bluuebunny/crossref_metadata_2025 huggingface dataset:
Production and identification of primary trisomics in diploid Agropyron cristatum (crested wheatgrass)
Authors: Imanywoha Justus , Jensen Kevin B. , Hole David
Published: May 2008

Six of the seven possible primary trisomics in Agropyron cristatum were produced. Based on morphology, arm length ratios, and C-banding patterns, they were identified as primary trisomics for chromosomes A, B, C, D, E, and G. Agropyron cristatum is one of several species constituting the crested wheatgrass complex. All species in this complex contain one basic genome (P). A study was conducted to produce and identify a primary trisomic series that will be used to map genes to individual chromosomes. A population of 157 plants were generated by crossing autotriploids (PPP) with diploid (PP) A. cristatum: 58 were diploid (2n = 14), 76 were primary trisomies (2n = 15), 17 were double trisomic (2n = 16), 4 were triple trisomics (2n = 14 + 3), 1 was telocentric trisomic (2n = 14 + 1 telo), and 1 was tetratrisomic (2n = 14 + 4). Karyotype analysis of acetoorcein-stained chromosomes was carried out using the CHROMPAC III computer program; for analysis of C-banded karyotypes, the computer imaging analysis program PCAS (Plant Chromosome Analysis System) was used to identify the primary trisomics. Of the 47 primary trisomics analyzed, 21 plants had one extra satellited chromosome E, 18 with the satellited D chromosome, 3 each for chromosomes B and G, and 1 each for chromosomes C and A. Chromosome pairing was studied in trisomies B, D, E, and G. Trisomics for chromosomes B and G were similar in their mieotic behavior. Each had a trivalent frequency of about 60% and pollen stainability of less than 40%. Trisomics for chromosomes D and E had a trivalent frequency of about 30% and pollen stainability of over 70%.Key words: trisomics, meiosis, hybridization, Agropyron cristatum, C-banding, karyotype.
A new source of cytoplasmic male sterility in pearl millet: RFLP analysis of mitochondrial DNA
Authors: Sujata V. , Sivaramakrishnan S. , Rai K. N. , Seetha K.
Published: May 2008

A new source of cytoplasmic male sterility (cms) in pearl millet (Pennisetum glaucum (L.) R.Br.) derived from a half-sib progeny of the Early Gene Pool (EGP 261) and used in a male-sterile line, ICMA 90111, was compared with other known cms sources for RFLP of mitochondrial (mt) DNA. Southern blot hybridization of mtDNA from ICMA 90111 digested with several restriction enzymes and probed with homologous mtDNA clones from pearl millet and heterologous gene clones from maize and wheat revealed the RFLP patterns of ICMA 90111 distinct from others studied so far. The dendrogram of male-sterile lines constructed from the Southern blot hybridization patterns indicated that ICMA 90111 represents a separate group. Our results suggest that this source of cms is unique in several respects.Key words: Pennisetum glaucum, cytoplasmic male sterility, mitochondrial DNA, RFLP.
Chromosomal mapping of the KlCYC1 gene from Kluyveromyces lactis
Authors: González-Siso M. Isabel , Freire-Picos M. Angeles , Cerdán M. Esperanza , Wésolowski-Louvel M. , Fukuhara H.
Published: May 2008

Chromosomal assignment of the KlCYC1 gene from Kluyveromyces lactis has been performed by hybridization of the labelled probe to a DNA blot of isolated chromosomes. A clear hybridization signal to chromosome VI is reported.Key words: Kluyveromyces lactis, cytochrome c gene, chromosomal mapping.
Genome analysis and replication behavior of a set of repetitive sequences of Lilium longiflorum
Authors: Jayawardene Nishan , Riggs C. Daniel , Hasenkampf Clare A.
Published: May 2008

The four clones, pLZH47, pLZ112, pLZ113, and pLZ122, previously assumed to contain DNA sequences that replicate during zygotene (zygDNA), actually had their replication behavior tested using a replication assay. Genome analysis was also done for each clone. All of the clones seem to be members of families of dispersed repetitive DNA. The number of copies per 2C genome are as follows: pLZH47, 13 500; pLZ112, >100; pLZ113, 200; and pLZ122, 3500. The replication assays measured the amount of hybridizable sequences available at the stage of leptotene (before zygotene DNA replication occurs) and at the stage of pachytene (after zygotene replication occurs). True zygDNA clones should have twice as many sequences to hybridize to at pachytene as at leptotene. None of the clones had the expected increase. One clone, pLZ122, did show a statistically significant increase (10%). It may consist of a mixture of zygDNA and non-zygDNA sequences. Alternatively, only 10% of the pLZ122 family members may function as zygDNA.Key words: meiosis, zygDNA sequences, synapsis, chromosome homology, genome structure.
An interchromosomal reciprocal translocation in wheat involving leaf rust resistance gene Lr34
Authors: Dyck P. L. , Kerber E. R. , Aung T.
Published: May 2008

'Thatcher' backcross lines RL6058 and RL6077 have adult-plant leaf rust resistance and were believed to have Lr34. However, genetic analysis revealed that the genes in the two lines were independent of each other. Previous work demonstrated that Lr34 is located on chromosome 7D. The leaf rust resistance gene in RL6058 must be on chromosome 7DS because no recombinants were observed between it and gene Lr29, known to be on chromosome 7DS. It was also linked with Rc3 (30.25 ± 2.88%), a gene for purple coleoptile on chromosome 7DS. It was independent of Lr19 and NS1 (nonsuppressor mutant), which are located on 7DL. The leaf rust resistance gene in RL6077 was independent of genes Lr19 and Lr29. The presence of quadrivalents in pollen mother cells of the RL6058/RL6077 hybrid indicates that the Lr34 gene in RL6077 may have been translocated onto another chromosome. Lr34 from RL6058 and RL6077 may have been combined in four F3 lines derived from their intercross.Key words: Triticum aestivum, wheat, leaf rust resistance.
Active maize genes are unmodified and flanked by diverse classes of modified, highly repetitive DNA
Authors: Bennetzen Jeffrey L. , Schrick Kathrin , Springer Patricia S. , Brown Willis E. , SanMiguel Phillip
Published: May 2008

We have characterized the copy number, organization, and genomic modification of DNA sequences within and flanking several maize genes. We found that highly repetitive DNA sequences were tightly linked to most of these genes. The highly repetitive sequences were not found within the coding regions but could be found within 6 kb either 3′ or 5′ to the structural genes. These highly repetitive regions were each composed of unique combinations of different short repetitive sequences. Highly repetitive DNA blocks were not interrupted by any detected single copy DNA. The 13 classes of highly repetitive DNA identified were found to vary little between diverse Zea isolates. The level of DNA methylation in and near these genes was determined by scoring the digestibility of 63 recognition/cleavage sites with restriction enzymes that were sensitive to 5-methylation of cytosines in the sequences 5′-CG-3′ and 5′-CNG-3′. All but four of these sites were digestible in chromosomal DNA. The four undigested sites were localized to extragenic DNA within or near highly repetitive DNA, while the other 59 sites were in low copy number DNAs. Pulsed field gel analysis indicated that the majority of cytosine modified tracts range from 20 to 200 kb in size. Single copy sequences hybridized to the unmodified domains, while highly repetitive sequences hybridized to the modified regions. Middle repetitive sequences were found in both domains.Key words: genome organization, interspersed repetitive DNA, DNA modification.
Construction of a sorghum RFLP linkage map using sorghum and maize DNA probes
Authors: Ragab R. A. , Dronavalli S. , Maroof M. A. Saghai , Yu Y. G.
Published: May 2008

Previous reports on sorghum restriction fragment length polymorphism (RFLP) mapping have been limited to the use of heterologous maize clones. In this study, both sorghum and maize probes were used to construct an RFLP map based on an F2 population from a cross between sorghum lines BSC 35 and BTX 631. A set of single-or low-copy number clones from a sorghum genomic library was preselected to use as hybridization probes. Forty-nine of the 101 clones (49%) tested were polymorphic between the two parental lines. In comparison, 53 of the 135 maize probes (39%) detected polymorphism with the same restriction enzymes. In total, 71 RFLP markers (38 sorghum and 33 maize) were placed into 15 linkage groups spanning 633 cM with an average marker distance of 8.9 cM. Comparison of our linkage map with other published sorghum maps, based on maize probes, showed resemblance for several linkage groups, indicating that these maps can be integrated. Homologous sorghum probes are useful in improving the coverage and resolution of RFLP linkage map in sorghum.Key words: RFLP, Sorghum bicolor, chromosomes, Zea mays.
Presence of various rye-specific repeated DNA sequences on the midget chromosome of rye
Authors: Kota Rama S. , Gill Bikram S. , Hulbert Scot H.
Published: May 2008

The chromosome 1R of rye, or the midget chromosome, is necessary for plump, viable seed development and fertility restoration in the alloplasmic line with rye cytoplasm and a hexaploid wheat nucleus. The midget chromosome of rye represents 1/15th of the physical length of the chromosome 1R of rye. C-banding analysis indicated that the centromeric and pericentric region (approximately 30% physical length) of the midget chromosome is heterochromatic and the distant 70% physical length is euchromatic. These data suggest that the midget chromosome may represent the pericentric region of the long arm of chromosome 1R. In contrast with earlier reports, our results indicate that an array of rye-specific repeated sequences (both dispersed and tandem) are present on the midget chromosome. Various rye-specific repeated DNA sequences that are present on the midget chromosome will be useful in constructing a long-range map and studying the genomic organization of the midget chromosome. It is unclear if any of these repeated DNA sequences are involved in the origin of the midget chromosome.Key words: midget chromosome, pericentric region, repeated DNA sequences, rye telomere associated sequence.
Characterization of a repetitive element detected by NheI in the genomes of Salmo species
Authors: Goodier John L. , Davidson William S.
Published: May 2008

The genomes of the two species in the genus Salmo (Atlantic salmon, S. salar; brown trout, S. trutta) contain a 380-bp repetitive element that is flanked by the recognition sequence of the restriction enzyme NheI. These elements, which comprise approximately 1.2% of the salmon genome, do not exist in long tandem arrays as is typical of satellite DNA. A comparison of the sequences of 16 salmon and 7 trout elements revealed that members of this family of repetitive DNA are closely related to one another (over 95% identity). Subfamily structure exists and there is evidence that members of the same subfamilies are found in both Salmo species. A search of the GenBank database indicated that sequences homologous to the NheI repeat are located within a 1424-bp segment inserted immediately downstream of the 5′ end of a Tc1 transposon-like sequence isolated from Atlantic salmon (A.R. Radice, B. Bugaj, D.H. Fitch, and S.W. Emmons, unpublished data; GenBank accession No. L12206).Key words: satellite DNA, Atlantic salmon, brown trout, Tc1-like transposon, evolution.
Minimal intraspecific variation in the sequence of the transcribed spacer regions of the ribosomal DNA of lake trout (Salvelinus namaycush)
Authors: Zhuo Lang , Sajdak S. L. , Phillips R. B.
Published: May 2008

Intraspecific variation in the sequence of the transcribed spacer regions of the ribosomal DNA (rDNA) in lake trout was examined by restriction mapping and sequencing of these regions amplified by the polymerase chain reaction. The length of the first internal transcribed spacer region (ITS-1) was 566 bases and the second internal transcribed spacer region (ITS-2) was 368 bases in lake trout. When the 1.4-kb region including the ITS-1, the 5.8S coding region, and the ITS-2 was amplified from 12 individuals from four populations and digested with eight different enzymes only one intraindividual polymorphism was found that occurred in each population. When the amplified ITS-1 region was sequenced from an additional 10 individuals from five populations, no interindividual variation was found in the sequence. A 6-kb portion of the rDNA repeat unit including 1.6 kb of the 18S coding region, the 5′ external spacer region (5′ ETS), and part of the adjacent intergenic spacer was cloned and a restriction map was prepared for these regions in lake trout. No intraspecific variation was found in the region adjacent to the 18S rDNA, which includes the 5′ ETS, although intraspecific and intraindividual length variation was found in the intergenic spacer region 3–6 kb from the 18S. Sequencing of a 609-b segment of the 5′ ETS adjacent to the 18S coding region revealed the presence of two 41-b repeats. The 198-b sequence between the repeats had some similarity to the 18S coding region of other fishes. Primers were designed for amplification of 559 b of the 5′ ETS using the polymerase chain reaction. No intraspecific variation in this region in lake trout was found when the DNA amplified from this region in 12 individuals from four populations was digested with eight restriction enzymes.Key words: ribosomal DNA, internal transcribed spacer regions, 5′ external spacer region, transcribed spacer, lake trout.
Walnut (Juglans spp.) genetic diversity determined by restriction fragment length polymorphisms
Authors: Fjellstrom R. G. , Parfitt D. E.
Published: May 2008

The genetic diversity of 13 Juglans species was characterized using nuclear RFLPs. Allelic frequencies among 41 Juglans populations were determined at 19 RFLP loci by hybridizing single locus probes to walnut DNAs digested with the restriction endonuclease EcoRI or HindIII. A 10-fold difference in species heterozygosity levels was seen among species in different sections of the genus. Differentiation among conspecific populations varied over threefold between species. Genetic differentiation among conspecific east Asian populations was larger than that seen among east Asian species, while the opposite trend was seen for Western Hemisphere species. Taxonomic affinities were also indicated by these results, suggesting that J. cinerea should be included as part of section Cardiocaryon rather than as a unique section, Trachycaryon. Juglans hindsii is classified as a distinct species and not a subspecies of J. californica. Strategies for germplasm preservation and species requiring marked collection efforts are given.Key words: Juglans, RFLP, genetic diversity, walnut.
Recovery of duplications by drug resistance selection in Caenorhabditis elegans
Authors: Marra Marco A. , Baillie D. L.
Published: May 2008

We have devised a scheme that facilitates rapid screening for duplications of essential loci. Our scheme takes advantage of the lev-1(x22) mutation, which confers resistance in a recessive fashion to the potent anthelmintic levamisole. We have tested our methodology by recovering two gamma ray induced duplications of let-56, the first essential gene to the left of unc-22. One of the duplications is attached to the fourth chromosome. The other duplication is attached to the X chromosome. This duplication contains a functional copy of the unc-22 gene, as well as functional copies of several essential loci adjacent to unc-22. Results we have obtained during analysis of this duplication are compatible with the notion that the copy of the unc-22 gene located on the duplication is subject to X chromosome dosage compensation.Key words: C. elegans, duplication, let-56, unc-22, X chromosome.
Placement of loci for avenins and resistance to Puccinia coronata to a common linkage group in Avena strigosa
Authors: Rayapati P. J. , Portyanko V. A. , Lee M.
Published: May 2008

Alcohol-soluble seed storage proteins of oat (avenins) were extracted from two diploid accessions representing the A genome and separated by high-resolution acid polyacrylamide gel electrophoresis. Polymorphisms were detected for three clearly resolved protein bands. Linkage analysis of 88 F2:3 families mapped the three bands to a single locus. Integration of avenin segregation data with an RFLP linkage map constructed from the same population, mapped the avenin locus to a linkage group containing a locus conferring resistance to nine isolates of Puccinia coronata. Linkage between genes encoding alcohol-soluble seed proteins and genes for resistance to Puccinia species was also observed for the homoeologous group 1 chromosomes of barley (1H), rye (1R), wheat (1A, 1B, 1D), and chromosomes 4 and 10 of maize.Key words: genetics, seed protein, disease resistance.
The identification of random amplified polymorphic DNA markers for daylength insensitivity in oat
Authors: Wight Charlene P. , Penner Greg A. , O'Donoughue Louise S. , Burrows Vernon D. , Molnar Stephen J. , Fedak George
Published: May 2008

Daylength insensitive accessions of Avena sativa L. are being used to develop cultivars that will flower normally when grown under short or long photoperiods. Field data indicate that the insensitivity trait is under the control of a single dominant gene, designated Di1. The random amplified polymorphic DNA (RAPD) technique and bulk segregant analysis of daylength sensitive and insensitive plants were used to find markers for this gene. Five of 200 random decamer primers tested produced polymorphic bands, which were shown to be linked to the trait using 30 homozygous insensitive and 30 homozygous sensitive F3 individuals. Three of the markers produced a band in the presence of the dominant allele, and two in its absence. Segregation analysis showed that markers 221 and 136 could be mapped to within 9.8 ± 4.6 and 13.9 ± 5.4 cM of the trait, respectively; that is, close enough to be useful in a breeding program. A study of different cultivars suggested that the band produced by primer 136 is actually the more closely linked marker and the only one present in the original Di1 gene donor CAV2700. The possibility of using both markers in populations derived from different cultivars is discussed.Key words: RAPD, molecular marker, oat, daylength insensitivity, photoperiod, bulk segregant analysis.
A genetic map of common bean to localize specific resistance genes against anthracnose
Authors: Adam-Blondon Anne-Françoise , Sevignac Mireille , Dron Michel , Bannerot Hubert
Published: May 2008

A bean genetic map was developed to locate resistance genes against anthracnose and genes involved in plant defense mechanisms. One hundred and fifty-seven markers (51 restriction fragment length polymorphism, 100 random amplified polymorphic DNA, 2 sequence characterized amplified regions, and 4 morphological markers) were used to construct a genetic map covering 567.5 cM of the bean genome. Morphological markers consisted in two resistance genes towards anthracnose (Are and RVI), a dominant gene for nuclear male sterility (Ms8) and a pod-shape character (SGou). This map was established by using a backcross population (BC1) of 128 individuals, derived from a cross between two European bean genotypes: Ms8EO2 and Corel. Nine percent of the markers showed segregation distortions and mapped to three regions. Clusters of 2–10 markers were observed in every linkage group. The possible origin of these clusters is discussed. Nineteen markers shared with a previously published bean linkage map allowed us to establish a preliminary correspondence between the two maps. Finally, seven genes involved in plant defense mechanisms were located on this map.Key words: Phaseolus vulgaris L., random amplified polymorphic DNA, restriction fragment length polymorphism, Colletotrichum lindemuthianum, male sterility.
Centromeric heterochromatin and satellite DNA in the Chironomus plumosus species group
Authors: Hankeln T. , Fillippova M. A. , Kiknadze I. I. , Aimanova K. G. , Schmidt E. R.
Published: May 2008

Species of the Chironomus plumosus group display significant differences in their amount of centromeric heterochromatin. A tandem-repetitive satellite-like DNA has been isolated from C. plumosus. This DNA accounts for a major part of the centromeric heterochromatin. The DNA element has a Sau3AI restriction site ("Sau elements") and a monomer length of 165 or 166 bp. It is A-T rich (73%) and reveals a moderate DNA curvature, as shown by gel migration and computer analysis. The chromosomal localization and genomic organization of Sau elements were studied in 24 Chironomus species by in situ hybridization and (or) Southern analysis. The DNA is predominantly located in the centromeric regions of nine species, six from the plumosus group and three others. In some cases, inter- and intra-specific differences in the size of the centromeric heterochromatin seem to correlate with the strength of Sau element hybridization signals. Few species contain Sau repeats outside of the centromeres (C. borokensis, C. plumosus). Additionally, Sau elements are revealed to be present in ectopic threads between centromeres, and in B chromosomes found in C. borokensis and C. annularius.Key words: satellite DNA, curved DNA, centromere, heterochromatin, Chironomus.
Genetic mapping in the 1R.1D wheat–rye translocated chromosomes
Authors: Lukaszewski Adam J.
Published: May 2008

Translocation chromosomes 1R.1D5+10−1 and 1R.1D5+10−2 were produced to improve bread-making quality in triticale and to manipulate the dosage of the Glu-D1 gene in wheat. They involve transfers of segments of the long arm of chromosome 1D of bread wheat to the long arm of rye chromosome 1R. The translocated long arms of the chromosomes were mapped genetically in wheat and triticale using polymorphism for C-banding patterns, allelic variation of the Glu-D1 gene, and a telocentric chromosome 1RL. The total frequency and the general distribution of recombination in the translocated arms was similar to that in normal long arms of group-1 chromosomes in wheat, rye, and triticale, except that the distal rye segments of the translocations showed a 15- to 20-fold increase in recombination frequency compared with normal 1R. Despite major differences in the physical structure of the translocated arms, both appeared very similar genetically, suggesting that genetic mapping is a poor indicator of the physical structure of translocations. Genetic length of the 1DL segment in chromosome 1R.1D5+10−1 was 31 cM, making the chromosome unsuitable for Glu-D1 dosage manipulation in wheat. The potential of chromosome 1R.1D5+10−2 for wheat breeding needs further testing. However, both chromosomes behave normally in hexaploid triticale.Key words: translocation, linkage, bread-making quality, wheat, triticale.
Genotypic variation of quantitative trait loci controlling in vitro androgenesis in maize
Authors: Murigneux A. , Bentolila S. , Hardy T. , Baud S. , Guitton C. , Jullien H. , Tahar S. Ben , Freyssinet G. , Beckert M.
Published: May 2008

A quantitative trait loci (QTL) analysis for androgenetic capability has been conducted on three different crosses in maize, including very high and nonresponding lines for androgenesis. The doubled haploid lines derived by anther culture from the crosses DH5 × DH7, A188 × DH7, and R6 × DH99 showed a range of 0–70%, 0–40%, and 0–50% androgenetic responding anthers, respectively. The genotypic heritability of means for this trait is close to 0.90 for A188 × DH7 and 0.78 for R6 × DH99. The QTL analysis involved in each population the mapping of more than 100 loci covering a large part of the genome with reasonably spaced markers averaging 12 cM. Different measurements describing the androgenetic process were studied: AC, percentage of responding anthers; ELS, number of androgenetic embryos produced per 100 plated anthers; PLE, number of plantlets regenerated per 100 embryos; PLA, number of plantlets per 100 plated anthers. In each cross, three to four QTLs were found for AC, explaining 30–40% of the phenotypic variation. The QTL detected for PLA was also strong QTL for AC or ELS. This agrees with the observation that these last two traits are good predictors for final plantlet yield. The QTLs found were specific, although the same line DH7 was used in two crosses and DH99 derived from DH5 and DH7 in the third cross. These results suggest that the transfer of the androgenetic capabilities in elite germplasm will still involve a phenotypic evaluation of the androgenetic performances. A backcross-assisted selection based only on the genotype at the QTL is probably possible but only within the crosses used for this QTL analysis.Key words: maize, RFLP, quantitative trait loci, in vitro androgenesis.
Occurrence and inheritance of microsatellites in Pinus radiata
Authors: Smith David N. , Devey Michael E.
Published: May 2008

Microsatellites are an important class of DNA marker because of their abundance and length hypervariability. As part of a project mapping the Pinus radiata genome, we have characterized some of the microsatellites in this species. Southern blots were screened with oligonucleotide probes [(CA)10, (GA)10, (GAA)9, (CAA)8, (CAC)5, (GACA)4] to assess their abundance. CA and GA were the most abundant microsatellites, while GAA was least abundant. A genomic library in lambda ZAP, covering 9 × 104 kb, was screened with a combined poly(CA) + poly(GA) probe and yielded 120 positives, approximately one CA or GA microsatellite every 750 kb of the P. radiata genome. It was found that 25% of the positives were embedded within highly repetitive DNA. Four of the five subclones sequenced contained compound microsatellites, with TA predominating as the additional repeat. Segregation analysis of PCR products for two microsatellites, PR4.6 and PR9.3, in 96 progeny of a controlled out-cross verified simple Mendelian inheritance. Both loci are highly polymorphic with Polymorphism Information Content values of 0.63 and 0.70 for PR4.6 and PR9.3, respectively. These results indicate that microsatellites are abundant in a conifer genome and can be valuable markers for pine mapping, fingerprinting, and population genetic studies.Key words: microsatellites, dinucleotide repeats, conifer genome, sequence tagged sites.
Marker-based inferences about fecundity genes contributing to inbreeding depression in Mimulus guttatus
Authors: Fu Yong-Bi , Ritland Kermit
Published: May 2008

Eight unlinked isozyme loci were used as genetic markers to characterize fecundity genes contributing to inbreeding depression in two selfed progeny arrays of Mimulus guttatus. Five fecundity traits were measured. Six of eight marked chromosomal segments were significantly associated with the expression of these traits. The number of genes detected for five traits in two progeny arrays varied, with an average of 2.8 genes per trait. Individual segments explained 1.44–9.29%, and together accounted for 3.85–11.32%, of phenotypic variation. Of 20 significant associations, 10 could be interpreted as exhibiting partial dominance, 7 overdominance, 3 partial recessivity, and 0 underdominance. Significant pairwise epistasis was rare. The results of this study suggest that inbreeding depression is caused by many deleterious genes of relatively small, partially dominant effects.Key words: linkage, isozymes, QTLs, inbreeding depression, Mimulus guttatus.
Genetic relationships and variation among ecotypes of seashore paspalum (Paspalum vaginatum) determined by random amplified polymorphic DNA markers
Authors: Liu Zhao-Wei , Jarret Robert L. , Duncan Ronny R. , Kresovich Stephen
Published: May 2008

Random amplified polymorphic DNA (RAPD) markers were used to assess genetic relationships and variation among ecotypes of the turfgrass seashore paspalum (Paspalum vaginatum Swartz). Vegetative tissues or seeds of 46 seashore paspalum ecotypes were obtained from various locations in the United States, Argentina, and South Africa. Leaf DNA extracts were screened for RAPD markers using 34 10-mer random primers. A total of 195 reproducible RAPD fragments were observed, with an average of six fragments per primer. One hundred and sixty-nine fragments (87% of the total observed) were polymorphic, among which 27 fragments (16%) were present in three or less ecotypes, indicating the occurrence of a high level of genetic variation among the examined accessions of this species. Cluster analysis (UPGMA) and principal coordinates analysis were performed on the RAPD data set. The results illustrate genetic relationships among the 46 ecotypes, and between ecotypes and their geographical origins. Ecotypes from southern Africa could be differentiated from the U.S. and most of the Argentinean ecotypes. With a few exceptions, ecotypes collected from Argentina, Hawaii, Florida, and Texas were separated into distinct clusters.Key words: RAPDs, polymerase chain reaction, genetic diversity, phenetic analysis.
Spreading synaptonemal complexes of B isochromosomes in the grasshopper Omocestus burri
Authors: Cerro A. L. del , Fernández A. , Santos J. L.
Published: May 2008

Meiotic pairing behaviour of one and two B isochromosomes (iso-Bs) in the grasshopper Omocestus burri was analysed by electron microscopy in surface-spread prophase I nuclei and compared with light microscopic observations of metaphase I. Iso-Bs display a peripheral location in the surface-spread nuclei and early pairing relative to that of the long members of the A set. Single iso-Bs undergo foldback pairing to give symmetrical hairpin loops. Two iso-Bs may show interarm pairing, mterchromosome pairing, or combinations of the two. Pericentromeric interarm pairing can be delayed in one or both Bs and this delay is mostly observed in bivalents with pairing partner switches. The iso-B bivalent frequencies observed in the three males analysed were 64, 44, and 41%, respectively; the two latter values were significantly lower than the 66% predicted by the random-end-pairing model. There is a reduction in the frequencies of iso-ring univalents (in 1B males) and bivalents (in 2B males) from pachytene to metaphase I. Similarities and differences between the pairing behaviour of iso-Bs from different species are also discussed.Key words: B isochromosomes, meiosis, grasshopper, synaptonemal complexes, pairing partner switches.
Preferential pairing estimates from multivalent frequencies in tetraploids
Authors: Sybenga J.
Published: May 2008

Mathematical models are presented for estimating preferential pairing and chiasma parameters in amphidiploids and autotetraploids on the basis of diakinesis or metaphase I configuration frequencies and are compared with other approaches of estimating affinity. With a preferential pairing factor p, estimated from quadrivalent and trivalent frequencies, and estimated chiasmate association factors for the two arms in quadrivalents (a(qu) and b(qu) for arms A and B, respectively) and in bivalents (a(bi) and b(bi)) a perfect fit between observed and predicted configuration frequencies can often be obtained in amphidiploids of several plant species, including Solanaceae and Gramineae. Since several proven autotetraploids give very similar apparent preferential pairing estimates, the biological significance of such parameters as preferential pairing and affinity factors is considered limited. The same is true for pairing parameters estimated by optimizing fit of configuration frequencies expected on the basis of theoretical models to observed data.Key words: amphidiploid, diakinesis, metaphase, meiosis, model, preferential pairing, tetraploid.
Molecular evidence that diploid Stylosanthes humilis and diploid Stylosanthes hamata are progenitors of allotetraploid Stylosanthes hamata cv. Verano
Authors: Curtis Mark D. , Manners John M. , Cameron Don F.
Published: May 2008

Restriction fragment length polymorphism analysis, using peroxidase, O-methyltransferase, phenylalanine ammonia-lyase, and coniferyl alcohol dehydrogenase cDNAs isolated from Stylosanthes humilis, as probes, provided molecular evidence for the genetic origin of the naturally occuring allotetraploid genotype Stylosanthes hamata cv. Verano (2n = 4x = 40). Hybridization patterns strongly suggest that the likely progenitors of S. hamata cv. Verano were a diploid S. humilis (2n = 2x = 20) and a diploid S. hamata (2n = 2x = 20) species.Key words: Stylosanthes spp., restriction fragment length polymorphism, allotetraploid, diploid.
Colchicine-induced heritable modification of chiasma frequency and distribution in perennial ryegrass (Lolium perenne)
Authors: Hassan Lutful , Jones R. Neil
Published: May 2008

One-week-old seedlings of inbred lines of perennial ryegrass (Lolium perenne L.) were given a 3-h period of treatment with 0.2% colchicine, and this treatment was found to have heritable effects on chromosome behaviour at meiosis. The mean pollen mother cell chiasma frequency was reduced, and there was a corresponding increase in the number of univalents per cell and also changes in cell and bivalent variances. Patterns of chiasma distribution within bivalents were also modified. The effects were seen in the generation in which the treatment was given and they were also observed in the following sexual generation.Key words: chiasmata, colchicine, Lolium perenne, meiosis, perennial ryegrass.
Analysis of annual Medicago species using RAPD markers
Authors: Brummer E. C. , Bouton J. H. , Kochert G.
Published: May 2008

Annual species of the genus Medicago have attracted interest as green manure and temporary forage crops. This study was conducted to determine if randomly amplified polymorphic DNA (RAPD) markers could be used to assess the variability within and among species. Several accessions of each six species (M. scutellata Mill., M. disciformis DC, M. murex Willd., M. truncatula Gaertn., M. polymorpha L., and M. rugosa Desr.) were studied. A phylogeny reconstructed with the computer program Phylogenetic Analysis Using Parsimony (PAUP) showed the same relationships as traditional taxonomy. Variation was present among accessions of all species. Several accessions were considerably different from others within the species (one of each M. scutellata and M. polymorpha) and four accessions of M. murex were differentiated by both morphology and RAPD banding patterns from the other accessions. These accessions may be useful to include in a core collection. Variation within accessions was present. Although the species are autogamous, the original seed collections may have been made from a number of plants in the same area. Also, some outcrossing or seed mixing may have occurred. Finally, at least 10 RAPD primers appear to be necessary in order to develop reliable estimates of relatedness among annual Medicago accessions.Key words: Medicago, annual medic, phylogeny reconstruction, RAPD, core collection.
The use of cell culture for subchromosomal introgressions of barley yellow dwarf virus resistance fromThinopyrum intermediumto wheat
Authors: Banks P. M. , Larkin P. J. , Bariana H. S. , Lagudah E. S. , Appels R. , Waterhouse P. M. , Brettell R. I. S. , Chen X. , Xu H. J. , Xin Z. Y. , Qian Y. T. , Zhou X. M. , Cheng Z. M. , Zhou G. H.
Published: May 2008

Barley yellow dwarf virus (BYDV) resistance has been transferred to wheat from a group 7 chromosome of Thinopyrum (Agropyron) intermedium. The source of the resistance gene was the L1 disomic addition line, which carries the 7Ai-1 chromosome. The resistance locus is on the long arm of this chromosome. BYDV resistant recombinant lines were identified after three or more generations of selection against a group 7 Th. intermedium short arm marker (red coleoptile) and selection for the presence of BYDV resistance. One recombinant line produced by ph. mutant induced homoeologous pairing and 14 recombinant lines induced by cell culture have been identified. Resistance in seven of the cell culture induced recombinants has been inherited via pollen according to Mendelian segregation ratios for up to eight generations. Meiotic analysis of heterozygotes indicates that the alien chromatin in the cell culture induced recombinants is small enough to allow regular meiotic behaviour. The ph-induced recombinant was less regular in meiosis. A probe, pEleAcc2, originally isolated from Th. elongatum and that hybridizes to dispersed repeated DNA sequences, was utilised to detect Th. intermedium chromatin, which confers resistance to BYDV, in wheat backgrounds. Quantification of these hybridization signals indicated that the translocations involved a portion of alien chromatin that was smaller than the complete long arm of 7Ai-1. Restriction fragment length polymorphism analysis confirmed the loss of the short arm of 7Ai-1 and indicated the retention of segments of the long arm of 7Ai-1. Two 7Ai-1L DNA markers always assorted with the BYDV resistance. A third 7Ai-IL DNA marker was also present in seven of eight recombinants. In all recombinants except TC7, the 7Ai-1L markers replaced the 7DL markers. None of the wheat group 7 markers was missing from TC7. It is concluded that all the resistant lines are the result of recombination with wheat chromosome 7D, except line TC7, which is the result of recombination with an unidentified nongroup 7 chromosome.Key words: Triticum, Agropyron, alien genes, translocation, somatic recombination, luteovirus.
Genome size, fluorochrome banding, and karyotype evolution in someHypochoerisspecies
Authors: Cerbah M. , Coulaud J. , Godelle B. , Siljak-Yakovlev S.
Published: May 2008

Four South American and two European species of Hypochoeris (Asteraceae) were studied using fluorochrome banding, and genome size was determined by flow cytometry, in order to obtain information about microevolution in this genus and about its primary origin. Fluorochrome banding patterns showed GC-rich repeated sequences, particularly around the nucleolar organizer regions. Few differences appeared among the South American species. Nevertheless, determination of nuclear DNA content and base composition revealed significant differences among these species. The phylogenetic position of Hypochoeris robertia, which has the smallest DNA content, is discussed with regard to chromosome evolution in this genus.Key words: Hypochoeris, Asteraceae, fluorochromes, flow cytometry, nucleolar organizer regions, microevolution.
Chromosome 5D instability in cell lines of Triticum tauschii and morphological variation in regenerated plants
Authors: Winfield M. O. , Karp A. , Lazzeri P. A. , Davey M. R.
Published: May 2008

Immature embryos of Triticum tauschii cultured on L2 medium with 30 g∙L−1maltose gave rise to compact and highly structured callus that readily regenerated shoots when transferred to MS medium supplemented with zeatin and indole-3-acetic acid. Two cell suspensions were initiated from the callus induced on L2 medium. An analysis of chromosome number in these cell suspensions after 3 months of culture showed that 95 and 75% of the cells had a normal complement. After 5 months, in both lines the majority of cells had chromosome complements of 2n = 13 and many of these aneuploid cells possessed a dicentric chromosome. C-banding indicated that the dicentric was often formed from chromosomes 2D and 5D. Fifty-six plants regenerated from callus were grown to maturity. Variation was observed in tiller number, flowering time, and seed-set; in two cases, the variation in early flowering was shown to be heritable. All the regenerants analysed had normal chromosome counts (2n = 2x = 14) and meiotic analyses of 35 plants revealed no obvious structural rearrangements.Key words: immature embryo culture, regeneration, chromosome, cell suspension, Triticum tauschii.
Assessment of genome origins and genetic diversity in the genusEleusinewith DNA markers
Authors: Salimath Shanmukhaswami S. , Oliveira Antonio C. de , Bennetzen Jeffrey L. , Godwin Ian D.
Published: May 2008

Finger millet (Eleusine coracana), an allotetraploid cereal, is widely cultivated in the arid and semiarid regions of the world. Three DNA marker techniques, restriction fragment length polymorphism (RFLP), randomly amplified polymorphic DNA (RAPD), and inter simple sequence repeat amplification (ISSR), were employed to analyze 22 accessions belonging to 5 species of Eleusine. An 8 probe – 3 enzyme RFLP combination, 18 RAPD primers, and 6 ISSR primers, respectively, revealed 14, 10, and 26% polymorphism in 17 accessions of E. coracana from Africa and Asia. These results indicated a very low level of DNA sequence variability in the finger millets but did allow each line to be distinguished. The different Eleusine species could be easily identified by DNA marker technology and the 16% intraspecific polymorphism exhibited by the two analyzed accessions of E. floccifolia suggested a much higher level of diversity in this species than in E. coracana. Between species, E. coracana and E. indica shared the most markers, while E. indica and E. tristachya shared a considerable number of markers, indicating that these three species form a close genetic assemblage within the Eleusine. Eleusine floccifolia and E. compressa were found to be the most divergent among the species examined. Comparison of RFLP, RAPD, and ISSR technologies, in terms of the quantity and quality of data output, indicated that ISSRs are particularly promising for the analysis of plant genome diversity.Key words: Eleusine coracana, finger millet, genome analysis, microsatellites, randomly amplified polymorphic DNA, restriction fragment length polymorphism, simple sequence repeats.
Synaptic abnormalities in spread nuclei of Secale. I. Inbred lines
Authors: Martínez M. , Cuadrado C. , Romero C.
Published: May 2008

The meiotic behaviour at metaphase I of two inbred lines of Secale cereale showed a decrease in the frequency of bound arms and the presence of univalents. The study of synaptonemal complex formation revealed that these inbred lines had asynapsis and many nuclei did not complete the pairing process. Synaptic abnormalities such as fold-back loops, short pairing partner switches, interstitial nonhomologous pairing regions, and asynchrony between bivalents were associated and correlated with interlocking. It is suggested that the asynapsis is due to a failure in the interlocking repair. All these abnormalities could affect the formation and maintenance of chiasmata and so could explain the metaphase I behaviour of these inbred lines and the differences between them.Key words: inbred lines, Secale cereale, synaptonemal complex, spreading, synaptic abnormalities.
Amplified extrachromosomal elements containing c-Myc and Pvt 1 in a mouse plasmacytoma
Authors: Mai S. , Hanley-Hyde J. , Coleman A. , Siwarski D. , Huppi K.
Published: May 2008

After adaptation of a mouse plasma cell tumor, MOPC265, to culture, we have found several unique chromosomal alterations in addition to the T(12;15) translocation and trisomy 11 frequently observed in plasmacytomas. Among these alterations is a specific coamplification of the c-Myc and Pvt 1 gene loci from mouse chromosome 15. Further analysis by fluorescence in situ hybridization demonstrates that the amplicons of c-Myc and Pvt 1 exist as extrachromosomal elements as well as within intact chromosomes. Most importantly, the presence of both Pvt 1 and c-Myc in these extrachromosomal elements indicates ongoing coselection for these loci in the propagation of MOPC265.Key words: amplification, c-Myc, Pvt 1, plasmacytoma.
A molecular marker based linkage map ofVitis
Authors: Lodhi M. A. , Ye G.-N. , Weeden N. F. , Reisch B. I. , Daly M. J.
Published: May 2008

Genetic linkage maps of Vitis (2n = 38) have been constructed from a single interspecific hybrid grape population (60 seedlings) of 'Cayuga White' × 'Aurore'. The maps were primarily based on 422 RAPD markers but also included 16 RFLP and isozyme markers. These maps had an average distance of 6.1 cM between markers and were developed using a double-pseudotestcross strategy. The 'Cayuga White' map had 214 markers covering 1196 cM and that of 'Aurore' spanned over 1477 cM with 225 markers. The 'Cayuga White' map consisted of 20 linkage groups, whereas 22 linkage groups comprised the 'Aurore' map. The number of groups reduced to 19, as in some instances two or more groups from one parent showed homology with a single group from the other parent on the basis of markers heterozygous in both parents. Each linkage group ranged in size from 14 to 135 cM in 'Aurore' and from 14 to 124 cM in 'Cayuga White'. These maps provide enough coverage of the genome to allow quantitative trait locus analysis and map-based gene cloning.Key words: grape genome, pseudotestcross, RAPD, recombination frequency, DNA content.
Genetics of Glossina palpalis palpalis: designation of linkage groups and the mapping of eight biochemical and visible marker genes
Authors: Gooding R. H. , Rolseth B. M.
Published: May 2008

The loci for three enzymes (hexokinase, phosphoglucomutase, and testicular esterase) and two eye-color mutants (brick and tan) are mapped on the X chromosome of Glossina palpalis palpalis. The loci occur in the order brick Hex (tan/Pgm) Est-t, with a recombination frequency of approximately 78% between the outer two loci. The locus for octanol dehydrogenase is located in linkage group II and the loci for malate dehydrogenase and phosphoglucose isomerase are separated by a recombination frequency of about 42.5% in linkage group III. Intrachromosomal recombination occurs at a much lower frequency in males than in females. The distribution of five biochemical marker genes in the linkage groups of G. p. palpalis is markedly different from that found in other higher flies.Key words: tsetse, Glossina palpalis palpalis, linkage map.
Biparental inheritance of RAPD markers in males of the pseudo-arrhenotokous miteTyphlodromus pyri
Authors: Perrot-Minnot Marie-Jeanne , Navajas Maria
Published: May 2008

In pseudo-arrhenotokous mites, haploid males develop from fertilized eggs that undergo paternal genome loss (PGL) during early embryogenesis. We present evidence that some of the paternal genome may be retained in males of the predatory mite Typhlodromus pyri Scheuten (Acari: Phytoseiidae). Two reproductively compatible populations were differentiated by two random amplified polymorphic DNA markers and the inheritance pattern in the offspring was analysed. Maternal transmission rates are variable and independent of the sex of the offspring and of the marker. These data suggest a nuclear origin and independent segregation of the markers. One marker (330 base pairs (bp)) was paternally transmitted to male as well as female offspring, the other (990 bp) was paternally transmitted to all females and some of the male offspring. We propose that the paternal set of inactivated chromosomes may be partially retained in some tissues of the haploid males or, alternatively, that a B chromosome does not follow the process of PGL in male embryos, thereby segregating with the maternal set. The possible mechanisms controlling the condensation and the segregation of the chromosome(s) retained are discussed on the basis of current hypotheses on chromosome inactivation in insects.Key words: pseudo-arrhenotoky, paternal genome loss, haplodiploidy, RAPD, phytoseiid mites.