Development of a wheat genotype combining the recessive crossability alleles kr1kr1kr2kr2 and the 1BL.1RS translocation, for the rapid enrichment of 1RS with new allelic variation

The main objective of the present work was to develop a wheat genotype containing both the recessive crossability alleles (kr1kr1kr2kr2), allowing high crossability between 6x wheat and diploid rye, and the 1BL.1RS wheat/rye translocation chromosome. This wheat genotype could be used as a recipient partner in wheat–rye crosses for the efficient introduction of new allelic variation into 1RS in translocation wheats. After crossing the wheat cultivars ‘Mv Magdaléna’ and ‘Mv Béres’, which carry the 1BL.1RS translocation involving the 1RS chromosome arm from ‘Petkus’, with the line ‘Mv9 kr1’, 117 F₂ plants were analysed for crossability, ten of which had higher than 50% seed set with rye and thus presumably carried the kr1kr1kr2kr2 alleles. Four of the ten plants contained the 1BL.1RS translocation in the disomic condition as detected by genomic in situ hybridization (GISH). The wheat × rye F₁ hybrids produced between these lines and the rye cultivar ‘Kriszta’ were analysed in meiosis using GISH. 1BL.1RS/1R chromosome pairing was detected in 62.4% of the pollen mother cells. The use of fluorescent in situ hybridization (FISH) with the repetitive DNA probes pSc119.2, Afa family and pTa71 allowed the 1R and 1BL.1RS chromosomes to be identified. The presence of the 1RS arm from ‘Kriszta’ besides that of ‘Petkus’ was demonstrated in the F₁ hybrids using the rye SSR markers RMS13 and SCM9. In four of the 22 BC₁ progenies analysed, only ‘Kriszta’-specific bands were observed with these markers, though the presence of the 1BL.1RS translocation was detected using GISH. It can be concluded that recombination occurred between the ‘Petkus’ and ‘Kriszta’ 1RS chromosome arms in the translocated chromosome in these plants.     

Production of a new wheat line possessing the 1BL.1RS wheat-rye translocation derived from Korean rye cultivar Paldanghomil

The 1BL.1RS translocations between wheat (Triticum aestivum L.) and rye (Secale cereale L.) are widely used in bread wheat breeding programs, but all modern wheat cultivars with the 1BL.1RS have shown genetic vulnerability due to one rye source – a German cultivar, Petkus. We have developed, a new 1BL.1RS wheat-rye translocation line from the backcross of the F₁ hybrid of wheat cv. Olmil and rye cv. Paldanghomil, both cultivars from Korea. The GISH technique was applied to identify the presence of rye chromatin in 467 BC₁F₆ lines selected from 77 BC₁F₅ lines. Only one line, Yw62–11, showed wheat-rye translocated chromosomes, with a somatic chromosome number of 2n=42. C-banding patterns revealed that the translocated chromosome was 1BL.1RS, showing prominent bands in the terminal and sub-terminal regions of the short arm as well as in the centromeric region and terminal region of the long arm. This new 1BL.1RS translocation line formed 21 bivalents like common wheat at meiotic metaphase I, thereby showing complete homology. Received: 28 February 2001 / Accepted: 17 April 2001     

A Mutant with Expression Deletion of Gene Sec-1 in a 1RS.1BL Line and Its Effect on Production Quality of Wheat

The chromosome arm 1RS of rye (Secale cereal L.) has been used worldwide as a source of genes for agronomic and resistant improvement. However, the 1RS arm in wheat has end-use quality defects that are partially attributable to the presence of ω-secalins, which are encoded by genes at the Sec-1 locus. Various attempts in removing the Sec-1 genes from the 1RS.1BL translocation chromosome have been made. In the present study, two new primary 1RS.1BL translocation lines, T917-26 and T917-15, were developed from a cross between wheat variety “{"type":"entrez-nucleotide","attrs":{"text":"A42912","term_id":"2298361"}}A42912” and Chinese local rye “Weining.” The lines T917-15 and T917-26 carried a pair of intact and homogeneous 1RS.1BL chromosomes. The line T917-26 also harbored an expression deletion of some genes at the Sec-1 locus, which originated from a mutation that occurred simultaneously with wheat-rye chromosome translocations. These results suggest that the accompanying mutations of the evolutionarily significant translocations are remarkable resources for plant improvement. Comparison of translocation lines with its wheat parent showed improvements in the end-use quality parameters, which included protein content (PC), water absorption (WA), sodium dodecyl sulfate sedimentation (SDSS), wet gluten (WG), dry gluten (DG) and dough stickiness (DS), whereas significant reduction in gluten index (GI) and stability time (ST) were observed. These findings indicate that 1RS in wheat has produced a higher amount of protein, although these comprised worse compositions. However, in the T917-26 line that harbored an expression deletion mutation in the Sec-1 genes, the quality parameters were markedly improved relative to its sister line, T917-15, especially for GI and DS (P < 0.05). These results indicated that expression deletion of Sec-1 genes significantly improves the end-use quality of wheat cultivars harboring the 1RS.1BL translocation. Strategies to remove the Sec-1 genes from the 1RS.1BL translocation in wheat improvement are discussed.     

黑麦碱基因（Sec–1）表达缺失的1RS／1BL易位系的鉴定

用改良的Giemsa C－带技术、DNA原位杂交和酸性聚丙烯酰胺凝胶电泳（A-PAGE）对来源于小麦品种绵阳11与不同黑麦自交系远缘杂交获得的高代株系（BC1F7）的染色体结构和醇溶蛋白进行了研究。结果发现,在鉴定的200个株系中,有45个株系经C-带和A-PAGE检测均一致地发现它们含有一对1RS /1BL易位染色体,而一个株系843-1-1,C-带鉴定、原位杂交结果均证明它含有一对1RS/1BL易位染色体,但A-PAGE醇溶蛋白图谱却不具有黑麦1RS染色体臂的黑麦碱特征带,而表达出既不同于黑麦碱又不同于亲本绵阳11的醇溶蛋白带型。这一结果表明,利用不同的黑麦亲本资源,可以获得黑麦碱基因Sec-1表达缺失的新的1RS/1BL易位系。这种新的1RS/1BL易位系缺失了影响小麦品质的黑麦碱蛋白,因此是进一步研究1RS/1BL 易位对小麦品质影响的珍贵材料。研究指出,在利用外源基因的植物育种中,外源种供体材料的遗传多样性是值得重视的基因资源。     

Transfer of the 1BL/1RS wheat-rye-translocation from hexaploid bread wheat to tetraploid durum wheat

Summary The present study describes a cytological stable alien chromosome translocation in tetraploid durum wheat. By crossing the hexaploid 1BL/1RS wheat-rye translocation line Veery to the tetraploid durum wheat cultivar Cando it was possible to select a 28 chromosomic strain homozygous for the 1BL/1RS translocation. The disease resistance potential of the short arm of rye chromosome 1R, which has been widely introduced in many hexaploid bread wheat cultivars could be now also used for the improvement of durum wheat.     

Conjugation of the 1BL/1RS translocation with qualitative and quantitative traits in the common wheat T.aestivum

The review considers the effect of the rye 1BL/1RS translocation in the common wheat genome on qualitative and quantitative traits: grain quality, resistance to diseases, productivity and adaptivity, parthenogenesis, regeneration in anther culture, frequency of chromosome aberrations and frequency of cross-pollination. Data on special features of transmission of the 1BL/1RS translocation through male and female gametes are presented.     

Characterization of Low Molecular Weight Glutenin Subunit Gene Representing Glu-B3 Locus of Indian Wheat Variety NP4

Low molecular weight (LMW) glutenin subunits represent major part (30%) of storage proteins in wheat endosperm and determine the quality of dough. Despite their importance few LMW glutenin genes have been characterized so far and none from Indian wheat variety. In the present investigation PCR technique was employed to characterize LMW-GS gene representing Glu-B3 locus from Indian bread wheat cultivar NP4. The deduced protein sequence coded by Glu-B3 locus of LMW-GS gene from NP4 showed the presence of regular structure of the repetitive domain with varying numbers of glutamine (Q) residues and the presence of 1^st cysteine residue within the repetitive domain at 40^th position in mature polypeptide. Such structure might increase and stabilize the gluten polymer through intermolecular interactions of the large numbers of glutamine side chains and cysteine residues for intermolecular disulphide bond formation leading to stronger dough quality of NP4. Moreover, Glu-B3 specific primers could also be used for identifying 1BL/1RS translocation in addition to amplifying LMW glutenin genes. There was no amplification in 1B/1R translocation lines as short arm of wheat was replaced by short arm of rye chromosome in these lines. Such information can be useful in wheat improvement for dough properties for better chapati and bread quality.     

Cytogenetic characteristics of wheat lines with modified 1RS.1BL rye-wheat translocation

The higher frequency (almost 90%) of inheritance through pollen of heterozygous hybrids has been shown for the modified 1RS.1BL translocation compared with the 1BL telocentric, and, as a result, the segregations at the Gli-B1 and Glu-B1 loci strongly deviated from the expected values. The distance between the Glu-B1 locus and the centromere was 15.7–24.4 cM. Products of the 1RS_m.1BL translocation “misdivision” were observed at a frequency of 0.05%. Both the Pavon MA1 lines and the winter wheat line with the 1RS_m.1BL _al translocation have shown a significant decrease in the level of homologous chromosome pairing, causing aneuploidy. These lines did not contain any reciprocal translocations with respect to the Kuyal’nik cultivar. A “hybrid desynapsis” has been observed in F₁ hybrids (Kuyal’nik × Pavon MA1) in contrast to analogous hybrids from a winter line by the 1RS_m.1BL _al type. No single case of the 21_Closed ^II formation has been observed among the studied 693 pollen mother cells (PMCs), which would have indicated the presence of pairing between the short arms of the 1RS_m.1BL translocations and the intact chromosome 1B.     

Identification of the 1RS rye chromosomal segment in wheat by RAPD analysis

The introgression of rye DNA into the wheat genome was studied using random decamer and specific primers with the polymerase chain reaction (PCR). DNA from paired near-isolines in Chisholm and Arkan backgrounds differing with respect to the presence of a 1 RS.1 BL translocation was amplified with 120 arbitrary sequence primers. Two of the primers (OPR 19 and OPJ07) amplified rye-specific DNA fragments. The OPR19 primer amplified a 1.35-kb fragment that appeared to be specific to the 1 RS.1 BL translocation, based on its presence only in lines carrying the 1 RS. 1 BL translocation. A fragment of the same size was also amplified in 1 RS.1 AL translocation lines. This 1 RS. 1 BL marker locus was designated Ximc 1. The other primer, OPJ07, amplified a 1.2-kb DNA sequence, that was designated Ximc 2, specific to the wheat-rye translocation in various wheat backgrounds. The sequences of the two marker loci were found to be different from each other. The Ximc 1 locus was a low-copy sequence which was also present in Balboa rye genomic DNA. Through the use of specific primers, the presence of the rye-specific marker was confirmed in hexaploid as well as in tetraploid wheat backgrounds. The use of RAPDs for the study of smaller alien introgressions into wheat is discussed.     

Molecular cytogenetic characterization of a new wheat-rye 1BL•1RS translocation line expressing superior stripe rust resistance and enhanced grain yield

Main conclusion

A new wheat-rye 1BL?1RS translocation line, with the characteristics of superior stripe rust resistance and high thousand-kernel weight and grain number per spike, was developed and identified from progenies of wheat-rye- Psathyrostachys huashanica trigeneric hybrids.

Abstract

The wheat-rye 1BL?1RS translocation line from Petkus rye has contributed substantially to the world wheat production. However, due to extensive growing of cultivars with disease resistance genes from short arm of rye chromosome 1R and coevolution of pathogen virulence and host resistance, these cultivars successively lost resistance to pathogens. In this study, a new wheat-rye line K13-868, derived from the progenies of wheat-rye-Psathyrostachys huashanica trigeneric hybrids, was identified and analyzed using fluorescence in situ hybridization (FISH), genomic in situ hybridization (GISH), acid polyacrylamide gel electrophoresis (A-PAGE), and molecular markers. Cytological studies indicated that the mean chromosome configuration of K13-868 at meiosis was 2n = 42 = 0.14 I + 18.78 II (ring) + 2.15 II (rod). Sequential FISH and GISH results demonstrated that K13-868 was a compensating wheat-rye 1BL?1RS Robertsonian translocation line. Acid PAGE analysis revealed that clear specific bands of rye 1RS were expressed in K13-868. Simple sequence repeat (SSR) and rye 1RS-specific markers ω-sec-p1/ω-sec-p2 and O-SEC5′-A/O-SEC3′-R suggested that the 1BS arm of wheat had been substituted by the 1RS arm of rye. At the seedling and adult growth stage, compared with its recurrent wheat parent SM51 and six other wheat cultivars containing the 1RS arm in southwestern China, K13-868 showed high levels of resistance to stripe rust (Puccinia striiformis f. sp. tritici, Pst) pathogens prevalent in China, which are virulent to Yr10 and Yr24/Yr26. In addition, K13-868 expresses higher thousand-kernel weight and more grain number per spike than these controls in two growing seasons, suggesting that this line may carry yield-related genes of rye. This translocation line, with significant characteristics of resistance to stripe rust and high thousand-kernel weight and grain number per spike, could be utilized as a valuable germplasm for wheat improvement.

     

Wheat chromosome instability in the selfed progeny of the double monosomics 1Rv-1A

Structural alterations of chromosomes are often found in wheat-rye hybrids. In the majority of cases modifications are observed for rye chromosomes, yet chromosome aberration cases are described for wheat, including the progeny of Triticum aestivum disomic and monosomic addition lines. Since wheat-rye substitution and translocation lines are the source of rye chromatin in wheat breeding programs, the information on possible chromosome changes in the genomes of introgressive forms is important. Chromosome behavior in F₁ meiosis and chromosomal composition of F₂ karyotypes for double monosomics 1Rv-1A were studied by applying C-banding, genomic in situ hybridisation (GISH) using rye genomic DNA, and sequential in situ hybridization using repetitive sequences pAs1, pSc119.2 and centromere specific pAet-06 as probes. The double monosomics 1Rv-1A were obtained by crossing of disomic substitution line with chromosome 1A replaced by Secale cereale 1Rv in the bread wheat Saratovskaya 29 (S29) background with S29. The results indicated a high frequency of bipolar chromosome 1Rv orientation, as compared to 1A, at metaphase I (MI) (58.6 and 34.7 % of meiocytes, respectively), and, at anaphase I (AI), chromatid segregation of 1Rv compared to 1A (70.53 and 32.14 % of meiocytes, respectively). In few cases desynapsis of wheat homologues was observed, at AI, the chromosomes randomly distributed between the poles or underwent chromatid segregation. At AI, the two wheat homologues separated onto sister chromatids in 10.89 % of cells.The plants F2 karyotypes were marked with aneuploidy not only of chromosomes 1A and 1Rv, but also of 1D, 2D, 3D, 3B, 3A, 4A, 6D, 6B, 6A, and 7D. Structural changes were observed for the chromosomes of the first homoeologous group (1Rv, 1A, 1D, 1B), as well as for 2B, 5D, 6B, and 7B. The chromosomes 1Rv and 6B often demonstrated aberrations. The types of aberrations were centromeric break, deletions of various sizes, and a changed repeat pSc119.2 localization pattern.     

Genetic mapping of Dn7, a rye gene conferring resistance to the Russian wheat aphid in wheat

The Russian wheat aphid is a significant pest problem in wheat and barley in North America. Genetic resistance in wheat is the most effective and economical means to control the damage caused by the aphid. Dn7 is a rye gene located on chromosome 1RS that confers resistance to the Russian wheat aphid. The gene was previously transferred from rye into a wheat background via a 1RS/1BL translocation. This study was conducted to genetically map Dn7 and to characterize the type of resistance the gene confers. The resistant line '94M370' was crossed with a susceptible wheat cultivar that also contains a pair of 1RS/1BL translocation chromosomes. The F₂ progeny from this cross segregated for resistance in a ratio of 3 resistant: 1 susceptible, indicating a single dominant gene. One-hundred and eleven RFLP markers previously mapped on wheat chromosomes 1A, 1B and 1D, barley chromosome 1H and rye chromosome 1R, were used to screen the parents for polymorphism. A genetic map containing six markers linked to Dn7, encompassing 28.2 cM, was constructed. The markers flanking Dn7 were Xbcd1434 and XksuD14, which mapped 1.4 cM and 7.4 cM from Dn7, respectively. Dn7 confers antixenosis, and provides a higher level of resistance than that provided by Dn4. The applications of Dn7 and the linked markers in wheat breeding are discussed.Communicated by J. Dvorak     

Development of a robust marker for <Emphasis Type="Italic">Psy-1</Emphasis> homoeologs and its application in improvement of yellow pigment content in durum wheat

Phytoene synthase-1 (Psy-1) homoeologs are associated with yellow pigment content (YPC) in endosperm of durum and bread wheat. In the present study, microsatellite variation in promoter region of Psy-A1 was identified in durum wheat and marker Psy-1SSR, targeting the microsatellite variation was developed which amplifies variation in Psy-A1 and Psy-B1 loci simultaneously. Psy-A1SSR was mapped within QYp.macs-7A, a major QTL for YPC identified earlier in PDW 233/Bhalegaon 4 population. Marker Psy-A1SSR was further validated in two different RIL populations and a set of 222 tetraploid wheat accessions including less cultivated tetraploid wheat species. Eight alleles of Psy-A1SSR were identified in 222 wheat accessions, while seven alleles were observed for Psy-B1SSR. Variation at Psy-A1SSR showed significant association with YPC, whereas no association was observed with Psy-B1SSR. Marker-assisted introgression of Psy-A1SSRe allele from PDW 233, to durum wheat cultivars MACS 3125 and HI 8498 resulted in improvement of YPC. Backcrossed BC₃F_2:4 and BC₂F_2:3 lines selected using Psy-A1SSR showed 89 to 98% gain in YPC over recurrent parents indicating robustness of marker. The marker can thus be utilized in marker-assisted improvement of YPC in durum wheat cultivars.     

Visualization of Secale cereale DNA in wheat germ plasm by fluorescent in situ hybridization

Homozygous wheat/rye (1BL/1RS or 1AS/ 1RL) translocation lines have significantly contributed to wheat production, and several other wheat/rye translocation lines show a potential promise against biotic and abiotic stresses. Detecting the presence of rye at the chromosome level is feasible by C-banding and isozyme protocols, but the diagnostic strength of genomic in situ hybridization for eventually analyzing smaller DNA introgressions has greater significance. As a first step we have applied the genomic in situ hybridization technique to detect rye chromosomes in a wheat background using germ plasm of agricultural significance. By this method rye contributions to the translocations 1BL/1RS, 1AL/1RS, 5AS/5RL and 6BS/6RL could be identified. Differential labelling has further enabled the detection of rye and Thinopyrum bessarabicum chromosomes in a trigeneric hybrid of Triticum aestivum/Th. bessarabicum//Secale cereale.     

Novel source of 1RS from Baili rye conferred high resistance to diseases and enhanced yield traits to common wheat

Rye is one of the most important related species used for wheat genetic improvement and breeding programs. In the present study, five novel 1BL.1RS translocations were developed and characterized from crossing of the common wheat line A42912 and a Chinese rye “Baili”. Codominant PCR and MC-FISH determined that these five translocation lines harbored a pair of 1BL.1RS chromosomes. The MC-FISH results indicated that several accompanying mutations on the wheat chromosomes occurred during the chromosome translocation process. These five new 1BL.1RS translocation lines also exhibited high resistance to stripe rust and powdery mildew and showed significantly better yield traits in the field. The present study indicates that Baili rye may carry yet untapped and potentially important sources of resistance, which may be used for wheat genetic improvement. These five novel primary 1BL.1RS translocations are likely to find application in wheat genetic improvement programs.     

Association between presence of <Emphasis Type="Italic">Triticum timopheevii</Emphasis> introgression and D-genome retention in hexaploid/tetraploid wheat crosses

The 2G Triticum timopheevii introgression harbours genes for multiple disease resistance and quality traits in bread wheat. In order to transfer this segment from bread wheat into durum, the bread wheat line Sunguard, which carries this introgressed 2G segment was crossed with three tetraploid durum parents. A significant difference was observed in the segregation ratio of the 2G segment in the different crosses at the F₂ generation with two of the three populations indicating segregation distortion against the hexaploid 2G segment. In these populations, the presence of the 2G segment was strongly correlated with the presence of D-genome chromosomes. These results were confirmed in the F₄ generation of these populations. Six plants were identified in the F₄ generation, which had retained the introgressed 2G segment in a homozygous condition and did not have a complete D-genome set. Two of these lines only had two non-homologous D-genome chromosomes in the F₅ generation. Thus, the 2G segment and possibly other translocations can be transferred into durum wheat through hexaploid/tetraploid hybridisation.     

Isolation and characterization of wheat-rye recombinants involving chromosome arm 1DS of wheat

Summary The introgression of genetic material from alien species is assuming increased importance in wheat breeding programs. One example is the translocation of the short arm of rye chromosome 1 (1RS) onto homoeologous wheat chromosomes, which confers disease resistance and increased yield on wheat. However, this translocation is also associated with dough quality defects. To break the linkage between the desirable agronomic traits and poor dough quality, recombination has been induced between 1RS and the homoeologous wheat arm IDS. Seven new recombinants were isolated, with five being similar to those reported earlier and two havina new type of structure. All available recombinantsw ere characterized with DNA probes for the loci Nor-R1, 5SDna-R1, and Tel-R1. Also, the amount of rye chromatin present was quantified with a dispersed rye-specific repetitive DNA sequence in quantitative dot blots. Furthermore, the wheat-rye recombinants were used as a mapping tool to assign two RFLP markers to specific regions on chromosome arms 1DS and 1RS of wheat and rye, respectively.     

Study of the effects produced by gamma-irradiation of common wheat F1 seeds using gliadins as genetic markers

A study of the effects produced by gamma-irradiation of dry F₁ seeds of common wheat at 200 Gy is described in the work. The experimental material was hybrids produced from near-isogenic lines based on Bezostaya 1. Irradiation led to a significant decrease in the productivity traits of F₁ plants but did not affect the survival of plants under the given growth conditions. It has been found that one of the effects of the F₁ seed irradiation was a relative, compared to the control, increase in the frequency of male gametes with the 1BL/1RS translocation that participated in the production of F₂ grains. The irradiation induced mutations at gliadin loci with a frequency of 7.4% (against 0.5% in the control).     

Genome inheritance in populations derived from hexaploid/tetraploid and tetraploid/hexaploid wheat crosses

Hexaploid/tetraploid and tetraploid/hexaploid wheat hybrids were established using the hexaploid (Triticum aestivum L.) bread wheat LRC2010-150 and the tetraploid durum wheat (T. turgidum spp. durum) WID802. Thirty F₂ progeny from each cross were characterised using Diversity Arrays Technology (DArTseq?) markers to determine whether there are differences between the crosses in the proportion of A, B and D genomic material inherited from each parent. Inheritance of the A and B genome from the tetraploid durum parent varied from 32 to 63% among the 60 lines assessed, and results indicated significant differences between the two F₂ populations in the mean overall proportion of chromosomes A and B inherited from each parent. Significant differences were also observed between the crosses in the proportion of chromosomal segments on 2B, 3A, 3B and 4A inherited from the tetraploid parent. The F₂ populations also showed significant differences in the average retention of D chromosomes per line with the tetraploid/hexaploid cross retaining a mean of 2.83 chromosomes while the reciprocal cross retained a mean of 1.8 chromosomes per line. A strong negative correlation was observed in individual lines from both populations between the proportion of the A and B genome inherited from the tetraploid durum parent and the retention of the D genome. The implication of these results for the design of efficient crossing strategies between hexaploid and tetraploid wheats is discussed.     

Identification of new T1BL.1RS translocation lines derived from wheat (Triticum aestivum L. cultivar “Xiaoyan No. 6”) and rye hybridization

Two new T1BL.1RS translocation lines, 48112 and 89121, derived from cross between common wheat (Triticum aestivum L.) cultivar “Xiaoyan No. 6” and rye (Secale cereale L.) cultivar “German White”, were developed and identified by using of molecular markers and cytogenetical methods, GISH and FISH. PCR results of primers NOR-R1 specific for rye and Glu-B3 for 1BS detected the presence of 1RS chromatin and absence of 1BS, and primer for gene 1Bx14 in 1BL indicated the existence of chromosome arm 1BL in the two lines. GISH and FISH methods confirmed the replacement of chromosome arm 1BS with 1RS. Further stripe rust resistant test and quality analysis demonstrated that the new 1BL.1RS translocation lines were higher resistant to mixed races of P. striiformis Westend and observed considerable better quality than other popularized T1BL.1RS cultivars in China. The two lines have been used in wheat breeding for high-yield potential and rust resistance.