RFLP mapping of BaYMV resistance gene rym3 in barley (Hordeum vulgare)

The rym3 (formerly designated ym3) gene conferring resistance to barley yellow mosaic virus (BaYMV) is effective against all strains of the virus but up to now has not been mapped to any chromosome. We performed a linkage analysis, using DNA extracted from individually harvested mature leaves of 153 F₂ plants derived from a cross between BaYMV-resistant cv ’Ishuku Shirazu’ carrying rym3 and susceptible cv ’Ko A’. Additionally, the F₃ lines derived from F₂ plants were grown in the BaYMV-infested field and examined for their reaction to BaYMV. Our results indicated that rym3 is located on the short arm of chromosome 5H and flanked by RFLP markers MWG28and ABG705A at distances of 7.2 and 11.7 cM, respectively. The chromosomal configuration estimated by DNA markers around rym3 and the utilization of these molecular markers for pyramiding with the BaYMV resistance genes in barley breeding programs are discussed. Received: 24 August 1998 / Accepted: 30 January 1999<@head-com-p1a.lf>Communicated by F. Salamini     

Identification and mapping of a new leaf stripe resistance gene in barley (Hordeum vulgare L.)

Pyrenophora graminea is the seed-borne pathogen causal agent of barley leaf stripe disease. Near-isogenic lines (NILs) carrying resistance of the cv ”Thibaut” against the highly virulent isolate Dg2 were obtained by introgressing the resistance into the genetic background of the susceptible cv ”Mirco”. The segregation of the resistance gene was followed in a F₂ population of 128 plants as well as on the F₃ lines derived from the F₂ plants; the segregation fitted the 1:2:1 ratio for a single gene. By using NILs, a RAPD marker associated with the resistance gene was identified; sequence-specific (STS) primers were designed on the basis of the amplicon sequence and a RILs mapping population with an AFLP-based map were used to position this molecular marker to barley chromosome 1 S (7HS). STS and CAPS markers were developed from RFLPs mapped to the telomeric region of barley chromosome 7HS and three polymorphic PCR-based markers were developed. The segregation of these markers was followed in the F₂ population and their map position with respect to the resistance gene was determined. Our results indicate that the Thibaut resistance gene, which we designated as Rdg2a, maps to the telomeric region of barley chromosome 7HS and is flanked by the markers OPQ-9₇₀₀ and MWG 2018 at distances of 3.1 and 2.5 cM respectively. The suitability of the PCR-based marker MWG2018 in selection- assisted barley breeding programs is discussed. Received: 22 June 2000 / Accepted: 16 October 2000     

High-resolution mapping of the Rym4/Rym5 locus conferring resistance to the barley yellow mosaic virus complex (BaMMV, BaYMV, BaYMV-2) in barley (Hordeum vulgare ssp. vulgare L.)

Soil-borne barley yellow mosaic virus disease – caused by a complex of at least three viruses, i.e. Barley mild mosaic virus (BaMMV), Barley yellow mosaic virus (BaYMV) and BaYMV-2 – is one of the most important diseases of winter barley in Europe. The two genes rym4, effective against BaMMV and BaYMV, and rym5, additionally effective against BaYMV-2, comprise a complex locus on chromosome 3HL, which is of special importance to European barley breeding. To provide the genetic basis for positional cloning of the Rym4/Rym5 locus, two high-resolution maps were constructed based on co-dominant flanking markers (MWG838/Y57c10 - MWG010/Bmac29). Mapping at a resolution of about 0.05% rec., rym4 has been located 1.07% recombination distal of marker MWG838 and 1.21% recombination proximal to marker MWG010. Based on a population size of 3,884 F₂ plants (0.013% recombination) the interval harbouring rym5 was delimited to 1.49±0.14% recombination. By testing segmental recombinant inbred lines (RILs) for reaction to the different viruses at a resolution of 0.05% rec. (rym4) and 0.019% rec. (rym5), no segregation concerning the reaction to the different viruses could be observed. AFLP-based marker saturation for rym4, using 932 PstI+2/MseI+3 primer combinations only resulted in three markers with the closest one linked at 0.9% recombination to the gene. Two of these markers detected epialleles arising from the differential cytosine methylation of PstI sites. Regarding rym5, profiling of 1,200 RAPD primers (about 18,000 loci) and 2,048 EcoRI+3/MseI+3 AFLP primer combinations (about 205,000 loci) resulted in one RAPD marker and seven AFLP markers tightly linked to the resistance gene. Flanking markers with the closest linkage to rym5 (0.05% and 0.88% recombination) were converted into STS markers. These markers provide a starting point for chromosomal walking and may be exploited in marker-assisted selection for virus resistance based on rym5.     

RFLP mapping of the Ha 2 cereal cyst nematode resistance gene in barley

 The cereal cyst nematode (CCN), Heterodera avenae Woll., is an economically damaging pest of barley in many of the world’s cereal-growing areas. The development of CCN-resistant cultivars may be accelerated through the use of molecular markers. A number of resistance genes against the pest are well known; one of them, the single dominant Ha 2 resistance gene, has been shown to be effective against the Australian pathotype and maps to chromosome 2 of barley. Segregation analysis identified two restriction fragment length polymorphism (RFLP) markers flanking the resistance gene in two doubled-haploid populations of barley. AWBMA 21 and MWG 694 mapped 4.1 and 6.1 cM respectively from the Ha 2 locus in the Chebec×Harrington cross and 4.0 and 9.2 cM respectively in the Clipper×Sahara cross. Analysis of a further seven sources of CCN resistance in the form of near-isogenic lines (NILs) indicates that all available sources of resistance to the Australian pathotype of CCN in barley represent the Ha 2 locus. Received: 5 December 1996 / Accepted: 20 December 1996     

Molecular mapping of a fertility restoration locus (Rfm1) for cytoplasmic male sterility in barley (Hordeum vulgare L.)

The Rfm1a gene restores the fertility of msm1 cytoplasmic male-sterile lines in barley. We identified three RAPD markers linked to the Rfm1 locus (CMNB-07/800, OPI-18/900, and OPT-02/700) using isogenic lines and segregating BC₁F₁ and F₂ populations. Using a previously developed linkage map of barley, we located CMNB-07/800 and OPT-02/700 beside MWG2218 on chromosome 6HS. The linkage between MWG2218 and the Rfm1 locus was demonstrated using the segregating BC₁F₁ and F₂ populations. To confirm the chromosomal locations of these markers, we converted them to STSs and tested against two sets of wheat–barley chromosome addition lines. These STS markers, CMNB-07/800, OPT-02/700, and MWG2218, were amplified only in the addition lines possessing the chromosome 6H, thereby providing additional evidence the Rfm1 locus is located on chromosome 6H. Homoeologous relationships among fertility restoration genes in Triticeae are discussed. Received: 27 March 2000 / Accepted: 25 June 2000     

Mapping of powdery mildew resistance genes in a newly determined accession of Hordeum vulgare ssp. spontaneum

The accession PI466197 of wild barley (Hordeum vulgare ssp. spontaneum) with a newly identified resistance to powdery mildew caused by Blumeria graminis f.sp. hordei was studied with the aim to localise the genes determining resistance on a barley genetic map using DNA markers. Molecular analysis was performed in the F₂ population of the cross between the winter variety ‘Tiffany’ and the resistant accession PI466197, consisting of 113 plants. DNA markers, 17 simple sequence repeats (SSRs), four sequence-tagged sites (STSs) and one cleaved amplified polymorphic sequence (CAPS) marker developed from the Mla locus sequence were used for genetic mapping and a two-locus model of resistance was shown. One of the resistance genes originating from H. vulgare ssp. spontaneum PI466197 was localised between the markers RGH1aE1 and Bmac0213 on the short arm of chromosome 1H, which is the position consistent with the Mla locus. The other gene was proven to be highly significantly linked with GBMS247, Bmac0134 and MWG878 on the short arm of chromosome 2H. The flanking markers were Bmac0134 and MWG878, assigned 4 and 8 cM from the resistance gene, respectively. Until now, no gene conferring powdery mildew resistance originating from H. vulgare has been located on the short arm of barley chromosome 2H.     

<Emphasis Type="Italic">rym15</Emphasis> from the Japanese cultivar Chikurin Ibaraki 1 is a new barley mild mosaic virus (BaMMV) resistance gene mapped on chromosome 6H

Breeding for resistant cultivars is the only way to prevent high yield loss in barley caused by the soil-borne barley mild mosaic virus (BaMMV) complex. We have characterized the BaMMV resistance of barley cv. Chikurin Ibaraki 1. Doubled haploid lines were obtained from the F₁ between the susceptible six-rowed winter barley cultivar, Plaisant, and Chikurin Ibaraki 1. Each line was tested for reaction to BaMMV by mechanical inoculation followed by DAS-ELISA. Of 44 microsatellites that covered the genome, 22 polymorphic markers were tested on one susceptible and one resistant bulk, each comprising 30 lines. Differential markers and additional microsatellite markers in the same region were then tested on the whole population. A bootstrap analysis was used to compute confidence intervals of distances and to test the orders of the resistance gene and the closest markers. A segregation of 84 resistant/98 susceptible lines fitted a 1:1 ratio (²=1.08, P=0.30), which corresponds to a single gene in this DH lines population. The resistance gene was flanked by two markers near the centromeric region of chromosome 6HS—Bmag0173, at 0.6±1.2 cM, and EBmac0874, at 5.8 ± 3.4 cM. We propose to name this new resistance gene rym15. This resistance gene and associated markers will increase the possibilities to breed efficiently for new cultivars resistant to the barley mosaic disease.Communicated by P. Langridge     

Molecular mapping of novel resistance genes against Barley Mild Mosaic Virus (BaMMV)

 In the present study three novel genes from barley accessions 10247 (ym8), Bulgarian 347 (ym9), and Russia 57 (ym11), which confer resistance to Barley Mild Mosaic Virus (BaMMV), were mapped using molecular markers. Bulked segregant analysis of four progenies segregating for resistance to BaMMV was followed by fine-scale mapping of the resistance genes using individual F₂ or BC₁F₂ plants. The resistance genes are inherited recessively and are located on the long arm of barley chromosome 4HL. A series of closely linked molecular markers are available for marker-assisted breeding programs. A marker (MWG2134) linked with resistance gene ym11 from Russia 57 was identified, which is diagnostic for the resistance gene. Received: 25 July 1997 / Accepted: 22 August 1997     

A high-resolution genetic map and a diagnostic RFLP marker for the Mlg resistance locus to powdery mildew in barley

The semi-dominantly acting Mlg resistance locus in barley confers race-specific resistance to the obligate biotrophic fungus Erysiphe graminis f.sp. hordei. A high-resolution genetic map was constructed at Mlg based on a cross between the near-isogenic barley lines Pallas BC₅ Mlg and Pallas mlg. A total of 2000 F₂ progeny were inspected by cleaved amplified polymorphic sequence (CAPS) analysis, defining a 4.47 cM interval encompassing the resistance locus. Pathogen challenge of the segregants with multiple powdery mildew isolates uncovered a novel resistance specificity in Pallas BC₅ Mlg. Probes from within 4.0 cM of Mlg were mapped in rice, revealing orthologues on five different rice chromosomes and suggesting multiple breaks of chromosomal collinearity in this region between the two grass species. The most tightly Mlg-linked RFLP marker, MWG032, was shown to reliably detect the presence of the resistance allele in a collection of 30 European barley cultivars. Received: 23 March 2000 / Accepted: 20 April 2000     

RFLP markers to identify the alleles on the Mla locus conferring powdery mildew resistance in barley

Summary To identify the mildew resistance locus Mla in barley with molecular markers, closely linked genomic RFLP clones were selected with the help of near-isogenic lines having the Pallas and Siri background. Out of 22 polymorphic clones 3 were located around the Mla locus on chromosome 5 with a distance of 5.1 + 2.9 cM (MWG 1H068), 4.2±1.7 cM (MWG 1H060) and 0.7 ± 0.7 cM (MWG 1H036), respectively. The polymorphic clone MWG 1H036 displayed the same RFLP pattern in both Pallas and Siri near-isogenic lines and in different varieties digested with six restriction enzymes possessing the same mildew resistance gene. The alleles of the Mla locus were grouped in 11 classes according to their specific RFLP patterns; 3 of these groups contain the majority of Mla alleles already used in barley breeding programs in Europe.     

Fine-mapping of the BaMMV, BaYMV-1 and BaYMV-2 resistance of barley (Hordeum vulgare) accession PI1963

Barley yellow mosaic disease caused by the bymoviruses barley mild mosaic virus (BaMMV) and barley yellow mosaic virus (BaYMV) is one of the economically most important diseases of winter barley in Europe. In European barley breeding programmes, resistance is currently due to only two genes—rym4, which is effective against viruses BaMMV and BaYMV-1, and rym5, which is effective against BaYMV-2. Diversification of resistance is therefore an important task. Because the accession PI1963 confers immunity against all European strains of barley yellow mosaic disease and is not allelic to rym5, we have attempted to develop closely linked markers in order to facilitate the efficient introgression of this resistance into adapted germplasm. By means of restriction fragment length polymorphism analysis, we located a gene locus for resistance to BaMMV, BaYMV-1 and BaYMV-2 of PI1963 on chromosome 4HL using a mapping population (W757) comprising 57 doubled haploid (DH) lines. Subsequent tests for allelism indicated that the BaMMV resistance gene in PI1963 is allelic to rym11. Two DH populations, IPK1 and IPK2, comprising 191 and 161 DH lines, respectively, were derived from the initial mapping population W757 and used for further analysis. As random amplified polymorphic DNA development did not facilitate the identification of more closely linked markers, simple sequence repeat (SSR) analyses were conducted. For population IPK1, the closest SSRs detected were Bmac181 and Bmag353, which flank the gene at 2.1 cM and 2.7 cM, respectively. For the IPK2 population, the SSR markers HVM3 and Bmag353 are located proximally at 2.5 cM and distally at 8.2 cM, respectively. In order to develop markers more tightly linked to rym11, a targeted amplified fragment length polymorphism (AFLP) marker identification approach was adopted using bulks comprising lines carrying recombination events proximal and distal to the target interval. Using this approach we identified six AFLP markers closely linked to rym11, with the two markers, E56M32 and E49M33, co-segregating with rym11 in both populations. The SSRs and AFLPs identified in this study represent useful tools for marker-assisted selection.     

半矮秆基因brh1在大麦中的精细定位

选用从大麦、小麦和水稻中分离的RFLP标记 ,构建了大麦半矮秆基因brh1精细图谱。以快中子处理六棱大麦品种Steptoe的种子 ,从M2 代中选择出brh1突变体FN5 3。brh1是一个极易鉴别的形态学标记 ,通过对FN5 3×Morex的F2 代群体进行鉴定表明 ,brh1基因为隐性 ,前人通过BSA法将其初步定位在大麦第 1染色体 (7H)短臂上 ,靠近端粒区。这一区间还有一个控制秆锈病抗性的显性基因Rpg1。所以 ,brh1的精细定位不仅对研究其本身具有重要意义 ,同时 ,也为Rpg1的图位克隆和功能研究提供了更大的重组配子群体。定位实验全部以F2 中具有brh1特征的个体为对象完成 ,鉴定工作在苗期进行。在该精细图上 ,brh1区间长15 .2cM ,各标记间的平均距离为 0 .8cM。其中 ,大麦的cDNA克隆MWG2 0 74B与brh1共分离。 2 0 74A在靠近着丝点一侧 ,与brh1相距 0 .8cM。BCD12 9和R3139在定位群体内呈现与MWG2 0 74A共分离。CDO5 4 5位于端粒一侧 ,距离brh1为 0 .8cM。根据禾谷类作物基因组的共线性原理 ,CDO5 4 5成功定位在水稻的同源染色体即第 6染色体短臂brh1区间内。然而 ,由于在定位亲本间缺乏多态性 ,BCD12 9和MWG2 0 74的 2条主带A和B均未能定位在水稻的共线性区段内。推测MWG2 0 74的其他各带可能被定位在水稻的目标区间内 ,从而有     

Genomics-based high-resolution mapping of the BaMMV/BaYMV resistance gene rym11 in barley (Hordeum vulgare L.)

Soil-borne barley yellow mosaic virus disease, caused by different strains of Barley yellow mosaic virus (BaYMV) and Barley mild mosaic virus (BaMMV), is one of the most important diseases of winter barley (Hordeum vulgare L.) in Europe and East Asia. The recessive resistance gene rym11 located in the centromeric region of chromosome 4HL is effective against all so far known strains of BaMMV and BaYMV in Germany. In order to isolate this gene, a high-resolution mapping population (10,204 meiotic events) has been constructed. F₂ plants were screened with co-dominant flanking markers and segmental recombinant inbred lines (RILs) were tested for resistance to BaMMV under growth chamber and field conditions. Tightly linked markers were developed by exploiting (1) publicly available barley EST sequences, (2) employing barley synteny to rice, Brachypodium distachyon and sorghum and (3) using next-generation sequencing data of barley. Using this approach, the genetic interval was efficiently narrowed down from the initial 10.72 % recombination to 0.074 % recombination. A marker co-segregating with rym11 was developed providing the basis for gene isolation and efficient marker-assisted selection.     

Allele-specific amplification of polymorphic sites for the detection of powdery mildew resistance loci in cereals

Primers for the polymerase chain reaction (PCR) were tailored to selectively amplify RFLP marker alleles associated with resistance and susceptibility for powdery mildew in cereals. The differentiation between marker alleles for susceptible and resistant genotypes is based on the discrimination of a single nucleotide by using allele-specific oligonucleotides as PCR primers. The PCR assays developed are diagnostic for RFLP alleles at the loci MWG097 in the barley genome and Whs350 in the wheat genome. The first marker locus is closely linked to MlLa resistance in barley, while the latter is linked to Pm2 resistance locus in wheat. PCR analysis of 31 barley and 30 wheat cultivars, with some exceptions, verified the presence or absence of the resistance loci investigated. These rapid PCR-based approaches are proposed as an efficient alternative to conventional procedures for selecting powdery mildew-resistant genotypes in breeding programs.     

Inheritance and genetic mapping of cucumber mosaic virus resistance introgressed from Lycopersicon chilense into tomato

Cucumber mosaic virus (CMV) infects a wide variety of crop plants and in tomato (Lycopersicon esculentum Mill.) causes significant economic losses in many growing regions, particularly the Mediterranean. The objective of the present study was to identify the number and map locations of genes controlling resistance to CMV in breeding lines (BC₁–inbreds) derived from the related wild species L. chilense. These lines also carried the gene Tm-2 ^a for resistance to ToMV, which facilitated the interpretation of disease symptoms. The segregation for CMV resistance in the BC₂F₁ and BC₂F₂ generations, following mechanical inoculation with subgroup-I isolates, was consistent with expectations for a single dominant gene, for which the symbol Cmr (cucumber mosaic resistance) was given. Resistant and susceptible BC₁-inbreds were analyzed with RFLP and isozyme markers to identify genomic regions introgressed from L. chilense. The only L. chilense-specific markers found were on chromosome 12; some resistant lines contained a single introgression comprising the entire short arm and part of the long arm of this chromosome, while others contained a recombinant derivative of this introgression. The chromosome 12 markers were significantly associated with CMV resistance in both qualitative and quantitative models of inheritance. The qualitative analysis, however, demonstrated that CMV resistance was not expressed as a reliable monogenic character, suggesting a lack of penetrance, significant environmental effects, or the existence of additional (undetected) resistance factors. In the quantitative analysis, the marker interval TG68 – CT79 showed the most significant association with CMV resistance. No association between CMV resistance and the Tm-2 ^a gene was observed. These breeding lines are potentially useful sources of CMV resistance for tomato improvement, in which context knowledge of the map location of Cmr should accelerate introgression by marker-assisted selection. Received: 9 August 1999 / Accepted: 22 December 1999     

RFLP analysis of rice (Oryza sativa L.) introgression lines

Summary Fifty-two introgression lines (BC₂F₈) from crosses between two Oryza sativa parents and five accessions of O. officinalis were analyzed for the introgression of O. officinalis chromosome segments. DNA from the parents and introgression lines was analyzed with 177 RFLP markers located at approximately 10-cM intervals over the rice chromosomes. Most probe/enzyme combinations detected RFLPs between the parents. Of the 174 informative markers, 28 identified putative O. officinalis introgressed chromosome segments in 1 or more of the introgression lines. Introgressed segments were found on 11 of the 12 rice chromosomes. In most cases of introgression, O. sativa RFLP alleles were replaced by O. officinalis alleles. Introgressed segments were very small in size and similar in plants derived from early and later generations. Some nonconventional recombination mechanism may be involved in the transfer of such small chromosomal segments from O. officinalis chromosomes to those of O. sativa. Some of the introgressed segments show association with genes for brown planthopper (BPH) resistance in some introgressed lines, but not in others. Thus, none of the RFLP markers could be unambiguously associated with BPH resistance.     

Molecular mapping of <Emphasis Type="Italic">Rym17</Emphasis>, a dominant and <Emphasis Type="Italic">rym18</Emphasis> a recessive barley yellow mosaic virus (BaYMV) resistance genes derived from <Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.

PK23-2, a line of six-rowed barley (Hordeum vulgare L.) originating from Pakistan, has resistance to Japanese strains I and III of the barley yellow mosaic virus (BaYMV). To identify the source of resistance in this line, reciprocal crosses were made between the susceptible cultivar Daisen-gold and PK23-2. Genetic analyses in the F₁ generation, F₂ generation, and a doubled haploid population (DH45) derived from the F₁ revealed that PK23-2 harbors one dominant and one recessive resistance genes. A linkage map was constructed using 61 lines of DH45 and 127 DNA markers; this map covered 1268.8 cM in 10 linkage groups. One QTL having a LOD score of 4.07 and explaining 26.8% of the phenotypic variance explained (PVE) for resistance to BaYMV was detected at DNA marker ABG070 on chromosome 3H. Another QTL having a LOD score of 3.53 and PVE of 27.2% was located at marker Bmag0490 on chromosome 4H. The resistance gene on chromosome 3H, here named Rym17, showed dominant inheritance, whereas the gene on chromosome 4H, here named rym18, showed recessive inheritance in F₁ populations derived from crosses between several resistant lines of DH45 and Daisen-gold. The BaYMV recessive resistance genes rym1, rym3, and rym5, found in Japanese barley germplasm, were not allelic to rym18. These results revealed that PK23-2 harbors two previously unidentified resistance genes, Rym17 on 3H and rym18 on 4H; Rym17 is the first dominant BaYMV resistance gene to be identified in primary gene pool. These new genes, particularly dominant Rym17, represent a potentially valuable genetic resource against BaYMV disease.     

Molecular mapping of the Rph7.g leaf rust resistance gene in barley (Hordeum vulgare L.)

In many temperate areas of the world, leaf rust is becoming an important disease of barley. In the last decade, new races of Puccinia hordei G. Otth have emerged which are virulent against the so-far most-effective race-specific resistance genes, such as Rph7. Marker-assisted selection greatly facilitates the pyramidization of two or more resistance genes in a single variety in order to achieve a more comprehensive resistance. Such a strategy requires the development of efficient and reliable markers. Here, we have developed a linkage map and found RFLP markers closely linked to the Rph7.g resistance gene on chromosome 3HS of barley. The receptor-like kinase gene Hv3Lrk that maps at 3.2 cM from Rph7.g was used to develop a PCR-based marker by exploiting a single nucleotide polymorphism. This marker was detected in 11 out of 12 (92%) barley lines having Rph7 and represents a valuable tool for marker-assisted selection. In addition, the identification of markers flanking Rph7.g provides the basis for positional cloning of this gene. Received: 1 December 1999 / Accepted: 28 February 2000     

Molecular mapping of powdery mildew resistance gene <Emphasis Type="Italic">Eg-3</Emphasis> in cultivated oat (<Emphasis Type="Italic">Avena sativa</Emphasis> L. cv. Rollo)

Powdery mildew is a prevalent fungal disease affecting oat (Avena sativa L.) production in Europe. Common oat cultivar Rollo was previously shown to carry the powdery mildew resistance gene Eg-3 in common with cultivar Mostyn. The resistance gene was mapped with restriction fragment length polymorphism (RFLP) markers from Triticeae group-1 chromosomes using a population of F₃ lines from a cross between A. byzantina cv. Kanota and A. sativa cv. Rollo. This comparative mapping approach positioned Eg-3 between cDNA-RFLP marker loci cmwg706 and cmwg733. Since both marker loci were derived from the long arm of barley chromosome 1H, the subchromosomal location of Eg-3 was assumed to be on the long arm of oat chromosome 17. Amplified fragment length polymorphism (AFLP) marker technology featured as an efficient means for obtaining markers closely linked to Eg-3.     

Fusarium head blight resistance in hexaploid wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis>)-<Emphasis Type="Italic">Lophopyrum</Emphasis> genetic lines and tagging of the alien chromatin by PCR markers

The objective of this research was to identify Fusarium head blight (FHB) resistance in wheat (Triticum aestivum)-Lophopyrum genetic lines that might complement FHB resistance in common wheat; and to identify DNA markers that can be used to tag the resistance gene in the alien chromatin (E or el₂ genome) for the development of improved wheat cultivars. FHB resistance was evaluated in 19 Chinese Spring-Lophopyrum elongatum (EE) substitution lines, two Thatcher-L. ponticum (el₁ and el₂) substitution lines, and four Thatcher-L. ponticum translocation lines. Significant resistance was identified in the substitution lines 7E(7A), 7E(7B), and 7E(7D). The homoeologous chromosome, 7el₂,also showed resistance in the Thatcher genetic background. Both the Thatcher-7el₁ substitution and translocation lines were susceptible, like Thatcher, indicating that there is no resistance gene on the 7el₁ chromosome. Simple sequence repeat (SSR) and cleaved amplified polymorphic sequences (CAPS) in homoeologous group 7 chromosomes were used to identify DNA markers located on 7E and 7el₂. As expected, the transferability of wheat SSR markers to Lophopyrum is low. Of the 52 SSR markers that we tested, only five were found to be co-dominant on 7E of L. elongatum versus 7A, 7B, and 7D, one of which is also positive on 7el₂. A CAPS marker, derived from the RFLP probe PSR129, can serve as a dominant marker for 7el₂ chromatin.Communicated by J. Dvorak