bluuebunny/crossref_metadata_2025 huggingface dataset:
Multivariate analysis of recombination between wild and cultivated genomes within the primary gene pool of pearl millet (Pennisetum typhoides)
Authors: Robert T. , Sarr A.
Published: April 2011

Recombination between wild and cultivated genomes of pearl millet were studied by multivariate analysis on morphological and physiological traits in backcross progenies from four cultivated × wild crosses. The cultivated genotypes, Souna and Thiotandé, have evolved in sympatric and allopatric situations, respectively, with wild forms. The distinct evolutionary history of the cultivated genotypes seems to have an incidence on the segregation pattern of their progenies with the wild relatives. Segregation distortions favouring the recovery of "wild-like" phenotypes were observed in progenies with Thiotandé as the cultivated parent. They are probably a consequence of the genetic divergence between this genotype and wild forms already shown at different levels of observation (histological, physiological, and genetic). On the other hand, when Souna is the cultivated parent, the recovery of "cultivated-like" phenotypes was shown to be easier with Souna as the female. This could be due to preferential homogametic fertilization favouring "Souna-type" gametes on Souna pistils owing to intergametophytic competition through a pollen–pistil interaction, already evidenced on the genotypes used here.Key words: pearl millet, multivariate analysis, segregation distortion, wild/cultivated genome recombination, genetic resources.
Transfer of a species cytoplasm specific (scs) gene from Triticum timopheevii to T. turgidum
Authors: Maan S. S.
Published: April 2011

Initial attempts to substitute euploid nuclei of Triticum turgidum L. or T. aestivum L. into Aegilops longissima S. &L. cytoplasm failed because an alien chromosome remained fixed in the Triticum nucleus. The alien chromosome had gene(s) conditioning sporophytic sterility (also known as the gameticidal or Cuckoo effect). Subsequently, an exceptional 29-chromosome, male-sterile plant with spontaneously improved female fertility was used as a source of Ae. longissima cytoplasm, and a fully fertile alloplasmic common wheat 'Selkirk' line was developed. However, alloplasmic 'Selkirk' crossed with durum wheat as a recurrent male parent did not produce euploid plants. Instead, chromosome 1D or telocentric 1DL of 'Selkirk' was retained and male-sterile plants with 29 chromosomes were obtained. They set two seed types: a few that were plump and viable (PVi) and a large number that were shrivelled and inviable (SIv). The 1DL was deleted by crossing these plants to T. timopheevii, backcrossing the F1's to T. timopheevii, and repeatedly backcrossing the timopheevii-like plants to durum as the recurrent male parent. The resulting euploid durum plants with Ae. longissima cytoplasm were male sterile and set a 1:1 ratio of PVi and SIv seeds. Thus, a species cytoplasm specific (scs) gene of T. timopheevii was transferred to durum and caused male sterility and abortion of embryos lacking this gene. In conclusion, (i) the scs gene was expressed as a dominant sterility gene, restored seed viability, and partial compatibility between the durum nucleus and Ae. longissima cytoplasm and (ii) a scs gene on 1DL also caused dominant sterility in durum but not in alloplasmic common wheat. Hence, alien scs homoeoallele(s) conditioned sterility and seed abortion in alloplasmic durum but not in T. aestivum and T. timopheevii.Key words: interspecific nucleocytoplasmic genetics, sporophytically controlled sterility, B-genome donor, scs gene.
Paternal and maternal effects on grain weight and protein percentage in crosses between hexaploid and tetraploid high- and low-protein wheat genotypes
Authors: Millet E. , Zaccai M. , Feldman M.
Published: April 2011

The inheritance of grain protein percentage and of grain weight were studied by crossing common and durum wheat cultivars with hexaploid and tetraploid breeding lines that excel in grain protein percentage. All high protein lines were descendants of the tetraploid wild emmer Triticum turgidum var. dicoccoides. One hexaploid cultivar was also crossed with a high-protein var. dicoccoides genotype. All crosses were made between low- and high-protein genotypes and were carried out reciprocally for any combination of genotypes; some of them between genotypes of the same ploidy level and some between hexaploid and tetraploid lines. Weight and protein percentage were determined in selfed and crossed grains that developed on the same spike. Mean weight and protein percentage were also determined in F2 grains of all crosses of the same ploidy level, either tetraploid or hexaploid. At any ploidy level, F1 grains resembled the selfed grains of the mother plant both in grain weight and in grain protein percentage, indicating a major maternal effect on both traits. F2 grains had similar grain weight to the heavy-grained parent, and their protein percentage was close to the midparents value. However, a slight indication of cytoplasmic inheritance of grain protein percentage was found in the comparison between most pairs of F2 reciprocals. The interspecific crosses (hexaploid with tetraploid combinations) yielded shrivelled seeds with highly reduced weight but relatively unchanged protein percentage. Weight reduction in the shrivelled hybrid grains (compared with the selfed ones) was more severe when the mother plant was hexaploid rather than tetraploid. The significance of the different tissues in determining grain weight and protein percentage is discussed.Key words: grain weight, grain protein percentage, maternal effect, paternal effect, reciprocal crosses, wheat, Triticum aestivum, Triticum turgidum var. dicoccoides.
Suppression of rust resistance in bread wheat (Triticum aestivum L.) by D-genome chromosomes
Authors: Bai D. , Knott D. R.
Published: April 2011

Several tests were done in bread wheat (Triticum aestivum L.) to demonstrate the occurrence of genes on D-genome chromosomes that suppress resistance to leaf rust (Puccinia recondita f. sp. tritici Rob. ex Desm.) and stem rust (Puccinia graminis f. sp. tritici Eriks. &Henn.). Ten rust-resistant wild tetraploid wheats (T. turgidum var. dicoccoides) were crossed with both durum (T. turgidum var. durum) and bread wheats. In all cases, resistance to leaf rust and stem rust was expressed in the hybrids with durum wheats but suppressed in the hybrids with bread wheats. Crosses were made between five diverse durum wheats and four diverse bread wheats. The pentaploid hybrid seedlings of 12 crosses were tested with leaf rust race 15 and in all cases the resistance of the durum parents was suppressed. Fourteen D-genome disomic chromosome substitution lines in the durum wheat 'Langdon' were tested with stem rust race 15B-1 and leaf rust race 15. Chromosomes 1B, 2B, and 7B were found to carry genes for resistance to stem rust but no suppressors were detected. Chromosomes 2B and 4B carried genes for resistance to leaf rust, and 1D and 3D carried suppressors. Crosses between seven D-genome monosomies of 'Chinese Spring' and three dicoccoides accessions showed that 'Chinese Spring' possesses genes on 1D, 2D, and 4D, which suppress the stem rust resistance of all three dicoccoides accessions. All three chromosomes must be present to suppress resistance, indicating that some form of complementary gene interaction is involved. In addition, 'Chinese Spring' carries a gene or genes on 3D that suppresses the leaf rust resistance of all three dicoccoides accessions, plus a gene or genes on 1D that suppresses the leaf rust resistance of only one of them. The data raise some interesting questions about the specificity of the suppressors. The high frequency of occurrence of suppressors in the bread wheat population suggests that they must have a selective advantage.Key words: Triticum aestivum, stem rust, leaf rust, rust resistance, suppressor.
Development of a selection index to improve market value of cultured Atlantic salmon (Salmo salar)
Authors: O'Flynn F. M. , Friars G. W. , Bailey J. K. , Terhune J. M.
Published: April 2011

Genetic parameters were estimated on growth and development traits using analyses of variance and covariance of 42 full-sib families from a select line, 39 full-sib families from a control line of the same strain, and 37 full-sib families from another unselected strain. The traits included percent 1 + smolts, percent sexually immature fish after 1 year in seawater (nongrilse), and fork length measured at intervals throughout the production cycle. The number of fish sampled per family was 30 of 300–1500 for all freshwater traits and 15–60, i.e., all individuals present, for all seawater traits. Heritability estimates of freshwater traits had a broad range (0.15–0.61), but estimates were lower for seawater traits (0.06–0.29). There was a general reduction in heritability estimates for traits measured at increasing ages both in freshwater and seawater. These reductions may in part represent declines of maternal and common environmental effects that inflate heritability estimated from full-sib families. The genetic correlations indicated positive associations between freshwater and seawater growth parameters. However, the correlations decreased with increasing intervals between measurements. A selection index was developed using the estimates of the genetic and phenotypic parameters for three economically important traits: percent 1 + smolts, percent nongrilse, and harvest length. The seawater traits, percent nongrilse, and fork length at 17 months (harvest length) were the most important in the index.Key words: Atlantic salmon, heritability, correlation, selection index, grilse, maturity.
Control of mating type heterokaryon incompatibility by the tol gene in Neurospora crassa and N. tetrasperma
Authors: Jacobson David J.
Published: April 2011

The mating-type of Neurospora crassa (A and a) have a dual function: A and a individuals are required for sexual reproduction, but only strains of the same mating type will form a stable vegetative heterokaryon. Neurospora tetrasperma, in contrast, is a naturally occurring A + a heterokaryon. It was shown previously that the mating-type genes of both species are functionally the same and are not responsible for this difference in heterokaryon incompatibility. This suggests that a separate genetic system determines the heterokaryon incompatibility function of mating type. The mutant tolerant (tol) in N. crassa, unlinked to mating type, acts as a specific suppressor of A + a heterokaryon incompatibility. In the present study, the wild-type alleles at the tol locus were introgressed reciprocally, from N. crassa into N. tetrasperma and from N. tetrasperma into N. crassa, to investigate the action of these alleles in the A + a heterokaryon incompatibility systems of these species. The wild-type allele from N. tetrasperma (tolT) acts as a recessive suppressor of A + a heterokaryon incompatibility in N. crassa. Furthermore, the wild-type allele from N. crassa (tolC) causes A and a to become heterokaryon incompatible in N. tetrasperma, while having no effect on the sexual reproduction. Therefore, the tol gene plays a major role in determining the heterokaryon compatibility of mating type in these species: tolC is an active allele that causes incompatibility and tolT an inactive allele that suppresses incompatibility by its inactivity.Key words: heterokaryon incompatibility, vegetative incompatibility, Neurospora, suppressors, mating type.
Alteration of gene expression in tomato plants (Lycopersicon esculentum) by drought and salt stress
Authors: Chen R. D. , Tabaeizadeh Z.
Published: April 2011

The effect of drought and NaCl treatments on polypeptide levels in both roots and leaves of tomato (Lycopersicon esculentum) seedlings was analyzed using two-dimensional polyacrylamide gel electrophoresis. In roots, comparison of silver-stained protein patterns showed that during drought treatment two proteins were highly accumulated and after rehydration they returned to the control level. The same changes were also observed under salinity stress. Moreover, salt treatment induced stress-specific proteins. In leaves, the in vivo labelling of intact leaves with 35S-labelled methionine showed that drought stress resulted in progressive changes in the protein pattern. There is de novo synthesis of proteins and repression of preexisting protein synthesis. The time course of appearance of newly synthesized proteins was different during water stress. The changes in proteins were usually reversible after rehydration of the seedlings. Leaves of NaCl-treated plants did not synthesize any salt stress specific polypeptides, but the synthesis of several drought-modulated proteins was affected. It is suggested that the quantitative and qualitative changes in protein synthesis may contribute to stress-resistant or stress-injury mechanisms.Key words: drought stress, Lycopersicon esculentum, protein synthesis, salt stress.
Haploids of the wild tetraploid potato Solanum acaule ssp. acaule: generation, meiotic behavior, and electrophoretic pattern for the aspartate aminotransferase system
Authors: Camadro E. L. , Masuelli R. W. , Cortés M. C.
Published: April 2011

Solanum acaule Bitt. (acl) is a wild tetraploid potato, with bivalent pairing in meiosis. This species has been regarded as a segmental allotetraploid by cytological genome analysis, and one of its subspecies, acaule, as a fixed heterozygote for one of the two loci that codify the dimeric enzyme aspartate aminotransferase (AAT). Since haploid plants of acl could constitute unique tools to prove these previous views, controlled crosses between acl and a haploid inducer were carried out to try to obtain gynogenetic haploids. Two haploid plants (2n = 2x = 24) were identified among the progenies derived from 100 pollinations. Meiotic and electrophoretic analyses were performed in both of these plants. The mean frequency of univalents and bivalents per cell were 10.64 and 6.72, respectively. At the tetrad stage, monads (1.1%), dyads (15.0%), and triads (36.0%) were observed in addition to tetrads. Male fertility, however, was very low. It is conjectured that chromosome distribution in anaphase I was irregular and that dyads originated by a second division restitution mechanism. For the AAT system, two zones of activity, with one gene each, were detected in haploids and control tetraploids. In the slow zone, the same three-banded phenotype was observed in all individuals, although the bands stained with less intensity in the haploids. These observations confirmed that 4x acl is a segmental allotetraploid and that alleles in homoeologous loci, conforming to a fixed heterozygous genotype, do not segregate in meiosis.Key words: haploid, Solanum acaule, fixed heterozygosity, segmental allotetraploid.
Genetic control of somatic embryogenesis in alfalfa
Authors: Kielly G. A. , Bowley S. R.
Published: April 2011

The genetic control of somatic embryogenesis in alfalfa (Medicago sativa L.) was studied using one nonembryogenic and three embryogenic genotypes: A70-34, a selection from 'Rangelander'; RA3, a selection from 'Regen-S'; and C2-4, a selection from a breeding population that had A70-34 in its pedigree. Crosses of embryogenic × embryogenic and embryogenic × nonembryogenic and S1 and BC1 testcrosses were evaluated for in vitro regeneration. Selfing reduced the expression of the trait. Somatic embryogenesis was dominant and explained by two loci. All three regenerating genotypes shared a common genetic system.Key words: alfalfa, Medicago sativa, somatic embryogenesis, tissue culture.
The sequential appearance of components of the synaptonemal complex during meiosis of the female rat
Authors: Dietrich Axel J. J. , Kok Ester , Offenberg Hildo H. , Heyting Christa , Boer Peter de , Vink Agnes C. G.
Published: April 2011

This paper describes the light microscopy (LM) and electron microscopy (EM) localization of synaptonemal complex (SC) antigens in oocytes of rats. For this purpose, we used monoclonal antibodies (Mabs) that recognize components of 30 + 33, 125, and 190 kDa antigens of SCs of rat spermatocytes. The LM localization was performed by immunofluorescence and the EM localization by immunogold staining. The reaction of the Mabs with oocytes was similar to the reaction with spermatocytes, but weaker. The 30 + 33 kDa as well as the 190 kDa antigens could always be demonstrated if axial elements of the SC were present, irrespective of whether these were paired or unpaired. Thus, these antigens could be detected from leptotene – early zygotene until diplotene. The 190-kDa antigen appeared in a diffuse manner just before the appearance of the 30 + 33 kDa antigens. The 30 + 33 kDa antigens were not only detected in the axial elements of SCs but also in characteristic aggregates, which appeared in zygotene and persisted until after the SCs had disappeared. Such aggregates had rarely been observed in spermatocytes. The 125 kDa antigen was only present in the tripartite segments of SCs, at the inner edge of the lateral elements. Thus, the reaction of the Mab against the 125 kDa antigen was detectable in zygotene, pachytene, and very early diplotene. It appeared later than 30 + 33 kDa and 190 kDa antigens and it disappeared earlier. We found that several steps of the immunostaining procedure could cause variation in the intensity of the Mab reaction.Key words: synaptonemal complex, immunocytochemistry, female meiosis, rat.
Synaptonemal complex formation and metaphase I bond distribution at low temperatures in nullisomic 5D – tetrasomic 5B hexaploid wheat
Authors: Morais L. , Queiroz A. , Viegas W. , Roca A. , Naranjo T.
Published: April 2011

Nullisomic 5D – tetrasomic 5B wheat plants were grown at 20 and 16 °C, and the level of paired and unpaired lateral elements in synaptonemal complex (SC) spreads was quantified in early-mid prophase I cells to ascertain the origin of the low frequency of metaphase I associations observed in plants held at 16 °C in the absence of the Ltp1 gene located on the long arm of chromosome 5D. The distribution of chromosome arm associations in metaphase I cells was studied using the C-banding technique. The results obtained confirm that asynapsis was the main cause of the reduction in the level of association in metaphase I at low temperature. Although a nonrandom distribution of chromosome arm associations at metaphase I was observed at both temperatures, this tendency was more visible at 16 °C, leading to the suggestion that at low temperatures differences in the specific ability of chromosome arms to form SCs and chiasmata are enhanced.Key words: synaptonemal complex, Ltp1 gene, metaphase I bonds, wheat, C-banding.
C-banded karyotypes of Brassica campestris, B. oleracea, and B. napus
Authors: Olin-Fatih Majlis , Heneen W. K.
Published: April 2011

The chromosome complements of three Brassica species, namely B. campestris (2n = 20), B. oleracea (2n = 18), and B. napus (2n = 38), were studied using the air-dry method and C-banding. Karyotypes and ideograms of late prophase chromosomes were constructed, since contracted metaphase chromosomes were generally not suitable for this purpose. The three species generally had a similar banding pattern, manifested in the presence of a centromeric C-band in all chromosomes and heterochromatic knobs at the telomeric end of some chromosomes. The centromeric C-bands were more pronounced in B. campestris than in B. oleracea. Depending on the centromeric position, the chromosomes were grouped into median, submedian, subterminal, and terminal types. All chromosome pairs were morphologically distinguishable. Only one nucleolar chromosome pair, with heterochromatic satellites, was observed in each species. When compared, it was possible to distinguish chromosomes of both B. campestris and B. oleracea type in B. napus, but conclusive evidence as to the origin of all chromosome pairs in B. napus was not at hand.Key words: Brassica, chromosomes, late prophase, C-bands, knob structures, karyotypes, idiograms.
Rf genes restore fertility in wheat lines with cytoplasms of Elymus trachycaulus and E. ciliaris
Authors: Jiang Jiming , Raupp W. John , Gill Bikram S.
Published: April 2011

Alloplasmic euploid wheat lines with the cytoplasm of Elymus trachycaulus (2n = 4x = 28, StStHtHt) and Elymus ciliaris (2n = 4x = 28, ScScYcYc) are male sterile and have reduced vigor. Fertile alloplasmic wheat plants are also recovered, but they always contain complete or partial chromosome additions of 1Ht or 1St (in E. trachycaulus derived lines) or 1Yc (in E. ciliaris derived lines) with specific Elymus gliadin genes (Gli-Ht1, Gli-St1, Gli-Yc1) and fertility restoration (Rf) genes. The Rf genes on 1Ht 1St and 1Yc were named as Rf-Ht1, Rf-St1, and Rf-Yc1, respectively. In this study, we crossed different disomic addition lines with one another to produce double monosomic additions either in E. trachycaulus or E. ciliaris cytoplasm. The chromosome constitution, transmission, and fertility of the selfed and backcrossed progenies of three double monosomic additions with 21″ + 3BS∙1YcS′ + 1HtS∙1HtS′ (cytoplasm from E. trachycaulus), 21″ + 3BS∙1YcS′ + 1HtS∙1HtS′ (cytoplasm from E. ciliaris), and 21″ + 3BS∙1YcS′ + 7AL∙S-1StS′ (cytoplasm from E. ciliaris) were analyzed. The results indicated that (i) Rf-Ht1 and Rf-St1 on 1Ht and 1St restored fertility to wheat with E. ciliaris cytoplasm; (ii) Rf-Yc1 on 1Yc restored fertility to wheat with E. trachycaulus cytoplasm; (iii) cytoplasms of E. ciliaris and E. trachycaulus are closely related; and (iv) certain E. trachycaulus and E. ciliaris chromosomes show preferential transmission.Key words: Elymus, Rf genes, wheat–Elymus hybrids, cytoplasmic genetics, genome evolution.
A trigeneric hybrid between Hordeum, Aegilops, and Secale
Authors: Cabrera A. , Martin A.
Published: April 2011

A trigeneric hybrid between Hordeum, Aegilops, and Secale was synthesized. The female parent was a fertile amphiploid between H. chilense and A. squarrosa and the male parent was S. cereale. The hybrid plant had the expected chromosome number of 2n = 21. Cytological analysis of pollen mother cells revealed no chromosome pairing. Morphology of the HchDR hybrid plant was similar to that of the Aegilops. The hybrid was sterile and no seed set was observed even after colchicine treeatment.Key words: Hordeum, Aegilops, Secale, trigeneric hybrid, cytology.
Inheritance and mutation of hypervariable (GATA)n microsatellite loci in a moth, Ephestia kuehniella
Authors: Traut Walther , Epplen Jörg T. , Weichenhan Dieter , Rohwedel Jürgen
Published: April 2011

We established homogeneous sublines that contained two or three homozygous DNA loci with long (GATA)n tracts from polymorphic Ephestia laboratory strains. Crossbreeding analysis assigned these loci to two or three different chromosomes, respectively. A nonrelated and rather recently isolated strain contained at least three other poly(GATA) loci located on different chromosomes. Germline mutations, visible as restriction fragment size changes between parents and offspring or loss of a poly(GATA) tract, are relatively rare in some strains but unusually frequent in the ml strain. The mutations affect not only GATA repeats but also flanking sequences. In five mutations investigated by crossbreeding, the altered poly(GATA)-containing restriction fragments remained in their original linkage groups.Key words: Bkm DNA, microsatellite, simple sequence repeats.
Cytology of intergeneric hybrids between Psathyrostachys and Elymus with Agropyron (Poaceae: Triticeae)
Authors: Jensen Kevin B. , Bickford Ira W.
Published: April 2011

This paper describes the cytogenetics and fertility of intergeneric hybrids of Psathyrostachys stoloniformis × Agropyron cristatum and two Elymus species, E. dentatus ssp. ugamicus and E. grandiglumis × A. cristatum. Bivalent frequencies of metaphase I cells in the F1 hybrid P. stoloniformis (NN) × Agropyron cristatum (PP) ranged from 0 to 4 per cell, with an average of 0.87 bivalent per cell and a c value of 0.07. The hybrid E. dentatus ssp. ugamicus (SSYY) × A. cristatum (PP) averaged 3.07 bivalents per cell and ranged from 0 to 7 with a c-value of 0.27. Bivalents were predominantly end to end associations. Meiotic analysis in E. grandiglumis (SSYYPP) × A. cristatum (PP) revealed an average of 6.84 bivalents per metaphase I cell with a c value of 0.73. This hybrid had a chromosome number of 2n = 30 rather than the expected 2n = 28. All hybrids had less than 1% stainable pollen and set no seed under open-pollination.Key words: chromosome pairing, meiosis.
The scs and Vi genes correct a syndrome of cytoplasmic effects in alloplasmic durum wheat
Authors: Maan S. S.
Published: April 2011

The nucleus of Triticum turgidum L. var. durum is incompatible with cytoplasms of Aegilops squarrosa L., Ae. cylindrica Host, Ae. uniaristata Vis., and Ae. longissima S. &M. However, durum lines with these cytoplasms were obtained by adding a telosome from Ae. uniaristata (un telosome) or a 1DL telosome from T. aestivum L. 'Selkirk'. The Ae. squarrosa and Ae. cylindrica 29-chromosome plants with 1DL telosome were partially fertile. While Ae. uniaristata or Ae. longissima 29-chromosome plants with 1DL or un telosome were male sterile. The four alloplasmic lines set a few plump and a large number of shrivelled seed from crosses with euploid durum. Only plump seed germinated and produced 29-chromosome plants in successive backcrosses. The telosomes must have a species cytoplasm specific (scs) gene(s) that improved nucleocytoplasmic (NCC) and embryo–endosperm compatibility (EEC), but scs was not transferred to a durum chromosome because telosomes remained meiotically unpaired in 29-chromosome plants. However, a scs gene with similar effects was transferred from T. timopheevii Zhuk. to Ae. longissima euploid durum. The resulting plants were male sterile and set a 1:1 ratio of plump and shrivelled seed. This paper reports that a vitality gene (Vi) restored NCC, EEC, seed viability, fertility, and vigor to Ae. longissima euploid F1's with scs from T. timopheevii. F1 progeny had a 1:1 ratio of fertile plants of normal vigor and low vigor plants (LVP). Thus, Vi had xenia effect, improved EEC, and corrected a syndrome of cytoplasmic effects in 50% of the F1's where Vi was epistatic or dominant to scs. The F2 and sucessive selfed progeny segregated for LVP but true breeding fertile plants were not obtained. Either scs and Vi were alleles, heterosexual gametes with scs and Vi were incompatible, scs had preferential transmission through the heterosexual gametophytes, or Vi was inactivated or remained unexpressed. Thus, scs and Vi had an unorthodox manner of inheritance and expression.Key words: Triticum, dfs, xenia effect, zygotic sterility, embryo–endosperm compatibility.
The genome origin and evolution of hexaploid Triticum crassum and Triticum syriacum determined from variation in repeated nucleotide sequences
Authors: Zhang Hong-Bin , Dvořák Jan
Published: April 2011

Hexaploid Triticum crassum Aitch &Hemsl. (syn. Aegilops crassa Boiss.) and Triticum syriacum Bowden [syn. Aegilops crassa Boiss. var. palaestina Eig, Aegilops vavilovii (Zhuk.) Chen.] are members of the T. crassum complex. Previous studies suggested that they have the D genomes of T. tauschii (Coss.) Schmalh., but the sources of the other genomes of these species remain uncertain. In the present investigation, variation in 27 repeated nucleotide sequences and the 5S rRNA loci was used to determine the genome origin of these hexaploid species. This study indicated that the two hexaploid species share two pairs of genomes that were contributed by a common ancestral tetraploid with a genome formula DcDcXX. It was concluded that the Dc genome was contributed by ancient T. tauschii and the X genome by an extinct species, possibly a species that was ancestral to the entire genus Triticum L. sensu Bowden except for T. tauschii. The third genome of hexaploid T. crassum is virtually identical to the D genome of extant T. tauschii and that of T. syriacum is identical to the Sse genome of T. searsii (syn. Aegilops searsii Feldman et Kislev). The genome formula of hexaploid T. crassum was proposed to be DcDcXXDD and that of T. syriacum DcDcXXSseSse to reflect the results reported here. The present study suggested that the apparent modification of the Dc and X genomes of the hexaploids resulted from evolutionary divergence.Key words: Triticum, Aegilops, Aegilops crassa, Aegilops vavilovii, phylogeny.
Application of chromosome-specific monoclonal antibodies in wheat genetics
Authors: Knox R. E. , Howes N. K. , Aung T.
Published: April 2011

A monoclonal antibody (P24B) to a wheat gliadin protein coded by a gene on the short arm of chromosome 1B was used as a chromosome marker. Somatic chromosome number for the 1B chromosome, as predicted by the level of binding of the antibody to extracts from seeds of single cross F2 and testcross F1 populations, was confirmed with sodium dodecyl sulfate – polyacrylamide gel electrophoresis and root-tip analysis. The implications of monoclonal antibodies as tools for cytogenetic analysis are discussed.Key words: polyacrylamide gel electrophoresis, aneuploid, cytogenetics, seed storage proteins.
Genetic analysis of heat shock response in three Drosophila species of the obscura group
Authors: Moltó M. Dolores , Pascual Luis , Martínez-Sebastián M. José , Frutos Rosa de
Published: April 2011

Heat shock response was investigated in three species of the obscura group of the Drosophila genus (D. subobscura, D. guanche, and D. madeirensis) by chromosome cytology analysis and [3H]uridine labeling. A set of eight puffs (2C, 15DE, 18C, 27A, 31CD, 85AB, 89A, and 94A) were induced after heat treatments in each of the three species; 18C, 27A, 89A, and 94A were the most heavily labeled in the autoradiograms after the induced conditions. From the in situ results using the major heat shock genes of D. melanogaster as a probe, it was inferred that the 18C, 94A, 89A, and 27A loci of the three obscura group species are homologous to D. melanogaster loci, which contain, HSP82, HSP70, HSP68, and HSPs encoding for the small heat shock proteins, respectively. When this organization was compared with that of D. melanogaster, fewer evolutionary changes, mainly gene duplications, were found to have occurred in the obscura group species than in the D. melanogaster group. In the three species analyzed in this work, as well as in the other Drosophila species studied, the heat shock genes are distributed on D and E Muller's elements, behaving as single copy genes that do not move around the genome.Key words: Drosophila, obscura group, polytene chromosome, heat shock.
The distribution of genes on human chromosomes as studied by in situ nick translation
Authors: Torre J. de la , Sumner A. T. , Gosalvez J. , Stuppia L.
Published: April 2011

We have studied the distribution of potentially active genes on human chromosomes, using two methods: DNAse I hypersensitivity and restriction enzyme – nick translation with enzymes sensitive to methylation of CpG doublets. DNAse hypersensitivity is known to be associated with potentially active genes, and, when the reaction is detected by "in situ" nick translation, produces an R-banding pattern. Digestion of chromosomes with HpaII or CfoI, both of which should preferentially cut unmethylated sequences in the CpG islands associated with the majority of genes, also produces R-banding patterns. Deviations are attributable to overdigestion of the chromosomes, leading to extraction of DNA and loss of the specific sites that were to be detected. Contrary to the results of a number of previous workers, we have failed to demonstrate any differences between the DNAse I hypersensitivity or the degree of methylation of the active and inactive X chromosomes in metaphases from females.Key words: human chromosomes, gene distribution, DNAse I hypersensitivity, in situ nick translation, R-banding, CpG islands, DNA methylation, inactive X chromosome.
Polymorphism of gliadin and unusual gliadin alleles in Triticum boeoticum
Authors: Metakovsky E. V. , Baboev S. K.
Published: April 2011

More than 50 gliadin electrophoretic patterns (Al-lactate, pH 3.1) have been found in a collection of 60 T. monococcum L. ssp. boeoticum accessions. Analyses of F2 seeds of the two intraspecies crosses revealed two unlinked gliadin-coding loci (Gli-A1bt and Gli-A2bt) in each genotype studied. Each locus controls synthesis of a block of codominantly inherited electrophoretic components. Resemblance of the component composition of some of these blocks and blocks found earlier in T. aestivum and T. durum indicates a close relationship between the A genomes of T. boeoticum and cultivated wheats. A null allele at Gli-A2bt (absence of α- and β-gliadins) in one of the accessions (k-59178) has been found that is inherited in accordance with the 3:1 (presence/absence) ratio. In the other cross, accession k-59173 has a Gli-1Abt-controlled alcohol-soluble polypeptide (probably, gliadin) located in the high molecular weight (HMW) glutenin region of the SDS–PAGE electrophoretrogram. This finding makes the consideration of any band found in wheat in this gel region as a "HMW glutenin subunit" doubtful without analysis of its genetic control. The obtained results, along with data on economically relevant traits, may aid for selection of breeding parents from T. boeoticum germplasm.Key words: Triticum boeoticum, polymorphism of gliadin, hybridological analysis, unusual alleles at Gli loci.
Physical localization of active and inactive rRNA gene loci in Hordeum marinum spp. gussoneanum (4x) by in situ hybridization
Authors: Linde-Laursen Ib , Ibsen Elly , Bothmer Roland Von , Giese Henriette
Published: April 2011

Two populations of the diploid and 10 populations of the tetraploid cytotype of Hordeum marinum ssp. gussoneanum were studied for the presence of chromosomal segments harbouring rDNA. Conventional cytological methods established the presence of only one satellited (SAT) chromosome pair in both cytotypes. This was supported by silver staining revealing two NORs and two standard-sized nucleoli. Two additional micronucleoli were observed in a few interphases of two tetraploid populations indicating the presence of an extra chromosome pair with very low nucleolus-forming activity. In situ hybridization with the wheat rDNA probe pTA71 identified intense signals at the nucleolar constrictions of the SAT chromosomes of both cytotypes and weaker signals in a chromosome pair of the tetraploid cytotype, morphologically similar to the SAT chromosomes but without visible nucleolar constrictions. This confirms the presence of rDNA in two chromosome pairs in the tetraploid cytotype. The morphological similarity between these two pairs and the SAT-chromosome pair of the diploid cytotype as well as an identical position of the signals in all three pairs give additional support to an autoploid origin of the tetraploid cytotype. The rDNA at the nucleolar constrictions consisted of two segments of condensed rDNA of different sizes connected by diffuse rDNA. The rDNA of the chromosome pair without nucleolar constrictions was condensed supporting that this conformation is connected with inactivity. The tripartite structure of the rDNA at the nucleolar constrictions corresponds to similar tripartite structures observed after silver staining and Giemsa C-banding.Key words: in situ hybridization, rDNA location, Hordeum marinum, autoploidy, inactive NORs.
Hybridization and tissue culture of Hordeum vulgare × Elymus canadensis
Authors: Dahleen L. S. , Joppa L. R.
Published: April 2011

Canada wild rye (CWR, Elymus canadensis L.) is winter hardy, drought tolerant, and resistant to barley yellow dwarf virus. Crosses between CWR and barley (Hordeum vulgare L.) produce sterile F1 hybrids. The objectives of this study were to compare callus and regeneration response with different media, to assess the effectiveness of in vitro colchicine treatment, and to determine whether chromosome changes occurred in regenerated plants. 'Betzes' barley was crossed with CWR and hybrid plants were recovered using embryo rescue. Immature inflorescences of the hybrids were placed on Gamborg's B5 medium supplemented with two levels of sucrose and two levels of 2,4-dichlorophenoxyacetic acid (2,4-D) to initiate callus growth. Media were solidified with either agar or gellum gum. Beginning at 8 weeks, a portion of the calli was placed on medium containing 20 mg/L colchicine for 10 days to double the chromosome number. Callus initiation was significantly greater with media containing gellum gum than with agar and with 5 mg/L 2,4-D than with 20 mg/L 2,4-D. Plantlet regeneration response to media paralleled the callus response. Chromosome counts of 1864 regenerants showed that 12% had chromosome numbers other than the expected 2n = 21. Chromosome numbers in regenerants ranged from 7 to 44. There was no benefit to using colchicine in the media. Evidence of chromosome recombination was observed. A backcrossing program to barley was initiated using all regenerants, while concentrating on plants with 2n = 42, which had some restored female fertility.Key words: somaclonal variation, intergeneric hybridization, Canada wild rye.
Meiotic chromosome structure: relationship between the synaptonemal complex and the chromatid cores
Authors: Rufas J. S. , Santos J. L. , Diez M. , Suja J. A.
Published: April 2011

The development of silver-stained synaptonemal complexes (SCs) and of chromatid cores was analyzed in squashed and surface-spread grasshopper spermatocytes using light and electron microscopy, respectively. This study was conducted to determine the relationship of the two chromosome structures and then obtain more insight into the meiotic chromosome structure. Pachytene cells observed by light microscopy showed thin silver-stained threads, representing SCs, along the centre of the bivalents. However, fully formed SCs, and an axial element corresponding to the univalent sex chromosome, appeared when these cells were observed by electron microscopy. During early diplotene no silver-stained threads were observed by light microscopy. However, fragmentation of the SCs was apparent in cells at the same stage when observed by electron microscopy. Both light and electron microscopy showed that chromosome cores were first detected in homologues of late diplotene – early diakinesis cells. During diakinesis the cores were not continuous but were interrupted where interstitial chiasmata occur. In prometaphase I – metaphase I cells these cores appeared continuous and double, i.e., each chromatid clearly showed its own core. We propose a model whereby the associated cores of sister chromatids act as frameworks for the formation of the SC lateral elements.Key words: meiosis, chromosome structure, synaptonemal complex, chromatid core.
Nonisotopic in situ hybridization and plant genome mapping: the first 10 years
Authors: Jiang Jiming , Gill Bikram S.
Published: April 2011

Nonisotopic in situ hybridization (ISH) was introduced in plants in 1985. Since then the technique has been widely used in various areas of plant genome mapping. ISH has become a routine method for physical mapping of repetitive DNA sequences and multicopy gene families. ISH patterns on somatic metaphase chromosomes using tandemly repeated sequences provide excellent physical markers for chromosome identification. Detection of low or single copy sequences were also reported. Genomic in situ hybridization (GISH) was successfully used to analyze the chromosome structure and evolution of allopolyploid species. GISH also provides a powerful technique for monitoring chromatin introgession during interspecific hybridization. A sequential chromosome banding and ISH technique was developed. The sequential technique is very useful for more precise and efficient mapping as well as cytogenetic determination of genomic affinities of individual chromosomes in allopolyploid species. A critical review is made on the present resolution of the ISH technique and the future outlook of ISH research is discussed.Key words: in situ hybridization, physical mapping, genome mapping, molecular cytogenetics.
Mitotic and meiotic irregularities in somatic hybrids of Lycopersicon esculentum and Solanum tuberosum
Authors: Wolters A. M. A. , Schoenmakers H. C. H. , Kamstra S. , Eden J. van , Koornneef M. , Jong J. H. de
Published: April 2011

Chromosome numbers were determined in metaphase complements of root-tip meristems of 107 tomato (+) potato somatic hybrids, obtained from five different combinations of parental genotypes. Of these hybrids 79% were aneuploid, lacking one or two chromosomes in most cases. All four hybrids that were studied at mitotic anaphase of root tips showed laggards and bridges, the three aneuploids in a higher frequency than the single euploid. Hybrid K2H2-1C, which showed the highest percentage of aberrant anaphases, possessed 46 chromosomes. Fluorescence in situ hybridization with total genomic DNA showed that this hybrid contained 23 tomato, 22 potato, and 1 recombinant chromosome consisting of a tomato chromosome arm and a potato chromosome arm. The potato parent of K2H2-1C was aneusomatic in its root tips with a high frequency of monosomic and trisomic cells and a relatively high frequency of cells with one fragment or telosome. Meiotic analyses of three tomato (+) potato somatic hybrids revealed laggards, which occurred most frequently in the triploid hybrids, and bridges, which were frequently present in pollen mother cells (PMCs) at anaphase I of hypotetraploid K2H2-1C. We observed putative trivalents in PMCs at diakinesis and metaphase I of eutriploid A7-82A and quadrivalents in part of the PMCs of hypotetraploid K2H2-1C, suggesting that homoeologous recombination between tomato and potato chromosomes occurred in these hybrids. All three hybrids showed a high percentage of first division restitution, giving rise to unreduced gametes. However, shortly after the tetrad stage all microspores completely degenerated, resulting in exclusively sterile pollen.Key words: tomato, potato, symmetric somatic hybrids, chromosomal irregularities, genomic in situ hybridization.
RFLP analyses and segregation of molecular markers in plants produced by in vitro anther culture, selfing, and reciprocal crosses of two lines of self-incompatible Solanum chacoense
Authors: Rivard Sylvain R. , Saba-El-Leil Marc K. , Landry Benoît S. , Cappadocia Mario
Published: April 2011

RFLP analyses were used to characterize several plant populations of Solanum chacoense Bitt. developed to investigate the generation of new S alleles at the self-incompatibility locus. The plant material consisted of two diploid parental lines, their anther culture derived (AC) progenies, their selfed progenies, and their reciprocal F1 hybrids. The RFLP analyses on the AC plants (121 individuals in total) permitted unambiguous identification of their origin. In particular, a distinction between plants originated from reduced (n) or unreduced (2n) microspores could be made. All the AC plants produced by gametic embryogenesis showed distinct RFLP patterns, whereas a number of clones (i.e., plants with identical RFLP patterns) were found among those regenerated via callus. The analyses conducted on the selfed progenies (69 plants) and the F1 hybrids (66 plants) showed only one case of accidental outcross. Segregation studies of the RFLP markers revealed significant deviations from expected Mendelian ratios in both AC-derived populations, as well as in the selfed progenies. Such deviations, however, were rare in the reciprocal F1 hybrids. These results are discussed in relation to the possible presence of genetic sieves operating during AC, illegitimate selfing, or during normal fertilization.Key words: anther culture, RFLP markers, distorted segregation, self-incompatibility, Solanum chacoense, wild potato.
Chromosome structure and pairing preferences in autotetraploid rye (Secale cereale)
Authors: Jenkins G. , Chatterjee R.
Published: April 2011

The influence of chromosome structure upon pairing behaviour during meiosis was investigated by comparing four autotetraploid genotypes of rye (Secale cereale) containing homologous chromosome sets with different degrees of structural similarity. The series provided a range of genotypes that, at one extreme, contained structurally identical chromosome sets and, at the other extreme, sets that are certainly more heterozygous in the genic sense and probably also more diverse from a purely structural viewpoint. Relative frequencies of pairing configurations at meiotic prophase and metaphase I were compared by electron microscopy of whole-mount surface-spread synaptonemal complex complements and light microscopy of squash preparations. Despite unexpectedly low quadrivalent frequencies over all four genotypes, higher mean bivalent frequencies appeared to be associated with greater homologue diversity. In other words, greater structural divergence between chromosome sets appears to facilitate more efficient discrimination between homologous and identical chromosomes that drives the formation of bivalents. Statistical comparisons were not able to confirm in some cases the significance of the observed pattern of pairing behaviour.Key words: autotetraploid, rye, synapsis, chiasmata.
Microsatellite polymorphism in Dioscorea tokoro, a wild yam species
Authors: Terauchi Ryohei , Konuma Akihiro
Published: April 2011

Six microsatellite loci were characterized in Dioscorea tokoro, a wild yam species in East Asia. All six loci were polymorphic in a sample of 23 individuals from natural populations in Japan. The microsatellite loci displayed many alleles (6.2 alleles per locus on average), and the observed heterozygosity (Ho = 0.54) as well as expected heterozygosity (He = 0.68) were high. The heterozygosities were far more than that previously detected by allozyme analysis of D. tokoro (Ho = 0.23, He = 0.28). Five microsatellite loci were sufficient to provide a paternity exclusion rate (Q) of Q = 0.98, which enables monitoring of the pollen-mediated gene flow between plants in a population. Microsatellite loci are abundant and highly polymorphic in D. tokoro and other plants and are therefore ideal markers for plant population genetic studies.Key words: microsatellite, simple sequence repeat, population genetics, Dioscorea tokoro.
Co-segregation of the gynomonoecious sex form1 gene (gsf1) of Tripsacum dactyloides (Poaceae) with molecular markers
Authors: Blakey C. A. , Dewald C. L. , Coe E. H.
Published: April 2011

The only monogenic trait in Tripsacum to date was first identified in the prolific sex form variant Tripsacum dactyloides (L.) L. forma prolificum Dayton et Dewald. The expression of this trait is controlled by the presence of a single-gene, recessive pistillate mutation hereby designated the gynomonoecious sex form1 gene (gsf1), after the registered plant germplasm accession GSF-I (PI483447) from which it was first identified. This trait confers a high degree of feminization to the primarily male floral structure of the Tripsacum rachis. Two molecular markers were found to co-segregate with the gsf1 gene in a diploid (2n = 36) F2 population of Tripsacum dactyloides, where the female parent (GSF-I) had been previously determined to be homozygous recessive for the gene. Phenotypic scoring data were compared with restriction fragment length polymorphism data and linkage relationships were determined. The gsf1 gene is located ~7 cM from tda48, a Tripsacum-derived molecular marker, and ~9 cM from npi286, a maize-derived molecular marker. The marker npi286 also maps within ~5 cM of the tassel seed2 locus (ts2) of maize, which confers a similar change in the inflorescence of the maize tassel.Key words: Tripsacum, gsf1, Eastern gamagrass, ts2, maize.