Identification of a microsatellite marker associated with Pm3 resistance alleles to powdery mildew in wheat

The Pm3 resistance locus, located on chromosome 1A in wheat, confers race‐specific resistance to the obligate biotrophic fungus Blumeria graminis (DC) E.O. Speer f. sp. tritici, the causal agent of powdery mildew. Several Pm3 alleles are still effective in controlling the disease in Europe. A genetic map was constructed to map the Pm3g allele in the recombinant inbred line progeny from the cross ‘RE9001’ (susceptible) בCourtot’ (resistant). Two microsatellite markers were closely mapped to Pm3g. The PSP2999 marker, which cosegregates with this allele, was shown to detect the presence of the Pm3g resistance allele in other cultivars. A collection of 56 wheat cultivars or advanced lines carrying one Pm3 allele was used to assess the allele‐specific amplification of the PSP2999 marker. The same amplification pattern was obtained for lines with Pm3a, Pm3b, Pm3e, Pm3f and Pm3g alleles. Twenty genotypes carrying Pm3d showed a specific amplification pattern. This marker allowed the detection of the Pm3d allele in highly resistant lines whose resistance gene combinations were unknown. It was concluded that PSP2999 is a useful marker to detect Pm3 alleles in parents and to manage them in breeding programmes.     

Evidence of allelism between genes Pm8 and Pm17 and chromosomal location of powdery mildew and leaf rust resistance genes in the common wheat cultivar'Amigo'

TIBL-1RS wheat-rye translocation cultivars utilized in wheat programmes worldwide carry powdery mildew resistance gene Pm8. Cultivar‘Amigo’possesses resistance gene Pm17 on its TIAL-1RS translocated chromosome. To be able to use Pm17efficiently in breeding programmes, this gene was transferred to a TIBL-1RS translocation in line Helami-105, and allelism between Pm8 and Pm17was studied. The progenies of the hybrids in the F₂ generation and F₃ families provided evidence that the two genes are allelic. Genetic studies using monosomic analyses confirmed that in cultivar‘Amigo', Pm17 and leaf rust resistance gene Lr24 are located on a translocated chromosome involving 1 A and 1B, respectively.     

Genetic, agronomic and quality comparisons of two 1AL.1RS. wheat-rye chromosomal translocations

The 1AL.1RS wheat-rye chromosomal translocation originally found in ‘Amigo’ wheat possesses resistance genes for stem rust, powdery mildew and greenbug biotypes B and C, but also has a negative effect on wheat processing quality. Recently, a second 1AL.1RS translocation carrying Gb6, a gene conferring resistance to greenbug biotypes B, C, E, G and I, was identified in the wheat germplasm line ‘GRS1201′. Protein analytical methods, and the DNA polymerase chain reaction were used to identify markers capable of differentiating the 1RS chromosome arms derived from ‘Amigo’ and ‘GRS1201′. The secalin proteins encoded by genes on 1RS chromosome arms differed in ‘Amigo’ and ‘GRS1201′. A 70 kDa secalin was found in the ‘Amigo’1AL.1RS, but did not occur in the ‘GRS1201’1AL.1RS. Polymorphisms detected by PCR primers derived from a family of moderately repetitive rye DNA sequences also differentiated the two translocations. When ‘GRS1201’was mated with a non-1RS wheat, no recombinants between 1RS markers were observed. In crosses between 1RS and non-1RS parents, both DNA markers and secalins would be useful as selectable markers for 1RS-derived greenbug resistance. Recombination between 1RS markers did occur when 1RS from ‘Amigo’ and 1RS from ‘GRS1201’were combined, but in such intermatings, the molecular markers described herein could still be used to develop a population enriched in lines carrying Gb6. No differences in grain yield or grain and flour quality characteristics were observed when lines carrying 1RS from ‘Amigo’ were compared with lines with 1RS from ‘GRS1201′. Hence, differences in secalin composition did not result in differential quality effects. When compared with sister lines with 1AL.1AS derived from the wheat cultivar ‘Redland’, lines with ‘GRS1201’had equal grain yield, but produced flours with significantly shorter mix times, weaker doughs, and lower sodium dodecyl sulphate sedimentation volumes.     

Genes for Powdery Mildew Resistance in Cultivars of Spring Wheat

Twenty-three cultivars of spring wheat were inoculated with nineteen different powdery mildew isolates; their ruction patterns hive been compared with those of twenty-two cultivars/lines carrying identified powdery mildew resistance genes. Applying the gene-for-gene hypothesis, it is evident that three cultivars have none of the resistance genes used, seven others (including ‘Solo’) may carry Pm4b, only. The resistance pattern of ‘Selpek’ is identical to A/-1 resistant cultivars of winter wheat and may be explained by the presence of Pm5. The resistance pattern of Pm5 (Mt-i) cultivars is very different from a number of ‘Kolibri’-related cultivars of spring wheat. Since either all or nothing of that specific pattern has been transferred to all cross progenies of ‘Kolibri’, a single gene is assumed to oe responsible for it, preliminarily designated as Ml-k. The cultivar ‘Mephisto’ carries the ‘Normandie’ resistance (Pwl 2, 9). In five cultivars to spring wheat the combined effects of at least two of the above-mentioned sources have been found. Despite the fact that ‘Normandie’ and ‘Sappo’ are not closely related. ‘Sappo’ shows the complete ‘Normandie’ resistance pattern plus that of Pm4b. The same is true for ‘Planet’ and ‘Walter’.     

Intergeneric Transfer (Rye to Wheat) of a Gene(s) for Russian Wheat Aphid Resistance

An octoploid triticale was derived from the F, of a Russian wheat aphid-resistant rye, ‘Turkey 77’, and ‘Chinese Spring’ wheat. The alloploid was crossed to common wheat, and to ‘Imperial’ rye/‘Chinese Spring’ disomic addition lines. F₂, progeny from these crosses were tested for Russian wheat aphid resistance and C-banded. A resistance gene(s) was found to be associated with chromosome arm IRS of the ‘Turkey 77’ rye genome. A monotelosomic IRS (‘Turkey 77’) addition plant was then crossed with the wheat cultivar ‘Gamtoos’, which has the 1BL.1RS ‘Veery’ translocation. Unlike the IRS segment in ‘Gamtoos’, the ‘Turkey 77’-derived 1 RS telosome did not express the rust resistance genes Sr31 and Ar26, which could then be used as markers. From the F, a monotelosomic 1 RS addition plant that was also heterozygous for the 1BL. 1 RS translocation was selected and testerossed with an aphid-susceptible common wheat, ‘Inia 66’ Meiotic pairing between the rye arms resulted in the recovery of five euploid Russian-wheat-aphid-resistant plants. One recombinant also retained Sr31 and Lr26 and was selfed to produce translocation homozygotes.     

Development and characterization of a new 1BL.1RS translocation line with resistance to stripe rust and powdery mildew of wheat

The 1BL.1RS wheat-rye translocation from Petkus rye has contributed substantially to the world wheat production. However, following the breakdown of disease resistance genes in 1RS, its importance for wheat improvement decreased. We have developed a new 1BL.1RS line, R14, by means of crossing rye inbred line L155, selected from Petkus rye to several wheat cultivars. One new gene each, for stripe rust and powdery mildew resistance, located on 1RS of the line R14, are tentatively named YrCn17 and PmCn17. YrCn17 and PmCn17 confer resistance to Puccinia striiformis f. sp. tritici pathotypes that are virulent on Yr9, and Blumeria graminis f. sp. tritici pathotypes virulent on Pm8. These two new resistances, YrCn17 and PmCn17, are now available for wheat improvement programs. The present study indicates that rye cultivars may carry yet untapped variations as potential sources of resistance.     

Genetic suppression of the cereal rye-derived gene Pm8 in wheat

The location of wheat gene Pm8 for resistance to powdery mildew in the 1RS chromosome segment derived from cereal rye cultivar Petkus was confirmed. There was reduced transmission of the 1BL.1RS chromosome relative to its wheat homologue in four of the five crosses examined. Pm8 was not expressed in some wheat cultivars and selections which possessed the 1RS chromosome identified by the presence of relevant genes for resistance to the three rusts, due to the presence of a dominant suppressor gene(s) in the wheat genome. The frequency of suppression in 1BL.1RS wheats from Mexico was significantly higher than in a group of wheats (both local and exotic) introduced from China and was probably much higher than in European wheats. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inheritance of the Powdery Mildew Resistance Gene Pm9 in Relation to Pm1 and Pm2 of Wheat

The inheritance of the powdery mildew resistance gene Pm9 originating from the hexaploid spring wheat cultivar ‘Normandie’ was analyzed in relation to Pm1 and Pm2. Two leaf segments of individual P_1?, P_2?, F_1? and F₂-plants of the cross ‘Normandie’ (Pm1, 2, 9) בFederation’ (no known Pm gene) were inoculated separately with two powdery mildew isolates. Using powdery mildew isolate No. 6 virulent for Pm1 and Pm2 but avirulent for Pm9, a 1 resistant (r): 3 susceptible (s) F₂-segregation was found for the Pm9 gene. Using powdery mildew isolate No. 3 virulent for Pm1 and Pm9 but avirulent for Pm2, a 3 (r): 1 (s) F₂-segregation was found for the Pm2 gene. Combining the data of both experiments (leaf segments of identical plants had been used), a 9 (sr): 3 (ss): 3 (rr): 1 (rs) segregation resulted for the F₂ of this cross: therefore, independent inheritance of the genes Pm2 and Pm9 can be concluded. Similarly, the cross ‘Mephisto’ (Pm1, 2, 9) בAmor’ (no known Pm gene) was analyzed. The Pm9 gene again showed a monogenically recessive inheritance, whereas Pm1 showed a monogenically intermediate segregation upon inoculation with powdery mildew isolate No. 9a virulent for Pm2 and Pm9 but avirulent for Pm1. Combining the single gene segregations, linkage between both genes was found among the progenies. A distance of 8.5 cM was calculated. Analyzing a set of spring wheat cultivars with seven defined powdery mildew isolates, the presence of Pm1, Pm2 and Pm9 in these lines was verified; in most cases, Pm1 occurred together with Pm9.     

Segregation for isozymes and HMW glutenins in a doubled-haploid cross of winter wheat carrying 1BL.1RS and 5DL.5RS translocations from rye

The doubled haploid (DH) wheat line ‘dh 5841’ carrying two translocations from rye, 5DL.5RS and 1BL.1RS, has been crossed to the subline of wheat cultivar ‘Amadeus 7143’ with a 1BL.1RS translocation. The resulting F₁ hybrid IJ 98 with a heterozygous 5DL.5DS‐5DL.5RS chromosome pair has been used to produce doubled haploids. A total of 57 DH lines were obtained from plantlets regenerated in anther culture after successful colchicine treatment and seed set. These lines were identified regarding the constitution of chromosome 5D (5DL.5DS or 5DL.5RS) by means of isoenzyme marker analysis. Thirty DH lines possessed the 5DL.5DS chromosome, while the remaining 27 lines carried the 5DL.5RS translocation. For some of these lines, the 5DL.5RS chromosome was cytologically confirmed by C‐banding. Furthermore, the DH lines were evaluated for their high molecular weight glutenin subunit composition. All possible combinations for the four independent loci —Skdh, Glu‐Al, Glu‐B1 and Glu‐D1— were detected in only 57 DH lines and no segregation distortion was observed.     

Molecular cytogenetic characterization and phenotypic evaluation of new wheat–rye lines derived from hexaploid triticale ‘Certa’ × common wheat hybrids

Hexaploid triticale contains valuable genes from both tetraploid wheat and rye and plays an important role in wheat breeding programmes. In order to explore the potential of hexaploid triticale ‘Certa’ in wheat improvement, two crosses were made using ‘Certa’ as female parent, and common wheat cultivars ‘Jinmai47’ (JM47) and ‘Xinong389’ (XN389) as male parents. The karyotyping of BCF_4:5 lines from Certa/JM47//JM47 and F_5:6 lines from Certa/XN389 was investigated using sequential fluorescence in situ hybridization (FISH). One 1B(1R) substitution line and five 1BL.1RS whole‐arm translocation lines were identified, one of which was found lacking ω‐secalin locus. Many structural alterations on wheat chromosomes were detected in the progeny. Great morphologic differences resulting from genetic variations were observed, among which the photosynthetic capability was increased while grain quality was slightly improved. Compared with both parents, the stripe rust resistance at adult stage was increased in lines derived from Certa/JM47//JM47, while it was decreased in lines derived from Certa/XN389. These newly developed lines might have the potential to be utilized in wheat improvement programmes.     

Chromosomal location of powdery mildew resistance gene Pm16 in wheat using SSR marker analysis

The use of resistant cultivars is a most economical way to control powdery mildew (Blumeria graminis f.sp. tritici) in wheat (Triticum aestivum L.). Identification of molecular markers closely linked to resistance genes can greatly increase the efficiency of pyramiding resistance genes in wheat cultivars. The objective of this study was to identify molecular markers closely linked lo the powdery mildew resistance gene Pm16. An F₂ population with 156 progeny was produced from the cross‘Chancellor’(susceptible) ב70281’ (resistant), A total of 45 SSR markers on chromosomes 4A and 5B of wheat and 15 SSRs on chromosome 3 of rice was used lo lest the parents, as well as the resistant and susceptible bulks: the resulting polymorphic markers were used to genotype the F₂ progeny. Results indicated that the SSR marker Xgwm159, located on the short arm of chromosome 5B, is closely linked to Pm16 (genetic distance: 5.3 CM). The cytogenetical data presented in an original report, in combination with this molecular analysis, suggests that Pm16 may he located on a translocated 4A.5BS chromosome.     

A sequence-specific PCR marker linked with Pm21 distinguishes chromosomes 6AS, 6BS, 6DS of Triticum aestivum and 6VS of Haynaldia villosa

To develop markers linked with Pm21 located on chromosome 6VS of Haynaldia villosa, a pair of primers (NAU/xibao15F and NAU/xibao15R) were designed according to the sequence of a serine/threonine kinase gene (Contig17515), whose expression was induced by Blumeria graminis and selected from the gene expression experiment using the Barley GeneChip. Using genomic DNA of various genetic stocks including the wheat variety ‘Yangmai#5’, H. villosa, Triticum durum–H. villosa amphiploid, seven T. aestivum–H. villosa addition lines involving chromosomes 1V–7V, the translocation line T6VS·6AL, and 21 nullisomic–tetrasomic and eight deletion lines of T. aestivum‘Chinese Spring’ as templates, four amplicons specific for 6VS, 6AS, 6BS and 6DS, respectively, were produced. F₂ individuals derived from the cross of ‘Yangmai#5’ × T6VS·6AL were analysed, and data indicate that NAU/xibao15₉₀₂ could be used as a co‐dominant marker for selecting Pm21 located on 6VS.     

Occurrence of 1BL.1RS wheat-rye chromosome translocation and of <Emphasis Type="Italic">Sr36/Pm6</Emphasis> resistance gene cluster in wheat cultivars registered in Hungary

The 1BL.1RS wheat-rye translocation and a wheat-Triticum timopheevii chromosomal introgression carry the Sr31, Lr26, Yr9 and Pm8 genes and the Sr36/Pm6 gene cluster, respectively. The objective of this study was to determine the distribution and impact of these two translocations in 220 wheat varieties registered in Hungary in the last 35 years until 2005. The 1BL.1RS translocation was introduced into Hungary via wheat cultivars ‘Avrora’ and ‘Kavkaz’, which were registered in 1970. New 1BL.1RS cultivars developed in Hungary first appeared in 1982. After reaching a maximum frequency of 50.0% among cultivars registered in Hungary in 1994, their presence declined steadily to 13.3% by 2005. The Sr36/Pm6 cultivars first appeared in 1980. Their frequency quickly reached 31.8% (1983–1984), but then dropped to between 9.6 and 18.5% (1990–2005). The two main Hungarian breeding programs showed opposing trends in the exploitation of these two translocations. In Martonvásár, 1BL.1RS played a dominant role, being present from 1993 to 1997 in ca. 95% of the released cultivars, while at the same time the use of Sr36/Pm6 was marginal. Conversely, among the Szeged cultivars, Sr36/Pm6 was present at high frequency (44.7% in 2002) with a low share of 1BL.1RS. In artificial field inoculation tests (1985–2003) both of the stem rust resistance genes provided significant resistance in all the years, though Sr36 proved more effective than Sr31. While Pm8 was not effective, except for the last 2 years, Pm6 exhibited significant resistance against powdery mildew in most of the 18 years tested. These data may help breeders to assess the usefulness of wheat-rye 1BL.1RS chromosome translocations and the Sr36/Pm6 resistance gene clusters in their future wheat improvement programs.     

12个小麦品种(系)白粉病抗性的遗传分析

利用17个不同来源和毒力的白粉菌菌株对12个小麦品种(系)进行苗期抗性鉴定和抗病性遗传分析,同时利用Pm2和Pm8基因的特异分子标记检测了相应基因。供试的12个品种至少能够抗11个白粉菌菌株。用E09、E20和Bg2菌株接种F₂群体,抗感植株分离比例和适合性测验证明这12个品种对不同白粉菌菌株的抗性均受1对显性基因控制。抗谱分析和基因紧密连锁分子标记(Xcfd81)分析表明良星66很可能含有Pm2或其等位基因。ω-黑麦碱基因(1RS染色体)和Glu-B1基因(1BS染色体)特异分子标记分析结果证明,山农20和郑麦9962含有T1BL·1RS易位染色体,即可能携带Pm8基因。由于Pm8基因对大多数菌株表现感病,所以这2个品种除Pm8外,还具有其他抗病基因。偃展4110与天民668对参试菌株的反应型表现一致,其他材料对不同菌株的反应型表现不同。     

Molecular detection of rye (Secale cereale L.) chromatin in wheat line 07jian126 (Triticum aestivum L.) and its association to wheat powdery mildew resistance

Powdery mildew (Pm), caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most serious diseases for common wheat in many regions around the world. Seeking for new resistance source is urgently required to meet the challenge of the rapid loss of resistance due to the co-evolution of the pathogen’s virulence. Wheat line 07jian126 (Triticum aestivum L.) is highly resistant to the Pm disease prevailing in Sichuan province of China. Previous study showed that a SSR marker Xbarc183 was linked to the Pm resistance in 07jian126, which might be controlled by a single dominant gene, designated as Pm07J126. In this study, two additional F₂ populations were used to confirm the linkage between Pm07J126 and Xbarc183. Furthermore, rye chromatin was detected in 07jian126 by molecular analysis of a rye-specific SCAR marker O5 which co-segregated with Pm07J126. This result indicated that Pm07J126 might originate from rye. The reaction patterns to 21 Bgt isolates and molecular marker analysis implied that Pm07J126 might be different from the known rye-derived Pm genes Pm7, Pm8, Pm17 and PmJZHM2RL. Chromosome observation, molecular marker, and A-PAGE analysis suggested that 07jian126 might be a rye introgression line and neither contain 1RS translocation nor secalins gene. Consequently, 07jian126 could be considered as a valuable resource for Pm resistance development of wheat. Besides, the molecular markers Xbarc183 and O5 are useful in marker-assisted selection of Pm07J126 in wheat breeding programs.     

Identification of powdery mildew resistance genes in common wheat (Triticum aestivum L. em Thell.). IX. Cultivars, land races and breeding lines grown in China

The objective of the study was to provide information about the occurrence and distribution of resistance genes in wheat cultivars, including old cultivars, land races and advanced breeding lines grown in China. Ninety-four accessions were analysed with a set of 11 differential powdery mildew isolates. Forty-four cultivars did not possess any major mildew resistance genes. Thirty cultivars revealed the response pattern of individual resistance genes. The most frequently encountered gene was Pm8, which occurred singly in 11 cultivars, combined either with Pm4a in three cultivars or with Pm4b in another three cultivars. However, 12 cultivars possessing the wheat-rye translocated chromosome pair T1BL-1RS did not express Pm8. Gene Pm2 was found in four cultivars and in combination with Pm6 in one cultivar. Genes Pm4a and Pm4b were observed in four and five cultivars, respectively. Another six cultivars carried Pm5. A gene combination of Pm2+Pm4b+Pm6 was found in one cultivar. Twelve cultivars and breeding lines exhibited a response pattern that could not be assigned to resistance genes or gene combinations present in the differential cultivars. Five out of these 12 cultivars/lines showed resistance to all the isolates tested. There is an urgent need to search for novel sources of mildew resistance in order to sustain resistance to existing and emerging powdery mildew pathogens.     

Characterization of stem rust resistant derivatives of wheat cultivar Amigo

Summary Originally developed for resistance to greenbug derived from Insave rye, Amigo wheat carries two genes for resistance to stem rust. One of these genes is associated with a rye chromosome 1RS segment carrying the Sec-1 protein marker and presumably greenbug resistance. The second gene which is genetically linked to leaf rust resistance is associated with an Agropyron-derived segment. Rust tests in Canada confirmed that these genes were Sr24 and Lr24. In contrast to Agent and certain 3D/Ag derivatives from Dr. E.R. Sears, the Amigo source of Sr24/Lr24 freely recombined with white seed colour during backcrossing.     

Identification of powdery-mildew-resistance genes in common wheat (Triticum aestivum L. em. Thell.). V. Old German cultivars and cultivars released in the former GDR

A total of 59 old wheat cultivars grown in Germany prior to 1960 were tested for mildew response using a collection of 12 differential isolates of Erysiphe graminis DC f. sp. tritici Marchal (Blumeria graminis (DC) Speer f. sp. tritici). Nineteen cultivars did not possess any major resistance gene and 25 were characterized by susceptible or intermediate responses. Fifteen cultivars revealed isolate-specific response patterns that could not be attributed to known major resistance genes or gene combinations. Many of the old German cultivars inherited a mildew-resistance gene from the Canadian cultivar ‘Garnet’ which is tentatively designated M1-Ga. Cultivars ‘Bretonischer Bartweizen’ (designated M1-Br) and ‘Adlungs Alemannen’ (designated M1-Ad) appeared to carry unknown resistance genes. Among 18 winter wheat cultivars released in the former GDR. eight showed susceptibility to all isolates used. Cv. “Borenos” carries resistance gene Pm3c. Five cultivars possess gene Pm4b. two cultivars gene pm5 and one cultivar a combination of genes Pm2 and Pm4b. Cultivar ‘Zentos’ was resistant to almost all isolates used. Its resistance might be conditioned by different unknown major resistance genes.     

Molecular cytogenetic analysis of a durum wheat ×Thinopyrum distichum hybrid used as a new source of resistance to Fusarium head blight in the greenhouse

Fusarium head blight (FHB, scab), caused by Fusarium graminearum Schwabe, is a serious and damaging disease of wheat. Although some hexaploid wheat lines express a good level of resistance to FHB, the resistance available in hexaploid wheat has not yet been transferred to durum wheat. A germplasm collection of Triticum durum× alien hybrid lines was tested as a potential source of resistance to FHB under controlled conditions. Their FHB reaction was evaluated in three tests against conidial suspensions of three strains of F. graminearum at the flowering stage. Two T. durum×Thinopyrum distichum hybrid lines, ‘AFR4’ and ‘AFR5′, expressed a significantly higher level of resistance to the spread of FHB than other durum‐alien hybrid lines and a resistant common wheat line ‘Nyu‐Bay’. Genomic in situ hybridization using total genomic DNA from alien grass species demonstrated that ‘AFR5’ had 13 or 14 alien genome chromosomes plus 27 or 28 wheat chromosomes, while ‘AFR4’ had 22 alien genome and 28 wheat chromosomes. All of the alien chromosomes present in these two lines belonged to the J genome. ‘AFR5’ is likely to be more useful as a source of FHB resistance than ‘AFR4’ because of its relatively normal meiotic behaviour, high fertility and fewer number of alien chromosomes. ‘AFR5’ shows good potential as a source for transferring FHB resistance gene into wheat. The development of T. durum addition lines carrying resistance genes from ‘AFR5’ is underway.     

Characterization of three wheat cultivars possessing new 1BL.1RS wheat-rye translocations

The wheat-rye 1BL.1RS translocation chromosomes have been used widely around the world in commercial wheat ( Triticum aestivum L.) production because of the presence of several disease resistance genes and a yield enhancement factor on the rye ( Secale cereale L.) chromosome. However, the recent reports of the loss of complete effectiveness of the disease resistance genes on the most commonly used 1BL.1RS chromosome have highlighted the need to seek and deploy additional sources of disease resistance genes. Three new sibling wheat cultivars, 'CN12', 'CN17' and 'CN18', were developed carrying 1RS arms derived from the rye inbred line L155. Genomic in situ hybridization and C-banding analysis revealed that all the three cultivars contained the rye chromosome 1RS arm fused to the wheat 1BL wheat chromosome arm. The three cultivars displayed high yields and high resistance to local powdery mildew and stripe rust pathotypes. Fluorescence in situ hybridization analysis indicated the different structure of 1BL.1RS chromosome between 'CN18' and the other two cultivars. The present study provides a new 1RS resource for wheat improvement.