bluuebunny/crossref_metadata_2025 huggingface dataset:
Gametophytic competition as influencing gene flow between wild and cultivated forms of pearl millet (Pennisetum typhoides)
Authors: Robert T. , Lespinasse R. , Pernès J. , Sarr A.
Published: April 2011

Intergametophytic competitions with prepotency of autopollen have been previously described in some cultivated lines of pearl millet (Pennisetum typhoides (Burm.) Stapf &Hubb.). This paper reports the analysis of intergametophytic competitions between pollen from wild and cultivated plants on stigmas of both wild and cultivated plants. Three inbred lines (two cultivated and one wild) and two land races (one cultivated and one wild) were used, each of them as pollen donors as well as plant receptors. These populations represent in some instances allopatric and sympatric evolutionary situations between wild and cultivated forms. Deviations from the equiprobability of gamete encounters for almost all progeny are clearly demonstrated and reveal a large amount of male gametophytic fitness variability in land-race populations. There is no marked hierarchy between pollen sources for their competitive ability, but taking into account the pollen-pistil interactions, preferential wild-wild and cultivated-cultivated gamete associations are noticeable. Thus, pollen competitions establish a fine reproductive limit between allopatric populations as well as between wild and cultivated sympatric populations. This soft reproductive "barrier" controls the gene flow between adjacent populations and could explain the success of pearl millet domestication, allowing the wild and cultivated types to keep their phenotypic integrity despite the gene flow.Key words: pearl millet, intergametophytic competitions, gene flow, domestication.
Temporal variation in the ribosomal DNA nontranscribed spacer of Aedes albopictus (Diptera: Culicidae)
Authors: Kambhampati Srinivas , Rai Karamjit S.
Published: April 2011

Length variation in ribosomal DNA (rDNA) nontranscribed spacer within and among populations of the mosquito Aedes albopictus was studied over a 3-year period in eight different populations from Texas. Statistically significant variation was detected among populations at each sampling date. Significant, but nondirectional, changes were observed within populations over time. An average of 78% of the total variance in the frequencies of spacer variants was attributable to the within-population component, suggesting local differentiation. The results corroborate those from a previous study on spacer length diversity in populations of A. albopictus from around the world and are similar to those from a study on temporal variation in allozyme frequencies in some of the same populations and sampling dates. We propose that a high rate of production of length variants and localized breeding structure could explain the observed high levels of within- and among-population variation in A. albopictus.Key words: rDNA, nontranscribed spacer, genetic structure, temporal variation, Aedes albopictus.
A genetic linkage map of Triticum tauschii (DD) and its relationship to the D genome of bread wheat (AABBDD)
Authors: Gill K. S. , Lubbers E. L. , Gill B. S. , Raupp W. J. , Cox T. S.
Published: April 2011

One hundred and seventy-eight loci have been mapped in Triticum tauschii (Coss.) Schmal. (2n = 14, DD) and Triticum aestivum L. em. Thell. (2n = 42, AABBDD). Thirty-five loci were mapped by aneuploid analysis in T. aestivum. One hundred and fifty-two loci, including 143 restriction fragment length polymorphisms (RFLPs), 8 proteins, and 1 leaf rust resistance gene, were mapped in an F2 population (60 plants) of T. tauschii. One hundred and twenty-seven loci were placed in linkage groups belonging to seven D-genome chromosomes of T. tauschii. The source of the probes was a PstI genomic library of T. tauschii, which gave 13% single-low copy clones. Four restriction endonucleases (DraI, EcoRI, EcoRV, HindIII) gave 75% polymorphism between the two parents. Nineteen clones detected multiloci ranging from two to nine in number. Deletions–insertions and point mutations were equally important for generating RFLPs. A hypervariable sequence was identified, which may have potential use in varietal fingerprinting. One marker was found to be linked to a rust-resistance gene. The map will be useful for determining genetic relationships in the Triticeae and for tagging genes of economic importance.Key words: restriction fragment length polymorphism, Triticum aestivum, leaf rust, isozymes, Aegilops squarrosa.
The molecular–genetic analysis of Triticum tauschii, the D-genome donor to hexaploid wheat
Authors: Lagudah E. S. , Appels R. , Brown A. H. D. , McNeil D.
Published: April 2011

DNA from Triticum tauschii (the D-genome donor to hexaploid wheat, Triticum aestivum) has been cloned using the restriction endonuclease PstI to generate fragments for insertion into the plasmid pBR322 or pUC118. A total of 143 clones were studied and demonstrated to contain one of the following sequence types: (i) a D-genome amplified repetitive sequence, (ii) polymorphic repetitive sequences ("fingerprint-type" sequences), (iii) polymorphic low to moderately repetitive sequences (PLR sequences), (iv) polymorphic low copy number sequences (PL sequences), and (v) invariant sequences. The D-genome amplified sequence was found to be located on all seven chromosomes. A genetic linkage map using PL and PLR sequences was produced by analysing F2 segregating progeny from crosses between two different taxa of T. tauschii. In addition to using DNA clones from T. tauschii, clones from other laboratories containing either anonymous sequences or genes coding for known products (e.g., 7S globulin, dehydrin, germin, storage protein) were used in the genetic linkage map. Multiple locations were mapped for the PLR sequences and were often clustered on single chromosomes. The restriction fragment length polymorphism markers and isozymes analysed were generally distributed over all the linkage groups that were identified and, when used in conjunction with published markers, provided the basis for a genetic map of T. tauschii.Key words: D genome, genetic linkage, restriction fragment length polymorphism, isozymes, chromosomal location.
The phylogeny of nine species of the Drosophila obscura group inferred by the banding homologies of chromosomal regions. I. Element B
Authors: Brehm Antonio , Krimbas Costas B. , Sourdis John , Cariou Marie-Louise
Published: April 2011

The phylogenetic relationships among nine Drosophila species belonging to the obscura group were investigated by establishing the segments displaying banding homologies in their element B (equivalent to the U element of D. subobscura). The phylogenetic ordering of the species was accomplished using overlapping inversions. Two African species, D. kitumensis and D. microlabis, were investigated. These species are homosequential for their element B gene arrangement but differ from that of D. obscura by several rearrangements. Drosophila obscura seems to be most closely related to D. subsilvestris, from which the respective element B gene arrangements differ at least by six inversions. Three species, D. obscura, D. ambigua, and D. tristis, are closely related and form a cluster. Drosophila obscura displays an element B polymorphism for a pericentric inversion for which D. ambigua is fixed for one gene arrangement and D. tristis for the other. Both D. ambigua and D. tristis share a short distal inversion in the small arm of the chromosome, and differ in this respect from D. obscura. Drosophila madeirensis, D. guanche, and D. subobscura all share the same element B gene arrangement, which is acrocentric, but metacentric in all the other species mentioned. It was found that the gene arrangements of the species from the obscura cluster seem to occupy an intermediate position between those of the species of the D. subobscura cluster and those of the African one. The data reported generally are in good agreement with information provided in the literature.Key words: Drosophila obscura group, polymorphism, element B.
Chromosomal fusion and meiotic behaviour in Delena cancerides (Araneae: Sparassidae). II. Chiasma position and its implications for speciation
Authors: Rowell D. M.
Published: April 2011

Chiasma position is compared among huntsman spider populations possessing telocentric chromosomes and Robertsonian metacentrics in the homozygous and heterozygous condition. The results indicate that heterozygosity for fusions results in a significant difference in chiasma position from both the telocentric forms and fusion homozygotes. Differences between fusion homozygotes and ancestral telocentric forms are small or absent, and there is no evidence of chiasma interference across the centromere. It is argued that the observed association between Robertsonian rearrangements and speciation may be as much a result of chiasma redistribution as of segregational factors.Key words: spiders, chiasma position, recombination, speciation.
Differential effects of specific chromosomal deficiencies on the development of the maize pollen grain
Authors: Kindiger B. , Beckett J. B. , Coe Jr. E. H.
Published: April 2011

A study was made of the differential effects of specific chromosomal deficiencies on the development of the maize pollen grain. Twenty-six B–A translocations involving 17 of the 20 chromosome arms were used to produce hypoploid plants in which one half of the microspores had a predictable chromosomal deletion. Breakpoints of the translocations were proximally located in most cases, although some were more distal. Deficient and normal male gametophytes from these hypoploids were studied cytologically to characterize developmental changes. Generally, loss of part of a chromosome arm caused abnormal microspore development, a slowing of the normal mitotic or developmental processes in the male gametophyte, or a termination of development. Slowing of development was observed as early as the quartet stage in deficient microspores from TB-1Sb and TB-9Sd hypoploids, while in others the developmental delay occurred later, mostly during the first pollen mitosis. The abnormal or blocked development associated with other deficiencies began as early as the quartet stage in deficient microspores of TB-1La hypoploids and as late as the first mitotic telophase in those of TB-6Lb, TB-6Lc, TB-9La, and TB-9Lc. The developmental modifications induced by the diverse deficiencies are dependent on the particular segment lost, demonstrating that components of normal microspore development identified in this study are controlled by genes located in specific parts of the genome.Key words: pollen, gametophyte, deletion, B–A translocations.
Analysis of centromere size in human chromosomes 1, 9, 15, and 16 by electron microscopy
Authors: Sanchez Laura , Martínez Paulino , Goyanes Vicente
Published: April 2011

Human chromosomes were treated with 5-azacytidine and analyzed by whole-mount electron microscopy. This base analogue produces undercondensation of heterochromatin and separation of the centromere from the bulk of pericentromeric heterochromatin in chromosomes 1, 9, 15, and 16, which allows clear delimitation of the centromere regions. A quantitative analysis of centromeres showed that chromosomes 1, 9, and 16 have centromeres of different size. The centromere of chromosome 15 is similar in size to that of chromosome 9 and different from those of chromosomes 1 and 16. No interindividual variation for centromere size was found. A positive correlation between centromere and chromosome size was found for the chromosomes analyzed.Key words: centromere size, human chromosomes, electron microscopy.
Fluram induces species-dependent C and G bands in mammalian chromosomes, revealing heterogeneous distribution of chromosomal proteins
Authors: Cuéllar T. , Gosálvez J. , Castillo P. Del , Stockert J. C.
Published: April 2011

Fluram (Fluorescamine; 4-phenylspiro(furan-2(3H),1′-phthalan)-3,3′-dione) is a fluorogenic reagent, which permits the detection of primary amines by forming highly fluorescent pyrrolinone derivatives. This reagent has been used on methanol – acetic acid fixed metaphase chromosomes of mouse and man and proved to be very effective in differentiating chromosome regions in both genomes. Mouse centromeric heterochromatin is highly reactive, showing intense fluorescence in all centromeric regions, whereas human chromosomes show no fluorescence in such regions. In addition, a G-like banding pattern is also obtained in both types of chromosomes. The differential reactivity of each chromosome region showed by this method demonstrates a heterogeneous distribution of chromosome proteins, resulting in a chromosome banding pattern, which is in this case species dependent.Key words: cytogenetics, chromosome banding, mammalian chromosomes, fluorescence microscopy, Fluram.
Repetitive DNA sequences from polyploid Elymus trachycaulus and the diploid progenitor species: detection and genomic affinity of Elymus chromatin added to wheat
Authors: Tsujimoto H. , Gill B. S.
Published: April 2011

A set of four repetitive DNA clones, pEt1, pEt2, pCb1, and pCb3, were isolated from SH-genome polyploid Elymus trachycaulus and H-genome diploid Critesion bogdanii. The clone Et1 represents a tandemly arranged telomeric sequence. Et2 represents tandem repeats interspersed along the entire length of individual chromosomes. The Cb1 sequence was more evenly dispersed. The Et1 clone shared homology with a 350 base pair family of rye sequences. The Cb3 sequence was evenly distributed in S- and H-genome species. All the repetitive DNA sequences were excellent markers for the specific detection and genomic affinity of Elymus chromatin added to wheat. All clones showed intragenomic variation in copy number and chromosomal location. Based on the analysis of this variation, we conclude that E. trachycaulus most probably originated from putative diploid H- and S-genome species resembling Critesion californicum and Pseudoroegneria spicata, respectively.Key words: wheatgrass, wheat–Elymus hybrid, addition lines, polyploidy, restriction fragment length polymorphism.
Variation for genetic recombination among tomato plants regenerated from three tissue culture systems
Authors: Compton Michael E. , Veilleux Richard E.
Published: April 2011

Shoot morphogenesis was compared among two tomato inbred lines, two mutant lines, and their eight reciprocal F1 hybrids in three tissue culture systems. The number of shoots per explant was greatest on tomato pedicel explants, intermediate on cotyledon calli, and poor on micropropagated shoot tips. Genetic recombination rates of F1 hybrid plants regenerated from three tissue culture systems were analyzed by backcrossing the regenerated plants with mutant parents and comparing the observed crossover frequencies with those expected based on control plants raised from seed. Increased recombination rates and map distance were observed among plants from micropropagated shoot tips (18.8%), cotyledon calli (17.3%), and pedicel explants (13.5%) between the markers sunny (sy) and baby leaf syndrome (bls), which flank the centromere on chromosome 3. Conversely, decreased recombination rates and map distance were observed between bls and the locus solanifolia (sf), which is more distal to the centromere on the same arm of chromosome 3 as bls. Increased recombination rates and map distance among plants from micropropagated shoot tips, cotyledon calli, and pedicel explants were also observed between the loci white virescence (wv) and anthocyanin reduced (are) on chromosome 2.Key words: genetic recombination, tomato, Lycopersicon esculentum, pedicel explants, micropropagation, callus culture, plant regeneration.
Estimates of outcrossing rates in Lathyrus latifolius populations
Authors: Godt Mary Jo W. , Hamrick J. L.
Published: April 2011

Isozyme markers were used to estimate parameters of the mating system of Lathyrus latifolius, a bumblebee-pollinated legume. Multilocus outcrossing estimates (mean tm = 0.807; range = 0.702–0.870) differed significantly from random outcrossing. Comparisons of single-locus outcrossing estimates (mean ts = 0.756; range = 0.627–0.852) and multilocus estimates suggested that biparental inbreeding contributed about 21% to the apparent rate of selfing. Significant heterogeneity in outcrossing rates occurred among the seven populations studied. A tendency for selection against inbred individuals, or heterozygote advantage, was apparent in all populations.Key words: mating system, Lathyrus latifolius, outcrossing rate, isozymes, Leguminosae.
Identification of restriction fragment length polymorphism and random amplified polymorphic DNA markers linked to downy mildew resistance genes in lettuce, using near-isogenic lines
Authors: Paran Ilan , Kesseli Richard , Michelmore Richard
Published: April 2011

Near-isogenic lines were used to identify restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) markers linked to genes for resistance to downy mildew (Dm) in lettuce. Two pairs of near-isogenic lines that differed for Dm1 plus Dm3 and one pair of near-isogenic lines that differed for Dm11 were used as sources of DNA. Over 500 cDNAs and 212 arbitrary 10-mer oligonucleotide primers were screened for their ability to detect polymorphism between the near-isogenic lines. Four RFLP markers and four RAPD markers were identified as linked to the Dm1 and Dm3 region. Dm1 and Dm3 are members of a cluster of seven Dm genes. Marker CL922 was absolutely linked to Dm15 and Dm16, which are part of this cluster. Six RAPD markers were identified as linked to the Dm11 region. The use of RAPD markers allowed us to increase the density of markers in the two Dm regions in a short time. These regions were previously only sparsely populated with RFLP markers. The rapid screening and identification of tightly linked markers to the target genes demonstrated the potential of RAPD markers for saturating genetic maps.Key words: lettuce, downy mildew, near-isogenic lines, disease resistance, restriction fragment length polymorphism, random amplified polymorphic DNA.
Genetics of adult-plant resistance of leaf rust in 'Frontana' and three CIMMYT wheats
Authors: Singh R. P. , Rajaram S.
Published: April 2011

Wheat (Triticum aestivum L.) cultivar 'Frontana' and three globally leaf rust resistant CIMMYT spring bread wheats, 'Parula', 'Trap', and 'Mango', which displayed seedling susceptibility to Mexican pathotypes TCB/TD and (or) TBD/TM of Puccinia recondita f.sp. tritici and which displayed high levels of adult-plant resistance, were genetically analyzed. The four wheats were intercrossed and crossed with seedling and adult-plant susceptible cultivars 'Inia 66' or 'Yecora 70', and also with 'RL6058', a tester for leaf rust resistance gene Lr34. Adult-plant resistance to leaf rust appeared to be based on four additive genes in 'Frontana' and three additive genes in each of the other resistant wheats. Gene Lr34 was confirmed to be present in all four wheats and appeared to be important in conferring adult-plant resistance in conjunction with other partially effective adult-plant resistance genes. Some of these latter genes appeared to be common in the four wheats, since limited segregation occurred when intercrossed. Genes Lr3, Lr10, Lr13, and Lr26 appeared to be independent of the adult-plant resistance. The resistance is expected to be durable, since the source of Lr34 and the additional genes was traced to 'Frontana', which has retained its field resistance since its release in 1943.Key words: adult-plant resistance, genetics, Puccinia recondita f.sp. tritici, Triticum aestivum.
Genetics of growth rate variation in bivalves: aneuploidy and heterozygosity effects in a Crassostrea gigas family
Authors: Thiriot-Quiévreux C. , Pogson G. H. , Zouros E.
Published: April 2011

Enzyme homozygosity and somatic aneuploidy are both known to adversely affect juvenile growth rate in marine bivalves. We have examined the joint effects of these two factors by scoring genotypes at nine segregating allozyme loci and counting the numbers of chromosomes lost in 30 cells in each of 83 full sibs of the Pacific oyster. A highly significant negative correlation was observed between the number of chromosomes missing and shell length in full sibs of the same age. No relationship was seen, however, between allozyme heterozygosity and either shell length or chromosome loss, nor was there any difference in the distribution of aneuploidy among genotypes at any given enzyme locus. Thus, the effects of homozygosity and aneuploidy on growth rate appear to have different genetic bases. Even in the most aneuploid oysters, more than half the cells examined had a complete chromosome complement of 2n = 20. This eliminates somatic aneuploidy as an explanation for the excess of enzyme homozygosity frequently observed in populations of marine molluscs. Significant deviations from Mendelian expectations, favoring homozygotes at some loci and heterozygotes at others, were recorded at eight of the nine allozyme loci, but these occurred independently of the aneuploidy observed. Our results suggest that within families a much larger component of variation in growth rate is due to aneuploidy than to allozyme genotype, but this conclusion cannot, at present, be extended to natural populations.Key words: aneuploidy, heterozygosity, growth rate, oysters.
Oat endosperm proteins associated with resistance to stem rust of oats
Authors: Howes N. K. , Chong J. , Brown P. D.
Published: April 2011

The presence of oat (Avena sativa L.) endosperm proteins, extracted with dimethylformamide mercaptoethanol – sodium dodecylsulfate and separated by dodecylsulfate polyacrylamide gel electrophoresis, was compared among cv. Rodney (carrying Pg4) and Rodney 0 derived backcross lines carrying single known genes Pg1, Pg2, Pg3, Pg8, Pg9, Pg13, Pg15, and Pg16, for stem rust resistance, and among other lines or cultivars with or without these genes. Most single-gene lines had polypeptide patterns similar to that of Rodney 0, a near-isogenic line with no known stem rust resistance. However, lines Rodney Pg3 and Rodney Pg9 were missing a 25.3-kDa avenin present in Rodney 0 and present in lines or cultivars that did not carry Pg9. The Rodney Pg13 line and several lines or cultivars that carried Pg13 were missing a 56.6-kDa polypeptide present in Rodney 0 and in several lines and cultivars that did not carry this gene. These results suggest that the Pg3/Pg9 and Pg13 loci were associated with the loci controlling the synthesis of the 25.3- and 56.6-kDa polypeptides, respectively. Results from genetic studies showed that gene Pg13 was linked in repulsion (linkage value 4.2 ± 1.9 cM) to the 56.6-kDa polypeptide locus.Key words: electrophoresis, oats, proteins, rust resistance.
C-banding polymorphisms in several accessions of Triticum tauschii (Aegilops squarrosa)
Authors: Friebe B. , Mukai Y. , Gill B. S.
Published: April 2011

A generalized C-banded karyotype of Triticum tauschii (Aegilops squarrosa) was established based on chromosome analysis of 15 accessions of diverse origin, including the two varieties eusquarrosa (with the former varieties typica, anathera, and meyeri) and strangulata. The C-banding pattern of T. tauschii chromosomes was similar to the D-genome chromosomes of cultivated bread wheat, T. aestivum, thus permitting their unequivocal identification and homoeologous chromosome designations. Whereas only minor variation in C-banding pattern was observed within the accessions, a large amount of polymorphic variation was found among the different accessions. However, this polymorphic variation did not prevent chromosome identification in these lines. One accession (TA 2462) was found to be homozygous for a reciprocal translocation involving the complete arms of chromosomes 1D and 7D. In situ hybridization using the D-genome specific probe pAS1 confirmed the presence of T1DS-7DL and T7DS.1DL translocation in the accession TA 2462.Key words: Triticum tauschii, C-banding, in situ hybridization.
Aminopeptidase B1: a centromere marker for chromosome 6B of wheat
Authors: Sacco Francisco , Tranquilli Gabriela , Gorgoschidse Liliana , Suarez Enrique
Published: April 2011

Recombination values between the centromere, Amp-B1, and Lr3 were evaluated using a 'Chinese Spring' double-ditelosomic line for chromosome 6B and the euploid variety 'Sinvalocho M.A.'. Recombination was not observed between the centromere and Amp-B1, but between the centromere and Lr3 the value was 52.8 ± 3.74%. A particular progeny during two successive backcross generations showed abnormal behaviour that resulted in a reduced number of recombinants between the centromere and Lr3, probably a consequence of the karyotypic instability of 'Sinvalocho M.A.'.Key words: wheat genetic map, aminopeptidases, rust reaction, centromere marker.
Genetic and cytogenetic analysis of Y-autosome translocations in the Mediterranean fruit fly, Ceratitis capitata
Authors: Kerremans Ph. , Gencheva E. , Franz G.
Published: April 2011

Radiation-induced translocations in the Mediterranean fruit fly, Ceratitis capitata, linking the Y chromosome to either autosome 3 or 4 produced pseudolinkage between sex and the mutations dark pupa (dp) and apricot eye (ap), respectively. The genetic behaviour of six new strains is described and the structural basis of five of them is determined through analysis of polytene and mitotic chromosomes. Five strains exhibited low levels of recombination; however, one strain produced a larger number than expected of aberrant, wild-type females. We provide evidence that this is the consequence of the survival of adjacent-1 segregation products until adulthood.Key words: medfly, mass rearing, genetic sexing, recombination, segregation.
Formation of a synthetic karyotype of tetraploid triticale
Authors: Badaev Nikolai S. , Badaeva Ekatherina D. , Dubovets Nadezhda I. , Bolsheva Nadezhda L. , Bormotov Vsevolod E. , Zelenin Alexander V.
Published: April 2011

Thirteen forms of 4x triticale were analyzed using a C-banding technique. All forms contained 14 R-genome chromosomes and 69 different combinations of A-, B-, and D-genome chromosomes from wheat were identified. The following general features of the formation of the synthetic karyotype of 4x triticale were found: there was a different rate at which homoelogous groups were stabilized; there was a selection against "hétérozygotes" (AB); and there was an effect exerted by the chromosomal constitution of some homoeologous groups on the rate and direction of stabilization in other groups. The two most probable variants of the wheat genome in 4x triticale are 1B, 2B, 3A, 4A, 5A, 6A, 7B and the reverse. The selection occurred at the level of homoeologues, and the selective advantages are determined by genotype-environment interactions. The environmental factors included both natural and artificial selection pressures. The data presented here can be used for the creation of a hypothesis concerning the practical approaches in chromosomal engineering of cereals.Key words: 4x triticale, general features of karyotype formation, C-banding.
Two-dimensional spreads of synaptonemal complexes from solanaceous plants. V. Tomato (Lycopersicon esculentum) karyotype and idiogram
Authors: Sherman Jamie D. , Stack Stephen M.
Published: April 2011

We used a hypotonic bursting technique to spread synaptonemal complexes (SCs) from tomato primary microsporocytes. Based on these spreads, we have prepared a karyotype and an idiogram for tomato SCs. Each SC was related to its corresponding chromosome by observing SCs from tomatoes that were trisomic for each chromosome. We have compared this SC karyotype with previously published pachytene chromosome karyotypes for tomato.Key words: synaptonemal complex, tomato, karyotype, idiogram.
Identification of a barley chromosomal interchange using N-banding and in situ hybridization techniques
Authors: Xu Jie , Kasha K. J.
Published: April 2011

The combination of N-banding and in situ hybridization was used to illustrate the rapid identification of the chromosomes involved in a newly formed chromosomal interchange (reciprocal translocation) in barley. The plant heterozygous for the interchange was derived from the backcross of 'Su Pie', a two-rowed Chinese winter barley cultivar (2n = 2x = 14), with pollen from a triploid interspecific F1 hybrid (2n = 3x = 21) obtained from the cross of 'Su Pie' × tetraploid Hordeum bulbosum accession GBC141 (2n = 4x = 28). Pollen mother cells of the interchanged plant exhibited one quadrivalent and five bivalents in 97.8% of cells. Partial sterility of florets was observed in spikes obtained from self-pollination and the plants morphologically resembled barley. Barley chromosomes were readily identified by N-banding from root-tip cells with one band missing from the short arm of one of the pair of chromosome 4. N-banding of metaphase I of meiosis revealed that chromosomes 1, 2, and 5 were not involved in the interchange. In situ hybridization with a rDNA probe showed that chromosomes 6 and 7 were paired as bivalents. In conclusion, chromosomes 3 and 4 are involved in the interchange with the breakpoint in the short arm of chromosome 4 between the two proximal N-bands. The use of chromosome-specific DNA probes for chromosome identification using in situ hybridization is proposed.Key words: barley, chromosomal interchange, N-banding, in situ hybridization, rDNA.
Oligonucleotide fingerprinting reveals various probe-dependent levels of informativeness in chickpea (Cicer arietinum)
Authors: Weising Kurt , Kaemmer Dieter , Weigand Franz , Epplen Jörg T. , Kahl Gunter
Published: April 2011

Synthetic oligonucleotides complementary to simple repetitive DNA sequences were used to detect inter- and intra-specific polymorphisms in a leguminous crop plant (chickpea, Cicer arietinum) and its wild relatives. All the investigated repetitive motifs [(GACA)4, (GATA)4, (GTG)5, (CA)8, (TCC)5, (GGAT)4, and (AGTTT)4] were abundantly present and polymorphic in the chickpea genome. Different probes revealed different levels of variability. Whereas species-specific banding patterns were obtained with the (GTG)5 probe, other probes revealed differences between accessions, or even individuals. The somatic multilocus patterns were stable for all probes.Key words: genetic polymorphism, simple repetitive sequences, DNA fingerprinting, synthetic oligonucleotide probes.
Molecular genetic analysis of phylogenetic relationships in the genus Hynobius by means of Southern blot hybridization
Authors: Kuro-o Masaki , Hikida Tsutomu , Kohno Sei-ichi
Published: April 2011

Variations in repetitive DNA were examined in nine salamander species of the genera Hynobius and Onychodactylus. The data from Southern blot hybridization were processed by Manhattan distance analysis, and unrooted trees were drawn. The resulting trees suggest that the genus Hynobius can be divided into three groups: group 1 contains only H. retardatus with 40 chromosomes; group 2 contains H. kimurae, which has 58 chromosomes and is a mountain-brook type of Hynobius (this group probably contains all mountain-brook types of Hynobius with 58 chromosomes); and group 3 contains the other six pond-type species examined here, each with 56 chromosomes. Group 3 probably contains all species of Hynobius with 56 chromosomes. Furthermore, group 3 can be further separated into two groups: the first group includes H. leechii, H. tsuensis, H. nebulosus, H. nigrescens, and H. tokyoensis from Chita; and the second group includes H. tokyoensis (except the population from Chita) and H. lichenatus. According to this analysis and other information, it seems that the population from Aichi Prefecture, which belongs to H. tokyoensis, should be identified as H. nebulosus. Furthermore, it appears that the genus Onychodactylus is phylogenetically distant from Hynobius and Salamandrella.Key words: Hynobius, repetitive DNA, Southern blot hybridization, phylogenetics, neighbor-joining method.
Two types of mouse (Mus musculus domesticus) Y chromosomes in Quebec
Authors: Nishioka Yutaka
Published: April 2011

A Y chromosomal repetitive sequence identified two types of Y chromosomes in mice (Mus musculus domesticus) caught near Ste. Anne de Bellevue, Quebec. One type is apparently identical to the Y chromosome found in Maryland, Delaware, and California, whereas the other type is similar, but not identical, to the Y chromosome present in M.m. poschiavinus, an Alpine race of M.m. domesticus. These findings suggest that the domesticus Y chromosome is highly polymorphic and thus useful for elucidating the relationships among American and European house mouse populations.Key words: mouse Y chromosome, polymorphism, Mus musculus domesticus, repetitive sequence, Quebec.
A feasibility study of the use of random amplified polymorphic DNA in the population genetics and systematics of grasshoppers
Authors: Chapco W. , Ashton N. W. , Martel R. K. B. , Antonishyn N. , Crosby W. L.
Published: April 2011

Single, short primers of arbitrary nucleotide sequence were used in polymerase chain reactions to amplify regions of DNA isolated from several melanopline and oedipodine grasshoppers collected from local Saskatchewan populations. This represents one of the first applications of the method, called randomly amplified polymorphic DNA (or RAPD), to natural populations. Twenty-four different oligonucleotide primers, nine nucleotides in length, yielded clear and reproducible bands corresponding to amplified products and separable by agarose gel electrophoresis. On average, about 8.1 bands (range 0–17) were obtained per primer per individual. The mean percent similarity between band profiles of conspecific individuals was 51.2%, whereas the mean value for individuals representing different species or genera was 35.0%. Clearly, greater numbers of insects and primers will be required to achieve a satisfactory level of phylogenetic resolution. Given RAPDs technical advantages and ease of execution, however, this should not be problematic to the molecular systematist.Key words: random amplified polymorphic DNA, polymerase chain reaction, grasshoppers, Melanoplinae, Oedipodinae.
Aneuploid analyses of hybrid necrosis and hybrid chlorosis in tetraploid wheats using the D genome chromosome substitution lines of durum wheat
Authors: Tsunewaki Koichiro
Published: April 2011

Chromosomal locations of the Ne1 gene, one of the two complementary genes for type 1 hybrid necrosis, and two complementary genes, Cs1 and Cs2, for type 2 hybrid chlorosis in tetraploid wheats were determined by aneuploid analyses employing the D genome chromosome substitution lines of 'Langdon' durum wheat. The Ne1 gene of 'Langdon' is located on chromosome 5B, whereas the Cs1 gene of Triticum dicoccum 'Hokudai' and the Cs2 gene of T. timopheevi are located on chromosomes 5A and 4G, respectively. Chromosomes 4B and 4G show almost complete functional compensation, though they rarely pair with each other, but chromosome 4D of T. aestivum 'Chinese Spring' has only half the ability of chromosome 4G in compensating for chromosome 4B on the fertilization ability of the male gamete. The results have demonstrated the usefulness of the D genome chromosome substitution lines of durum wheat for determining the chromosomes carrying major genes in tetraploid wheat. The results of these studies support the reallocation of chromosome 4A to the B genome.Key words: durum wheat, hybrid necrosis, hybrid chlorosis, aneuploid analyses, chromosome substitution lines.
Inheritance of an anomalous flavonol glycoside gene in soybean
Authors: Buzzell R. I. , Buttery B. R.
Published: April 2011

The inheritance of a third allele at the Fg2/fg2 locus in soybean (Glycine max) was determined. This allele, assigned symbol Fg2-b, resulted in a different phenotype (flavonol class) than Fg2 now designated Fg2-a. Fg2-b gave different flavonol classes in combination with each of Fg1, Fg3, and Fg4 than Fg2-a does in combination with these alleles.Key words: Glycine max, soybean, flavonol glycoside genes.
Methodology of gene transfer by homoeologous recombination into Triticum turgidum: transfer of K+/Na+ discrimination from Triticum aestivum
Authors: Dvořák J. , Gorham J.
Published: April 2011

Triticum aestivum (2n = 6x = 42) differs from T. turgidum (2n = 4x = 28) by superior ability to exclude Na+ and accumulate K+ under salt stress. Chromosome 4D has a major affect on the enhancement of this trait in T. aestivum. To transfer this trait to T. turgidum, T. turgidum chromosome 4B was targeted for homoeologous recombination with chromosome 4D in the genetic background of T. turgidum, utilizing recessive mutant ph1c to enhance meiotic heterogenetic chromosome pairing. Since the basis of the genetic control of this trait by chromosome 4D was not known, a large population of random recombinant lines involving the alien chromosome and the wheat chromosome had to be produced. It was hypothesized that assaying lines in such a population for the trait would facilitate identification of those in which the gene or genes controlling the trait were incorporated into the T. turgidum chromosome. Forty lines with recombinant chromosomes were obtained. Thirty-nine recombination events involving chromosome 4D involved the targeted chromosome 4B. The ratio of K+/Na+ in leaves of plants grown under salt stress was determined for 27 lines. Nine lines showed enhanced K+/Na+ ratios. Evidence is presented that this trait is controlled by a single gene locus, designated here as Kna1. The locus is distal to the subterminal C-band in the long arm of chromosome 4D.Key words: wheat, linkage map distortion, salt stress tolerance.
A genetic linkage map of restriction fragment length polymorphism loci for Brassica rapa (syn. campestris)
Authors: Chyi Y.-S. , Hoenecke M. E. , Sernyk J. L.
Published: April 2011

A genetic linkage map has been constructed based on restriction fragment length polymorphism DNA markers for Brassica rapa L. using a segregating F2 progeny from a cross between the yellow sarson type 'R500' and the canola-type 'Horizon'. The map contains 360 marker loci detected by 269 genomic clones derived from a PstI library of 'Westar' (Brassica napus L.). The map consists of 10 linkage groups, covering a total of 1876 recombination units. The occurrence of substantial genome rearrangement during the evolution of B. rapa is evident from (i) a large number of homologous duplicate sequences either at genetically adjacent locations or in different linkage groups and (ii) a number of missing sequences in one or the other parental genome, detected as null alleles. Divergence of the parental genotypes is further supported by the frequency of loci with skewed allele segregation ratios. Comparison of molecular and cytogenetic data on genome structure is discussed. The probe set and map are being used to facilitate rapeseed breeding.Key words: Brassica campestris, Brassica rapa, genome structure, linkage map, restriction fragment length polymorphism.
Cytology of recessive sexual-phase mutants from wild strains of Neurospora crassa
Authors: Raju Namboori B. , Leslie John F.
Published: April 2011

Wild-collected strains of Neurospora crassa harbor recessive mutations that are expressed in the sexual phase when homozygous. Thirty-two representative mutants that produced barren perithecia were examined cytologically. Six of these mutants failed to form asci. Of the remaining 26, chromosome pairing was disturbed in 12 and meiosis was disturbed at pachytene or diplotene in 5. Seven mutants showed normal meiosis I but then diverged from the normal sequence, and two showed perithecial beak abnormalities. In many mutants, ascus development and nuclear divisions continued after the initial defect, albeit abnormally. Nuclear divisions were often delayed, essentially uncoupling them from other ascus events such as the formation of enlarged spindle pole body plaques, ascospore wall membranes, and spore delimitation. All 32 mutants were recessive and none showed obvious morphological abnormalities during vegetative growth. This phenotype contrasts sharply with that of numerous laboratory-induced ascus mutants, which are frequently expressed pleiotropically in the vegetative phase and several are dominant in the sexual phase.Key words: natural populations, sexual phase, recessive mutations, meiotic mutants, ascus development.
Chromosome rearrangement patterns of an SD chromosome (SDKona-2) in Drosophila melanogaster caused by hybrid dysgenesis
Authors: Ault Jeffrey G.
Published: April 2011

The types and frequencies of spontaneous chromosome rearrangements caused by hybrid dysgenesis were studied in a second chromosome autosome of Drosophila melanogaster. This second chromosome, being an SD chromosome, had two important advantages over other autosomes for this study: (i) it had the two inversions characteristic of a standard SD-72 chromosome type, which distinguished it from its homolog in polytene chromosome spreads, and (ii) because of the meiotic drive associated with the segregation distorter system, it was preferentially transmitted to the next generation. The chromosome mutation frequency of this chromosome (given the name SDKona-2) was 8.3 and 11.7% in the F2 and F3 generations, respectively. The types of new chromosome rearrangements observed in the first four generations included paracentric inversions, pericentric inversions, duplications, deletions, reciprocal translocations (involving the third chromosome), and transpositions. Small paracentric inversions were the most common type of new rearrangement. Later, over 35 generations, some of these new rearrangements changed, either by becoming more complex or by being replaced with yet another new chromosome rearrangement. Duplications were unstable and were replaced by paracentric inversions whose breakpoints were on either side of the duplication. Transpositions arose both from a single multibreak event and from a series of two-break events.Key words: chromosome rearrangements, hybrid dysgenesis, segregation distorter, Drosophila melanogaster.
Characterization of telomeres in Hordeum vulgare chromosomes by in situ hybridization. II. Healed broken chromosomes in telotrisomic 4L and acrotrisomic 4L4S lines
Authors: Wang Shaoke , Lapitan Nora L. V. , Roder Marion , Tsuchiya Takumi
Published: April 2011

The ends of barley chromosomes hybridize in situ to the telomeric sequences of Arabidopsis thaliana. It was confirmed that the cross-hybridizing sequences in barley are found at the absolute ends of the chromosomes by exonuclease Bal31 digestion. The Bal31 experiments also indicated that telomere-like sequences do not occur in high copies at interstitial sites in barley. To determine whether healing of broken chromosomes occurred in aneuploid lines of barley containing extra chromosomes with breakages in different parts, in situ hybridization with the A. thaliana telomere on telotrisomic 4L and acrotrisomic 4L4S lines was conducted. Telosome 4L possesses breaks in the centromere and in an interstitial location in the long arm, while acrosome 4L4S possesses interstitial breaks in both long and short arms. In situ hybridization revealed the presence of telomere sequences on both broken ends of telosome 4L and acrosome 4L4S. In telosome 4L, telomere sequences were present even at the broken site of the centromere. These results show that broken ends of barley chromosomes were healed. Such healing may explain the stability of these chromosomes through many generations.Key words: telomere, centromere, telosome, acrosome, acrotrisomic, telotrisomic.
RFLP mapping of rye chromosome 7R reveals a highly translocated chromosome relative to wheat
Authors: Rognli O. A. , Devos K. M. , Chinoy C. N. , Harcourt R. L. , Atkinson M. D. , Gale M. D.
Published: April 2011

A RFLP map of rye, Secale cereale, chromosome 7R was constructed using 22 DNA probes including genes coding for leaf acyl carrier protein III, chloroplast fructose-1,6-bisphosphatase, α-amylase-2, EmBP-1, and a peroxidase. All probes had previously been located in wheat, Triticum aestivum, and a comparison of the wheat and rye maps reveals that chromosome 7R contains four segments that are homologous with segments of chromosomes of four homoeologous groups of wheat, 5L, 4L, 7S and 7L including the centromere, and 2S. Within these segments the rye and wheat maps are colinear and orientated in the same way relative to the centromere. The implications of rearrangements such as detected in 7R for triticale breeding and interspecific chromosome recombination and manipulation are discussed.Key words: rye, Secale cereale, RFLP, genetic map, chromosome 7R, colinearity.
Characterization of a major tandemly repeated DNA sequence (RBMII) prevalent among many species of waterfowl (Anatidae)
Authors: Madsen Cort S. , McHugh Kevin P. , Kloet Siwo R. de
Published: April 2011

We have investigated the evolution of a 190 base pair tandemly repeated DNA sequence (RBMII) in 27 different species of waterfowl. In this paper we show that the RBMII sequence is present in many species belonging to 7 of the 11 Anatid tribes. Inter- and intra-tribal differences in repeat presence indicate that, although the RBMII sequence has been maintained among widely divergent species, it is rapidly evolving. Restriction enzyme analyses suggest very different hierarchical repeat organizations among different species. DNA sequence comparisons of 32 cloned monomer units from five different species revealed what appears to be a nonrandom distribution of sequence divergence, as well as large differences (up to 25-fold) in intraspecific sequence variation between relatively closely related species.Key words: repeated DNA, Anatidae, sequence variation.
Resistance to wheat leaf rust and stem rust in Triticum tauschii and inheritance in hexaploid wheat of resistance transferred from T. tauschii
Authors: Innes R. L. , Kerber E. R.
Published: April 2011

Twelve accessions of Triticum tauschii (Coss.) Schmal. were genetically analyzed for resistance to leaf rust (Puccinia recondita Rob. ex Desm.) and stem rust (Puccinia graminis Pers. f.sp. tritici Eriks. and E. Henn.) of common wheat (Triticum aestivum L.). Four genes conferring seedling resistance to leaf rust, one gene conferring seedling resistance to stem rust, and one gene conferring adult-plant resistance to stem rust were identified. These genes were genetically distinct from genes previously transferred to common wheat from T. tauschii and conferred resistance to a broad spectrum of pathogen races. Two of the four seedling leaf rust resistance genes were not expressed in synthetic hexaploids, produced by combining tetraploid wheat with the resistant T. tauschii accessions, probably owing to the action of one or more intergenomic suppressor loci on the A or B genome. The other two seedling leaf rust resistance genes were expressed at the hexaploid level as effectively as in the source diploids. One gene was mapped to the short arm of chromosome 2D more than 50 cM from the centromere and the other was mapped to chromosome 5D. Suppression of seedling resistance to leaf rust in synthetic hexaploids derived from three accessions of T. tauschii allowed the detection of three different genes conferring adult-plant resistance to a broad spectrum of leaf rust races. The gene for seedling resistance to stem rust was mapped to chromosome ID. The degree of expression of this gene at the hexaploid level was dependent on the genetic background in which it occurred and on environmental conditions. The expression of the adult-plant gene for resistance to stem rust was slightly diminished in hexaploids. The production of synthetic hexaploids was determined to be the most efficient and flexible method for transferring genes from T. tauschii to T. aestivum, but crossing success was determined by the genotypes of both parents. Although more laborious, the direct introgression method of crossing hexaploid wheat with T. tauschii has the advantages of enabling selection for maximum expression of resistance in the background hexaploid genotype and gene transfer into an agronomically superior cultivar.Key words: Triticum tauschii, rust resistance, gene expression, gene transfer, wheat, synthetic hexaploid.