Genetic diversity of wheat–rye 1BL.1RS translocation lines derived from different wheat and rye sources

Many studies have been conducted to determine the relative effects of the 1BL.1RS translocation on various traits in wheat. The effects of different wheat (Triticum aestivum L.) genetic backgrounds and rye (Secale cereale L.) sources have been addressed as major factors for inconsistent agronomic performance and end-use-quality traits of 1BL.1RS translocation wheats. However, all these studies were accomplished by using 1BL.1RS translocations with impure wheat genetic bases and narrow rye origins. The objective of this study was to test the genetic effects of centric fusion translocations by using primary 1BL.1RS lines derived from various pure wheat lines and rye sources. Twenty-one primary 1BL.1RS translocation lines were created from crosses between two pure wheat lines and three Chinese local rye varieties. These translocation lines and their wheat parents were then evaluated in southwestern China. The results provide direct evidence of the diverse effects of the different wheat parents and rye sources, taking part in 1BL.1RS translocations, on resistance to diseases, agronomic performance, and end-use quality traits. The highest amount of genetic diversity was observed in 1BL.1RS translocations derived from the same wheat lines and diverse rye varieties. The results suggest that the genetic diversity of 1BL.1RS translocation lines may originate from the different wheat genetic backgrounds, from different rye sources, from their interaction, and from the translocation itself. Creation of diverse 1BL.1RS translocations offers ample possibilities to introduce more variation into wheat for improved performance.     

Isolation of mildew resistant wheat-rye translocation lines from a double substitution line

A powdery mildew resistant double disomic wheat-rye substitution line carrying rye chromosomes 1R and 2R was crossed with normal bread wheats. The F₂ generation was analysed cytologically by C-banding. Wheat-rye chromosome translocations involving both rye chromosomes 1R and 2R were frequent in F₂. Lines with translocations of 1R and 2R were harvested separately. After four generations of selfing and selection for mildew resistance and fertility, fully fertile resistant lines were selected and analysed cytologically. Lines with 1BL/1RS and 2BS/2RL translocations were identified. The resistance on chromosome 1RS could not be shown to be different from control varieties carrying the same rye segment, while the resistance on 2RL is much broader than the earlier known 2RL derived resistance in the line Transec. This revised version was published online in July 2006 with corrections to the Cover Date.     

PCR-based markers for detection of different sources of 1AL.1RS and 1BL.1RS wheat–rye translocations in wheat background

The rye ( Secale cereale L.) chromosome arm 1RS is one of the most successfully used alien resources in wheat ( Triticum aestivum L.) improvement, and it is still being widely utilized by many breeding programmes. With increasing application of marker-assisted selection in wheat breeding, development of an efficient molecular marker system to monitor and track 1AL.1RS and 1BL.1RS wheat–rye translocations is of practical value. In this study, we systematically evaluated the utility of eight rye-specific molecular markers in detecting 1RS chromatins with different origins in diverse wheat genetic backgrounds. Two such markers, PAWS5/S6 and SCM9 were identified that were able to differentiate multiple sources of wheat–rye translocations involving 1RS. A duplex polymerase chain reaction (PCR) procedure was developed with two rye-specific markers PAWS5/S6 and RIS and tested in a set of representative wheat lines. The two rye-specific markers and the duplex PCR procedure established in this study provided a useful tool in marker-assisted selection of materials containing desirable 1RS chromatin in wheat breeding.     

Identification of Rye Chromosome 1R Translocations and Substitutions in Hexaploid Wheats Using Storage Proteins as Genetic Markers

Grain protein compositions of 106 advanced generation backcross lines from crosses involving ‘Amigo’ (1AL.1RS), ‘Aurora’, ‘Kavkaz’, ‘Skorospelka-35’ and ‘Sunbird’ (all 1BL.1RS) and ‘Gabo’ 1DL.1RS parents and 152 cultivars with unknown pedigree were analysed by one-dimensional SDS-PAGE. Eighty seven backcross lines and 16 cultivars carried one or other of these translocations, 2 cultivars had a 1R (1B) substitution, whereas 5 backcross lines were found to be heterogeneous for the 1BL.1RS translocation. The translocation lines were easily identified by the presence of secalins (Sec-1) controlled by rye chromosome arm IRS and a simultaneous loss of the gliadin (Gli-1) and/or triticin (Tri-1) protein bands controlled by the replaced wheat chromosome arm (1AS, 1BS or 1DS). Certain gliadins, showing no allelic variation among the genotypes analysed, were identified as markers for chromosome arms 1AS (M_r= 34 kd) and IBS (M_r= 42,33 kd). The whole chromosome substitutions 1R (1B) were recognized by scoring for the presence of Sec-1 and HMW secalin bands, Sec-3 (controlled by rye chromosome arm 1RL) and the absence of Gli-B1 and HMW glutenin subunits, Glu-B1 (controlled by wheat chromosome arm 1BL). The results have shown that protein electrophoresis provides a rapid and reliable technique for screening genotypes for these translocations and substitutions in a breeding programme.     

Identification of the spontaneous 7BS/7RL intergenomic translocation in one F1 multigeneric hybrid from the Triticeae tribe

The F1 AABBRH^ch hybrids studied here were produced by crosses between the Portuguese triticale cultivar 'Douro' (AABBRR) and the tritordeum line HT9 (AABBH^chH^ch). Fluorescent in situ hybridization performed with genomic DNA probes genomic in situ hybridization (GISH) from rye and Hordeum chilense allowed the unequivocal parental genomes discrimination in all hybrids. Among 55 plants, one presented a spontaneous wheat–rye translocation which was successfully detected after GISH. Recombinant chromosomes identification was made after reprobe with pTa71 and pSc119.2. Nine rDNA loci were detected by pTa71 and pSc119.2 identified the chromosome arms involved in the translocation, after comparing the observed hybridization patterns with those described by several authors. We identified the spontaneous wheat–rye translocation as being the 7BS/7RL. Many wheat–rye translocations have been found (e.g. 1BL.1RS and 1AL.1RS), but as far as we know, this is the first time that this translocation is reported. We considered it helpful for wheat breeding programmes as it could provide the transference of interesting agronomic characteristics from rye (e.g. leaf rust resistance) to wheat.     

Further manipulation by centric misdivision of the 1RS.1BL translocation in wheat

Complete chromosomes 1R and 1B were reconstructed in wheat from the centric wheat-rye translocation 1RS.1BL. Three substitutions: 1R(1A), 1R(1B), 1R(1D), and three new centric translocations: 1RS.1AL, 1RS.1BL, 1RS.1DL were produced from the reconstructed chromosome 1R. Each one of these has the same rye chromosome arm 1RS which was present in the original translocation 1RS.1BL of ‘Kavkaz’ wheat. Reconstructed chromosome 1B and a normal chromosome 1R were used to produce a new 1RS.1BL translocation. This translocation has the long arm from the original 1RS.1BL translocation of ‘Kavkaz’, but a different 1RS arm. The third generation centric translocations were mitotically stable and were normally transmitted to progeny. Misdivision frequency of the reconstructed chromosomes 1R did not change relative to normal 1R, whereas the misdivision frequency of the two reconstructed chromosomes 1B tested was significantly higher relative to normal 1B. These experiments demonstrate that repeated cycles of centric breakage and fusion do not impair the function of centromeres in wheat and rye but may change chromosome's susceptibility to misdivision. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Use of Monosomic Rye Addition Lines for Transferring Rye Chromatin into Bread Wheat

Hybrid plants with 21 pairs of wheat chromosomes and with a haploid rye genome were produced by backcrossing a primary octoploid triticale with its parental hexaploid wheat. Upon a second backcrossing or selfing, the rye chromosomes were eliminated rapidly. Added rye chromosomes, in varying numbers, affected the transmission rate of wheat chromosomes significantly. Loss of wheat chromosomes ranging from 0.06 to 0.35 per plant in different populations was observed. In these plants a remarkably high incidence of wheat/rye and rye/rye translocations occurred. Translocations were identified by using the C-banding technique. Among 837 analyzed plants 64 wheat/rye and 256 rye/rye translocations were identified. In different generations of backcrossing or selfing the frequency of wheat/rye translocations varied between 4.23 % and 14.67 %. All 14 rye chromosome arms were involved in translocations but with different frequencies. BC₁F₃ plants with homozygous wheat/rye translocations were isolated The results indicate that monosomic wheat/rye addition lines may be directly used as an effective means to transfer genetic material from rye into bread wheat.     

Biochemical, molecular, and cytogenetic technologies for characterizing 1RS in wheat: A review

Chromosome arm 1RS of rye ( Secale cereale L.), when transferred to wheat ( Triticum sp.), significantly influences variety performance, because it carries genes for resistance to disease and insect pathogens. Inserted into wheat, 1RS also promotes haploid production, affects end-product quality, and sometimes affects yield. Therefore, its detection by breeders and geneticists is important. The entire 1RS arm is present in chromosome substitutions and in Robertsonian translocations involving chromosomes 1A, 1B, or 1D of wheat. In recombinant lines, a segment of 1RS has been exchanged with a segment of a group-1 wheat chromosome. Determining the wheat chromosome arm involved in a translocation, the source of rye chromatin, and the amount of 1RS chromatin introduced is necessary for a complete characterization of the introgressed segment. Biochemical, molecular, and cytogenetic technologies are described which enable such a characterization of 1RS in wheat. Examples of using gel electrophoresis, high-performance liquid chromatography, monoclonal antibodies, rye-specific molecular probes, RFLP and PCR assays, chromosome banding, in situ hybridization, and flow cytometry are provided. A comparison of these technologies is made and the advantages and disadvantages of each technology are discussed relative to modern wheat breeding efforts. This revised version was published online in July 2006 with corrections to the Cover Date.     

1BL·1RS特异性分子标记的筛选及其对不同来源小麦品种1RS易位染色体的鉴定

1BL?1RS易位系在我国小麦育种和生产中占有重要地位,快速而准确地鉴定1BL?1RS易位系对小麦品质改良具有重要意义。本研究选用15个1BL?1RS特异性STS、SCAR和RAPD标记及22个1RS染色体上的SSR标记,检测不同来源的1BL?1RS易位系78份以及非1BL?1RS易位系品种10份和黑麦材料3份,其中1BL?1RS易位系包括周8425B及其衍生系36份、兰考906及其衍生系5份、矮孟牛及其衍生系8份和洛类1BL?1RS易位系品种29份。结果表明,7个STS标记、1个SCAR标记、3个RAPD标记和3个黑麦SSR标记可作为鉴别1BL?1RS易位系的可靠分子标记,其中ω-sec-p1/ω-sec-p2、ω-sec-p3/ω-sec-p4、H20和SECA2/SECA3标记最好,扩增效果稳定,重复性好,条带清晰,实验操作简单。周8425B及其衍生系、兰考906及其衍生系、矮孟牛及其衍生系与洛类1BL?1RS易位系的1RS染色体在分子标记检测中没有差异。     

A set of new 1RS translocations from wheat cv. Amigo in a uniform genetic background

Wheat-rye translocation 1RS.1AL from cv. Amigo is still popular in wheat breeding and commercial cultivars. It introduces several disease and pest resistance genes from rye into wheat, and appears to enhance root system development. To create a set of uniform stocks for precise tests, the rye arm 1RS was separated from the wheat arm in the translocation by misdivision of centromeres in univalents, fused into a complete chromosome 1R, and then re-translocated to all group-1 wheat chromosomes 1A, 1B and 1D, creating a set of three translocation and three substitution lines in a uniform background of cv. Pavon 76. Misdivision frequencies of the chromosomes mirrored those observed earlier in that shorter chromosomes broke less frequently than the long ones, and chromosomes from previous misdivision-fusion events misdivided more frequently than normal intact chromosomes. This set of chromosome lines with 1RS from cv. Amigo increases to three the number of such translocations stocks in wheat.     

利用1RS特异标记和染色体原位杂交技术鉴定小麦1BL·1RS易位系

以小麦-黑麦1BL·1RS易位系(Kavkaz、山农030-1)、1AL·1RS易位系(Amigo)、荆州黑麦、八倍体小黑麦劲松49、1R-7R二体异附加系以及普通小麦中国春、辉县红、铭贤169、Chancellor等为材料,对65个黑麦1RS特异标记进行鉴定,从中筛选出8个稳定的标记,即NOR-1、SECA2/SECA3、SCSS30.2、Sec1Gene、Sec1Pro、ω-Sec-P1/P2、ω-Sec-P3/P4和IB-267,可用于检测1AL·1RS易位系或1BL·1RS易位系;另外3个特异标记O-SEC5′-A/O-SEC3′-R、IAG95-1和SCM-9可用于区别1RS来源不同的1AL·1RS和1BL·1RS易位系。利用这11个标记和染色体原位杂交技术对40份山东省近年育成小麦品种(系)进行检测,发现潍麦8号、鲁麦14、济宁13、山农664、山农优麦3号和烟农25为1BL·1RS易位系,而且是1RS的整臂易位系,未检测到1AL·1RS易位系和其他易位类型。     

About the origin of 1RS.1BL wheat-rye chromosome translocations from Germany

In order lo investigate the origin of two of the German 1RS. 1BL wheat-rye translocations used world-wide in breeding, a number of DNA probes were considered which (a) were critical for the short arm of the rye chromosome 1 R and (b) should show a specificity for the gene pool of Petkus rye. The DNA probe CDO580 was revealed as a specific one. (1) It clearly differentiated 1RS.1AL (‘Amigo’). 1RS.lBL (‘Salmon’) and 1RS.1DL (‘Gabo’) from the two German sources. (2) Both translocation wheats deriving from the Weihenstephan (Munich) and from the Salzmünde (Halle/S.) origin showed an identical DNA fragment which was typical for the gene pool of Petkus rye. It is supposed that both German sources have one progenitor in common.     

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.     

Identification of seven telotrisomics of rye (Secale cereale L.)

Summary Seven monotelotrisomics emerged spontaneously from primary trisomics of rye cv. Esto. Analyses of karyotype, of chromosome pairing in meiosis and of Giemsa banding pattern were used to identify monotelotrisomics in rye as IRS, 1RL, 3RS, 4RS, 4RL, 6RS and 7RL. Vitality and fertility were better than in primary trisomics. The extra telocentrics were well transmitted through the female gamete. Transmission through the male gamete was in all cases less than trasmission through the female gamete.     

Three classes of loci controlling preharvest sprouting in rye (Secale cereale L.) discerned by means of bidirectional selective genotyping (BSG)

Bidirectional selective genotyping (BSG) carried out on recombinant inbred lines (RILs) derived from the 541 × Ot1-3 intercross revealed three classes of selection responsive loci underlying preharvest sprouting (PHS) in rye. Ten PHS directional loci (PHSD) located on chromosomes 1RL (3), 3RS (2), 3RL (2), 5RL (2), and 7RS (1) responded significantly to both directions of the disruptive selection and were epistatic to the remaining two classes. Nine PHS resistance loci (PHSR) mapped on chromosomes 1RS, 1RL, 2RS, 3RS, 4RS, 5RS, 5RL, and 6RL (2) responded only to selection for sprouting resistance, being neutral for selection carried out in opposite direction. Eight PHS enhancing loci mapped on chromosomes 2RL, 3RL, 4RL, 5RL, 6RS, and 7RS (3) were affected by selection for sprouting susceptibility and did not respond to selection for sprouting resistance. Map positions of the selection responsive loci coincided with QTLs for PHS and alpha-amylase activity (AA) detected earlier, but BSG coupled with molecular mapping increased precision of PHS dissection in rye. Efficient strategy of marker assisted selection for preharvest sprouting resistance in rye should be based on PHSD and PHSR loci.     

小麦-黑麦1RS/1BL新易位系的创制和分子细胞遗传学鉴定

利用普通小麦（Triticum aestivum L．）品种小偃6号与黑麦（Secale cereale L．）品种德国白粒杂交，选育出一批带有黑麦抗病性状的小偃6号类型种质材料。应用连续C-分带-基因组原位杂交（sequent C-banding-GISH）技术对上述材料进行染色体组成分析，筛选出2个小麦-黑麦1RS/1BL纯合易位系BC152-1-1和BC01-89-1。其中，BC152-1-1（2n=42）除含有1对1RS/1BL易位染色体外，未见其他染色体变异；BC01-89-1（2n=43）除含有1对1RS/1BL纯合易位染色体外，还附加1条两端缺失的3R染色体。高分子量麦谷蛋白亚基（HMW-GS）组成分析和品质分析结果表明，BC152-1-1和BC01-89-1不仅含有来自小偃6号的14＋15优质亚基，而且其蛋白质含量、湿面筋含量和SDS沉降值等品质性状都得到显著改良。     

Dosage Response of Rye Genes in a Wheat Background

Wheat (Triticum aestivum L.) breeders often utilize alien sources to supply new genetic variation to their breeding programs. However, the alien gene complexes have not always behaved as desired when placed into a wheat background. The introgressed genes of interest may be linked to undesirable genes, expressed at low levels or not at all. The short arm of rye (Secale cereale L.) chromosome one (1RS) contains many valuable genes for wheat improvement. In order to study rye gene response to varying copy number, wheat lines were constructed which contained zero, two or four doses of 1RS. The meiotic behavior of rye chromosome 1R, and wheat/rye translocation chromosomes, 1AL/1RS and 1BL/1RS was studied in the F₁ hybrids between wheat lines carrying 1R or the translocation chromosomes. The IRS arm was transmitted at a very high frequency; 98 % of the F₂ plants had at least one of the chromosomes with a IRS arm. In addition, 44 % of the F₂ plants received at least one copy of the chromosomes from each parent. Analysis of the meiotic behavior of the IRS arm suggested that few euploid wheat gametes were formed. Therefore, most of the pollen must have contained IRS. It is unknown whether the lack of euploid wheat pollen could account for the high transmission frequency of the rye chromosomes. There may have been differential survival of the embryos receiving the rye chromosome as well.     

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.     

Similarities and differences between Amaranthus species and cultivars and estimation of outcrossing rate on the basis of electrophoretic separations of urea-soluble seed proteins

Wheat-rye translocation line (2BS/2RL) has been developed for resistance to biotype L of Hessian fly and agronomically useful traits. AFLP analysis using 64 primer pairs was conducted in order to identify 2RL-specific polymorphisms between “Coker 797” (non-2RL), near-isogenic line (NIL) carrying 2RL, and “Hamlet”. Nine primer combinations identified twelve reproducible polymorphic fragments in the NIL carrying 2RL. These twelve fragments were cloned and sequenced with an aim towards converting AFLP markers into sequence tagged sites (STS). A comparison of the 12 sequences with non-redundant accessions in the NCBI database using the BLAST search option indicated that one fragment of approximately 200 bp in length (amplified using primer combination E+AAC / M+CTA) was highly homologous with the rye-specific repetitive sequence R173-1 and Wis-2-lA, a retrotransposon-like element in wheat. Two STS primers (SJ07 and SJ09) out of twelve STS primer sets enabled the detection of polymorphisms between Coker 797 and NIL carrying 2RL. In order to verify whether the polymorphism detected by primers SJ07 and SJ09 was in fact the result of the presence of 2RL, additional plant material was examined. Amplified products of about 260 bp fragment with the SJ07 primer set were generated in rye cvs.“Chilbohomil” and “Jochunhomil”, triticale experimental line Suwon 15, and wheat experimental line K-14 (1AL/1RS & 2BS/2RL), as well as NIL carrying 2RL and Hamlet, but not in Coker 797 (non-2RL), “Keumgangmil” (non-translocation wheat), KS92WGRC17 (PI592729 /;/ 6BS/6BL-6RL), KS92WGRC19 (P1592731 /;/ 4BS/4BL-6RL), “TAM200” (1AL/1RS), and “Siouxland” (1BL/1RS). Our data suggest that primer set SJ07 amplifies a “2RL-specific” fragment of diagnostic value. This revised version was published online in August 2006 with corrections to the Cover Date.     

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.