 115 AFLPs, eight ISSRs and the ‘piping’ trait locus) organized into 30 linkage groups, 18 of them with at least four markers. These maps cover, respectively, 57.2% of the A. bracteatus genome estimated as 3693 cM long, and 31.6% of the A. comosus genome calculated as 4146 cM. A rough estimate of 120 and 127 kbp/ cM on average was found for the relationship between physical and genetic distance for A. bracteatus and A. comosus, respectively.     

Molecular markers linked to the Aegilops variabilis-derived root-knot nematode resistance gene Rkn-mn1 in wheat

Aegilops variabilis no. 1 is the only known source of resistance to the root‐knot nematode Meloidogyne naasi in wheat. Previous studies showed that a dominant gene, Rkn‐mn1, was transferred to a wheat translocation line from the donor Ae. variabilis. Random amplified polymorphic DNA (RAPD) analysis was performed on the wheat cultivar ‘Lutin’, on Ae. variabilis, on a resistant disomic addition line and on a resistant translocation line. For genetic and molecular studies, 114‐117 BC₃F₂ plants and F₃‐derived families were tested. Five DNA and one isozyme marker were linked to Rkn‐mn1. Three RAPD markers flanking the Rkn‐mn1 locus were mapped at 0 cM (OpY16_‐1065), 0.8 cM (OpB12_‐1320) and 1.7 cM (OpN20_‐1235), respectively. Since the Rkn‐mn1 gene remained effective, its introduction into different wheat cultivars by marker‐assisted selection is suggested.