bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of a 2.6 kb single/low copy DNA sequence on chromosomes of wheat (Triticum aestivum) and rye (Secale cereale) by fluorescence in situ hybridization
Authors: Dong Haishui , Quick James S.
Published: May 2008

A fluorescence in situ hybridization procedure was developed to detect a 2.6 kb single/low copy DNA sequence on chromosomes of wheat (Triticum aestivum) and rye (Secale cereale). The probe, pTtksuI26, was from the wheat genomic library generated at Kansas State University and was labeled with Bio-11-dUTP by nick translation. The signal was amplified by a protocol of avidin–FITC (fluorescein isothiocyanate), biotinylated goat anti-avidin antibody, avidin–FITC. Two rye chromosomes and several wheat chromosomes showed the hybridization sites. The multiple sites in wheat are probably the result of the homoeologous nature of the three genomes in wheat. The ability to detect the hybridization signal of a small single/low copy DNA sequence is a very important step towards the physical mapping of plant genomes. This procedure might also be useful for studying the genomic relationship among wheat relative species.Key words: wheat, Triticum aestivum, rye, Secale cereale, fluorescence in situ hybridization, single copy DNA mapping.
Use of RFLPs to determine the chromosome composition of tetraploid triticale (A/B)(A/B)RR
Authors: Lelley T. , Kazman E. , Devos K. M. , Gale M. D.
Published: May 2008

Tetraploid triticale, (A/B)(A/B)RR (2n = 28), is a botanical novelty, an amphiploid composed of a diploid rye and a 14 chromosome wheat genome made up of chromosomes of the A and B genomes of tetraploid wheat. Restriction fragment length polymorphism (RFLP) markers were used to elucidate the chromosome composition of the mixed wheat genome of 35 different tetraploid triticale lines. Of 128 possible A/B chromosome pair combinations, only 6 were found among these lines, with a prevalence of the 1A, 2A, 3B, 4B, 5B, 6B, and 7B karyotype. In most triticale lines stable wheat genomes made up of only homologous A or B genome chromosome pairs were identified, however, in some lines homoeologous chromosome pairs were found. In this paper we demonstrate that RFLPs can be used successfully as an alternative to C-banding for the identification of the chromosome composition of tetraploid triticale and discuss the possible selective advantage of specific chromosome composition.Key words: tetraploid triticale, mixed wheat genome, RFLR
RFLP mapping inBrassica nigraindicates differing recombination rates in male and female meioses
Authors: Lagercrantz Ulf , Lydiate Derek J.
Published: May 2008

A genetic linkage map of Brassica nigra, comprised of 288 loci in eight linkage groups, was constructed. The linkage groups varied in size from 72 to 159 cM and the total map length was 855 cM. The recurrent parent used in the backcross was extremely heterozygous. This allowed recombination to be estimated separately for female (recurrent parent) meiosis and male (F1) meiosis over a large proportion of the genome. Significant differences between male and female recombination frequencies were observed on all six linkage groups where data was available for both sexes. Enhanced male recombination frequencies were observed that were associated with proterminal regions, while enhanced female recombination frequencies were adjacent to putative centromeres. It is possible that the distinct genotypes of the F1(male) and recurrent (female) parents contributed to the observed differences in recombination. However, this study emphasizes the need to consider potential sex differences, in both the rate and the position of recombination, when planning genetic experiments and breeding programmes.Key words: genetic map, sex dependent recombination, centromeres, telomeres.
Amplification ofAcin tomato is correlated with highActransposition activity
Authors: Peterson Peter W. , Yoder John I.
Published: May 2008

We have assayed the transposition activity of the maize transposable element Ac in transgenic tomato plants that had a single copy of Ac. We found that Ac elements were in either a high or low activity state and that an Ac insertion could cycle from low to high activity within a generation. The different transposition activities were not simply due to the chromosomal position of the element, because the same Ac insertion had different levels of activity in sibling plants. Transposition activity was measured by two methods, one genetic and one physical; both assays gave similar results for each plant studied. Notably, plants with active Ac elements had progeny with amplified Ac copy number, while no amplification was detected in lines containing Ac in a low activity state. Analysis of lines with amplified elements revealed that the elements could be either clustered or dispersed. Our results were consistent with amplification being the result of transposition.Key words: Ae, transposable element, amplification, transposition.
Gene action for adult-plant resistance to powdery mildew in wheat
Authors: Das M. K. , Griffey C. A.
Published: May 2008

Gene action for adult-plant resistance to powdery mildew was studied using generation mean analyses of parents and of F1, F2, and backcross populations derived from a diallel cross of one susceptible and three adult-plant resistant wheat cultivars. Joint scaling tests showed that an additive–dominance model was sufficient to explain the variability in the expression of adult-plant resistance in one cross, while digenic epistasis was involved in the other five crosses. Additive gene effects were predominant; however, dominance was significant in four crosses, additive × additive interaction was significant in three crosses, additive × dominance interaction was significant in three crosses, and dominance × dominance interaction was significant in one cross. Therefore, selection for adult-plant resistance would likely be most effective in advanced generations derived from crosses among the adult-plant resistant cultivars Redcoat, Houser, and Massey.Key words: gene action, adult-plant resistance, Blumeria, Erysiphe graminis f.sp. tritici, Triticum aestivum.
Molecular analysis of evolutionary patterns in U genome wild wheats
Authors: Chee P. W. , Talbert L. E. , Lavin M.
Published: May 2008

The theory of pivotal–differential evolution states that one genome of polyploid wheats remains stable (i.e., pivotal) during evolution, while the other genome or genomes may become modified (i.e., differential). A proposed mechanism for apparent modification of the differential genome is that different polyploid species with only one genome in common may exchange genetic material. In this study, we analyzed a set of sympatric and allopatric accessions of tetraploid wheats with the genomic constitutions UM and UC. The U genome of these species is from Triticum umbellulatum and is considered to be the pivotal genome. The M and C genomes, from T. comosum and T. dichasians, respectively, are considered to be the differential genomes. Low copy DNA was analyzed using "sequence tagged site" primer sets in the polymerase chain reaction, followed by digestion with restriction enzymes. Genetic similarity matrices based on shared restriction fragments showed that sympatric accessions of different U genome tetraploid species did not tend to share more restriction fragments than did allopatric accessions. Thus, no evidence for introgression was found. Analysis of the diploid progenitor species showed that the U genome was less variable than the M and C genomes. Additionally, comparison of diploid and polyploid species using genome-specific primer sets suggests a possible polyphyletic origin for T. triunciale and T. machrochaetum. Thus, our results suggest that the differential nature of the M and C genomes may be the result of variability introduced by the diploid progenitors and not the result of frequent introgression events after formation of the polyploid.Key words: wild wheat, evolution, introgression, PCR.
Comparison of restriction fragment length polymorphisms in wild and cultivated barley
Authors: Maroof M. A. Saghai , Biyashev Ruslan , Zhang Qifa
Published: May 2008

This study was undertaken to assess the relative level of molecular diversity between cultivated barley, Hordeum vulgare ssp. vulgare (HV), and one of its wild relatives, H. vulgare ssp. spontaneum (HS), and to identify possible restriction fragment length polymorphism (RFLP) patterns that may provide information concerning the phylogenetic relationship between these two barley groups. A total of 363 barley accessions were assayed, including 95 entries of HV collected from 36 major barley growing countries of the world and 268 entries of HS from 25 natural populations in Israel and Iran. The 26 RFLP marker loci used in the survey represent single-copy, low-copy, and repetitive DNA sequences and mark all of the chromosome arms. A randomization test, on the basis of equal sample sizes, showed that HS is more polymorphic than HV, as evaluated by the number of alleles and diversity indices. The analysis also indicated extensive RFLP differentiation between these two barley groups; highly significant differences of allele frequencies were detected at the majority of the loci. The HV sample can be subdivided according to winter or spring growth habits, and two- or six-rowed spikes. Analysis of genetic polymorphisms in these subgroups showed that levels of diversity were about equal in spring and winter groups and also in the groups with two- and six-rowed spikes. However, significant differences of allelic frequencies were detected between subgroups of the two divisions.Key words: Hordeum vulgare, genetic diversity, germplasm.
Origin of B chromosomes in cultivated rye
Authors: Niwa K. , Sakamoto S.
Published: May 2008

Cultivated rye (Secale cereale) and its weedy relative (S. segetale) carry B chromosomes. The B chromosomes are known to be morphologically alike at somatic metaphase and they are of the standard type in natural populations. To clarify the cytogenetic relationship between the standard B chromosomes of S. cereale and those of S. segetale, we made four crosses between Afghan S. segetale with two standard B chromosomes as a pistillate parent and Turkish, Iranian, Korean, and Japanese S. cereale, all with two standard B chromosomes as pollen parents. We observed the pairing of B chromosomes at diakinesis in pollen mother cells in all F1 hybrids with four standard B chromosomes, two from each of the pistillate and the pollen parents. The degree of pairing of B chromosomes in all F1 hybrids with four standard B chromosomes was similar to or somewhat lower than, that in parental strains with four standard B chromosomes. These results showed that the standard B chromosomes in S. segetale from Afghanistan are homologous with those in S. cereale from Turkey, Iran, Korea, and Japan. We therefore propose monophyletic origin of the standard B chromosomes in S. segetale and S. cereale.Key words: Secale, B chromosomes, origin, cultivated rye, weedy rye.
Temporal frequency stability and absence of effects on mating behaviour for an autosomal supernumerary segment in two natural populations of the grasshopperEyprepocnemis plorans
Authors: López-León M. D. , Martín-Alganza A. , Pardo M. C. , Cabrero J. , Camacho J. P. M.
Published: May 2008

Interannual evolution of a polymorphism for a supernumerary segment in the smallest autosome of the grasshopper Eyprepocnemis plorans has been analysed in two natural populations. The polymorphism seemed to be stable in both populations, despite its undertransmission through heterozygous females carrying B chromosomes. Analyses of the effects of the extra segment on mating behaviour failed to show differential mating success in any sex or consistent effects on mating pattern. These results are discussed in relation to the maintenance of this polymorphism in natural populations.Key words: supernumerary segments, heterochromatin, repetitive DNA.
Molecular cloning of a bovine ornithine decarboxylase cDNA and its use in the detection of restriction fragment length polymorphisms in Holsteins
Authors: Yao Jianbo , Zadworny David , Kühnlein Urs , Hayes J. Flan
Published: May 2008

A cDNA coding for ornithine decarboxylase (ODC) was isolated from a bovine liver cDNA library. The clone (1758 base pairs) consisted of 5′- and 3′-untranslated regions of 185 and 187 nucleotides, respectively, and an open reading frame of 1383 nucleotides encoding an ODC protein (Mr51 342 daltons) of 461 amino acids. Comparison of the nucleotide and the predicted amino acid of the cDNA with other mammalian ODCs showed a very high degree of homology both at the DNA and protein levels. The bovine ODC mRNA was identified by northern blot to be a single species with a molecular size of 2.35 kilobase pairs. Primer extension analysis indicated that the 5′-untranslated region of the bovine ODC mRNA was 312 nucleotides long. Southern blot analysis of bovine genomic DNA revealed restriction fragment length polymorphisms when cleaved with restriction enzymes PstI, MspI, TaqI, and BglI.Key words: bovine, ornithine decarboxylase, cloning, restriction fragment length polymorphism.
Genetic control and chromosomal location of Triticum timopheevii-derived resistance to septoria nodorum blotch in durum wheat
Authors: Ma H. , Hughes G. R.
Published: May 2008

The genetic control of resistance, expressed as restricted lesion development in seedling plants, to septoria nodorum blotch of wheat was studied under controlled environmental conditions, using the parental, F1, F2, F3, BC1F1, and BC1F2 generations of crosses of Triticum timopheevii-derived resistant durum lines S3-6, S9-10, and S12-1 with the susceptible durum cv. Sceptre. The seedling resistance of these three resistant sources, derived from T. timopheevii (PI 290518), was monogenically controlled. The chromosomal location of the resistance gene identified was determined by crossing the complete set of 'Langdon' – 'Chinese Spring' D-genome disomic substitution lines with S12-1. Tests of the F1 and F2 generations of each cross indicated that only chromosome 3A was associated with resistance. Therefore, the resistance gene is considered to be located on chromosome 3A and has been designated temporarily as SnbTM.Key words: Leptosphaeria nodorum, Stagonospora nodorum, Phaeosphaeria nodorum, glume blotch, disease resistance, substitution lines, Triticum durum.
An evaluation of sequence tagged microsatellite site markers for genetic analysis withinCitrusand related species
Authors: Kijas J. M. H. , Fowler J. C. S. , Thomas M. R.
Published: May 2008

Microsatellites, also called sequence tagged microsatellite sites (STMSs), have become important markers for genome analysis but are currently little studied in plants. To assess the value of STMSs for analysis within the Citrus plant species, two example STMSs were isolated from an intergeneric cross between rangpur lime (Citrus × limonia Osbeck) and trifoliate orange (Poncirus trifoliata (L.) Raf.). Unique flanking primers were constructed for polymerase chain reaction amplification both within the test cross and across a broad range of citrus and related species. Both loci showed length variation between test cross parents with alleles segregating in a Mendelian fashion to progeny. Amplification across species showed the STMS flanking primers to be conserved in every genome tested. The traits of polymorphism, inheritance, and conservation across species mean that STMS markers are ideal for genome mapping within Citrus, which contains high levels of genetic variability.Key words: citrus, microsatellites, sequence-tagged site, STS.
DNA-strand breaks in chromosomes of early mouse embryos as detected by in situ nick translation and gap filling
Authors: Patkin Eugene L. , Kustova Maria E. , Noniashvili Ekaterina M.
Published: May 2008

The nick translation and gap filling procedures, without external addition of nicking enzymes, were performed in situ on fixed chromosomes of mouse preimplantation and postimplantation embryos and of bone marrow in order to detect possible DNA single-strand breaks (nicks and (or) gaps). All chromosome preparations were made using the same technique. Nick translation of chromosomal DNA with DNA polymerase I (Pol I) or gap filling with the Klenow fragment of Pol I in the presence of biotinylated-dUTP, demonstrated a regular absence of label on chromosomes of postimplantation embryos and bone marrow. No difference in sensitivity was found between the holoenzyme and the Klenow fragment. In preimplantation embryos, the chromosome reactivity in nick translation was highest at the blastocyst stage and varied according to cleavage divisions of the zygote.Key words: DNA-strand break, chromosomes of mouse embryos, in situ nick translation.
Disomic Thinopyrum intermedium addition lines in wheat with barley yellow dwarf virus resistance and with rust resistances
Authors: Larkin P. J. , Banks P. M. , Lagudah E. S. , Appels R. , Xiao Chen , Zhiyong Xin , Ohm H. W. , McIntosh R. A.
Published: May 2008

Zhong 5 is a partial amphiploid (2n = 56) between Triticum aestivum (2n = 42) and Thinopyrum intermedium (2n = 42) carrying all the chromosomes of wheat and seven pairs of chromosomes from Th. intermedium. Following further backcrossing to wheat, six independent stable 2n = 44 lines were obtained representing 4 disomic chromosome addition lines. One chromosome confers barley yellow dwarf virus (BYDV) resistance, whereas two other chromosomes carry leaf and stem rust resistance; one of the latter also confers stripe rust resistance. Using RFLP and isozyme markers we have shown that the extra chromosome in the Zhong 5-derived BYDV resistant disomic addition lines (Z1, Z2, or Z6) belongs to the homoeologous group 2. It therefore carries a different locus to the BYDV resistant group 7 addition, L1, described previously. The leaf, stem, and stripe rust resistant line (Z4) carries an added group 7 chromosome. The line Z3 has neither BYDV nor rust resistance, is not a group 2 or group 7 addition, and is probably a group 1 addition. The line Z5 is leaf and stem rust resistant, is not stripe rust resistant, and its homoeology remains unknown.Key words: Agropyron, intermediate wheatgrass, leaf rust, stem rust, stripe rust, luteovirus.
Association of a RAPD marker with linolenic acid concentration in the seed oil of rapeseed (Brassica napus L.)
Authors: Tanhuanpää P. K. , Vilkki J. P. , Vilkki H. J.
Published: May 2008

The F2 progeny (64 individuals) from the cross between oilseed rape (Brassica napus L.) cultivar Topas and R4 (a low linolenic mutation line) was analyzed with 8 RFLPs and 34 RAPDs to discover a genetic tag for gene(s) affecting linolenic acid concentration. According to variance analysis (ANOVA), one RAPD marker (25a) was significantly associated with linolenic acid content; the linolenic acid concentration in the seeds of F2 individuals showing the marker (includes both homo- and hetero-zygotes) was 7.43 ± 1.35% and in those lacking the marker was 5.70 ± 1.52%. Marker 25a may be used to facilitate selection for fatty acid composition in future breeding programs of oilseed rape.Key words: Brassica napus, RFLP, RAPD, linolenic acid.
Genomic clones encoding 11S globulins in oats (Avena sativaL.)
Authors: Tanchak Michael A. , Giband Marc , Potier Bernard , Schernthaner Johann P. , Dukiandjiev Stefan , Altosaar Illimar
Published: May 2008

We have isolated two complete genomic clones, Glav1 and Glav3, encoding 11S globulins (legumins) in oat. The structure of Glav1 deviates from that of the typical legumin gene. This clone possesses an extra intron and an extra exon that is composed entirely of repeats of sequences found elsewhere in the clone. If this exon is functional, the protein encoded by Glav1 will contain novel octapeptide and hendecapeptide repeats. The two Glav clones show stronger and more extensive homology with one another than with the two previously published genomic clones, OG1-E1 and ASglob5. This result suggests that the oat globulin gene family may be divided into distinct subfamilies or that there may be significant cultivar-specific differences among members of this gene family.Key words: Avena sativa, gene structure, globulin, legumin.
Mitochondrial DNA diversity in wild and cultivated sorghum
Authors: Deu Monique , Hamon Perla , Dufour Philippe , D'hont Angélique , Lanaud Claire , Chantereau Jacques
Published: May 2008

Cultivated sorghum (Sorghum bicolor ssp. bicolor) is classified into five main races on the basis of spikelet morphology. Isozyme analyses provided new insight into the genetic diversity of sorghum and revealed marked geographic grouping, while nuclear restriction fragment length polymorphisms showed racial differentiation and intraguinea race differentiation. Wild sorghum is diploid or tetraploid and African sorghum (S. bicolor ssp. arundinaceum) is classified into four races, that are considered to be progenitors of cultivated sorghum. We performed mitochondrial DNA analyses to compare the diversity of wild and cultivated sorghum and to study the genetic origin of guinea margaritiferum. The same overall patterns were obtained with the different phenogram construction techniques. Our results confirmed the specificity of guinea margaritiferum and demonstrated the presence of two genetic entities within this subrace. Another guinea group was also noted, which corresponded to Asian guinea roxburghii. In wild sorghum, the arundinaceum race appeared to be homogenous, while the verticilliflorum race was separated into two groups, one of which was associated with the arundinaceum race. The diversity observed in cultivated forms was found to be encompassed within the wild pool, except for one guinea margaritiferum group. There did not seem to be any particular relationship between wild races and cultivated races.Key words: Sorghum, RFLP, mitochondrial diversity, domestication.
Fluorescent in situ hybridization of a bacterial artificial chromosome
Authors: Hanson Robert E. , Zwick Michael S. , Choi Sangdun , Islam-Faridi M. Nurul , Wing Rod A. , Price H. J. , Stelly David M. , McKnight Thomas D.
Published: May 2008

Fluorescent in situ hybridization (FISH) of a 130 kilobase cotton (Gossypium hirsutum L.) bacterial artificial chromosome (BAC) clone containing a high proportion of single-copy DNA produced a large pair of FISH signals on the distal end of the long arm of a pair of chromosomes of the D-genome species G. raimondii Ulbr. and produced a fainter pair of signals on a small submetacentric pair of chromosomes of the A-genome species G. herbaceum L. The signals were syntenic with a nucleolar organizer region in G. raimondii and G. herbaceum. Signal pairs were easily recognized in interphase and metaphase cells either with or without suppression of repetitive sequences with unlabeled G. hirsutum C0t-1 DNA. High quality FISH results were consistently obtained and image analysis was not required for viewing or photography. Results indicate that FISH of BAC clones is an excellent tool for the establishment of new molecular cytogenetic markers in plants and will likely prove instrumental in the development of useful physical maps for many economically important crop species.Key words: bacterial artificial chromosome, BAC, Gossypium, in situ hybridization, physical mapping.
Three-to-one segregation from reciprocal translocation quadrivalents inNeurosporaand its bearing on the interpretation of spore-abortion patterns in unordered asci
Authors: Perkins David D. , Raju Namboori B.
Published: May 2008

In Neurospora, viable ascospores become black (B) when mature, whereas ascospores that are deficient for a chromosome segment are inviable and usually fail to blacken. The presence of a chromosome rearrangement can be recognized and the type of rearrangement can usually be inferred by visual inspection of asci. When a cross is heterozygous for a reciprocal translocation, asci with eight black ascospores (8B:0W) and asci with eight abortive unpigmented ("white" (W)) ascospores (0B:8W) are theoretically produced in equal numbers if homologous centromeres are equally likely to segregate from the quadrivalent in alternate or adjacent modes. In addition, 4B:4W asci are produced with a frequency characteristic of each reciprocal translocation. Information on ascospore-abortion patterns in Neurospora crassa has come predominantly from unordered ascospore octads ejected from the perithecium. Unordered asci of the 4B:4W type were initially presumed to originate by interstitial crossing over in a centromere-breakpoint interval and their frequency was used as a predictor of centromere locations. However, 4B:4W asci can result not only from interstitial crossing over but also from nondisjunction of centromeres at the first meiotic division, which leads to 3:1 segregation. Ordered linear 4B:4W asci retain the sequence information necessary for distinguishing one mode of origin from the other but unordered asci do not. Crossing over results in one abortive duplication–deficiency ascospore pair in each opposite half of a linear ascus, while 3:1 segregation places both abortive ascospore pairs together, either in the distal half or the basal half of the ascus. In the present study, perithecia were opened and intact linear asci were examined in crosses heterozygous for a varied sample of translocations. Three-to-one segregation rather than interstitial crossing over is apparently the main cause of 4B:4W asci when breakpoints are near centromeres, whereas crossing over is responsible for most or all 4B:4W asci when breakpoints are far-distal. Three-to-one segregation does not impair the usefulness of ejected unordered asci for detecting chromosome rearrangements. Ejected octads are superior to ordered linear asci for distinguishing one type of rearrangement from another, because ascus ejection from the perithecium does not occur until viable ascospores are fully pigmented, enabling true 0B:8W asci to be distinguished from those with eight immature ascospores.Key words: ascospore abortion, ascus analysis, Neurospora, nondisjunction, reciprocal translocation, three-to-one segregation.
Characterization of a dispersed repetitive DNA sequence associated with the CCDD genome of wild rice
Authors: Kiefer-Meyer M. C. , Reddy A. S. , Delseny M.
Published: May 2008

A HindII repetitive fragment (pOD3) was isolated and cloned from the genomic DNA of an accession of Oryza latifolia, a wild rice species that possesses a tetraploid CCDD genome. Southern blot analysis using this clone as a probe demonstrated that this repetitive DNA sequence had a dispersed organization in the CCDD genome and seemed to be highly specific for this genome type. This fragment is the first CCDD-specific repeated DNA sequence to be described. The hybridization pattern is similar for most CCDD accessions tested, although a few showed no hybridization signal. The nucleotide sequence of the element cloned in pOD3 was determined and analysed. The 1783 base pair long repeated sequence shows no homology with other known nucleotide sequences. In addition, none of the amino acid sequences deduced from the potential open reading frames contained in the pOD3 repeat is homologous to any known protein. The nucleotide sequence presents several internal repeats, direct or inverted, but their significance remains unknown.Key words: rice, dispersed repetitive DNA sequences, genome-specific sequences.
Aneuhaploids and tetrasomics in rice (Oryza sativaL.) derived from anther culture of trisomics
Authors: Wang Z. X. , Iwata N.
Published: May 2008

Eight types of aneuhaploids (Aneuhaplo 4, 5, 6, 8, 9, 10, 11, and 12) and eight types of tetrasomics (Tetraplo 4, 5, 6, 7, 8, 9, 10, and 12) of rice have been obtained from anther culture of trisomics. This paper reports the plant morphology of these aneuploids and their chromosome behavior at metaphase I. Aneuhaploids for different chromosomes are distinguishable from each other and are morphologically similar to the parental trisomics, suggesting that the extra chromosome has similar genetic effects on plant morphology at the haploid level as at the diploid level. Similarly, tetrasomics with different extra chromosomes are distinguishable from each other and are similar morphologically to the parental trisomic. However, stronger changes in morphological characters were observed in tetrasomics compared with trisomics having the same extra chromosome, as a result of a dosage effect of the extra chromosomes. Comparing plant size between aneuhaploid, tetrasomic, and trisomic with the same extra chromosome, it was shown that the trisomic was the largest, the tetrasomic was of medium size, and the aneuhaploid was the smallest, except for those plants with an extra chromosome 8 in which plant size is dramatically decreased in both the aneuhaploid and the tetrasomic. At metaphase I, aneuhaploids showed chromosome configurations of 1 II + 11 I and 13 I. The frequency of the 1 II + 11 I configuration is higher than 70%, indicating that homologous chromosomes in aneuhaploids tend to stay associated in meiosis. Intragenome chromosome pairing (2 II + 9 I), so called secondary association, was observed in the aneuhaploid for chromosome 5. Tetrasomic plants showed 5 kinds of chromosome configurations: 1 IV + 11 II, 1 III + 11 II + 1 I, 13 II, 12 II + 2 I, and 11 II + 4 I. A chromosome configuration of 13 II was often observed in tetrasomics with shorter extra chromosomes and a chromosome configuration of 1 IV + 11 II was often observed in tetrasomics with longer extra chromosomes. Aneuhaploids had complete seed sterility. Tetrasomics showed very poor pollen fertility and complete seed sterility, except for a few shriveled seeds that were observed in Tetraplo 6 and 9. This is the first report in rice where many aneuhaploids and tetrasomics have been characterized. This information will help to further unravel rice aneuploidy and cytogenetics. The aneuploids obtained here will be very useful tools for the study of genetics and breeding in rice.Key words: rice, aneuhaploids, tetrasomics, morphology, cytology.
Characterization of a library from a single microdissected oat (Avena sativa L.) chromosome
Authors: Chen Qianfa , Armstrong Ken
Published: May 2008

A plasmid library of oat chromosome No21, the smallest chromosome of the complement, was constructed by microdissection and microcloning. The chromosome was deproteinized with proteinase K and digested with Sau3A and linker adaptors were ligated to the DNA fragments. From the single chromosome (less than 0.4 pg), 10 μg of DNA was obtained after 2 rounds of PCR amplification. Cloning experiments with the amplified DNA produced as many as 500 000 recombinant clones from the single chromosome. The 500 clones evaluated ranged in size from 150 to 1700 base pairs (bp) with an average size of 650 bp. These were approximately 41% high-copy and 59% low/unique copy clones. Tandem repeats were absent in the library and may have been selected against by a combination of the Sau3A digestion, which is sensitive to C-methylation, and the PCR amplification. Many low-copy dispersed repetitive sequences were present in the library. These were present primarily on A- and D-genome chromosomes. Southern blot analysis revealed that the unique-copy clones were suitable for restriction fragment length polymorphism analysis and that they mapped to the pertinent oat nullisomic lines.Key words: microdissection and microcloning, high density RFLP mapping, Sau3A linker adaptor, monosomics and nullisomics, Avena sativa L.
Microsatellite and amplified sequence length polymorphisms in cultivated and wild soybean
Authors: Maughan P. J. , Maroof M. A. Saghai , Buss G. R.
Published: May 2008

The objectives of this study were to (i) assess the extent of genetic variation in soybean microsatellites (simple sequence repeats or SSRs), (ii) assay for amplified sequence length polymorphisms (ASLPs), and (iii) evaluate the usefulness of SSRs and ASLPs as genetic markers. Five microsatellites detected a total of 79 variants (alleles) in a sample of 94 accessions of wild (Glycine soja) and cultivated soybean (G. max). F2segregation analysis of four of the five microsatellites identified these variants (alleles) with four loci located in independent linkage groups. The number of alleles per microsatellite locus ranged from 5 to 21; to our knowledge these are the largest numbers of alleles for single Mendelian loci reported in soybean. Allelic diversity for the SSR loci was greater in wild than in cultivated soybean. Overall, 43 more SSR alleles were detected in wild than in cultivated soybean. These results indicate that SSRs are the marker of choice, especially for species with low levels of variation as detected by other types of markers. Two alleles were detected at each of the three ASLP loci examined. A total of six ASLP alleles were observed in cultivated soybean and five were observed in wild soybean; all alleles detected in wild soybean were present in cultivated soybean. Allelic diversity values for the ASLP loci were near previous estimates for restriction fragment length polymorphisms and therefore ASLPs may be useful as genetic markers in site-directed mapping.Key words: microsatellite, simple sequence repeat, soybean, amplified sequence length polymorphism, genetic mapping.
Analysis of an enhancer trap expressed in regeneratingDrosophilaimaginal discs
Authors: Addison William R. , Brook William J. , Querengesser Laura D. , Tiong Stanley Y. K. , Russell Michael A.
Published: May 2008

In Drosophila, imaginal discs are the undifferentiated larval precursors of the pattern of epidermal and sensory neural cells in each adult segment. Although cell fates are already specified by late third instar, disc fragments can either regenerate or duplicate after growth in culture. The outcome depends on signaling between cells across the healed wound and involves a redeployment of the expression patterns of selector genes and other disc pattern genes. We recently used the enhancer-trap method to screen for such genes that are expressed ectopically at the wound-heal site in imaginal discs undergoing regeneration. Here we report the cloning by plasmid rescue of transcribed sequences adjacent to one such enhancer-trap insertion. Using Northern analysis and in situ hybridization we show that one transcript is expressed in the embryo and in imaginal discs in a pattern similar to that of the enhancer trap. We also, by imprecise excision of the enhancer-trap insertion, generated a series of flanking deletions that were mapped using Southern analysis and complementation.Key words: Drosophila, imaginal discs, enhancer traps, regeneration genes.
The genomic identification of some monosomics of Avena sativa L. cv. Sun II using genomic in situ hybridization
Authors: Leggett J. M. , Markhand G. S.
Published: May 2008

Genomic in situ hybridization using total genomic DNA extracted from the C genome diploid species Avena eriantha (2n = 2x = 14, genome CpCp) was used to identify monosomics (2n = 6x − 1 = 41) of the constituent genomes of the hexaploid cultivated oat A. sativa L. cv. Sun II (2n = 6x = 42, genomes AACCDD). The results demonstrate 3 AD/C and 6 C/AD chromosome translocations, indicate that five of the missing monosomics are derived from the C genome, and show that there are duplicates within the partial monosomic series. Chromosome polymorphisms between some monosomic lines are also demonstrated.Key words: Avena, monosomics, genomic in situ hybridization, genomic identification.
Agrobacterium-mediated transformation of large-flowered purslane (Portulaca grandiflora H.)
Authors: Rossi-Hassani Badr-Din , Bennani Fadoua , Zryd Jean-Pierre
Published: May 2008

Transformation of Portulaca grandiflora has been developed with Agrobacterium tumefaciens strains A281 and T1272. Transformation was assessed by the following criteria: selection of hormone independent callus, antibiotic-resistant callus, and transgenic antibiotic-resistant plants. In addition, DNA hybridization analysis demonstrated that the DNA from tumor lines contained sequences homologous to binary vector T-DNA of strain A281. Following transformation with strain T1272, segregation analysis of the progeny of transgenic plants showed that the transgene was inherited in a Mendelian manner. The kanamycin-resistant progeny tested contained the T-DNA sequence of the strain T1272.Key words: Agrobacterium tumefaciens, binary vector, DNA transfer, regeneration, Portulaca grandiflora.
Synaptic abnormalities in spread nuclei of Secale. II. Secale vavilovii
Authors: Martínez M. , Romero C. , Cuadrado C.
Published: May 2008

Secale vavilovii PMCs have more univalents and a lower frequency of bound arms at metaphase I than other diploid Secale species. The spreading technique applied at prophase I showed that the nuclei were able to complete synapsis at pachytene. However, 25% of the nuclei analyzed, which had more than 90% of their total length paired, showed two abnormalities: long fold-back loops, which were located mainly on the nucleolar organizer bivalent, and pairing-partner switches, probably involving all the chromosome complement. These synaptic abnormalities are unusual in diploid species and give rise to a high frequency of nonhomologous pairing regions and, therefore, could produce desynapsis, which could explain the data obtained from metaphase I. The possible origin of the unusual synaptic abnormalities of S. vavilovii is discussed.Key words: S. vavilovii, synaptonemal complex, spreading, synaptic abnormalities.
Fluorescent in situ hybridization and C-banding analyses of highly repetitive DNA sequences in the heterochromatin of rye (Secale montanum Guss.) and wheat incorporating S. montanum chromosome segments
Authors: Cuadrado Angeles , Jouve Nicolás
Published: May 2008

The molecular characterization of C-banded regions of Secale montanum Guss. by means of in situ hybridization was performed in order to provide new information about their chromosome structure relative to cultivated rye, Secale cereale L. Accurate identification of individual chromosomes was achieved using simultaneous and (or) successive fluorescent in situ hybridization (FISH) and C-banding. FISH identification was performed using total rye DNA, three highly repetitive rye DNA sequences (pSc119.2, pSc74, and pSc34), and the ribosomal RNA probes pTa71 (18S, 5.8S, and 26S rDNA) and pTa794 (5S rDNA). FISH was also used to identify the chromosome segment involved in two spontaneous translocation lines recovered from a 'Chinese Spring' – S. montanum wheat–rye addition line. FISH analysis revealed the exact translocation breakpoints and allowed the identification of the transferred rye segments. The value of this type of analysis is discussed.Key words: Secale cereale, Secale montanum, rye, repetitive DNA, fluorescence in situ hybridization.
The molecular characterization of the genome of Muraena helena L. I. Isolation and hybridization of two MboI-restricted DNA fractions
Authors: Pichiri G. , Nieddu M. , Mezzanotte R. , Coni P. P. , Salvadori S. , Deiana M. , Deiana A. M.
Published: May 2008

To investigate the genome of the anguilliform fish Muraena helena at the molecular level we characterized total DNA by agarose gel electrophoresis after cleavage with AluI, HaeIII, MboI, and DdeI restriction endonucleases. Subsequently, we isolated the DNA from two specific electrophoretic fractions to be used as probes for Southern and in situ hybridization experiments. One such fraction showed an electrophoretic pattern typical of highly repetitive DNA localized in the centromeres of many chromosomes. The other fraction was shown to be located in the nucleolar organizer region, partially coincident with 45S rDNA, and to be composed of highly repetitive sequences.Key words: fish chromosomes, rDNA, highly repetitive DNA.
Pre-annealing of total genomic DNA probes for simultaneous genomic in situ hybridization
Authors: Anamthawat-Jónsson K. , Reader S. M.
Published: May 2008

We used pre-annealing of differently labelled total genomic DNA probes to perform simultaneous genomic in situ hybridization on mitotic and meiotic chromosomes of interspecific hybrids between plant species of the Tribe Triticeae. The species origin of chromosomes was demonstrated by a two-colour fluorescence after in situ hybridization with directly labelled probes incorporating fluorescein (visualized green) and rhodamine (visualized red). The pre-annealing blocked out common DNA sequences between the different genomes, hence increasing species specificity of the probes. The method is simple and rapid because the hybridization takes only about 2 h, including the pre-annealing step, and hence the whole process can be accomplished easily within a working day making it suitable for routine analysis of chromosomes and genomes.Key words: pre-annealing, genomic in situ hybridization, total genomic DNA probe, cereal species.
DNA markers for downy mildew resistance genes in sorghum
Authors: Gowda P. S. Bhavanishankara , Frederiksen Richard A. , Magill Clint W. , Xu Guo-Wei
Published: May 2008

The random amplified polymorphic DNA technique was used to find markers for a downy mildew resistance gene in sorghum. Of the 674 random primers screened for polymorphism, 2 amplified fragments were linked to a downy mildew resistance gene in sorghum line SC414. Utilization of an existing restriction fragment length polymorphism mapping population (IS3620C × BTx623) also revealed two markers that are linked to a different resistance gene in another sorghum line, BTx623.Key words: sorghum, downy mildew, RFLP, RAPD.
Analysis of the distal 5′ region of the humanCYP17gene
Authors: Maghsoudlou Sepehr Steve , Hughes Timothy R. , Hornsby Peter J.
Published: May 2008

In order to search for additional regulatory elements in the human CYP17 (steroid 17α-hydroxylase) gene and to compare it with potential regulatory elements in bovine CYP17 genes, 3.5 kb of 5′ flanking region of CYP17 was cloned and analyzed. The newly acquired sequence was shown to be a highly defective copy of the human endogenous retrovirus HERV-K family. This retroviral sequence was itself interrupted by a novel element, a low copy number repeat occurring about 20 times in the human genome, including a known copy in the human catechol-O-methyltransferase gene. A reanalysis of the entire 5′ flanking region of human CYP17 indicates that only the 300 bp immediately distal to the promoter is of unique sequence; other regulatory sequences, including any that are similar to the upstream region of the bovine genes, are unlikely to occur within 5.5 kb of the promoter.Key words: Human CYP17 gene, endogenous retrovirus, low-copy-number repeats.
Genetic diversity in Mediterranean diploid and tetraploidBromusL. (sectionBromusSm.) populations
Authors: Ainouche Malika , Misset Marie-Thérèse , Huon André
Published: May 2008

The levels of genetic diversity assessed from allozyme data were investigated in 25 populations of Mediterranean Bromus intermedius, B. squarrosus, B. lanceolatus, and B. hordeaceus from Algeria. The geographically restricted diploids B. intermedius and B. squarrosus displayed less genetic diversity (the mean population gene diversity of Nei (Hu) ranged from 0.03 to 0.12) than the widespread tetraploid colonizers B. lanceolatus and B. hordeaceus (Hu = 0.07–0.27). Deviations from Hardy–Weinberg expectations in diploid populations of B. intermedius and B. squarrosus were observed owing to heterozygote excess at several loci and suggested that these self-fertilizing species may have substantial amounts of allogamy. Tetraploid populations of B. lanceolatus and B. hordeaceus were largely homozygous at homologous loci and frequently exhibited intergenomic fixed heterozygosity in accordance with their alloploid origin. Genetic variation at the infraspecific level was mostly distributed within populations in the four species, B. hordeaceus showing the lowest level of interpopulation differentiation (Gst = 0.06) and the highest level of gene flow (Nm = 3.75). Consistent gene flows are in agreement with the strongest intercontinental invasive behaviour of B. hordeaceus. Less differentiation was reported in the literature among later introduced B. hordeaceus populations from England and Australia, indicating reduced differentiation under the process of colonization. Moderate divergence occured among the four taxa, with interspecific genetic identities ranging from 0.87 to 0.93. In spite of substantial genetic similarity, species were clearly differentiated, with each tetraploid being more closely related to a diploid: B. hordeaceus to B. squarrosus and B. lanceolatus to B. intermedius.Key words: Bromus, enzyme electrophoresis, population genetics, colonizing abilities, allopolyploidy.
Refined physical mapping of theSec-1locus on the satellite of chromosome 1R of rye (Secale cereale)
Authors: Busch W. , Herrmann R. G. , Martin R.
Published: May 2008

The Sec-1 locus (ω-secalin) of rye (Secale cereale L.) was mapped in the satellite of the short arm of chromosome 1R using fluorescence in situ hybridization and a genomic probe called pSec2B. Sec-1 is located in the middle of the satellite at the junction of the proximal euchromatic and the distal heterochromatic regions. Double hybridization experiments using rDNA and pSec2B showed that the NOR spans over the secondary constriction of the short arm of chromosome 1R and that there is a clearly visible gap between the NOR and Sec-1. Heterologous hybridization of pSec2B to barley visualized the B-hordein locus on chromosome 1H.Key words: fluorescence in situ hybridization, physical mapping, genetic mapping, secalin, rye, B-hordein, rDNA.
Quantitative trait locus analysis of fatty acid concentrations in maize
Authors: Alrefai Rudaina , Berke Terry G. , Rocheford Torbert R.
Published: May 2008

A study was conducted to determine the number and chromosomal location of quantitative trait loci (QTL) influencing the concentration of five fatty acids in 200 F2S1lines derived from an Illinois High Oil (IHO) by Illinois Low Oil (Early Maturity) (ILO(EM)) cross. Restriction fragment length polymorphism (RFLP) analysis was performed on the 200 S1lines and concentrations of palmitic (16:0), stearic (18:0), oleic (18:1), linoleic (18:2), and linolenic (18:3) acids were determined in self-pollinated kernels harvested from plants grown in replicated field trials during 1992 and 1993. A series of 74 cDNA and genomic clones were used and these revealed 80 polymorphic loci spaced, on average, 24 cM apart throughout the maize genome. Analysis of variance detected significant (p < 0.05) associations between several RFLP loci and the concentration of each fatty acid. A total of 15 RFLP loci clustered in 12 chromosomal regions were associated with the concentration of 16:0, 17 loci clustered in 10 regions were associated with the concentration of 18:0, 12 loci clustered in eight regions were associated with the concentration of 18:1 and 18:2, and 17 loci clustered in eight regions were associated with the concentration of 18:3. Multiple linear regression models consisting of four RFLP loci explained 24 and 62% of the total phenotypic and genotypic variation (R2) among the 200 F2S1lines for 16:0, five loci explained 51 and 71% of the variation for 18:0, three loci explained 67 and 79% of the variation for 18:1, two loci explained 67 and 81% of the variation for 18:2, and seven loci explained 52 and 78% of the variation for 18:3 in these 200 F2S1lines. The ratio of 18:1 to 18:2 was tightly interrelated as the same QTL were associated with the concentrations of 18:1 and 18:2. A quantitative trait locus that explained 63% of the phenotypic variation in the ratio of 18:1 to 18:2 is tightly linked to umc65 on chromosome 6 in the region of the linoleic acid1 locus.Key words: maize, fatty acid, oleic, linoleic, RFLP, QTL.