Showing papers in "Genome in 1991"
TL;DR: A standard karyotype based on N-banding, C- banding, and modified C- Banding has been constructed for Triticum aestivum L. 'Chinese Spring' and an idiogram and nomenclature system have been developed for the description of individual bands.
Abstract: A standard karyotype based on N-banding, C-banding, and modified C-banding has been constructed for Triticum aestivum L. 'Chinese Spring'. An idiogram and a nomenclature system have been developed ...
505 citations
TL;DR: A restriction fragment length polymorphism (RFLP) map for barley (Hordeum vulgare L.) has been developed on the basis of a population of anther culture derived, doubled haploids from the F1 of cultivars 'Proctor' × 'Nudinka'.
Abstract: A restriction fragment length polymorphism (RFLP) map for barley (Hordeum vulgare L.) has been developed on the basis of a population of anther culture derived, doubled haploids from the F1 of cult...
421 citations
TL;DR: One hundred and seventy-eight loci have been mapped in Triticum tauschii (Coss.), and a hypervariable sequence was identified, which may have potential use in varietal fingerprinting.
Abstract: One hundred and seventy-eight loci have been mapped in Triticum tauschii (Coss.) Schmal. (2n = 14, DD) and Triticum aestivum L. em. Thell. (2n = 42, AABBDD). Thirty-five loci were mapped by aneuplo...
294 citations
TL;DR: The rapid screening and identification of tightly linked markers to the target genes demonstrated the potential of RAPD markers for saturating genetic maps.
Abstract: Near-isogenic lines were used to identify restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) markers linked to genes for resistance to downy mildew (Dm) in lettuce. Two pairs of near-isogenic lines that differed for Dm1 plus Dm3 and one pair of near-isogenic lines that differed for Dm11 were used as sources of DNA. Over 500 cDNAs and 212 arbitrary 10-mer oligonucleotide primers were screened for their ability to detect polymorphism between the near-isogenic lines. Four RFLP markers and four RAPD markers were identified as linked to the Dm1 and Dm3 region. Dm1 and Dm3 are members of a cluster of seven Dm genes. Marker CL922 was absolutely linked to Dm15 and Dm16, which are part of this cluster. Six RAPD markers were identified as linked to the Dm11 region. The use of RAPD markers allowed us to increase the density of markers in the two Dm regions in a short time. These regions were previously only sparsely populated with RFLP markers. The rapid screening and identification of tightly linked markers to the target genes demonstrated the potential of RAPD markers for saturating genetic maps.
261 citations
TL;DR: Two-base repeats are abundant in plant genomes and could provide a large number of polymorphic markers for studies of plant population genetics, suggesting that two-base repeat sites were clustered in the genome.
Abstract: Tandem DNA repeats of two-base pairs are potentially important tools for population genetic studies because of their abundance and length variation. As part of our research into the ecology of tropical forest plants, we began a study of dinucleotide repeat regions in several genera of tropical trees. Genomic libraries in bacteriophage lambda were screened with the oligonucleotide probes poly(GT) and poly(AG). Both types of repeat regions were abundant in the genomes of all six plant species examined. Using the size of inserts in the phage libraries and number of phage screened, we estimated that there were 5 x 10(3) to 3 x 10(5) poly(AC) sites per genome, with slightly more AG than AC sites. When libraries were made from smaller fragments of genomic DNA, abundance estimates were higher, suggesting that two-base repeat sites were clustered in the genome. Poly(AC) sites were 16-22 bp in length, and four of the five sequenced were adjacent to either poly(AG)or poly(AT) sites. Other repeat region s appeared in DNA flanking the AC sites. This further demonstrated that two-base repeats and other repetitive DNA were clustered in the genome. Two-base repeats are abundant in plant genomes and could provide a large number of polymorphic markers for studies of plant population genetics.
256 citations
TL;DR: Phylogenetic inference based strictly on transversion differences confirmed traditional generic and tribal groupings, i.e., Prosimulium fuscum (Syme & Davies) is close to ProSimulium magnum (Dyar & Shannon); Simulium decorum (Walker), SimULium venustum s.l. (Say), and Simulius vittatum s.
Abstract: Universal primers constructed from the 16S ribosomal RNA gene in the Drosophila yakuba mitochondrial genome were successfully used to amplify, via the polymerase chain reaction, the homologous regi...
217 citations
TL;DR: This study expanded the study to include unadapted germ-plasm lines from the various South American centers of origin, Africa, and China, where considerable morphological and physiological variability has been reported to exist.
Abstract: Peanut germ plasm consists of the cultivated allotetraploid species Arachis hypogaea L. and a large number of wild species, which are nearly all diploids. Our previous work indicated a very low lev...
216 citations
TL;DR: This RFLP study in B. napus provides important information on genome organization of functional DNA sequences and complements the current RFLp mapping effort in Brassica oleracea.
Abstract: F2 segregation analyses of DNA restriction fragment length polymorphisms (RFLPs) detected between two cultivars of canola ('Westar' × Topas') was used to construct a detailed genetic map of Brassic...
173 citations
TL;DR: DNA from Triticum tauschii (the D-genome donor to hexaploid wheat, Triticus aestivum) has been cloned using the restriction endonuclease PstI to generate fragments for insertion into the plasmid pB.
Abstract: DNA from Triticum tauschii (the D-genome donor to hexaploid wheat, Triticum aestivum) has been cloned using the restriction endonuclease PstI to generate fragments for insertion into the plasmid pB...
147 citations
TL;DR: To study patterns of variability at a large number of loci, restriction fragment length polymorphism genotypes at 25 loci in a germ-plasm collection of 102 T. tauschii accessions were determined and Hedrick's probability of genotypic identity, botanical varieties T. typica and T. anathera were very similar to each other.
Abstract: Triticum tauschii (Coss.) Schmal. (genome DD), a diploid progenitor of hexaploid wheat (Triticum aestivum L.; AABBDD), grows across large areas of southwest Asia and contains more genetic variability for disease and insect resistance, isozymes, and seed storage proteins than the D genome of T. aestivum. To study patterns of variability at a large number of loci, we determined restriction fragment length polymorphism genotypes at 25 loci in a germ-plasm collection of 102 T. tauschii accessions. All accessions were homozygous at all loci, so "alleles" and "genotypes" were equivalent. Twenty loci were polymorphic, with two to six genotypes per locus and polymorphic indexes ranging from 0.06 to 0.74. Linkage disequilibrium was widespread. On the basis of Hedrick's probability of genotypic identity, botanical varieties T. t. ssp. eusquarrosa var. typica and T. t. ssp. eusquarrosa var. anathera were very similar to each other, as were T. t. ssp. strangulata and T. t. ssp. eusquarrosa var. meyeri, with a large g...
146 citations
TL;DR: A repetitive DNA sequence unique to the rye genome is described and is present on all seven rye chromosomes and the hybridization patterns in Southern blots indicate that it is not organised as blocks of tandem arrays and in situ hybridization shows thatIt is dispersed throughout the rye chromosomes.
Abstract: In this paper we describe a repetitive DNA sequence unique to the rye genome. The corresponding DNA probe (pAW173) was cloned as a 450-bp fragment and does not hybridize to wheat or barley DNA and is not related to five other repeated DNA families characterised in rye. This new family (designated the R173 family) consists of moderately repeated DNA (~ 15 000 units per genome) and is present on all seven rye chromosomes. The hybridization patterns in Southern blots indicate that it is not organised as blocks of tandem arrays and in situ hybridization shows that it is dispersed throughout the rye chromosomes. The probe has been successfully used as a molecular marker in identifying rye genetic material in a wheat background.Key words: repetitive DNA sequence, rye-specific DNA, molecular marker.
TL;DR: umerous genetic differences characterized each cultivated type, suggesting a polyphyletic origin for L. sativa and other L. serriola populations or some other unknown entities were involved in the evolution of cultivated lettuce.
Abstract: We have examined 67 accessions of Lactuca sativa L and five related species for variation at restriction fragment length polymorphism loci Fifty-five clones were used to probe genomic DNA digeste
TL;DR: Variation in the intergenic spacer region of the ribosomal RNA genes (located at the Nor locus) was assayed in a collection of 411 accessions of Triticum tauschii from Turkey, USSR, Iran, Afghanisan, Pakistan, and China and showed a high level of recombination with the 5SDna-2 locus, which was also located on chromosome 5D.
Abstract: Variation in the intergenic spacer region of the ribosomal RNA genes (located at the Nor locus) was assayed in a collection of 411 accessions of Triticum tauschii from Turkey, USSR, Iran, Afghanisa...
TL;DR: Under salinity, the amphiploid greatly outperformed CS in grain yield, biomass, and other characters, indicating that it is more salt tolerant than CS.
Abstract: Bread wheat cv. Chinese Spring (CS), an amphiploid from a cross between CS and salt-tolerant Lophopyrum (= Agropyron) elongatum (Host) Love, 19 of 21 possible disomic substitution lines of L. elong...
TL;DR: A 1:2 ratio of biotin-labeled genomic DNA of barley to blocking (unlabeled, sheared) DNA of wheat was sufficient to reveal brownish labeled barley chromosome domains against bluish background of unlabeled wheat chromatin in metaphase, prophase, and interphase nuclei of wheat-barley addition lines.
Abstract: A technique for in situ hybridization is reported that can be used to detect barley chromatin in wheat background using total genomic DNA as a probe. A 1:2 ratio of biotin-labeled genomic DNA of ba...
TL;DR: The distribution of telomere repeats in Hordeum vulgare (barley) and Secale cereale (rye) was studied by DNA–DNA in situ hybridization to root-tip chromosome preparations, indicating that individual telomeres may contain different numbers of repeats of the telomeric sequence.
Abstract: The distribution of telomeric repeats in Hordeum vulgare (barley) and Secale cereale (rye) was studied by DNA–DNA in situ hybridization to root-tip chromosome preparations. Biotinylated synthetic oligomers, (TTTAGGG)6 and (CCCTAAA)6, homologous to the consensus sequence of the Arabidopsis thaliana telomeric repeat, were used as probes, and hybridization sites were detected by Texas red fluorescence or horseradish peroxidase catalyzed precipitation of diaminobenzidine. After examination in the light microscope, the same preparations were transferred to the electron microscope for high-resolution analysis. Sites of hybridization were visualized as single or double dots at the end of most chromosome arms. The sizes of the signal dots varied widely, indicating that individual telomeres may contain different numbers of repeats of the telomeric sequence. In contrast to many mammals, no telomere repeats were detected other than at the ends of the chromosomes. At interphase, signals were concentrated in one regio...
TL;DR: Two haptens, biotin and digoxigenin, were used to label two highly repetitive plant DNA sequences, which were simultaneously localized by in situ hybridization on chromosome spreads of rye, Secale cereale cv.
Abstract: Two haptens, biotin and digoxigenin, were used to label two highly repetitive plant DNA sequences: pTa71 (a clone containing a ribosomal DNA sequence from wheat, Triticum aestivum) and pSc119.2 (a clone containing a 120-bp tandem repeat sequence from rye, Secale cereale). These probes were simultaneously localized by in situ hybridization on chromosome spreads of rye, Secale cereale cv. Petkus Spring. The ability to localize two sequences simultaneously will be of major importance for physically ordering DNA sequences along plant chromosomes.Key words: physical mapping, DNA–DNA in situ hybridization, Secale, fluorescent mapping, multiple labelling.
TL;DR: A G banding technique combining trypsin and hot saline treatments was used to analyze the chromosomes of two grasshopper species, Eyprepocnemis plorans and Locusta migratoria, both of which contain both standard and supernumerary heterochromatin.
Abstract: A G banding technique combining trypsin and hot saline treatments was used to analyze the chromosomes of two grasshopper species, Eyprepocnemis plorans and Locusta migratoria, both of which contain both standard and supernumerary heterochromatin. Although this technique does not produce G bands like those in mammalian chromosomes, it serves to characterize heterochromatic regions whose nature has been inferred from other banding techniques (C, N, CMA, and DAPI banding). The light regions revealed by G banding contain GC-rich DNA sequences, the more prominent of which coincide with nucleolus organizer regions (NORs). Furthermore, the proximal heterochromatin in E. plorans was heterogeneous, and the standard and supernumerary heterochromatin showed conspicuous differences in organization. Supernumerary heterochromatin is an exception to the regular patterns shown by the standard heterochromatin. The findings are related to the mechanism of action of these banding techniques.Key words: banding techniques, gr...
TL;DR: Five mechanisms of 2n egg formation were identified: synaptic variant (genetically first division restitution), delayed meiotic division (first division restitution and second division restitution); omission of the second division (the prevalent mechanism), irregular anaphase II (second division restitution; and failure of second cytokinesis (second Division restitution).
Abstract: The occurrence of 2n eggs in 381 haploids from six tetraploid parents and in 127 plants representing five diploid wild species was detected using 2x × 4x crosses. Sixty-two percent of the haploids and 24% of the wild-species plants produced 2n eggs. Twenty-six haploids and 17 species plants that gave high seed set in 2x × 4x crosses were examined cytologically to determine the frequency and mechanisms of 2n egg formation. There was significant variation in the frequency of 2n eggs among haploids (7–57%) and among species plants (4.9–57.3%). Five mechanisms of 2n egg formation were identified: synaptic variant (genetically first division restitution); delayed meiotic division (first division restitution and second division restitution); omission of the second division (the prevalent mechanism, second division restitution); irregular anaphase II (second division restitution); and failure of second cytokinesis (second division restitution). 2n eggs can be formed by more than one mechanism within a clone. The...
TL;DR: It is concluded that the low level of mtDNA polymorphism in A. albopictus is a result of recent range expansion and that the mixture of haplotypes is a likely result of human-aided gene flow among populations.
Abstract: A survey of restriction fragment polymorphism in mitochondrial DNA (mtDNA) of 17 populations of the mosquito Aedes albopictus was undertaken. The mtDNA size was estimated to be about 17.5 kbp. The level of polymorphism was low, with over 99% of the fragments being shared in common among the 17 populations. Three populations, Mauritius, Singapore, and Hong Kong, contained individuals with both the ancestral and novel mtDNA haplotypes. We conclude that the low level of mtDNA polymorphism in A. albopictus is a result of recent range expansion and that the mixture of haplotypes is a likely result of human-aided gene flow among populations.Key words: mitochondrial DNA, genetic variation, genetic structure, Aedes albopictus.
TL;DR: A detailed characterization of the 5S rRNA genes of tomato with respect to chromosome assignment, chromosomal localization, copy number, and physical size is reported.
Abstract: The 5S ribosomal RNA (rRNA) genes represent one of the most abundant gene families in eukaryotic genomes and have been a model system for the study of molecular organization and evolution of multigene families in eukaryotes. This paper reports a detailed characterization of the 5S rRNA genes of tomato (Lycopersicon esculentum) with respect to chromosome assignment, chromosomal localization, copy number, and physical size. By restriction fragment length polymorphism, the tandemly repeated 5S rRNA genes were assigned to a region of chromosome 1 of tomato. These results were confirmed by in situ hybridization onto tomato metaphase chromosomes. The single hybridization signal was localized to the short arm of chromosome 1, in a region close to the centromere. Based on reconstruction experiments, it was estimated that the 400-bp repeating unit occurs in approximately 1000 copies per haploid genome. Physical characterization of the entire locus was then performed by means of pulsed-field gel electrophoresis. Di...
TL;DR: It is suggested that in wheat, pairing initiation sites are distributed throughout at least the distal halves of the arms and that the alignment of telomeres may be critical for pairing success.
Abstract: Metaphase I pairing of deficient chromosomes was analyzed in a set of 'Chinese Spring' (CS) wheat (Triticum aestivum L. em. Thell.) plants with varying lengths of deficiencies in the long arm of chromosome 4A (6, 8, 11, 17, 23, 34, 36, 39, and 50% missing), the long arm of chromosome 5B (49% missing), and the long arm of chromosome 2B (33% missing). Pairing in homologous chromosomes between deficient and complete arms was greatly reduced even by small differences in arm length. In deficiency homozygotes and in an isochromosome derived from a deficient 4AL arm, pairing of the two deficient arms was high and approached that of two complete arms. In plants where deficient and complete arms competed for pairing partners, pairing was exclusively between arms of the same length. These results suggest that in wheat, pairing initiation sites are distributed throughout at least the distal halves of the arms and that the alignment of telomeres may be critical for pairing success. Genetic mapping of the deficiency b...
TL;DR: Differences found in the desynaptic (dy) mutant of maize in microsporocytes were a statistically significant wider dimension of the synaptonemal complex central region and also less twisting of synapsed configurations at pachytene.
Abstract: The phenotype of the desynaptic (dy) mutant of maize in microsporocytes at meiotic prophase was compared with normal microsporocytes of a closely related strain and with microsporocytes of a maize inbred line (KYS) assumed to be normal. Strikingly more univalents and open arms of bivalents were found in the mutant cells than in normal cells at diakinesis, and where there was heterozygosity for a distal knob (heterochromatic region), separation was usually equational, indicating the occurrence of normal crossing-over followed by failure of chiasma maintenance in the mutant. Differences found in the mutant by electron microscopy were a statistically significant wider dimension of the synaptonemal complex central region and also less twisting of synapsed configurations at pachytene. It is suggested that these are side-effect symptoms of a defect in the synaptonemal complex (or associated substance), which is expressed later as sporadic loss of chiasma maintenance.Key words: desynaptic, chiasma maintenance, s...
TL;DR: Sequence analysis of six related clones of Brachycome dichromosomatica indicated that some regions of the sequence are more highly conserved than others or, alternatively, that some adenine residues at the NdeII site are methylated.
Abstract: Supernumerary B chromosomes represent one of many causes of numerical chromosome variation that exist in higher plants and animals. Sequences of DNA unique to B chromosomes of Brachycome dichromosomatica were enriched prior to cloning and resultant clones hybridizing only to plants containing B chromosomes were further investigated. Sequences of DNA that were characterised include members of a family of 176-bp tandem repeats that are specific to the B chromosomes of B. dichromosomatica, an annual Australian native plant species with only two pairs of A chromosomes and up to three dispensable B chromosomes. Sequence analysis of these six related clones indicated that some regions of the sequence are more highly conserved than others or, alternatively, that some adenine residues at the NdeII site are methylated. The repeat is homologous to DNA from Brachycome ciliaris var. languinosa but not to DNA from other related taxa growing in the vicinity of the B. dichromosomatica populations.
TL;DR: Transient expression of marker genes (cat and uidA) delivered by the Biolistics microprojectile bombardment technique has been detected in immature zygotic embryos of wheat.
Abstract: Transient expression of marker genes (cat and uidA) delivered by the Biolistics microprojectile bombardment technique has been detected in immature zygotic embryos of wheat (Triticum aestivum L.). The DNA expression vectors that gave maximal expression of both cat (pCaMVI1CN) and uidA (pCaMVI1GusN) genes had an alcohol dehydrogenase (Adh1) intron 1 cloned in between the cauliflower mosaic virus (CaMV35S) promoter and the coding region of the gene. Detection of chloramphenicol acetyltransferase (CAT) activity in response to cat gene was complicated by the presence of an inhibitor of CAT activity as well as an endogenous CAT-Iike activity. The results of enzymatic assays were confirmed by an ELISA technique using CAT-specific antibodies, whereas the β-glucuronidase (GUS) activity following the introduction of the uidA gene was confirmed by both histochemical and fluorometric techniques.Key words: cereal transformation, gene expression, ELISA, wheat.
TL;DR: Restriction fragment length polymorphisms have several advantages over conventional genetic markers and as a result have received increased attention from plant breeders and geneticists.
Abstract: Restriction fragment length polymorphisms (RFLPs) have several advantages over conventional genetic markers and as a result have received increased attention from plant breeders and geneticists. Th...
TL;DR: Deviations from the equiprobability of gamete encounters for almost all progeny are clearly demonstrated and reveal a large amount of male gametophytic fitness variability in land-race populations.
Abstract: Intergametophytic competitions with prepotency of autopollen have been previously described in some cultivated lines of pearl millet (Pennisetum typhoides (Burm.) Stapf &Hubb.). This paper reports the analysis of intergametophytic competitions between pollen from wild and cultivated plants on stigmas of both wild and cultivated plants. Three inbred lines (two cultivated and one wild) and two land races (one cultivated and one wild) were used, each of them as pollen donors as well as plant receptors. These populations represent in some instances allopatric and sympatric evolutionary situations between wild and cultivated forms. Deviations from the equiprobability of gamete encounters for almost all progeny are clearly demonstrated and reveal a large amount of male gametophytic fitness variability in land-race populations. There is no marked hierarchy between pollen sources for their competitive ability, but taking into account the pollen-pistil interactions, preferential wild-wild and cultivated-cultivated...
TL;DR: That sex-linked fragments do not occur in the congener Campylorhynchus griseus suggests that their entrapment and amplification on the W chromosome in C. nuchalis occurred since the divergence of the two species.
Abstract: Jeffrey's minisatellite probe 33.15, which screens dozens of hypervariable loci throughout the genome, detects female-specific fragments in stripe-backed wrens (Campylorhynchus nuchalis). HaeIII subdivides the single large female-specific fragment observed with other enzymes into a polymorphic suite of fragments of similar total molecular weight among patterns. Sex-linked HaeIII haplotypes are perfectly transmitted from mother to daughter but not to sons. These results suggest that the female-specific HaeIII fragments represent variable subunits of a single long tandem repetitive array composed of approximately 20-bp repetitive units located outside the pairing region of the W chromosome. That sex-linked fragments do not occur in the congener Campylorhynchus griseus suggests that their entrapment and amplification on the W chromosome in C. nuchalis occurred since the divergence of the two species.Key words: minisatellites, sex chromosome, W chromosome, amplification.
TL;DR: The diminution in DNA amount with evolutionary specialisation appears to be a genomic strategy to dispense with the less important DNA associated with heterochromatic segments.
Abstract: In 23 species of Papaver L., 2C nuclear DNA amounts range from 4.64 pg in Papaver persicum (2n = 14) to 22.43 pg in Papaver orientale (2n = 42), revealing a fivefold variation within the genus. How...
TL;DR: The analysis of flanking regions showed that individual members of the R173 family are generally not found in the vicinity of other characterised families of repetitive DNA.
Abstract: In contrast to all other characterised families, repetitive DNA sequences of the rye-specific R173 family occur generally as a monomer and have an unusually long repeat unit. A genomic library was generated from a wheat line with three copies of the short arm of chromosome 1 of rye, 1RS. Seventy-seven λ clones, representing independent members of the family, were isolated by hybridization to pAW173. They share a common region of approximately 3.5 kbp, which is free of large internal repeats and therefore constitutes the basic unit of the dispersed R173 family. The analysis of flanking regions showed that individual members of the R173 family are generally not found in the vicinity of other characterised families of repetitive DNA. The flanking regions of four selected λ clones were different from each other and comprised both repetitive and low-copy sequences. A restriction fragment length polymorphism probe, mapping to the short arm of chromosome 1, was obtained by subcloning of flanking regions of the R...