Rye Chromosome 1R Research Articles

Genomic, RNA, and ecological divergences of the Revolvertransposon-like multi-gene family in Triticeae

BackgroundRevolver is a newly discovered multi-gene family of transposable elements in the Triticeae genome. Revolver encompasses 2929 to 3041 bp, has 20 bp of terminal inverted repeated sequences at both ends, and contains a transcriptionally active gene encoding a DNA-binding-like protein. A putative TATA box is located at base 221, with a cap site at base 261 and a possible polyadenylation signal AATAAA at base 2918. Revolver shows considerable quantitative variation in wheat and its relatives.ResultsRevolver cDNAs varied between 395 and 2,182 bp in length. The first exon exhibited length variation, but the second and third exons were almost identical. These variants in the Revolver family shared the downstream region of the second intron, but varied structurally at the 5' first exon. There were 58 clones, which showed partial homology to Revolver, among 440,000 expressed sequence tagged (EST) clones sourced from Triticeae. In these Revolver homologues with lengths of 360-744 bp, the portion after the 2nd exon was conserved (65-79% homology), but the 1st exon sequences had mutually low homology, with mutations classified into 12 types, and did not have EST sequences with open reading frames (ORFs). By PCR with the 3'-flanking region of a typical genomic clone of Revolver-2 used as a single primer, rye chromosomes 1R and 5R could be simultaneously identified. Extensive eco-geographic diversity and divergence was observed among 161 genotypes of the single species Triticum dicoccoides collected from 18 populations in Israel with varying exposures to abiotic and biotic stresses (soil, temperature, altitude, water availability, and pathogens).ConclusionsOn the base of existing differences between Revolver variants, the molecular markers that can distinguish different rye chromosomes were developed. Eco-geographic diversification of wild emmer T. dicoccoides in Israel and high Revolver copy numbers are associated with higher rainfall and biotic stresses. The remarkable quantitative differences among copy numbers of Revolver in the same species from different ecosystems suggest strong amplification activity within the last 10,000 years. It is the interesting finding because the majority of Triticeae high-copy transposable elements seem to be inactive at the recent time except for BARE-1 element in Hordeum and the fact might be interesting to perceive the processes of plant adaptive evolution.

Preferential elimination of chromosome 5R of rye in the progeny of 5R5D dimonosomics

Transmission of chromosome 5R of rye (Secale cereale L.) and chromosome 5D of common wheat (Triticum aestivum L.) through gametes of 5R5D dimonosomics (2n = 42, 20W" + 5R' + 5D') was studied. Chromosome 5R was found to have lower competitiveness as compared to 5D. Gametes with the rye chromosome were two times less often involved in the formation of a progeny. The combined frequency of the karyotypes of wheat (5D5D) and wheat monosomics (5D) was 11.6-fold higher than the frequency of the karyotypes of substitution lines (5R5R) and monosomics for the rye chromosome (5R). The karyotypes of 10.38% of hybrid plants had aberrant 5R chromosomes with different translocations formed as a result of breakages in the centromere and in the proximal region of the long arm. Telocentrics for the short arm (t5RS), i5RS isochromosomes, and chromosomes with a terminal deletion T5RS.5RL-del were identified. The absence of amplification of SSR markers mapped on 5RS and the detection of PCR products for a number of 5RL markers (ineluding the genome-specific rye marker Xrms115) permitted nine plants carrying only the long arm of chromosome 5R to be revealed. Since t5RL telocentrics were not detected by the cytological analysis, the results obtained allow us to suggest the presence of small intercalary translocations of the long arm of chromosome 5R in chromosome 5D or in other wheat chromosomes.

Identification of 1BL·1RS Wheat-Rye Chromosome Translocations via 1RS Specific Molecular Markers and Genomic in situ Hybridization

Sixty-five rye-specific molecular markers were validated with two 1BL·1RS wheat-rye chromosome translocations(Kavkaz and Shannong 030-1),one 1AL·1RS wheat-rye chromosome translocation(Amigo),Jingzhouheimai,octoploid Triticale Jinsong 49,1R-7R addition lines,Chinese Spring,Huixianhong,Mingxian 169,and Chancellor.Eleven markers were selected due to stable amplification,clear PCR products in electrophoresis gels,and good repeatability,of which eight markers,i.e.,NOR-1,SECA2/SECA3,SCSS30.2,Sec1Gene,Sec1Pro,ω-Sec-P1/P2,ω-Sec-P3/P4,and IB-267 amplified specific bands associated with 1AL·1RS and 1BL·1RS translocations.Another three markers,O-SEC5'-A/O-SEC3'-R,IAG95-1,and SCM-9,were able to discriminate wheat-rye translocations involving different sources of 1RS.Both molecular markers and genomic in situ hybridization were used to detect the frequency of 1BL·1RS translocations in forty Shandong varieties(lines)bred in recent years.Among the forty varieties(lines),only 15%(Weimai 8,Lumai 14,Jining 13,Shannong 664,Shannongyoumai 3,and Yannong 25)harbored the 1BL·1RS translocation with the whole short arm of chromosome 1R of rye,and no 1AL·1RS or other translocation types were found.

Activation of Rye 5RL Neocentromere by an Organophosphate Pesticide

An interstitial constriction located on the long arm of rye chromosome 5R (5RL) shows neocentromeric activity at meiosis. In some meiocytes this region is strongly stretched orienting with the true centromere to opposite poles at metaphase I, and keeping sister chromatid cohesion at anaphase I. We found previously that the frequency of neocentric activity varied dramatically in different generations suggesting the effect of environmental factors. Here we studied the behavior of the 5RL neocentromere in mono- and ditelosomic 5RL, and mono-, and disomic 5R wheat-rye addition lines, untreated and treated with an organophosphate pesticide. The treated plants form neocentromeres with an about 4.5-fold increased frequency compared to untreated ones, demonstrating that the pesticide promotes neocentric activity. The neocentromere was activated irrespectively of the pairing configuration or the presence of a complete or truncated 5R centromere. Fluorescence in situ hybridization (FISH) with 2 repetitive sequences (UCM600 and pSc119.2) present at the constriction showed kinetic activity at several locations within this region. Immunostaining with anti-α-tubulin showed that treated plants have abnormal spindles in 46% of the metaphase I cells, indicating that disturbances in spindle formation might promote neocentromere activation.

Aneuploidy among androgenic progeny of hexaploid triticale (XTriticosecale Wittmack)

Doubled haploids are an established tool in plant breeding and research. Of several methods for their production, androgenesis is technically simple and can efficiently produce substantial numbers of lines. It is well suited to such crops as hexaploid triticale. Owing to meiotic irregularities of triticale hybrids, aneuploidy may affect the efficiency of androgenesis more severely than in meiotically stable crops. This study addresses the issue of aneuploidy among androgenic regenerants of triticale. Plant morphology, seed set and seed quality were better predictors of aneuploidy, as determined cytologically, than flow cytometry. Most aneuploids were hypoploids and these included nullisomics, telosomics, and translocation lines; among 42 chromosome plants were nulli-tetrasomics. Rye chromosomes involved in aneuploidy greatly outnumbered wheat chromosomes; in C0 rye chromosomes 2R and 5R were most frequently involved. While the frequency of nullisomy 2R was fairly constant in most cross combinations, nullisomy 5R was more frequent in the most recalcitrant combination, and its frequency increased with time spent in culture with up to 70% of green plants recovered late being nullisomic 5R. Given that 5R was not involved in meiotic aberrations with an above-average frequency, it is possible that its absence promotes androgenesis or green plant regeneration. Overall, aneuploidy among tested combinations reduced the average efficiency of double haploid production by 35% and by 69% in one recalcitrant combination, seriously reducing the yield of useful lines.

A Cytological Map of the Short Arm of Rye Chromosome 1R Constructed with 1R Dissection Stocks of Common Wheat and PCR-Based Markers

The short arm of rye chromosome 1R (1RS) is introduced into many common wheat cultivars because of its agronomic importance. The gametocidal system has been used to produce dissection lines carrying segments of rye chromosome 1R. We focused on establishing more dissection lines for 1RS and on obtaining PCR-based markers specific to 1RS. We established 66 1RS dissection lines carrying 1RS segments of chromosome 1R derived from a common wheat cultivar ‘Burgas 2’ and obtained 27 markers. We conducted a PCR analysis using the dissection lines and markers, and divided 1RS into 17 regions separated by the breakpoints. Comparison of the ‘Burgas 2’ 1RS map with another map of 1RS derived from ‘Imperial’ rye implied a restructuring between the 2 1RS chromosomes.

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.

The relationship between two tandem repeat families in rye heterochromatin

A bacterial artificial chromosome (BAC) library constructed from the short arm of rye (Secalecereale L.) chromosome 1R has been screened for clones containing copies of the pSc200 tandem repeat family, most abundant in rye subtelomeric heterochromatin. The molecular organization of the monomer array and adjacent sequences has been studied in BAC-126/C20. Digestion of the array with various restriction endonucleases reveals no higher-order organization. The DNA adjacent to the pSc200 array consists of different repeats, including retrotransposon derivatives and another tandemly repeated family, termed XbaI, with a monomer length of 576 bp, 475 of which show 82% similarity to the long terminal repeat of the known Cereba retrotransposon. Sequencing of the 13 kb long genomic region in BAC-126/C20 revealed a direct junction of the pSc200 and XbaI monomers. The arrays of both families terminate at the same AT-rich sequence CAAAAAT. Another recombination signal is the presence of palindromes in the close proximity to the junction site. The presence of microhomologies promotes the action of proteins involved in double-strand DNA break repair. To our knowledge, it is the first discovery of the direct junction of monomers that are longer than 100 bp and belong to different families of plant tandem repeats.

Characterisation of a specific class of typical low molecular weight glutenin subunits of durum wheat by a proteomic approach

Glutenin polymers are formed by high (HMW-GS) and low molecular weight glutenin subunits (LMW-GS). The latter group of subunits has been less characterised compared to the former due to their great number and heterogeneity. In order to gain more information on the LMW-GS, we have used a durum wheat line carrying a 1BL.1RS translocation, in which the short arm of the chromosome 1B is replaced by the short arm of the chromosome 1R of rye. This line was obtained using the durum wheat cultivar Cando, in which the translocation is present, crossed and back-crossed four times with the Italian durum wheat cultivar Svevo. Comparative electrophoretic and mass spectrometric analyses carried out on LMW-GS prepared from the durum wheat cultivar Svevo and the line carrying the 1BL.1RS translocation have provided further information on these complex group of proteins. In particular, all the three types of typical LMW-GS (LMW-s, LMW-m and LMW-i) were identified in Svevo, whereas the latter group is the only one present in the line with the 1BL.1RS translocation, thus confirming previous findings of the association of the LMW-i type subunits with genes present on chromosome 1A.

Genetically directed differential subtraction chain products related to in vitro response of immature embryos of rye (Secale cereale L.): isolation, characterization, and expression analysis

Winter rye (Secale cereale L.) is known to be recalcitrant to tissue culture response (TCR). Moreover, the mechanisms controlling TCR are poorly recognized. In the present study, a Genetically Directed Differential Subtraction Chain (GDDSC) strategy was used to isolate genomic regions associated with TCR. Two pairs of bulks, R-NR and E > 90–E < 25, were prepared, and for each pair, the bulk was used both as a tester and as a driver. After eight rounds of subtraction, 45 unique GDDSC products were obtained. To verify the connection between GDDSCs and TCR two approaches were applied: Real-Time RT-PCR analysis and genetic mapping. The expression profiles of four out of six investigated products agrees with the phenotype and subtraction direction. Two from the developed GDDSC-SCAR markers showed polymorphism in lines L9 and L318, the parental components of a mapping population. The polymorphic SCAR GDDSC markers were mapped on the rye chromosome 4R (SCAR-GDDSC NR 440BamHI) and 6R (SCAR-GDDSC E < 25 340BamHI). The marker E < 25_340B9 was localized in the border region of QTL for embryogenic callus production.

Transmission of the Chromosome 1R in Winter Wheat Germplasm Aimengniu and Its Derivatives Revealed by Molecular Markers

In order to clarify the transmission of the rye chromosome 1R in winter wheat germplasm Aimengniu and its derivatives, 17 derivatives and 7 types of Aimengniu were examined through molecular-marker technology. The results showed that the chromosome arm 1RS of Neuzucht was transmitted to 5 of the 7 types of Aimengniu, i.e., Aimengniu II and Aimengniu IV-Aimengniu VII, no segment of 1RS was identified in Aimengniu I or Aimengniu III. As for the 17 derivatives, the 1RS chromosome arm of Aimengniu was transmitted to 11 derivatives, part segments of 1RS were found in 1 derivative, while no segment was found in the remaining 5 ones. The results provided the evidence that molecular-marker technology was an efficient approach and suitable for analysis of the transmission of chromosome 1R.

Molecular cytogenetic and agronomic characterization of advanced generations of wheat × triticale hybrids resistant toDiuraphis noxia(Mordvilko): application of GISH and microsatellite markers

The PI 386148 triticale from Russia is among the highest resistant line to the Russian wheat aphid (RWA) (Diuraphis noxia (Mordvilko)). This triticale line was used as the male parent in crosses with Lamar wheat (Triticum aestivum L.). The F1 plants were backcrossed to Lamar wheat. The progenies were tested for RWA biotype 1 reaction for at least eight backcross and selfing generations. Five lines from these selections were identified for their resistance to the RWA and their seeds were increased for agronomic and other characterizations. Molecular and cytological analyses of these lines were performed using genomic in situ hybridization and rye chromosome-specific microsatellites markers. Three lines were cytologically stable and carried a pair of rye (Secale strictum (C. Presl) C. Presl) chromosomes as disomic addition lines of 1R. One line was unstable and showed a moderate level of mixoploidy with monosomic additions of 1R. Duplication of rye chromosome 1R was also identified. No wheat-rye chromosome interchange was detected, suggesting little homology between S. strictum and T. aestivum chromosomes. Specific microsatellite primers were used to identify the rye chromosomes present in each line. One rye chromosome, 1R, from the donor species contains genes for RWA resistance. Grain yield and test weight of three of the lines were similar to some adapted released wheat varieties under stress conditions.

Development and application of EST-STS markers specific to chromosome 1RS ofSecale cereale

Molecular markers are important tools that have been used to identify the short arm of rye chromosome 1R (1RS) which contains many useful genes introgressed into wheat background. Wheat expressed sequence tag (EST) sequences are valuable for developing molecular markers since ESTs are derived from gene transcripts and more likely to be conserved between wheat and its relative species. In the present study, 35 sequence-tagged site (STS) primers were designed based on EST sequences distributed on homology group 1 chromosomes of Triticum aestivum and used to screen specific markers for chromosome 1RS of Secale cereale . Two primer pairs different from the early studies, STS WE3 , which amplified a 1680-bp and a 1750-bp fragment, and STS WE126 , which produced a 850-bp fragment from rye genome, were proved to be specific to chromosome 1RS since the corresponding fragments were only amplified from 1R chromosome addition line and wheat-rye lines with chromosome 1RS, but not from wheat-rye 2R-7R chromosome addit...

Cytological dissection and molecular characterization of chromosome 1R derived from 'Burgas 2' common wheat

Rye chromosome 1R harbors many agronomically important genes such as resistance genes for rusts. Using the gametocidal system, we dissected the 1R chromosome substituted for wheat chromosome 1B in a common wheat cultivar 'Burgas 2'. The gametocidal system induces chromosomal breakage in the 1R chromosome, as well as in wheat chromosomes. We cytologically examined a pool of prescreened common wheat plants that had been shown to have single or multiple rearranged 1R chromosomes and established 95 common wheat lines carrying single 1R segments. We conducted PCR analysis of these lines, termed '1R dissection lines', using 10 PCR-based 1R-specific markers. We mapped the 10 PCR-based markers along the 1R chromosome with the breakpoints of the 1R dissection lines. Based on the PCR result and the positions of the primary and secondary constrictions, we could separate the breakpoints of the rearranged 1R chromosomes into 12 regions along the 1R chromosome. On the other hand, using the breakpoints, we could separate the PCR-based markers from each other except for two markers. These dissection lines are useful in mapping DNA markers and may facilitate the construction of contig maps.

Development of microsatellite markers specific for the short arm of rye (Secale cereale L.) chromosome 1

We developed 74 microsatellite marker primer pairs yielding 76 polymorphic loci, specific for the short arm of rye chromosome 1R (1RS) in wheat background. Four libraries enriched for microsatellite motifs AG, AAG, AC and AAC were constructed from DNA of flow-sorted 1RS chromosomes and 1,290 clones were sequenced. Additionally, 2,778 BAC-end-sequences from a 1RS specific BAC library were used for microsatellite screening and marker development. From 724 designed primer pairs, 119 produced 1RS specific bands and 74 of them showed polymorphism in a set of ten rye genotypes. We show that this high attrition rate was due to the highly repetitive nature of the rye genome consisting of a large number of transposable elements. We mapped the 76 polymorphic loci physically into three regions (bins) on 1RS; 29, 30 and 17 loci were assigned to the distal, intercalary and proximal regions of the 1RS arm, respectively. The average polymorphism information content increases with distance from the centromere, which could be due to an increased recombination rate along the chromosome arm toward's the telomere. Additionally, we demonstrate, using the data of the whole rice genome, that the intra-genomic length variation of microsatellites correlates (r = 0.87) with microsatellite polymorphism. Based on these results we suggest that an analysis of the microsatellite length variation is conducted for each species prior to microsatellite development, provided that sufficient sequence information is available. This will allow to selectively design microsatellite markers for motifs likely to yield a high level of polymorphism.

A novel resource for genomics of Triticeae: BAC library specific for the short arm of rye (Secale cereale L.) chromosome 1R (1RS).

BackgroundGenomics of rye (Secale cereale L.) is impeded by its large nuclear genome (1C~7,900 Mbp) with prevalence of DNA repeats (> 90%). An attractive possibility is to dissect the genome to small parts after flow sorting particular chromosomes and chromosome arms. To test this approach, we have chosen 1RS chromosome arm, which represents only 5.6% of the total rye genome. The 1RS arm is an attractive target as it carries many important genes and because it became part of the wheat gene pool as the 1BL.1RS translocation.ResultsWe demonstrate that it is possible to sort 1RS arm from wheat-rye ditelosomic addition line. Using this approach, we isolated over 10 million of 1RS arms using flow sorting and used their DNA to construct a 1RS-specific BAC library, which comprises 103,680 clones with average insert size of 73 kb. The library comprises two sublibraries constructed using HindIII and EcoRI and provides a deep coverage of about 14-fold of the 1RS arm (442 Mbp). We present preliminary results obtained during positional cloning of the stem rust resistance gene SrR, which confirm a potential of the library to speed up isolation of agronomically important genes by map-based cloning.ConclusionWe present a strategy that enables sorting short arms of several chromosomes of rye. Using flow-sorted chromosomes, we have constructed a deep coverage BAC library specific for the short arm of chromosome 1R (1RS). This is the first subgenomic BAC library available for rye and we demonstrate its potential for positional gene cloning. We expect that the library will facilitate development of a physical contig map of 1RS and comparative genomics of the homoeologous chromosome group 1 of wheat, barley and rye.

Isolation of wheat–rye 1RS recombinants that break the linkage between the stem rust resistance gene SrR and secalin

Chromosome 1R of rye is a useful source of genes for disease resistance and enhanced agronomic performance in wheat. One of the most prevalent genes transferred to wheat from rye is the stem rust resistance gene Sr31. The recent emergence and spread of a stem rust pathotype virulent to this gene has refocused efforts to find and utilize alternative sources of resistance. There has been considerable effort to transfer a stem rust resistance gene, SrR, from Imperial rye, believed to be allelic to Sr31, into commercial wheat cultivars. However, the simultaneous transfer of genes at the Sec-1 locus encoding secalin seed storage proteins and their association with quality defects preclude the deployment of SrR in some commercial wheat breeding programs. Previous attempts to induce homoeologous recombination between wheat and rye chromosomes to break the linkage between SrR and Sec-1 whilst retaining the tightly linked major loci for wheat seed storage proteins, Gli-D1 and Glu-D3, and recover good dough quality characteristics, have been unsuccessful. We produced novel tertiary wheat-rye recombinant lines carrying different lengths of rye chromosome arm 1RS by inducing homoeologous recombination between the wheat 1D chromosome and a previously described secondary wheat-rye recombinant, DRA-1. Tertiary recombinant T6-1 (SrR+ Sec-1-) carries the target gene for stem rust resistance from rye and retains Gli-D1 but lacks the secalin locus. The tertiary recombinant T49-7 (SrR- Sec-1+) contains the secalin locus but lacks the stem rust resistance gene. T6-1 is expected to contribute to wheat breeding programs in Australia, whereas T49-7 provides opportunities to investigate whether the presence of secalins is responsible for the previously documented dough quality defects.

Epigenetic Control May Explain Large Within-Plant Heterogeneity of Meiotic Behavior in Telocentric Trisomics of Rye

In telocentric trisomics (telotrisomics) of organisms in which the chromosomes normally have two distinct arms, a single chromosome arm with a centromere is present in addition to a complete diploid set of chromosomes. It is the simplest form of polysomy and suitable for analyzing meiotic pairing and recombination patterns in situations where chromosomes compete for pairing. When no suitable meiotic chromosome markers are available, four metaphase I configurations can be distinguished. Their relative frequencies are indicative of the pairing and recombination patterns. In short arm (1RS) telotrisomics of chromosome 1R of rye (Secale cereale) we observed great differences in pairing and recombination patterns among spikes from different tillers and clones of the same plants. Anthers within spikes were only very rarely different. We analyzed a large number of genotypes, including inbreds as well as hybrids. The effects of genetic and environmental conditions on heterogeneity, if any, were limited. Considering that the reproductive tissue of a spike is derived from one primordial cell, it seems that at the start of sexual differentiation there was variation among cells in chromosomal control, which at meiosis determines pairing and crossing-over competence. We suggest that it is an epigenetic system that rigidly maintains this pattern through generative differentiation. In competitive situations the combination most competent for pairing will pair preferentially, forming specific meiotic configurations with different frequencies for different spikes of the same plant. This would explain the heterogeneity between spikes and the homogeneity within spikes. The epigenetic system could involve chromatin conformation or DNA methylation. There were no signs of heterochromatinization.

Rapid EST isolation from chromosome 1R of rye

BackgroundTo obtain important expressed sequence tags (ESTs) located on specific chromosomes is currently difficult. Construction of single-chromosome EST library could be an efficient strategy to isolate important ESTs located on specific chromosomes. In this research we developed a method to rapidly isolate ESTs from chromosome 1R of rye by combining the techniques of chromosome microdissection with hybrid specific amplification (HSA).ResultsChromosome 1R was isolated by a glass needle and digested with proteinase K (PK). The DNA of chromosome 1R was amplified by two rounds of PCR using a degenerated oligonucleotide 6-MW sequence with a Sau3AI digestion site as the primer. The PCR product was digested with Sau3AI and linked with adaptor HSA1, then hybridized with the Sau3AI digested cDNA with adaptor HSA2 of rye leaves with and without salicylic acid (SA) treatment, respectively. The hybridized DNA fragments were recovered by the HSA method and cloned into pMD18-T vector. The cloned inserts were released by PCR using the partial sequences in HSA1 and HSA2 as the primers and then sequenced. Of the 94 ESTs obtained and analyzed, 6 were known sequences located on rye chromosome 1R or on homologous group 1 chromosomes of wheat; all of them were highly homologous with ESTs of wheat, barley and/or other plants in Gramineae, some of which were induced by abiotic or biotic stresses. Isolated in this research were 22 ESTs with unknown functions, probably representing some new genes on rye chromosome 1R.ConclusionWe developed a new method to rapidly clone chromosome-specific ESTs from chromosome 1R of rye. The information reported here should be useful for cloning and investigating the new genes found on chromosome 1R.

Neocentric activity in chromosome 5R of rye revealed by haploidy

Schlegel, R. 1987. Neocentric activity in chromosome 5R of rye revealed by haploidy. - Hereditas 107: 1–6. Lund, Sweden. ISSN 0018–0661. Received October 2, 1986 In metaphase I and anaphase I of haploid ‘Petka’ rye a particular univalent chromosome with a proximal constriction can be observed in most of the pollen mother cells. A similarly shaped chromosome was also found in polyhaploid wheat-rye hybrids, triticale × wheat hybrids. and in a monosomic wheat-rye addition line derived from several rye genotypes. This chromosome behaves as a dicentric since co-orientation of the ordinary centromere and a second centromere-like structure is evident. However, the neocentric activity does not originate in the telomeres, but is confined to the proximal region of the long arm of this submeta-centric chromosome, which has been identified as chromosome 5R by the C-banding pattern (5Rq21).