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.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

Characterization of wheat-alien translocations conferring resistance to diseases and pests: current status

Summary Wild relatives of common wheat, Triticum aestivum, and related species are an important source of disease and pest resistance and several useful traits have been transferred from these species to wheat. C-banding and in situ hybridization analyses are powerful cytological techniques allowing the detection of alien chromatin in wheat. C-banding permits identification of the wheat and alien chromosomes involved in wheat-alien translocations, whereas genomic in situ hybridization analysis allows determination of their size and breakpoint positions. The present review summarizes the available data on wheat-alien transfers conferring resistance to diseases and pests. Ten of the 57 spontaneous and induced wheat-alien translocations were identified as whole arm translocations with the breakpoints within the centromeric regions. The majority of transfers (45) were identified as terminal translocations with distal alien segments translocated to wheat chromosome arms. Only two intercalary wheat-alien transloctions were identified, one induced by radiation treatment with a small segment of rye chromosome 6RL (H25) inserted into the long arm of wheat chromosome 4A, and the other probably induced by homoeologous recombination with a segment derived from the long arm of a group 7 Agropyron elongatum chromosome with Lr19 inserted into the long arm of 7D. The presented information should be useful for further directed chromosome engineering aimed at producing superior germplasm.Contribution No. 96-55-J from the Kansas Experimental Station, Kansas State University, Manhattan, KS 66506-5502, USA.     

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。     

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.     

Basic studies on hybrid wheat breeding using the 1BL-1RS translocation chromosome / Aegilops kotschyi cytoplasm system 1. Development of male sterile and maintainer lines with discovery of a new fertility-restorer

The Aegilops kotschyi cytoplasm and a 1BL-1RS translocation chromosome that consists of the long arm of wheat chromosome 1B and the short arm of rye chromosome 1R were transferred to six spring common wheat cultivars by repeated backcrossing. Resistance to leaf rust race 21B conditioned by the Lr26 gene and a secalin subunit encoded by the Sec-1 gene, both on the 1RS arm, were used as the selection markers of the translocation chromosome. Five of the six cultivars used were converted to complete male steriles, whereas the remaining one, cv. Kitamiharu 48, retained normal fertility, after transfer of both the 1BL-1RS chromosome and Ae. Kotschyi cytoplasm. Conventional gene analysis suggested that Kitamiharu 48 carries an incompletely dominant fertility-restoring gene. The F₁ hybrids between the male steriles and ordinary common wheat cultivars recovered fertility only at a low level, indicating that a single dose of the Rfv1 gene on the 1BS arm of wheat is insufficient for full fertility restoration under spring-sowing condition. Our results are in clear contrast to complete fertility restoration under fall-sowing condition reported by Nonaka et al. (1993). Combination of the 1BL-1RS chromosome / Ae. Kotschyi cytoplasm system with a new fertility-restoring gene discovered in Kitamiharu 48 may provide a breakthrough for spring-type hybrid wheat. This revised version was published online in August 2006 with corrections to the Cover Date.     

Confirmation of a 1A/1R Wheat-Rye Chromosome Translocation in the Wheat Variety 'Amigo'

Differential chromosome staining by using the Giemsa C- banding technique and test crosses have revealed rye chroma tin in the hexaploid wheat variety ‘Amigo’ which resulted from wheat crosses with the octoploid triticale ‘Gaucho’. The results demonstrated a pair of translocated wheat chromosomes involving the short arm of rye chromosome 1R and the long arm of the homoeologous wheat chromosome 1A (1Aq/1Rp translocation). The localization of the translocation breakpoint is supposed 10 be within the centromeric region.     

川麦42的1BS染色体臂对小麦主要农艺性状的遗传效应

川麦42的1BS染色体臂来源于人工合成小麦亲本Syn769。利用川麦42与含1BL/1RS易位系的四川小麦品种川农16构建的127个重组自交系(RIL, F₈),经3年4个环境的遗传评价,比较了川麦42的1BS和川农16的1RS染色体臂对小麦产量构成因子和产量的遗传效应。结果表明,RIL群体中川麦42的1BS染色体臂株系和川农16的1RS染色体臂株系在分蘖力、成穗率、全生育期、小穗数、收获指数和籽粒产量6个性状上存在显著差异; 1BS染色体臂有利于提高成穗率和收获指数,而1RS染色体臂有利于提高分蘖能力和增加小穗数,1BS株系的籽粒平均产量比1RS株系增加2.91%。鉴于1RS染色体臂上的抗条锈病基因丧失抗性,其携带的黑麦碱基因对加工品质有明显的负向作用,而川麦42的1BS染色体臂携带高抗条锈病基因YrCH42, 并对小麦籽粒产量有正向作用,因此建议在小麦遗传改良中利用川麦42的1BS替换1RS染色体臂。     

小麦–黑麦易位系T1BL·1RS在小麦品种中的分布及其与小麦赤霉病抗性的关联

黑麦1R染色体短臂(1RS)携带条锈病、叶锈病、秆锈病、白粉病和蚜虫等抗性基因。为了检测1RS上是否携带与赤霉病抗性相关的基因,本研究采用1RS特异标记Xscm9对192个来自不同国家的品种/系构成的小麦自然群体和1个重组自交系(RIL)群体(宁7840与Chokwang杂交的F_7群体,共184个系)进行了分子检测,并在2011 2013年采用单花滴注法于温室中进行赤霉病抗性鉴定。结果发现,自然群体中22个品种携带1RS,携带1RS的株系三季赤霉病平均病小穗率(PSS)均显著低于不携带1RS株系的PSS(P0.01),表明1RS对降低病小穗率有显著作用。分子标记和基因组原位杂交(GISH)检测结果表明,宁7840携带1RS。通过对宁7840/Chokwang衍生的RIL群体进行赤霉病抗性鉴定和基因型分析,发现不论主效赤霉病抗性基因Fhb1(标记Xsts142)存在与否,携带1RS株系的PSS显著低于不携带1RS株系的PSS(P0.01);方差分析表明,宁7840携带的Fhb1与1RS在赤霉病抗扩展性上无显著互作(P0.05)。因此认为,黑麦1RS染色体很可能携带赤霉病扩展抗性相关基因,与Fhb1基因有累加效应。     

Quality effect of wheat-rye (1R) translocation in 'Pavon 76'

A growing interest exists in using wheat for producing both hard and soft wheat products. It would be desirable if 1RS translocations in hard wheat could produce flour suitable for soft wheat products. The objective of this study was to test the effects of centric translocations of chromosome 1 from different rye sources for end‐use quality. The quality influences of the 1RS and 1RL translocations and 1R substitutions from different rye sources were studied in a set of hard spring wheat ‘Pavon 76’(CIMMYT) lines in three environments in Georgia. The protein concentration of the 1RL translocations was the highest while the 1RS translocations showed no difference in protein concentration compared with that of controls. The 1RS translocations increased alkaline water retention capacity while the 1RL translocations reduced it. T1DSAE1RL was preferred for soft wheat products over other genotypes.     

对基因组原位杂交信号释译可能出现的片面性——来自一个小麦易位系(A-3)中外源遗传物质鉴定的启示

利用基因组原位杂交(GISH)和种子醇溶蛋白电泳(A-PAGE)技术对一个可能携带有10倍体长穗偃麦草(Thinopyrum ponticum (Host) Liu & Wang)遗传物质的小麦新种质A-3进行了综合鉴定. 用普通小麦"中国春"(Triticum aesticum L. cv. Chinese Spring)基因组(ABD)DNA作探针, 拟鹅观草[Pseudoroegneria stipifolia(Czern e     

An STS marker distinguishing the rye-derived powdery mildew resistance alleles at the Pm8/Pm17 locus of common wheat

A sequence‐tagged site marker has been developed from restriction fragment length polymorphism marker probe IAG95 for the rye‐derived powdery mildew resistance Pm8/Pm17 locus of common wheat. This polymerase chain reaction marker enables the amplification of DNA fragments with different sizes from T1AL.1RS and T1BL.1RS wheat‐rye translocation cultivars with chromatin from ‘Insave’ and ‘Petkus’ rye, respectively, and therefore will be very useful in distinguishing Pm8‐carrying cultivars from Pm17‐carrying cultivars. Results obtained with that marker were compared with resistance tests performed on detached primary leaves of 29 wheat lines from two populations derived from doubled haploid production. The molecular assay corresponded well with the resistance tests in all the lines, and therefore will be helpful for the identification of Pm17 in lines in which other Pm genes or quantitative trait loci are present.     

Evidence for Monotelodisomics in Rye (Secale cereale L.)

Monotelodisomics of chromosome arms 2RL and 6RL were observed in progenies of rye trisomics. The monotelodisomic of chromosome arm 6RL (2n = 13 + 6RL) is vital and is well transmitted through the pollen. In the progeny of monotelodisomic 2RL. (2n = 13 + 2RL) no monotelodisomic but one monotelotrisomic of chromosome arm 2RS (2n = 14 + 2RS), one trisomic with an aberrant chromosome consisting (if chromosome arm IRS and a part of chromosome arm 2RL (2n = 14 + 2RSL) and one double telotrisomic of chromosome 2R (2n = 13 + 2RS + 2RL) have been identified.     

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.