bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a second generation linkage map for almond using RAPD and SSR markers
Authors: Joobeur T , Periam N , Vicente M C de , King G J , Arús P
Published: April 2011

Fifty-four RAPD (random amplified polymorphic DNA) markers and 6 SSRs (simple sequence repeats) were included in a molecular marker map with 120 RFLPs (restriction fragment length polymorphisms) and 7 isozyme genes previously constructed using the offspring of a cross between the almond (Prunus amygdalus) cultivars 'Ferragnès' and 'Tuono'. Only highly reproducible RAPDs segregating 1:1 were used. To identify these markers, a total of 325 primers were screened, from which 41 produced RAPDs useful for mapping. Polymorphism was detected in six of the eight Prunus SSRs (simple sequence repeats) studied, thus enabling these to be mapped. All markers were placed on the 8 linkage groups previously identified. The number of new markers included in the map of 'Ferragnès' was 33 for a total of 126, and 30 in the map of 'Tuono' for a total of 99. The sizes of the maps of 'Ferragnès' (415 cM) and 'Tuono' (416 cM) were similar, representing a 5% increase over the maps constructed solely with isozymes and RFLPs. The estimated total size of the almond map was of 457 cM. Some markers were placed in zones with low density of markers and others in the extreme of linkage groups. The use of RAPD markers to complete genetic maps constructed with transferable markers is discussed.Key words: almond, Prunus amygdalus, RAPD, SSR, mapping.
Meiotic recombination in sexual diploid and apomictic triploid dandelions (Taraxacum officinale L.)
Authors: Baarlen Peter van , van Dijk Peter J , Hoekstra Rolf F , Jong J Hans de
Published: April 2011

Taraxacum officinale L. (dandelion) is a vigorous weed in Europe with diploid sexual populations in the southern regions and partially overlapping populations of diploid sexuals and triploid or tetraploid apomicts in the central and northern regions. Previous studies have demonstrated unexpectedly high levels of genetic variation in the apomictic populations, suggesting the occurrence of genetic segregation in the apomicts and (or) hybridization between sexual and apomictic individuals. In this study we analysed meiosis in both sexual diploid and apomictic triploid plants to find mechanisms that could account for the high levels of genetic variation in the apomicts. Microscopic study of microsporocytes in the triploid apomicts revealed that the levels of chromosome pairing and chiasma formation at meiotic prophase I were lower than in that of the sexual diploids, but still sufficient to assume recombination between the homologues. Nomarski DIC (differential interference contrast) microscopy of optically cleared megasporocytes in the apomicts demonstrated incidental formation of tetrads, which suggests that hybridization can occur in triploid apomicts.Key words: apomixis, autosegregation, diplospory, meiotic recombination, meiotic restitution, subsexual reproduction.
Chromosome structure ofTriticum timopheeviirelative toT. turgidum
Authors: Rodríguez S , Perera E , Maestra B , Díez M , Naranjo T
Published: April 2011

The chromosome structure of four different wild populations and a cultivated line of Triticum timopheevii (2n = 28, AtAtGG) relative to Triticum turgidum (2n = 28, AABB) was studied, using genomic in situ hybridisation (GISH) and C-banding analysis of meiotic configurations in interspecific hybrids. Two wild accessions and the cultivated line showed the standard C-banding karyotype. The other two accessions are homozygous for translocation 5At/3G and translocations 1G/2G and 5G/6G. GISH analysis revealed that all the T. timopheevii accessions carry intergenome translocations 6At/1G and 1G/4G and identified the position of the breakpoint in translocation 5At/3G. C-banding analysis of pairing at metaphase I in the hybrids with T. turgidum provides evidence that four species-specific translocations (6AtS/1GS, 1GS/4GS, 4GS/4AtL, and 4AtL/3AtL) exist in T. timopheevii, and that T. timopheevii and T. turgidum differ in the pericentric inversion of chromosome 4A. Bridge plus acentric fragment configurations involving 4AL and 4AtL were identified in cells at anaphase I. This result suggests that the paracentric inversion of 4AL from T. turgidum does not exist in T. timopheevii. Both tetraploid species have undergone independent and distinct evolutionary chromosomal rearrangements. The position, intercalary or subdistal, of the breakpoints in species-specific translocations and inversions contrasts with the position, at or close to the centromere, of intraspecific translocations. Different mechanisms for intraspecific and species-specific chromosome rearrangements are suggested.Key words: Triticum timopheevii, chromosome pairing, translocation, evolution, C-banding, GISH.
Simple sequence repeats inCucumismapping and map merging
Authors: Danin-Poleg Y , Reis N , Baudracco-Arnas S , Pitrat M , Staub J E , Oliver M , Arus P , deVicente C M , Katzir N
Published: April 2011

Thirty-four polymorphic simple-sequence repeats (SSRs) were evaluated for length polymorphism in melon (Cucumis melo L.) and cucumber (Cucumis sativus L.). SSR markers were located on three melon maps (18 on the map of 'Vedrantais' and PI 161375, 23 on the map of 'Piel de Sapo' and PI 161375, and 16 on the map of PI 414723 and 'Dulce'). In addition, 14 of the markers were located on the cucumber map of GY14 and PI 183967. SSRs proved to be randomly distributed throughout the melon and cucumber genomes. Mapping of the SSRs in the different maps led to the cross-identification of seven linkage groups in all melon maps. In addition, nine SSRs were common to both melon and cucumber maps. The potential of SSR markers as anchor points for melon-map merging and for comparative mapping with cucumber was demonstrated.Key words: microsatellites, Cucumis melo, melon, Cucumis sativus, cucumber, comparative mapping.
DNA content, rDNA loci, and DAPI bands reflect the phylogenetic distance between Lathyrus species
Authors: Ali Hoda Badry Mohammed , Meister Armin , Schubert Ingo
Published: April 2011

The nuclear DNA content, the proportion of A+T base pairs, the chromosomal positions of 5S and 25S rRNA genes, as well as of DAPI (4',6-diamidino-2-phenylindole) bands are described for seven species belonging to three different sect ions of the genus Lathyrus. These data and chromosome measurements allowed to establish precise idiograms and to discriminate most of the chromosome pairs of the seven species. The karyotypic features correlate well with the phylogenetic distances between these species.Key words: Lathyrus karyotypes, 5S/25S rDNA loci, FISH, DAPI banding pattern, nuclear DNA content.
An integrated SSR and RFLP linkage map ofSorghum bicolor(L.) Moench
Authors: Bhattramakki Dinakar , Dong Jianmin , Chhabra Ashok K , Hart Gary E
Published: April 2011

We report the development, testing, and use (for genetic mapping) of a large number of polymerase chain reaction (PCR) primer sets that amplify DNA simple sequence repeat (SSR) loci of Sorghum bicolor (L.) Moench. Most of the primer sets were developed from clones isolated from two sorghum bacterial artificial chromosome (BAC) libraries and three enriched sorghum genomic-DNA (gDNA) libraries. A few were developed from sorghum DNA sequences present in public databases. The libraries were probed with radiolabeled di- and trinucleotide oligomers, the BAC libraries with four and six oligomers, respectively, and the enriched gDNA libraries with four and three oligomers, respectively. Both types of libraries were markedly enriched for SSRs relative to a size-fractionated gDNA library studied earlier. However, only 2% of the sequenced clones obtained from the size-fractionated gDNA library lacked a SSR, whereas 13% and 17% of the sequenced clones obtained from the BAC and enriched gDNA libraries, respectively, lacked a SSR. Primer sets were produced for 313 SSR loci. Two-hundred sixty-six (85%) of the loci were amplified and 165 (53%) of the loci were found to be polymorphic in a population composed of 18 diverse sorghum lines. (AG/TC)nand (AC/TG)nrepeats comprised 91% of the dinucleotide SSRs and 52% of all of the SSRs at the polymorphic loci, whereas four types of repeats comprised 66% of the trinucleotide SSRs at the loci. Primer sequences are reported for the 165 polymorphic loci and for eight monomorphic loci that have a high degree of homology to genes. Also reported are the genetic map locations of 113 novel SSR loci (including four SSR-containing gene loci) and a linkage map composed of 147 SSR loci and 323 RFLP (restriction fragment length polymorphism) loci. The number of SSR loci per linkage group ranges from 8 to 30. The SSR loci are distributed relatively evenly throughout approximately 75% of the 1406-cM linkage map, but segments of five linkage groups comprising about 25% of the map either lack or contain few SSR loci. Mapping of SSR loci isolated from BAC clones located to these segments is likely to be the most efficient method for placing SSR loci in the segments.Key words: DNA libraries, linkage mapping, Sorghum bicolor, SSRs.
The sex-determining genedoublesexin the flyMegaselia scalaris: Conserved structure and sex-specific splicing
Authors: Kuhn Sylvia , Sievert Volker , Traut Walther
Published: April 2011

The well-known sex-determining cascade of Drosophila melanogaster serves as a paradigm for the pathway to sexual development in insects. But the primary sex-determining signal and the subsequent step, Sex-lethal (Sxl), have been shown not to be functionally conserved in non-Drosophila flies. We isolated doublesex (dsx), which is a downstream step in the cascade, from the phorid fly Megaselia scalaris, which is a distant relative of D. melanogaster. Conserved properties, e.g., sex-specific splicing, structure of the female-specific 3' splice site, a splicing enhancer region with binding motifs for the TRA2/RBP1/TRA complex that activates female-specific splicing in Drosophila, and conserved domains for DNA-binding and oligomerization in the putative DSX protein, indicate functional conservation of dsx in M. scalaris. Hence, the dsx step of the sex-determining pathway appears to be conserved among flies and probably in an even wider group of insects, as the analysis of a published cDNA from the silkmoth indicates.Key words: sex-determining cascade, splice regulation, DNA-binding domain, oligomerization.
Characterization of an opsin gene from the ascomycete Leptosphaeria maculans
Authors: Idnurm Alexander , Howlett Barbara J
Published: April 2011

An opsin gene (ops) has been characterized from Leptosphaeria maculans, the ascomycete that causes blackleg disease of Brassica species. This is the second opsin identified outside the archaeal and animal kingdoms. The gene encodes a predicted protein with high similarity (70.3%) and identity (53.3%) to the nop-1 opsin of another ascomycete Neurospora crassa. The L. maculans opsin also has identical amino acid residues in 20 of the 22 residues in the retinal-binding pocket of archaeal opsins. Opsin, on the fourth largest chromosome of L. maculans and 22 cM from the mating type locus, is the first cloned gene to be mapped in L. maculans. Opsin is transcribed at high levels in mycelia grown in the presence and absence of light; this pattern is in contrast with that of the N. crassa opsin, which is transcribed only in the light.Key words: opsin, Phoma lingam, Brassica napus.
New evidence for the synteny of rice chromosome 1 and barley chromosome 3H from rice expressed sequence tags
Authors: Smilde W Diederik , Halukova Jana , Sasaki Takuji , Graner Andreas
Published: April 2011

To provide improved access to the wealth of resources and genomic information that is presently being developed for rice a set of 88 rice expressed sequence tags (ESTs) previously mapped on rice chromosome 1 in the cross 'Nipponbare' × 'Kasalath' was used for comparative mapping in a cross of the barley cultivars 'Igri' and 'Franka'. As expected, most (89%) of the clones gave distinct banding patterns in barley of which about one-third was polymorphic between 'Igri' and 'Franka'. These polymorphisms were mapped, and most of these (56%) confirmed that rice chromosome 1 and barley chromosome 3H are syntenous. All single-copy markers identified conserved collinear positions, while markers with multiple copies did so in a few cases only. The markers that were not fitting in the collinear order were distributed randomly across the barley genome. The comparative maps of barley chromosome 3H and rice chromosome 1 comprise in total 26 common markers covering more than 95% of the genetic length of both chromosomes. A 30-fold reduction of recombination is seen around the barley centromere, and synteny may be interrupted in this region. However, the good overall synteny on a mesoscale (110 cM) justifies the use of rice as a platform for map-based cloning in barley.Key words: Oryza sativa, Hordeum vulgare, RFLP, synteny, comparative mapping.
Resistance gene analogs in barley and their relationship to rust resistance genes
Authors: Collins N , Park R , Spielmeyer W , Ellis J , Pryor A J
Published: April 2011

Regions of amino acid conservation in the NBS domain of NBS-LRR resistance proteins facilitated the PCR isolation of eight resistance gene analog (RGA) sequences from genomic DNA of rice, barley, and Aegilops tauschii. These clones and other RGAs previously isolated from maize, rice, and wheat were assigned to 13 classes by DNA-sequence comparison and by their patterns of hybridisation to restricted barley DNA. Using a doubled-haploid mapping population, probes from 12 RGA classes were used to map 17 loci in the barley genome. Many of these probes have been used for mapping in wheat, and the collective data indicate that the positions of orthologous RGAs are conserved between barley and wheat. RGA loci were identified in the vicinity of barley leaf rust resistance loci Rph4, Rph7, and Rph10. Recombinants were identified between RGA loci and Rph7 and Rph10, while a cluster of RGA sequences detected by probe 5.2 cosegregated with Rph4 in 55 F2lines.Key words: barley, Hordeum vulgare, rust, Puccinia, resistance gene analog, RGA, resistance.
Exploitation ofArabidopsis-tomato synteny to construct a high-resolution map of theovate-containing region in tomato chromosome 2
Authors: Ku Hsin-Mei , Liu Jiping , Doganlar Sami , Tanksley Steven D
Published: April 2011

High-resolution genetic and physical maps were constructed for the region of chromosome 2 containing the major fruit-shape locus ovate. A total of 3000 NIL F2and F3NILs derived from Lycopersicon esculentum cv. Yellow Pear (TA503) × L. pennellii (a wild tomato) were used to position ovate adjacent to the marker TG645 and flanked by markers TX700 and BA10R (a 0.03-cM interval). BAC libraries and a BIBAC library were screened with the closest marker, TG645. Genetic mapping with the ends of isolated BAC clones revealed that two BAC clones (100 and 140 kb) both contained the ovate locus. Screening of sequences from these BAC clones revealed synteny between this segment of tomato chromosome 2 and the chromosome-4 region of Arabidopsis containing the BAC clone ATAP22. Microsynteny between the two genomes was exploited to find additional markers near the ovate locus. The placement of ovate on a BAC clone will now allow cloning of this locus and, hence, may open the door to understanding the molecular basis of fruit development and also facilitate the genetic engineering of fruit-shape characteristics. This also represents the first time that microsynteny with Arabidopsis has been exploited for positional cloning purposes in a different plant family.Key words: map, fruit development, colinearity, positional cloning.
Identification and validation of QTLs for salt tolerance during vegetative growth in tomato by selective genotyping
Authors: Foolad M R , Zhang L P , Lin G Y
Published: April 2011

The purpose of this study was to identify quantitative trait loci (QTLs) for salt tolerance (ST) during vegetative growth (VG) in tomato by distributional extreme analysis and compare them with the QTLs previously identified for this trait. A BC1population (N = 792) of a cross between a moderately salt-sensitive Lycopersicon esculentum Mill. breeding line (NC84173, maternal and recurrent parent) and a salt-tolerant L. pimpinellifolium (Jusl.) Mill. accession (LA722) was evaluated for ST in solution cultures containing 700 mM NaCl + 70 mM CaCl2(electrical conductivity, EC [Formula: see text] 64 dS/m and ψw[Formula: see text]35.2 bars). Thirty-seven BC1plants (4.7% of the total) that exhibited the highest ST were selected (referred to as the selected population), grown to maturity in greenhouse pots and self-pollinated to produce BC1S1progeny seeds. The 37 selected BC1S1progeny families were evaluated for ST and their average performance was compared with that of the parental BC1population before selection. A realized heritability of 0.50 was obtained for ST in this population. The 37 selected BC1plants were subjected to restriction fragment length polymorphism (RFLP) analysis using 115 markers, and marker allele frequencies were determined. Allele frequencies for the same markers were also determined in an unselected BC1population (N = 119) of the same cross. A trait-based marker analysis (TBA), which measures differences in marker allele frequencies between selected and unselected populations, was used to identify marker-linked QTLs. Five genomic regions were detected on chromosomes 1, 3, 5, 6, and 11 bearing significant QTLs for ST. Except for the QTL on chromosome 3, all QTLs had positive alleles contributed from the salt tolerant parent LA722. Of the five QTLs, three (those on chromosomes 1, 3, and 5) were previously identified for this trait in another study, and thus were validated here. Only one of the major QTLs that was identified in our previous study was not detected here. This high level of conformity between the results of the two studies indicates the genuine nature of the identified QTLs and their potential usefulness for ST breeding using marker-assisted selection (MAS). A few BC1S1families were identified with most or all of the QTLs and with a ST comparable to that of LA722. These families should be useful for the development of salt tolerant tomato lines via MAS.Key words: Lycopersicon esculentum, L. pimpinellifolium, salt tolerance, vegetative growth, restriction fragment length polymorphism (RFLP), quantitative trait loci (QTLs), trait-based analysis.
MicroMeasure: A new computer program for the collection and analysis of cytogenetic data
Authors: Reeves Aaron
Published: April 2011

The ability to identify individual chromosomes in cytological preparations is an essential component of many investigations. While several computer software applications have been used to facilitate such quantitative karyotype analysis, most of these programs are limited by design for specific types of analyses, or can be used only with specific hardware configurations. MicroMeasure is a new image analysis application that may be used to collect data for a wide variety of chromosomal parameters from electronically captured or scanned images. Unlike similar applications, MicroMeasure may be individually configured by the end user to suit a wide variety of research needs. This program can be used with most common personal computers, and requires no unusual or specific hardware. MicroMeasure is made available to the research community without cost by the Department of Biology at Colorado State University via the World Wide Web at http://www.biology.colostate.edu/MicroMeasure.Key words: MicroMeasure, computer program, chromosome measurement, cytogenetics.
Low glucosinolate Brassica juncea breeding line revealed to be nullisomic
Authors: Cheng B F , Séguin-Swartz G , Somers D J , Rakow G
Published: April 2011

The low glucosinolate Brassica juncea breeding line 1058 was derived from a BC1F3 plant of an interspecific cross between high glucosinolate Indian B. juncea (genome AABB, 2n = 36) line 60143 and B. rapa (genome AA, 2n = 20) canola strain CZY. Line 60143 had 2n = 36 chromosomes (18 bivalents at metaphase I) and strain CZY had 2n = 20 chromosomes (10 bivalents). Line 1058 was nullisomic, with 2n - 2 = 34 chromosomes, with 17 bivalents formed at metaphase I and an even chromosomal segregation of 17:17 at anaphase I. In F1 hybrid plants of the cross 1058 × CZY, 98.3% of the pollen mother cells had 10 bivalents and seven univalents. This is evidence that plants of line 1058 are nullisomic, missing one pair of B-genome chromosomes.Key words: low glucosinolate mustard, meiotic behaviour, cytogenetics.
Interspecific chromosomal rearrangements in monosomic addition lines of Allium
Authors: Barthes L , Ricroch A
Published: April 2011

Monosomic alien addition lines (MAALs) are useful for assigning linkage groups to chromosomes. We examined whether the chromosomal rearrangements following the introduction of a single onion (Allium cepa) chromosome into the Allium fistulosum genome were produced by homeologous crossing over or by a nonreciprocal conversion event. Among the monosomic lines available, 17 were studied by fluorescent genomic in situ hybridisation, using total A. cepa genomic DNA as the probe and total A. fistulosum genomic DNA as the competitor. In this way, rearrangements such as chromosomal translocations between A. cepa and A. fistulosum were identified as terminal regions consisting of tandem DNA repeats. Homeologous crossing over between the two closely related genomes occurred in 4 of the 17 lines, suggesting that such events are not rare. On the basis of a detailed molecular cytogenetic characterisation, we identified true monosomic alien addition lines for A. cepa chromosomes 3, 4, 5, 7, and 8 that can reliably be used in genetic studies.Key words: chromatin transfer, genomic in situ hybridisation, GISH, monosomic alien addition lines, MAALs, Allium.
A peach linkage map integrating RFLPs, SSRs, RAPDs, and morphological markers
Authors: Dettori Maria Teresa , Quarta Roberta , Verde Ignazio
Published: April 2011

A linkage map was obtained using a BC1progeny (Prunus persica × (P. persica × P. ferganensis)). The map is composed of 109 loci (74 RFLPs, 17 SSRs, 16 RAPDs, and two morphological traits) distributed in 10 linkage groups. Loci, segregating in five different ratios, were integrated in the map with JoinMap 2.0 software. The map covers 521 cM of the peach genome. The average distance between adjacent loci is 4.8 cM. Two monogenic traits, flesh adhesion (F/f) and leaf glands (E/e), were placed on the map. Thirty-two loci in common with a saturated linkage map of Prunus allowed a comparative analysis to be made between the two maps. Homologies were found among the respective linkage groups. No relevant differences were observed in the linear order of the common loci.Key words: peach, linkage map, Prunus persica, Prunus ferganensis, molecular markers.
Molecular organization of 5S rDNA in fishes of the genusBrycon
Authors: Wasko Adriane Pinto , Martins Cesar , Wright Jonathan M , Galetti Jr. Pedro Manoel
Published: April 2011

There are few reports on the genomic organization of 5S rDNA in fish species. To characterize the 5S rDNA nucleotide sequence and chromosomal localization in the Neotropical fishes of the genus Brycon, 5S rDNA copies from seven species were generated by PCR. The nucleotide sequences of the coding region (5S rRNA gene) and the nontranscribed spacer (NTS) were determined, revealing that the 5S rRNA genes were highly conserved, while the NTSs were widely variable among the species analyzed. Moreover, two classes of NTS were detected in each species, characterized by base substitutions and insertionsdeletions. Using fluorescence in situ hybridization (FISH), two 5S rDNA chromosome loci that could be related to the two 5S rDNA NTS classes were observed in at least one of the species studied. 5S rDNA sequencing and chromosomal localization permitted the characterization of Brycon spp. and suggest a higher similarity among some of them. The data obtained indicate that the 5S rDNA can be an useful genetic marker for species identification and evolutionary studies.Key words: Brycon, FISH, nontranscribed spacer, nucleotide sequence, 5S rDNA.
A new meiotic abnormality inZea mays: multiple spindles associated with abnormal cytokinesis in both divisions
Authors: Caetano-Pereira Creucí Maria , Pagliarini Maria Suely
Published: April 2011

We report here a new meiotic abnormality recorded in one plant of an inbred line of Zea mays. After an apparently normal prophase I, chromosomes did not congregate in a single metaphase plate. Bivalents remained scattered in the cytoplasm, giving rise to several spindles. Despite the occurrence of multiple spindles, meiosis I proceeded normally, forming a varied number of nuclei at telophase I. The presence of one or a few chromosomes in the nucleus was enough to induce local cytokinesis, which was evident from metaphase I. Each cell resulting from meiosis I expressed its own program and progressed through the cell cycle. Therefore, failure of chromosome congregation on a single plate also occurred at meiosis II, where further irregular cytokinesis was observed. As a consequence of the two abnormalities, polyads occurred, resulting in pollen grains of different sizes and in sterility at a frequency of up to 93.5%.Key words: maize, meiosis, cytokinesis, multiple spindles, polyads.
Genetic and physical characterization of chromosome 4DL in wheat
Authors: Milla MA Rodriguez , Gustafson J P
Published: April 2011

The long arm of chromosome 4D in wheat (Triticum aestivum L.) has been shown in previous studies to harbor genes of agronomic importance. A major dominant gene conferring Aluminum (Al) tolerance (Alt2 in 'Chinese Spring' and AltBHin 'BH 1146'), and the Kna1 locus controlling the K+/Na+discrimination in saline environments have been mapped to this chromosome arm. However, accurate information on the genetic and physical location of markers related to any of these genes is not available and would be useful for map-based cloning and marker-assisted plant breeding. In the present study, using a population of 91 recombinant inbred lines segregating for Al tolerance, we provide a more extensive genetic linkage map of the chromosome arm 4DL based on RFLP, SSR, and AFLP markers, delimiting the AltBHgene to a 5.9-cM interval between markers Xgdm125 and Xpsr914. In addition, utilizing a set of wheat deletion lines for chromosome arm 4DL, the AltBHgene was physically mapped to the distal region of the chromosome, between deletion breakpoints 0.70 and 0.86, where the kilobase/centimorgan ratio is assumed to be low, making the map-based cloning of the gene a more realistic goal. The polymorphism rates in chromosome arm 4DL for the different types of markers used were extremely low, as confirmed by the physical mapping of AFLPs. Finally, analysis of 1 Mb of contiguous sequence of Arabidopsis chromosome 5 flanking the gene homologous to the BCD1230 clone (a cosegregating marker in our population coding for a ribulose-5-phosphate-3-epimerase gene), revealed a previously identified region of stress-related and disease-resistance genes. This could explain the collinearity observed in comparative mapping studies among different species and the low level of polymorphism detected in the chromosome arm 4DL in hexaploid wheat.Key words: wheat, aluminum, mapping, AFLP, SSR.
Expression, mapping, and genetic variability ofBrassica napusdisease resistance gene analogues
Authors: Fourmann Marie , Charlot Florence , Froger Nicole , Delourme Régine , Brunel Dominique
Published: April 2011

Numerous sequences analogous to resistance (R) genes exist in plant genomes and could be involved in resistance traits. The aim of this study was to identify a large number of Brassica napus sequences related to R genes and also to test the adequacy of specific PCR-based tools for studying them. Different consensus primers were compared for their efficiency in amplifying resistance-gene analogues (RGAs) related to the nucleotide-binding-site subgroup of R genes. Specific primers were subsequently designed to fine-study the different RGAs and we tested their efficiency in three species related to B. napus: Brassica oleracea, Brassica rapa, and Arabidopsis thaliana. Forty-four B. napus RGAs were identified. Among 29 examined, at least one-third were expressed. Eighteen RGAs were mapped on 10 of the 19 B. napus linkage groups. The high variability within these sequences permitted discrimination of each genotype within a B. napus collection. The RGA-specific primers amplified RGAs in the B. oleracea and B. rapa genomes, but the sequences appear to be poorly conserved in A. thaliana. Specific RGA primers are a precise tool for studying known-sequence RGAs. These sequences represent interesting markers that could be correlated with resistance traits in B. napus or related Brassica genomes.Key words: RGAs, Brassica, NBS-LRR, resistance, molecular markers.
Mapping genetic factors affecting the reaction toXanthomonas axonopodispv. phaseoliinPhaseolus vulgarisL. under field conditions
Authors: Tar'an B , Michaels T E , Pauls K P
Published: April 2011

The objectives of the present study were to evaluate the field effects of Xanthomonas axonopodis pv. phaseoli (Xap), which causes common bacterial blight (CBB) on common bean (Phaseolus vulgaris L.), and to identify genetic factors for resistance to CBB using a linkage map constructed with random amplified polymorphic DNA (RAPD), restriction fragment length polymorphism (RFLP), simple sequence repeat (SSR), and amplified fragment length polymorphism (AFLP) markers. One hundred and forty-two F2:4lines, derived from a cross between 'OAC Seaforth' and 'OAC 95-4', and the parents were evaluated for their field reaction to CBB. In the inoculated plots, the reaction to CBB was negatively correlated with seed yield, days to maturity, plant height, hypocotyl diameter, pods per plant, and harvest index. A reduction in seed yield and its components was observed when disease-free and CBB-inoculated plots were compared. The broad-sense heritability estimate of the reaction to CBB was 0.74. The disease segregation ratio was not significantly different from the expected segregation ratio for a single locus in an F2generation. The major gene for CBB resistance was localized on linkage group (LG) G5. A simple interval mapping procedure identified three genomic regions associated with the reaction to CBB. One quantitative trait loci (QTL), each on LG G2 (BNG71DraI), G3 (BNG21EcoRV), and G5 (PHVPVPK-1) explained 36.3%, 10.2%, and 42.2% of the phenotypic variation for the reaction to CBB, respectively. Together, these loci explained 68.4% of the phenotypic variation. The relative positions of these QTL on the core common bean map and their comparison with the previous QTL for CBB resistance are discussed.Key words: common bean, molecular markers, common bacterial blight.
α-Catulin maps to the familial dysautonomia region on 9q31
Authors: Demacio Paula C , Ray Peter N
Published: April 2011

Familial dysautonomia is a severe autosomal-recessive neurodegenerative disease that primarily affects the Ashkenazi Jewish population. We present the mapping of α-catulin and show that it maps precisely to the familial dysautonomia candidate region on 9q31. Patient sequence analysis identified two new sequence variants, which show linkage disequilibrium with this disease. A G to A transition at nucleotide 423 in exon 3 is a silent base change that does not alter the Val residue at position 141. A G to C transversion at nucleotide 1579 changes the Glu at postion 527 to Gln. These base changes were analyzed in several patients, unaffected Ashkenazi Jewish controls, and non-Jewish controls. Because of the presence of these sequence variants in several unaffected individuals, α-catulin is unlikely to be the causative gene in this disease.Key words: familial dysautonomia, α-catulin, sequence variant.
SRY-related (Sox) genes in the genome of European Atlantic sturgeon (Acipenser sturio)
Authors: Hett Anne Kathrin , Ludwig Arne
Published: April 2011

The Sox-gene family represents an ancient group of transcription factors involved in numerous developmental processes and sex determination in vertebrates. SOX proteins are characterized by a conserved high mobility group (HMG)-box domain, which is responsible for DNA binding and bending. We studied Sox genes in sturgeon, one of the most primitive groups of fishes characterized by a high chromosome number. Male and female genomes were screened for Sox genes using highly degenerate primers that amplified a broad range of HMG boxes. A total of 102 clones, representing 22 different sequences coding for 8 Sox genes, was detected and classified according to their orthologues. Sox2, Sox3, Sox4, Sox9, Sox11, Sox17, Sox19, and Sox21 were found in sturgeon; these genes represent Sox groups B, C, E, and F. In a phylogenetic analysis (neighbor-joining, maximum likelihood, maximum parsimony), these genes clustered with their mouse orthologues. In the case of Sox4, Sox17, and Sox21, we found evidence of gene duplication.Key words: Acipenseridae, gene evolution, sex determination, Sox genes.
Phylogenetic relationships among Secale species revealed by amplified fragment length polymorphisms
Authors: Chikmawati T , Skovmand B , Gustafson J P
Published: April 2011

Amplified fragment length polymorphism (AFLP) data were utilized to analyze the phylogenetic relationships among 29 accessions representing 14 of the most commonly recognized ranked species or subspecies in the genus Secale. We observed 789 AFLP markers of 1130 fragments utilizing 18 P-/M- and E-/M- primer combinations. All polymorphic fragments were used to construct phenetic and phylogenetic trees. The resulting phenogram and cladogram had similar tree topologies. Cluster analysis showed that Secale sylvestre was the most distantly related to all other ryes. Annual forms were grouped together, and the perennial forms appeared more closely related to each other. This suggested that life cycle could have played an important role in determining the relationships among Secale species. Secale sylvestre was considered to be the most ancient species, whereas Secale cereale was the most recently evolved species. Amplified fragment length polymorphism analysis clearly separated all Secale species into only 3 major species groups, within the genus Secale: S. sylvestre, Secale montanum (syn. Secale strictum) for perennial forms, and S. cereale for annual forms. This study demonstrated that the AFLP approach is a useful tool for discriminating species differences, and also gave a much better resolution in discerning genetic relationships among Secale species as compared with previous studies using other approaches.Key words: AFLP, Secale, phylogenetic relationship.
5S rDNA genome regions of Lens species
Authors: Fernández M , Ruiz M L , Linares C , Fominaya A , Pérez de la Vega M
Published: April 2011

The length variability of the nontranscribed spacer (NTS) of the 5S rDNA repeats was analyzed in species of the genus Lens by means of PCR amplification. The NTS ranged from ~227 to ~952 bp. The polymorphism detected was higher than previous NTS polymorphisms described in this genus. Three NTS length variants from Lens culinaris subsp. culinaris and 2 from Lens culinaris subsp. orientalis were sequenced. The culinaris NTS fragment lengths were 239, 371, and 838 bp, whereas the orientalis ones were 472 bp and 506 bp, respectively. As a result of sequence similarities, 2 families of sequences were distinguished, 1 including the sequences of 838 and 506 bp, and others with the sequences of 239, 371, and 472 bp. The 1st family was characterized by the presence of a repeated sequence designated A, whereas the 2nd family showed a single A sequence and other repeated sequences designated B, C, and D. The presence of an (AT)n microsatellite was also observed in the 2nd family of sequences. The fragments, which included the 239-bp and 838-bp NTS sequences, as well as the intergenic spacer (IGS) of the 18S–5.8S–26S ribosomal DNA also from L. culinaris subsp. culinaris, were used to localize the nucleolar organizer region (NOR) and the 5S rDNA loci in the chromosomes of several species of the genus Lens by means of fluorescence in situ hybridization (FISH). The selective hybridization of the 2 NTS probes allowed us to distinguish between different 5S rDNA chromosomal loci.Key words: Lens, lentil, ribosomal loci, 5S, FISH, NTS polymorphism, NOR.
Effects of B chromosomes on the activity of nucleolar organizer regions in the grasshopper Eyprepocnemis plorans: activation of a latent nucleolar organizer region on a B chromosome fused to an autosome
Authors: Cabrero J. , Alché J. D. , Camacho J. P. M.
Published: April 2011

Four nucleolar organizer regions (NORs) are active in standard males of the grasshopper Eyprepocnemis plorans. They are located near the centromeric regions of the S9, S10, S11, and X chromosomes. Changes in the pattern of NOR activity have been observed in the presence of a B2 type supernumerary chromosome. Males with one B show a higher mean number of active NORs per cell than do zero B males owing to significant increases in the activity of the NORs on the S11 and the X. Zero B and one B embryos, however, showed similar patterns of activity. In a male carrying a centric fusion between a B and one of the L1 chromosomes, the activation of a latent NOR, present at the telomere of the long arm of the B, parallelled a significant decrease of NOR activity on the S9 and S10 bivalents stemming from a competition between different NORs in the presence of the B. Thus, while in zero B males the activity of the S10 NOR influences that of the NORs on the X and S9 in a negative way, in one B males it does not do so, although such an influence is observed in the B–L1 fusion male where the activity of the S10 NOR again decreases significantly. On the other hand, the activities of the NORs on the S9 and S11 show a significant positive interdependence in both zero B and one B males where S11 NOR activity is increased but do not do so in the B–L1 fusion male, which shows a significant decrease in the S9 NOR activity.

Key words: Eyprepocnemis plorans, B chromosome, nucleolus.
Analysis of low concentrations of 5-bromo-2-deoxyuridine on sister chromatid exchanges in human lymphocytes
Authors: Richer Claude-Lise , Senécal-Quevillon Micheline , Duquette Pierre
Published: April 2011

To determine a concentration of 5-bromo-2-deoxyuridine (BrdU) sufficient for sister chromatid differentiation (SCD), and yet having a minimal effect on the number of sister chromatid exchanges ((SCEs), we assessed the effect produced on the number of SCEs by low concentrations (1, 3, and 10 μg/mL) of BrdU. SCD was not obtained in 19% of the 31 subjects with 1 μg/mL of BrdU, while the differentiation was adequate for all samples treated with 3 and 10 μg/mL. We statistically analysed the effects of these three different doses and found no significant difference in the number of SCEs obtained with the doses of 1 and 3 μg/mL, but a significant difference was observed between these two concentrations and 10 μg/mL. We therefore suggest that the dose of 3 μg/mL, while sufficient to produce reliable differential staining, still permits an adequate evaluation of the base line of SCEs and appears to enhance the sensitivity of the test to evaluate between-individual variations. Our experiments also underline that SCE counts should include the centromere exchanges.

Key words: sister chromatid exchanges, sister chromatid diffentiation, low doses of BrdU on SCE.
Quantitative genetic studies of yield, yield components, and phenological and agronomic characters in spring faba bean
Authors: Kao H. M. , McVetty P. B. E.
Published: April 2011

Hayman's diallel cross analysis was employed to investigate the nature of the genetic control and heritability of yield, yield components, and phenological and agronomic characters in F1 and F2 generations of spring faba beans (Vicia faba L.). High-yielding S4 inbred lines from five open-pollinated faba bean cultivars were used as parents to generate complete F1 and F2 diallels. The S5 inbred line parents and the 20 cross combinations were planted in randomized complete block experiments with six replications. All characters in the F1 diallel and in the F2 diallel with the exception of days from planting to maturity met all of the assumptions required for Hayman's diallel analysis. Yield, total dry matter, harvest index, and pods per plant exhibited significant apparent overdominance in both the F1 and F2 diallels. It is concluded that substantial immediate increases in yield and total dry matter could be expected from exploiting the apparent overdominant gene action found for these characters in these crosses via F1 hybrids or synthetics.

Key words: total dry matter, harvest index, diallel crosses, inheritance, Vicia faba L.
Interspecific hybrids involving the recently described diploid taxon Avena atlantica
Authors: Leggett J. M.
Published: April 2011

Chromosome pairing affinities of interspecific hybrids involving the newly discovered species Avena atlantica with A. strigosa, A. hirtula, A. prostrata, A. damascena, A. maroccana, and A. sativa are described. The complete and regular chromosome pairing observed in the hybrids involving A. hirtula and A. strigosa confirms the genomic designation to be AsAs. The chromosome pairing in the A. prostrata, A. damascena, A. maroccana, and A. sativa hybrids indicates that A. atlantica is no more closely related to these species than the other members of the AsAs genomic group.

Key words: Avena, meiosis, hybridization, phylogeny.
Locating the Agropyron segment in wheat–Agropyron transfer no. 12
Authors: Eizenga G. C.
Published: April 2011

Twelve lines of wheat (Triticum aestivum L.) were originally identified as having a segment of Agropyron elongatum chromatin carrying a gene for resistance to leaf rust (Puccinia recondita tritici) transferred to wheat chromosome 7D. By studying the chromosome pairing of one of these lines, transfer no. 12, with telosomes 7AL, 7AS, 7BL, 7BS, 7DL, 7DS, and 7AgS, it was determined that the Agropyron chromatin was carried on the long arm of wheat chromosome 7A rather than 7D. This determination was confirmed by acetocarmine–N-banding.

Key words: Triticum aestivum, Agropyron elongatum, transfer lines, Puccinia recondita tritici, telosomic analysis.
Chromosome segregation from cell hybrids. III. Segregation is independent of spindle constitution
Authors: Zelesco Paula A. , Graves Jennifer A. Marshall
Published: April 2011

Hamster β-tubulin (detected as a mutant subunit that confers Colcemid resistance) is either not expressed or is underexpressed in Chinese hamster–mouse somatic cell hybrids. This selectivity of tubulin expression suggests that a uniparental mouse spindle might preferentially engage mouse chromosomes and lead to loss of hamster chromosomes. However, the repression of hamster tubulin was found to have no bearing on the direction of chromosome segregation occurring in eight hybrids studied, some of which segregated predominantly mouse and others hamster chromosomes.

Key words: chromosome segregation, cell hybrids, spindle, tubulin.
Chromosome pairing and aneuploidy in tetraploid triticale. II. Unstabilized karyotypes
Authors: Lukaszewski Adam J. , Apolinarska Barbara , Gustafson J. Perry , Krolow K.-D.
Published: April 2011

In the progeny of tetraploid triticale plants that segregated for either one, two, or three pairs of homoeologous wheat chromosomes, plants were selected that had 13 pairs of homologues and 1 pair of presumed wheat homoeologues. Segregation ratios of "homoeologues" were close to 1:2:1 except for group 4, where no 4B homozygotes were recovered. Aneuploid frequency among 190 progeny of the segregating plants was 4.74%. C-banding at meiosis showed that "homoeologues" paired with frequencies ranging from 0.1 to 1.74 paired arms per chromosome. The only exception was the 4A–4B pair, which did not synapse. It was concluded that the high pairing frequencies between "homoeologous" chromosomes were due to translocations that had accumulated during line development. With few exceptions, translocations could not be detected by C-banding. The results demonstrate that genome recombination in polyploid species may occur at two levels simultaneously: by segregation of complete chromosomes and by translocations between homoeologues.

Key words: C-banding, homoeologous pairing, translocations.
The higher order structure of the centromere
Authors: Rattner J. B. , Lin C. C.
Published: April 2011

The architecture of the centromere region of mouse chromosomes has been studied in cells grown in the presence of 5-azacytidine. This drug interferes with normal condensation producing elongated centromere regions. It has been found that this effect is reversible in the presence of the drug, allowing the observation of the repackaging of the extended centromere into a structure exhibiting native centromere morphology. Light microscopy as well as transmission and scanning electron microscopy of this condensation process suggests that the native centromere is formed by the helical folding of a subfiber with an approximate diameter of 100 nm. This fiber is in turn composed of loops of the 30-nm fiber class. The boundary between successive gyres of the subfiber are obscured at the completion of condensation resulting in the formation of a homogenous 250- to 300-nm fiber that is the native centromere. These observations provide evidence for an additional level of chromatin organization within the metaphase chromosome.

Key words: centromere, azacytidine.
Preferential intragenomic chromosome pairing in two new diploid intergeneric hybrids between Hordeum and Secale
Authors: Gupta P. K. , Fedak George
Published: April 2011

Intergeneric hybrids involving Hordeum californicum with Secale anatolicum and Hordeum bogdanii with Secale cereale ssp. segetale were produced at a frequency of 1.3% of pollinated florets. Chiasmata frequencies of plants ranged from 0.13 to 0.21 per cell in the first hybrid combination and from 0.30 to 0.68 per cell in the second. The paucity of heteromorphic bivalents indicated absence of a close relationship between parental genomes. The associations in bivalents could be classified into Secale–Secale (R–R), Hordeum–Hordeum (H–H), and Secale–Hordeum (R–H) on the basis of difference in size of the chromosomes of Secale and Hordeum. Using a binomial distribution, it is shown that there was preferential intragenomic (R–R, H–H) chromosome pairing, which was attributed to the presence of homologous chromosome segments on nonhomologous chromosomes of the same genome. The distribution of Hordeum and Secale chromosomes to the poles at anaphase occurred at random.

Key words: Hordeum, Secale, hybrids (intergeneric), chromosome pairing.