Abnormal condensation of meiotic chromosomes caused by the mei8 mutation in rye Secale cereale L

Inheritance of two spontaneous meiosis-specific mutations with similar cytologic phenotype was studied. Both mutations were independently obtained from two rye populations (Vyatka variety and weedy rye). Both mutations are recessive, allelic, and monogenically inherited; the corresponding gene is designated mei8. The mutant alleles of the gene cause abnormal meiotic chromosome structure expressed as irregular compaction along the chromosome length, chromatin stickiness at all stages of meiosis, and chromosome fragmentation in anaphase I.     

Anthocyanin biosynthesis genes location and expression in wheat–rye hybrids

Studies into gene expression in a foreign background contribute toward understanding of how genes derived from different species or genera manages to co-exist in a common nucleus, on the one hand, and help to estimate possible effectiveness of wide hybridization for cultivated plant improvement, on the other hand. The aim of this study was to investigate conservation of wheat and rye expression networks, using the anthocyanin biosynthesis pathway (ABP) genes as a model system. We isolated and analyzed ABP genes encoding enzymes acting at different steps of the pathway: chalcone-flavanone isomerase (CHI), flavanone 3-hydroxylase (F3H), anthocyanidin synthase (ANS), and anthocyanidin-3-glucoside rhamnosyltransferase (3RT). The rye ABP genes locations we determined (Chi on chromosome 5RL, F3h on 2RL, Ans on 6RL, 3Rt on 5RL, the regulatory Rc—red coleoptile—gene on 4RL) were in agreement with the rearrangements established between rye and wheat chromosomes. Expression of the ABP structural genes was studied in wheat–rye chromosome addition and substitution lines. F3h activation by the Rc gene was found to be critical for the red coleoptile trait formation. It was shown that the rye regulatory Rc gene can activate the wheat target gene F3h and vice versa wheat Rc induces expression of rye F3h. However, lower level of expression of rye F3h in comparison with that of the two wheat orthologues in the wheat–rye chromosome substitution line 2R(2D) was observed. Thus, although work of the wheat and rye ABP gene systems following the formation of wheat–rye hybrids is finely coordinated, some divergence exists between rye and wheat ABP genes, affecting level of gene expression.     

AFLP markers tightly linked to the aluminum-tolerance gene Alt3 in rye (Secale cereale L.)

Rye (Secale cereale L.) is considered to be the most aluminum (Al)-tolerant species among the Triticeae. It has been suggested that aluminum tolerance in rye is controlled by three major genes (Alt genes) located on rye chromosome arms 3RL, 4RL, and 6RS, respectively. Screening of an F₆ rye recombinant inbred line (RIL) population derived from the cross between an Al-tolerant rye (M39A-1–6) and an Al-sensitive rye (M77A-1) showed that a single gene controls aluminum tolerance in the population analyzed. In order to identify molecular markers tightly linked to the gene, we used a combination of amplified fragment length polymorphism (AFLP) and bulked segregant analysis techniques to evaluate the F₆ rye RIL population. We analyzed approximately 22,500 selectively amplified DNA fragments using 204 primer combinations and identified three AFLP markers tightly linked to the Alt gene. Two of these markers flanked the Alt locus at distance of 0.4 and 0.7 cM. Chromosomal localization using cloned AFLP and a restriction fragment length polymorphism (RFLP) marker indicated that the gene was on the long arm of rye chromosome 4R. The RFLP marker (BCD1230) co-segregated with the Alt gene. Since the gene is on chromosome 4R, the gene was designated as Alt3. These markers are being used as a starting point in the construction of a high resolution map of the Alt3 region in rye. Received: 29 March 2000 / Accepted: 9 July 2001     

Identification and development of diagnostic markers for a powdery mildew resistance gene on chromosome 2R of Chinese rye cultivar Jingzhouheimai

Chinese rye cultivar Jingzhouheimai (Secale cereale L.) shows a high level of resistance to powdery mildew. Identification, location, and mapping of the resistance gene would be helpful for developing a highly resistant germplasm or cultivar in wheat. Using sequential C-banding, GISH, and marker analysis, an addition chromosome with powdery mildew resistance was identified in a line derived from a cross between Chinese wheat landrace Huixianhong and rye cultivar Jingzhouheimai. The line, designated H-J DA2RDS1R(1D), had 44 chromosomes including two pairs of rye chromosomes, 1R and 2R, and lacked a pair of wheat chromosomes 1D, that is, it is a double disomic addition disomic substitution line. According to its reaction to different isolates of the powdery mildew pathogen, the resistance gene in H-J DA2RDS1R(1D) differed from the Pm8 and Pm7 genes located earlier on rye chromosomes 1R and 2R, respectively. In order to determine the location of the resistance gene, line H-J DA2RDS1R(1D) was crossed with wheat landrace Huixianhong and the F2 population and corresponding F2:3 families were tested for disease reaction and assessed with molecular markers. The results showed that a resistance gene, designated PmJZHM2RL, is located in rye chromosome arm 2RL.     

Effect of the 5R(5A) Alien Chromosome Substitution on the Growth Habit and Winter Hardiness of Wheat

The growth habit, ear emergence time, and frost tolerance of wheat/rye substitution lines have been studied in cultivars Rang and Mironovskaya Krupnozernaya whose chromosome 5A is substituted with chromosome 5R of Onkhoyskaya rye. Hybrid analysis has demonstrated that the spring habit of the recipient cultivars Rang and Mironovskaya Krupnozernaya is controlled by dominant gene Vrn-A1 located in chromosome 5A. Onokhoyskaya rye has a dominant gene for the spring habit (Sp1) located in chromosome 5R. It has been found that the resultant 5R(5A) alien-substitution lines have a winter type of development and ears do not emerge during summer in plants sown in spring. The change in growth habit has been shown to be related to the absence of the rye Sp1 gene expression in the substitution lines. The winter hardiness of winter 5R(5A) alien-substitution lines has been studied under the environmental conditions of Novosibirsk. Testing the lines in the first winter demonstrated that their winter survival is 20–27%. The possible presence of the frost resistance gene homeoallelic to the known genes Fr1 and Fr2 of the common wheat located on chromosomes 5A and 5D, respectively, is discussed.     

Linkage of Genes Controlling Morphological Traits with Isozyme Markers of Rye Chromosomes

Data on linkage of 12 rye genes controlling morphological traits (el, Vs, ln, w, np, ct2, Hs, Ddw, cb, mn, vi1, mp) with one or several isozyme markers of individual rye chromosomes (2R–7R) are presented. Linkage of the following gene pairs was established: chromosome 2R: Est3/5–el, el–-Glu, Sod2–el, Sod2–Vs; chromosome 3R: ln–Got4; chromosome 4R: w–Got1, np–Got1; chromosome 5R: Est4–ct2, Est6/9–ct2, ct2–Est2, ct2–Aco2, Est2–Hs, Aco2–Hs, Est2–Ddw, Aco2–Ddw; chromosome 6R:Lap2–cb, cb–Aco1, Est10–mn; chromosome 7R: Acph2/3–vi1, Got2–vi1, mp–Acph2/3. The reasons for mapping a very small number of genes in rye in spite of high intraspecific variability of this species are discussed. An approach is suggested to improve this situation by simultaneous identification and mapping of all diverse spontaneous mutations maintained in heterozygous state in various rye cultivars.     

Gene mutations in rye causing embryo lethality in hybrids with wheat: allelism and chromosomal localisation

In crosses between hexaploid wheat and inbred lines of rye, a small number of rye genotypes produce seeds carrying undifferentiated, non-viable embryos. Hybrids between such lines and those not showing this phenotype were used as pollen donors in crosses with bread wheat in order to determine the genetic basis of disturbed embryo development. A single gene, designated Eml-R1b, is causing this character. Molecular markers associated with F₂ genotypes derived from a contrasting rye inbred progeny were used for a linkage study. Recombinant inbred lines of an F₅ population served as testers. Eml-R1b maps to chromosome arm 6RL, along with two co-segregating microsatellite loci, Xgwm1103 and Xgwm732. Complementary interactions of deleterious genes in wheat and rye are discussed.     

The Effect of Parental Genotypes of Rye Lines on the Development of Quantitative Traits in Primary Octoploid Triticale: Spike Fertility

The number of seeds and seed setting in the main spike were studied in primary octoploid triticale obtained from crosses between the common wheat cultivar Chinese Spring and 66 inbred rye lines. In some rye lines, the mutations of self-fertility were identified in the S, Z, or T incompatibility loci. The number of seeds was determined under controlled self-pollination of the main spike. In the set of triticale examined, each trait exhibited high variation. Hence, the rye lines were suggested to carry gene alleles both increasing and decreasing these traits in triticale. All the traits studied were significantly influenced by environmental conditions. Ten triticale lines were identified, which had the largest seed setting under self-pollination. Seven out of ten samples with the high number of seeds carried mutations in the Tlocus and in the three samples, the unidentified self-fertility mutations were present. The triticale lines with mutations in theS and Z loci displayed much lower self-fertility on average. The ways and means of identifying and mapping the rye gene responsible for distinctions between the triticale quantitative traits are discussed.     

Mapping the nucleolus organizer region,seed protein loci and isozyme loci on chromosome 1R in rye

Summary The nucleolus organizer region located on the short arm of chromosome 1R of rye consists of a large cluster of genes that code for ribosomal RNA (designated the Nor-R1 locus). The genes in the cluster are separated by spacer regions which can vary in length in different rye lines. Differences in the spacer regions were scored in two families of F₂ progeny. Segregation also occurred, in one or both of the families, at two seed protein loci and at two isozyme loci also located on chromosome 1R. The seed protein loci were identified as the Sec 1 locus controlling -secalins located on the short arm of chromosome 1R and the Sec 3 locus controlling high-molecular-weight secalins located on the long arm of 1R. The two isozyme loci were the Gpi-R1 locus controlling glucose-phosphate isomerase isozymes and the Pgd 2 locus controlling phosphogluconate dehydrogenase isozymes. The data indicated linkage between all five loci and map distances were calculated. The results indicate a gene order: Pgd 2 ... Sec 3 ... [centromere] ... Nor-R1 ... Gpi-R1 ... Sec 1. Evidence was obtained that rye possesses a minor 5S RNA locus (chromosome location unknown) in addition to the major 5S RNA locus previously shown to be located on the short arm of chromosome 1R.     

Genetic analysis of rye (Secale cereale L.) Genetics of male sterility of the G-type

Summary The genetics and relationships between the genes in rye located in the nucleus and cytoplasm of the male sterility of the G-type were investigated. A factor inducing male sterility was found in the cytoplasms or rye cv Schlägler alt and rye cv Norddeutscher Champagner. Monogenic inheritance was observed in linkage tests. Using primary trisomies of rye cv Esto, the nuclear gene ms1 was found to be located on chromosome 4R. Modifying genes, probably masked in normal cytoplasm but expressed in male-sterility-inducing cytoplasm together with gene ms1, were located on chromosomes 3R (ms2) and 6R (ms3). Mono-, di-, and trigenic inheritance types were found in backcross progenies of trisomies.     

Molecular genetic mapping of the <Emphasis Type="Italic">sy1</Emphasis> and <Emphasis Type="Italic">sy9</Emphasis> asynaptic genes in rye (<Emphasis Type="Italic">Secale cereale</Emphasis> L.) using microsatellite and isozyme markers

Studies of phenotypical expression of synaptic mutations in combination with the localization of corresponding genes on a genetic map permit individual stages of the meiotic process to be differentiated. Two rye asynaptic genes, sy1 and sy9, were mapped with the use of microsatellite markers (SSR) in the pericentromeric regions of the long chromosome arms 7R and 2R, respectively. The sy9 gene cosegregated with two SSR markers Xscm43 and Xgwm132. The asynaptic gene sy1 was mapped within the interval between the isozyme locus Aat2 and two cosegregating loci Xrems1188 and Xrems1135 that are located at a distance of 0.4 cM proximally and 0.1 cM distally with respect to the gene lous. Possible evolutionary relationships of the mapped genes with homeological loci of the Triticeae species and more distant cereal species, such as maize and rice, are discussed.     

RFLP mapping of genes affecting plant height and growth habit in rye

Summary RFLP mapping of chromosome 5R in the F₃ generation of a rye (Secale cereale L.) cross segregating for gibberellic acid (GA₃)-insensitive dwarfness (Ct2/ct2) and spring growth habit (Sp1/sp1) identified RFLP loci close to each of these agronomically important genes. The level of RFLP in the segregating population was high, and thus allowed more than half of the RFLP loci to be mapped, despite partial homozygosity in the parental F₂ plant. Eight further loci were mapped in an unrelated F₂ rye population, and a further two were placed by inference from equivalent genetic maps of related wheat chromosomes, allowing a consensus map of rye chromosome 5R, consisting of 29 points and spanning 129 cM, to be constructed. The location of the ct2 dwarfing gene was shown to be separated from the segment of the primitive 4RL translocated to 5RL, and thus the gene is probably genetically unrelated to the major GA-insensitive Rht genes of wheat located on chromosome arms 4BS and 4DS. The map position of Sp1 is consistent both with those of wheat Vrn1 and Vrn3, present on chromosome arms 5AL and 5DL, respectively, and with barley Sh2 which is distally located on chromosome arm 7L (= 5HL).     

Chromosomal location of alcohol dehydrogenase gene(s) in rye,using wheat-rye addition lines

Following disc electrophoresis on standard gels, rye seed extracts showed two bands (ADH-3 and 5) for alcohol dehydrogenase. The ADH-3 band was homologous to the ADH band observed in other diploid species of the Triticinae, and with the ADH-3 band of 4 × and 6 × wheat. It is proposed that the rye isoenzymes ADH-3 and 5 are governed respectively, by the genes Adh _R1 and Adh _R2. Using bread wheat (Holdfast) lines with disomic addition of individual rye (King II) chromosomes, we found that the ADH-5 band was associated with the addition of rye chromosome IV (after Riley), indicating thereby that Adh _R2 gene is located on this chromosome. The products of Adh _R1 and Adh _R2 do not form active heterodimers, among themselves, but do form active dimers with wheat ADH monomers. It is suggested that the use of chromosomal addition lines may provide a method for locating genes for those enzymes, where the rye and wheat isoenzymes are electrophoretically distinct.     

Isolation and characterization of a new MATE gene located in the same chromosome arm of the aluminium tolerance (Alt1) rye locus

• Aluminium (Al) toxicity is the major constraint for crop productivity in acid soils. Wild rye species (Secale spp.) exhibit high Al tolerance, being a good source of genes related to this trait. The Alt1 locus located on the 6RS chromosome arm is one of the four main loci controlling Al tolerance in rye and is known to harbour major genes but, so far, none have been found.
• Through synteny among the short arm of the rye chromosome 6R and the main grass species, we found a candidate MATE gene for the Atl1 locus, later named ScMATE3, which was isolated and characterized in different Secale species.
• The sequence comparisons revealed both intraspecific and interspecific variability, with high sequence conservation in the Secale genus. SNP with replacement substitution that changed the structure of the protein and can be involved in the Al tolerance trait were found in ScMATE3 gene. The predicted subcellular localization of ScMATE3 is the vacuolar membrane which, together with the phylogenetic relationships performed with other MATE genes of the Poaceae related to Al detoxification, suggest involvement of ScMATE3 in an internal tolerance mechanism. Moreover, expression studies of this gene in rye corroborate its contribution in some Al resistance mechanisms.
• The ScMATE3 gene is located on the 6RS chromosome arm between the same markers in which the Alt1 locus is involved in Al resistance mechanisms in rye, thus being a good candidate gene for this function.

     

Genetics and molecular mapping of a male fertility restoration locus (Rfg1) in rye (Secale cereale L.)

 A gene determining the restoration of cytoplasmic genic male sterility (CMS) caused by the Gülzow (G)-type cytoplasm was mapped by analyzing an F₂ and F₃ population comprising 140 and 133 individual plants, respectively. The target gene, designated Rfg1, was mapped on chromosome 4RL distally to three RFLP (Xpsr119, Xpsr167, Xpsr899) and four RAPD (XP01, XAP05, XR11, XS10) loci. Xpsr167 and Xpsr899 are known to be located on the segment of chromosome 4RL which was ancestrally translocated and is homoeologous to the distal end of other Triticeae 6S chromosomes. It is suggested that Rfg1 may be allelic to the gene determining the restoration of rye CMS caused by the Pampa (P) cytoplasm (chromosome 4RL) and to Rfc4 that on rye addition lines of chromosome 4RL restores male fertility of hexaploid wheat with T. timopheevi cytoplasm. Homoeoallelism to two loci for cytoplasmic-male-sterility restoration on chromosomes 6AS and 6BS in hexaploid wheat is also suggested. Received: 1 December 1997 / Accepted: 10 February 1998     

Characterisation of two gene subunits on the 1R chromosome of rye as orthologs of each of the Glu-1 genes of hexaploid wheat

The visco-elastic properties of bread flour are firmly associated with the presence or absence of certain HMW subunits coded by the Glu-1 genes. Identifying allelic specific molecular markers (AS-PCR) associated with the presence of Glu-1 genes can serve as a valuable tool for the selection of useful genotypes. This paper reports the use of primers designed from nucleotide sequences of the Glu-D1 gene of wheat (AS-PCR for Glu-D1y10) that recognise and amplify homologous sequences of the Glu-R1 gene subunits of rye. The primers amplify the complete coding regions and provided two products of different size in rye, in wheats carrying the substitution 1R(1D) and in rye-wheat aneuploid lines carrying the long arm of chromosome 1R. The location, the molecular characterisation of these sequences and their expression during grain ripening seem to demonstrate that the amplification products correspond to structural genes encoding the high-molecular-weight (HMW) glutenins of rye. The homology of the rye gene to subunits encoding HMW glutenins in wheat was confirmed by Southern blots and sequencing. The amplification-products were cloned, sequenced and characterised, and the sequences compared with the main glutenin subunits of wheat and related species. Further, an RT-PCR experiment was performed using primers designed from the sequence of both amplified products. This assay demonstrated that both sequences are expressed in endosperm during grain ripening. The results of these analyses suggest that both gene subunits correspond to x- and y-type genes of the Glu-R1 locus of rye. Received: 11 December 2000 / Accepted: 17 April 2001     

Meiotic mutants of rye Secale cereale L. II. The nonhomologous synapsis in desynaptic mutants sy7 and sy10

We studied the expression and inheritance of two spontaneous mutations found in different populations of rye Secale cereale L. that cause high univalent frequency in meiosis and low fertility. Both mutations were inherited as monogenic recessives. For each of the mutations the corresponding gene symbols (sy7 and sy10) were suggested although their allelism has not been studied. These mutants differ in chiasma frequency and in the number of univalents per meiocyte. Electron microscopy of the wholemount surface-spread synaptonemal complexes (SCs) from microsporocytes of both mutants revealed that during meiotic prophase I random synapsis began and progressed that involved not only homologous but also nonhomologous chromosomes. SCs were formed with frequent changes of pairing partners (switches) and intrachromosomal foldbacks of unpaired axial elements. As a result, incompletely synapsed, non-homologous and multivalent SCs were formed in mutants by the stage analogous to pachytene in normal plants. In sy7 a maximum in the number of switches and foldbacks were observed at zygotene, whereas in sy10 this occurred at pachytene. We suggest that it is the process of recognition of homology that is impaired in both mutants. This leads to indiscriminate synapsis and prevents chiasma formation. Both mutants may be classified as desynaptic.     

Microsatellite mapping of genes that determine supernumerary spikelets in wheat (T. aestivum) and rye (S. cereale)

The wheat and rye spike normally bears one spikelet per rachis node, and the appearance of supernumerary spikelets is rare. The loci responsible for the ‘multirow spike’ or MRS trait in wheat, and the ‘monstrosum spike’ trait in rye were mapped by genotyping F₂ populations with microsatellite markers. Both MRS and the ‘monstrosum’ trait are under the control of a recessive allele at a single locus. The Mrs1 locus is located on chromosome 2DS, co-segregating with the microsatellite locus Xwmc453. The placement of flanking microsatellite loci into chromosome deletion bin 2DS-5 (FL 0.47–1.0) delimited the physical location of Mrs1 to the distal half of chromosome arm 2DS, within the gene rich region 2S0.8. The Mo1 locus maps about 10 cM from the centromere on chromosome arm 2RS. The similar effect on phenotype of mo1 and mrs1, together with their presence in regions of conserved synteny, suggest that they may well be members of an orthologous set of Triticeae genes governing spike branching. The practical importance of the MRS spike is that it produces more spikelets per spike, and thereby enhances the sink capacity of wheat, which is believed to limit the yield potential of the crop.     

Generation of PCR-based markers for the detection of rye chromatin in a wheat background

Oligonucleotide primers were developed to detect the presence of four rye sequences using a PCR assay. These assays give a rye-specific signal from wheat DNA template which contains various rye chromosomes or chromosome segments. The sequences identified were associated with the nucleolar organiser region, the 5S-Rrna-R1 locus, the telomere, and a widely dispersed, rye-specific repetitive element Ris-1. The primers amplified from the well-established loci Nor-R1 and 5S-Rrna-R1 on rye chromosome arm 1RS, and also located a 5s-Rrna locus on chromosome 3R. The telomere-associated sequence was present on every rye chromosome, and was also present, at a low copy number, in both wheat and barley. These assays will be particularly useful for introgression programmes aimed at reducing the rye content of the 1BL.1RS wheat-rye translocation. When multiplexed, the primers will enable a rapid, simultaneous assay for a number of distinct rye loci, which can be derived from a small portion of mature endosperm tissue.     

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