bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction of a YAC library from barley cultivar Franka and identification of YAC-derived markers linked to theRh2 gene conferring resistance to scald (Rhynchosporium secalis)
Authors: Schmidt Dagmar , Röder Marion S , Dargatz Harald , Wolf Norbert , Schweizer Günther F , Tekauz Andy , Ganal Martin W
Published: April 2011

The Rh2 resistance gene of barley (Hordeum vulgare) confers resistance against the scald pathogen (Rhynchosporium secalis). A high-resolution genetic map of the Rh2 region on chromosome 1 (7H) was established by the use of molecular markers. Tightly linked markers from this region were used to screen existing and a newly constructed yeast artificial chromosome (YAC) library of barley cv. Franka composed of 45 000 clones representing approximately two genome equivalents. Corresponding YAC clones were identified for most markers, indicating that the combined YAC library has good representation of the barley genome. The contiguous sets of YAC clones with the most tightly linked molecular markers represent entry points for map-based cloning of this resistance gene.Key words: yeast artificial chromosomes, map-based cloning, disease resistance gene, library screening, Hordeum vulgare.
Genetic analysis and molecular mapping of a pale flower allele at theW4locus in soybean
Authors: Xu Min , Palmer Reid G
Published: April 2011

In soybean (Glycine max (L.) Merr.), the w4-mutable line that harbors the w4-m allele was identified in 1983. It was proposed that this line contained an autonomous transposable element at the W4 locus, which is a major locus controlling the biosynthesis of anthocyanin. The w4-m allele can revert to the W4 allele that produces the wild-type phenotype, or sometimes to other alleles that produce intermediate phenotypes. Mutant plants that produce pale flowers were identified among the progeny of a single germinal revertant event from the w4-mutable line. Through genetic analysis, we established that the pale-flower mutation was conditioned by a new allele (w4-p) at the W4 locus. The w4-p allele is dominant to the w4 allele but recessive to the W4 allele, and the w1 allele has an epistatic effect on the w4-p allele. The pale-mutant line (w4-pw4-p) was designated as Genetic Type Collection number T369. An F2mapping population derived from the cross of Minsoy (W4W4) × T369 (w4-pw4-p) was used to map the W4/w4-p locus, using simple sequence repeat (SSR) markers. The W4 locus was located at one end of molecular linkage group D2, 2.3 cM from the SSR marker Satt386 and close to the nearby telomere.Key words: Glycine max, w4-mutable line, transposable element, SSR markers
QTL mapping of BNYVV resistance from the WB41 source in sugar beet
Authors: Gidner Sara , Lennefors Britt-Louise , Nilsson Nils-Otto , Bensefelt Jan , Johansson Evert , Gyllenspetz Ulf , Kraft Thomas
Published: April 2011

The most important rhizomania-resistance gene in sugar beet is the Rz1 gene from the Holly Sugar Company in California, the source widely used to breed partially resistant varieties. Other important gene sources are WB41 and WB42, which both originate from Beta vulgaris subsp. maritima collected in Denmark, and which have been reported to be similar. The major resistance gene in WB42 is known as Rz2. We studied the resistance in WB41 and used markers to map the major resistance gene in this source, which we call Rz3. It was identified on chromosome III. This is the chromosome that Rz1 and Rz2 have been mapped to. Data from greenhouse tests and ELISA showed that Rz3 had incomplete penetrance, with heterozygotes varying widely in resistance levels. The involvement of additional minor genes in the strong resistance of the original WB41 source cannot be excluded.Key words: BNYVV, WB41, rhizomania, QTL, Beta vulgaris, AFLP, SSR.
Development and characterization of microsatellite markers inCynara cardunculusL.
Authors: Acquadro Alberto , Portis Ezio , Lee David , Donini Paolo , Lanteri Sergio
Published: April 2011

Cynara cardunculus L. is a species native to the Mediterranean basin that comprises 2 crops, globe artichoke (var. scolymus L.) and cultivated cardoon (var. altilis DC), as well as wild cardoon (var. sylvestris (Lamk) Fiori). Globe artichoke represents an important component of the South European agricultural economy but is also cultivated in North Africa, the Near East, South America, the United States, and China. Breeding activities and molecular marker studies have been, to date, extremely limited. Better knowledge of the genome of the species might be gained by developing a range of molecular markers. Here, we report on the development of 14 microsatellites (simple sequence repeats (SSRs)) through a novel approach that we have defined as the microsatellite amplified library (MAL). The approach represents a combination of amplified fragment length polymorphism and a primer extension based enriched library, is rapid, and requires no hybridization enrichment steps. The technique provided a ~40-fold increase in the efficiency of SSR identification compared with conventional library procedures. The developed SSRs were applied for genotyping 36 accessions of C. cardunculus, including a core of 27 varietal types of globe artichoke, 3 accessions of cultivated cardoon, and 6 Sicilian accessions of wild cardoon. Principal coordinates analysis made it possible to differentiate both cultivated and wild forms from each other.Key words: globe artichoke, wild and cultivated cardoon, molecular markers, AFLP, MAL (microsatellite amplified library).
Meiotic recombination in the ZW pair of a tinamid bird shows a differential pattern compared with neognaths
Authors: Pigozzi M I , Solari A J
Published: April 2011

The tinamid bird Nothura maculosa, along with other species of the order Tinamiformes and all of the existent ratites, form the infraclass Paleognathae, the most primitive living birds. Previous work has shown that in all studied Neognathae, the ZW pair shows strictly localized recombination in a very short pseudoautosomal region, while in paleognath birds, the ZW pairs have mostly free recombination. The present observations show that the ZW pair of N. maculosa has a recombination pattern departing from both neognaths and other Paleognath birds, as there is a single crossover but occurring at random points along a significant part of the long arm of the W chromosome. This recombination pattern agrees with the presence of intercalary and terminal heterochromatin in the W chromosome, suggesting an exceptional, additional step of recombination suppression.Key words: recombination, ZW pair, avian sex chromosomes, sex chromosome heteromorphism.
EST-derived SSR markers from defined regions of the wheat genome to identifyLophopyrum elongatumspecific loci
Authors: Mullan Daniel J , Platteter Amanda , Teakle Natasha L , Appels Rudi , Colmer Timothy D , Anderson Joseph M , Francki Michael G
Published: April 2011

Lophopyrum elongatum, a close relative of wheat, provides a source of novel genes for wheat improvement. Molecular markers were developed to monitor the introgression of L. elongatum chromosome segments into hexaploid wheat. Existing simple sequence repeats (SSRs) derived from genomic libraries were initially screened for detecting L. elongatum loci in wheat, but only 6 of the 163 markers tested were successful. To increase detection of L. elongatum specific loci, 165 SSRs were identified from wheat expressed sequence tags (ESTs), where their chromosomal positions in wheat were known from deletion bin mapping. Detailed sequence analysis identified 41 SSRs within this group as potentially superior in their ability to detect L. elongatum loci. BLASTN alignments were used to position primers within regions of the ESTs that have sequence conservation with at least 1 similar EST from another cereal species. The targeting of primers in this manner enabled 14 L. elongatum markers from 41 wheat ESTs to be identified, whereas only 2 from 124 primers designed in random positions flanking SSRs detected L. elongatum loci. Addition and ditelosomic lines were used to assign all 22 markers to specific chromosome locations in L. elongatum. Nine of these SSR markers were assigned to homoeologous chromosome locations based on their similar position in hexaploid wheat. The remaining markers mapped to other L. elongatum chromosomes indicating a degree of chromosome rearrangements, paralogous sequences and (or) sequence variation between the 2 species. The EST-SSR markers were also used to screen other wheatgrass species indicating further chromosome rearrangements and (or) sequence variation between wheatgrass genomes. This study details methodologies for the generation of SSRs for detecting L. elongatum loci.Key words: Lophopyrum elongatum, expressed sequence tags (EST), simple sequence repeat (SSR), EST-SSR, synteny, alien introgression.
Characterization ofStowawayMITEs in pea (Pisum sativumL.) and identification of their potential master elements
Authors: Macas Jiří , Koblíková Andrea , Neumann Pavel
Published: April 2011

We have investigated miniature inverted-repeat transposable elements (MITEs) of the Stowaway family and corresponding Mariner-like master elements that could potentially facilitate their mobilization in the genome of the garden pea (Pisum sativum L.). The population of pea Stowaway MITEs consists of 103–104copies dispersed in the genome. Judging from a sequence analysis of 17 isolated Stowaway elements and their flanking genomic regions, the elements are relatively uniform in size and sequence and occur in the vicinity of genes as well as within repetitive sequences. Insertional polymorphism of several elements was detected among various Pisum accessions, suggesting they were still transpositionally active during diversification of these taxa. The identification of several Mariner-like elements (MLEs) harboring intact open reading frames, capable of encoding a transposase, further supports a recent mobilization of the Stowaway elements. Using transposase-coding sequences as a hybridization probe, we estimated that there are about 50 MLE sequences in the pea genome. Among the 5 elements sequenced, 3 distinct subfamilies showing mutual similarities within their transposase-coding regions, but otherwise diverged in sequence, were distinguished and designated as Psmar-1 to Psmar-3. The terminal inverted repeats (TIRs) of these MLE subfamilies differed in their homology to the TIRs of Stowaway MITEs. The homlogy ranged from 9 bp in Psmar-3 to 30 bp in Psmar-1, which corresponds to the complete Stowaway TIR sequence. Based on this feature, the Psmar-1 elements are believed to be the most likely candidates for the master elements of the Stowaway MITEs in pea.Key words: Mariner-like transposons, master elements, Stowaway MITEs, insertional polymorphism, Pisum sativum.
Chromosomal distribution of genes in diploid Elytrigia elongata that promote or suppress pairing of wheat homoeologous chromosomes
Authors: Dvořák Jan
Published: April 2011

Triticum aestivum L. lines with added or substituted chromosomes of Elytrigia elongata (Host) Nevski were hybridized with Hordeum bulbosum L. to obtain haploids and with Triticum urartu Thum. to obtain interspecific hybrids. Chromosome pairing at metaphase I was investigated in the resulting haploids and hybrids and the parental addition and substitution lines. Genes that promoted pairing of homologous or homoeologous chromosomes were found on chromosome arms 3ES, 3EL, 4ES, 5Ep, and chromosome 6E of E. elongata. Genes that suppressed pairing of homoeologous chromosomes were found on chromosome arms 4EL and 7Eq. It is concluded that genes promoting or suppressing pairing of homoeologous chromosomes are ubiquitous among diploid species.

Key words: wheat, Triticum, wheatgrass, Elytrigia elongata, heterogenetic pairing, chromosome pairing, pairing promotion, pairing suppression.
Persisting demibivalents: a unique meiotic behaviour in Cuscuta babylonica Choisy
Authors: Pazy Batia , Plitmann Uzi
Published: April 2011

Idiosyncratic chromosome behaviour during meiosis was found in pollen mother cells of Cuscuta babylonica Choisy, a thread-like holoparasitic herb. Its main features are among the following: (i) telomeric association between homologues through most stages of the process, which leads to persisting chromatid bivalents (= "demibivalents"); (ii) uncommon chromosome segregation in first and second anaphase; and (iii) prolonged intensified heterochromatinization. Although "regular" in its own way, this process leads to the formation of unviable products. Its further investigation might contribute to our understanding of the role of the spindle and chromosome movement in the ordinary process of meiosis.

Key words: meiosis (abnormal), persisting demibivalents, Cuscuta babylonica.
Undifferentiated sex chromosomes in Mastotermes darwiniensis Froggatt (Isoptera; Mastotermitidae) and the evolution of eusociality in termites
Authors: Bedo D. G.
Published: April 2011

Meiosis and mitosis was studied in males of the primitive termite Mastotermes darwiniensis, which is closely related to the Dictyoptera. In mitotic metaphase cells 98 chromosomes were found with a matching 49 bivalents at metaphase I. Mastotermes darwiniensis has a largely acrocentric karyotype with no sex-linked translocation complexes, like those found in many other termite species, or other sex chromosome differentiation. These observations suggest that ancestral termites probably had karyotypes with many small chromosomes lacking sex chromosome differentiation and that there is no connection between the evolution of sex-linked translocation complexes and eusociality.

Key words: sex chromosomes, Mastotermes, termites, eusociality.
Diploid perennial intergeneric hybrids in the tribe Triticeae. III. Hybrids among Secale montanum, Pseudoroegneria spicata, and Agropyron mongolicum
Authors: Wang Richard R.-C.
Published: April 2011

Four new intergeneric diploid hybrids were synthesized in the greenhouse with the aid of embryo culture. Hybrids of Pseudoroegneria spicata × Secale montanum and P. spicata ssp. inermis × S. montanum, both having the genome formula SR, averaged 12.97 I + 0.49 II + 0.01 III at metaphase I. The hybrids of Agropyron mongolicum × S. montanum, which have the PR genomes, had an average of 12.86 I + 0.51 II + 0.03 III + 0.004 IV. The hybrid (SP) between P. spicata ssp. inermis and Agropyron mongolicum had a mean configuration of 8.05 I + 2.86 II + 0.07 III + 0.01 IV. All hybrids had intermediate spike morphology, respective to their parents, and were sterile. Mitotic preparations of root-tip cells of these hybrids suggested that the chromosomes of different genomes were spatially separated. The meiotic pairings of these hybrids indicated that chromosome homology between the S and P genomes is higher than either the S and R or the P and R. Both SR and PR hybrids represent new genomic combinations. The SP hybrid is equivalent to the dihaploid of P. tauri. All of these hybrids should be of value for breeding and taxonomy.

Key words: intergeneric hybrids, genome, Secale, Pseudoroegneria, Agropyron.
Cytogenetic studies of aneuploids in rapeseed. II. Morphology, fertility, and cytology of self-pollinated progenies of monosomic plants of Brassica napus L.
Authors: Chang Ru-ying , Tai William , Fan Z.
Published: April 2011

Cytogenic studies were conducted on self-pollinated progenies from two monosomic lines of Brassica napus to ascertain the mode of transmission of the monosomic chromosome. An approximately 1:1 ratio of disomic to monosomic plants was obtained. Only one nullisomic plant was found among a total of 71 plants analyzed. The 1:1 ratio and the anaphase I disjunction (19–18) suggest that the gametes (n) were twice as competitive or functional as their counterpart (n − 1). Since quadrivalents were observed in the disomic plants and only trivalents in the monosomics, the monosomic chromosomes were believed to be the ones that were involved in the formation of multivalents. The percentage of multivalent association in monosomic plants was almost double that in disomic plants. In the disomic plants, an average of 11.96% of pollen mother cells had one to two quadri-valents. The average frequency of trivalents in the monosomics was 23.63%. It was suggested that pairing of these homologs was genetically controlled with a dosage effect. The absence of one chromosome increased the frequency of multivalents.

Key words: monosomic, Brassica, rapeseed, aneuploid.
Crown rust resistance in progeny from a derived tetraploid × natural tetraploid cross in Avena
Authors: Karow R. S. , McNamara K. R. , Forsberg R. A.
Published: April 2011

The F1 plants and F2 and F3 populations obtained from a cross between the derived oat tetraploid C.I.7232 and natural tetraploid oat Avena barbata Pott. var. Excoimbra Se1.20 were evaluated for reaction to crown rust. The adult F2 plants exhibited a hypersensitive crown rust resistance reaction and were intermediate to their parents in other characteristics. The F2 and F3 seedling and adult plant populations differed in their response to the same mixture of crown rust races, i.e., a two gene segregation ratio at the seedling stage but only one gene segregation in adult plant tests. The resistance of Se1.20 was found to be a type of "stage" resistance that was effective only in vegetative (seedling) growth stages. The resistance gene of Se1.20 could not be detected in progenies that were rust tested as adult plants.

Key words: Puccinia coronata, Avena, derived tetraploid.
Inheritance of isozymes in seed and bud tissues of blue and Engelmann spruce
Authors: Ernst S. G. , Keathley D. E. , Hanover J. W.
Published: April 2011

Thirteen loci from 11 enzyme systems were identified among full-sib and half-sib progeny of blue and Engelmann spruce. Eleven of the loci were expressed in bud, embryo, and megagametophyte tissue; the remaining two loci were expressed only in embryo and megagametophyte tissue. There were no mobility differences observed between loci expressed in seed and bud tissues. The mode of inheritance for 10 of the loci was confirmed based on progeny genotypic distributions. For the two loci not expressed in bud tissue, acid phosphatase (Acp-2) and diaphorase (Dia-2), inheritance was inferred from pooled segregation ratios of megagametophytes from open-pollinated seed from heterozygous females. The inheritance of glutamate oxaloacetate transaminase (Got-3) was also inferred from segregation ratios and diploid embryo phenotypes of open-pollinated progeny owing to a lack of variability at this locus among the 40 parents in the mating design. Two loci, aldolase (Ald) and malate dehydrogenase (Mdh-2), were monomorphic among the 20 parents of both species.

Key words: isozymes, Engelmann spruce, blue spruce, Picea.
Digenomic triploids for an assessment of chromosome relationships in the cultivated diploid Brassica species
Authors: Attia T. , Busso C. , Röbbelen G.
Published: April 2011

To assess the chromosomal relationships in the cultivated diploid Brassica species, four digenomic triploid combinations were synthesized and meiotically analyzed. Two of the four digenomic combinations contained the B genome of B. nigra, one with two (BC.B) and the other with only one B genome (C.BC). In these combinations preferential pairing between the two homologous genomes with the third single genome was predominant. Since gene actions suppressing pairing between chromosomes of related genomes had not been proven to exist in Brassica, this phenomenon is assumed to be conditioned by structural chromosomal differences reflecting the distant phylogenetic relationship of B. nigra to each of B. oleracea (CC) and B. campestris (AA). On the other hand, two other digenomic triploids having two A genomes and one C genome showed a low preferential pairing of the two homologous A genomes (to form 10 II + 9 I). Moreover, a high tendency for an allosyndetic pairing between the A and C genomes was expressed by the formation of one or more trivalents in over 50% of PMCs in the two combinations A.AC and AC.A. This demonstrated a high meiotic pairing potential and a small evolutionary difference between the chromosomes of B. campestris (AA) and B. oleracea (CC).

Key words: Brassica, triploid (digenomic), phylogenetics, pairing (chromosome).
Sexual isolation between Drosophila melanogaster females and D. simulans males. II. Influence of female receptivity on hybridization
Authors: Carracedo Maria C. , Casares P. , Miguel E. San
Published: April 2011

Hybridization between Drosophila melanogaster females and D. simulans males was measured in sympatric and allopatric populations of these sibling species by means of nonchoice tests. Greater sexual isolation was found in allopatric populations over sympatric ones. Notable age differences at which females reached sexual maturity were detected in the D. melanogaster populations. Females with an earlier sexual maturity also showed greater receptivity. Remarkably, female receptivity was the main factor accounting for frequency of hybridization. The role that both male and female mate propensities and discrimination abilities play in natural selection for sexual isolation is discussed.

Key words: sexual isolation, Drosophila, female receptivity, hybridization.
Inheritance of DDT dehydrochlorination and of a mechanism restricting uptake of DDT in the mosquito Aedes aegypti
Authors: Rathor H. R. , Wood R. J.
Published: April 2011

Crosses and backcrosses were made between the T8 dichlorodiphenyltrichloroethane (DDT) resistant strain and NS susceptible strain. Each generation was tested for resistance, for internal levels of DDT and dichlorodiphenyldichloroethylene (DDE) (thus "DDT uptake" (DDT + DDE) and percentage DDT dehydrochlorination in vivo), and for DDT dehydrochlorination in vitro, both at the larval and adult stages. The patterns of inheritance of uptake and dehydrochlorination were different. At both life stages, dehydrochlorination (both in vivo and in vitro) was intermediate in the F1, reverting to or exceeding the parental strains in the backcrosses except in adult tests on the backcrosses to the susceptible strain where it remained intermediate. Uptake increased very substantially in the F1 compared with either parental strain and was also high in the backcrosses. This was interpreted as being due to the disruption of an uptake-restricting mechanism in T8 brought about by outcrossing. Larval resistance in the various generations was correlated significantly with dehydrochlorination, both in vivo and in vitro but bore no clear relation to uptake. Resistance in adults was found not to be correlated significantly with either.

Key words: DDT dehydrochlorination, pesticide resistance, DDT uptake, DDT resistance, dehydrochlorination in vivo and in vitro assays.
Polyploid polymorphism in Andropogon gerardii
Authors: Keeler K. H. , Kwankin B. , Barnes P. W. , Galbraith D. W.
Published: April 2011

The relationship between nuclear DNA content and chromosome number was investigated in Andropogon gerardii. The distribution of cytotypes in a natural population of this grass was also examined. Nuclear DNA content was determined using flow cytometry rather than the traditional method of Feulgen microphotometry. Our results demonstrate the increased accuracy and speed of this new method in the detection and study of polyploidy. Nuclear DNA content is strongly correlated to chromosome number in Andropogon gerardii (r = 0.971, P <0.01). The natural population of this grass was found to consist of plants with 2N = 60 chromosomes (hexaploid cytotype) and 2N = 80 chromosomes (octoploid cytotype), in equal proportions. Intermediate cytotypes were lacking in the natural population, although three progeny plants grown in the greenhouse from wild-collected seed show intermediate values of nuclear DNA content and have 2N = 70 chromosomes. The two coexisting cytotypes are intermingled and show no difference in microhabitats. The absence of septaploids in the natural population suggests that the two cytotypes are probably reproductively isolated.

Key words: polyploidy, DNA contents, flow cytometry, polymorphism.
Use of 4x–2x crosses to determine gene–centromere map distances of isozyme loci in Solanum species
Authors: Douches David S. , Quiros Carlos F.
Published: April 2011

With the meiotic abnormality described as the parallel spindles mechanism operating during anaphase II, first division type restitution 2n gametes (FDR) were identified in selected diploid Solanum clones. Generating 4x–2x FDR testcrosses of the general form aaaa × Aa with these diploid parents provided a means of estimating gene–centromere linkages with the application of half-tetrad analysis to the segregating tetraploid progenies. In this study, gene–centromere map distances were obtained for 10 isozyme loci and the yellow tuber flesh locus (Y). Electrophoretic assay of the tetraploid progenies yielded pooled gene–centromere linkage estimates for Got-1 (0.9 map units, mu), Pgm-2 (2.0 mu), Sdh-1 (8.3 mu), Aps-1 (13.5 mu), Adh-1 (15.8 mu), Prx-3 (18.0 mu), Idh-1 (18.4 mu), Pgi-1 (26.0 mu), 6-Pgdh-3 (30.1 mu), Mdh-1 (33.5 mu), and y (16.8 mu). These linkage data were combined with previously reported diploid testcross linkage data to show that these 11 markers are distributed over at least 8 of the 24 chromosome arms in the potato genome. In addition, gene order for the Idh-1/Sdh-1 linkage block (36.8 mu) was predicted to be of the sequence Id1-1 –centromere–Sdh-1, which is similarly found in Lycopersicon. Because of the codominant nature of these enzyme-coding loci, the theoretical expectations for 4x–2x FDR segregation were tested in this crop. Tests for reciprocity of exchange products of pooled data for 6-Pgdh-3, Mdh-1, Pgi-1, Adh-1, and Sdh-1 families yielded good fits to the expected 1:1 ratio. With these defined electrophoretic markers available, more critical genetic analyses can be extended to a number of genetic and breeding problems concerning the potato.

Key words: half-tetrad analysis, 4x–2x, isozymes, Solanum, linkages.
Polytene chromosome mapping in Ceratitis capitata (Diptera: Tephritidae)
Authors: Bedo D. G.
Published: April 2011

Polytene chromosome reference maps of the five autosomes of Ceratitis capitata from male pupal orbital bristle trichogen cells are presented and a correlation is established between two of them and the two largest of the five autosomes in the haploid mitotic complement. Characteristic features of each chromosome are described identifying areas that are difficult to analyze and noting the existence of common alternative band expression. A quantitative analysis of the mitotic karyotype of C. capitata indicates that the two smallest autosome pairs cannot be reliably distinguished. This may present problems with future attempts to establish homologies between the remaining mitotic and polytene chromosomes. A comparison of polytene chromosome banding patterns from salivary gland and trichogen cells failed to find any homologous regions, or even to identify homologous chromosomes. The banding differences are not explained by variation in puffing patterns, heterochromatin expression, or polyteny levels, but appear to reflect fundamental differences in banding patterns of the chromosomes in each tissue.

Key words: Ceratitis capitata, polytene chromosome map, mitotic chromosome measurements.
Genetic control of environmentally induced DNA variation in flax genotrophs
Authors: Al-Saheal Y. A. , Larik A. S.
Published: April 2011

Heritable changes can be induced in the amount of nuclear DNA of the Stormont Cirrus variety (PL) of flax when grown in the specific environments of nitrogen and phosphorus, but such changes did not occur in variety Royal (R). Changes occurred in the amount of nuclear DNA of R when the PL nuclear and cytoplasmic factors were introduced by crossing. In the experiments reported here, tests were made on the plasticity of the F1's of their reciprocal crosses to PL and R to understand why L and S genotrophs are stable. The results suggest that there may be a feedback from nucleus to cytoplasm in L0, which inactivates the cytoplasmic factor. Possibly a paramutation-like mechanism adjusts the different amount of DNA, or heterochromatin, between the homologous chromosomes in heterozygotes. L3 and S3 DNA has reverted to the same amount as in PL. This reversion in DNA appears to be accompanied by an increase in stability rather than in any gain in plasticity.

Key words: environment, flax, genotrophs, DNA variation.
Alien chromosome addition in durum wheat. II. Advanced progeny
Authors: Schulz-Schaeffer J. , Haller S. E.
Published: April 2011

Alien chromosome addition in durum wheat was accomplished by backcrossing and selling an amphiploid derivative F10 strain of Triticum turgidum L. var. durum × Agropyron intermedium (Host) Beauv. The number of chromosome pairs increased from an average of 10.4 bivalents in the B1F1 to 18.5 bivalents in the B1F7 generation. Stabilization of chromosome pairing was improved as expressed in the range of bivalents (0–21 in the B1F1 and 16–21 in the B1F7 generation). Backcrossing to the durum wheat parent resulted in the elimination of some Agropyron chromosomes and in others becoming pairs. A hexaploid Agrotriticum with the constitution AABBII resulted. The I genome consists of a group of seven chromosome pairs from A. intermedium.Key words: Agrotriticum, Agropyron intermedium, chromosome pairing.
Pattern of inheritance of a larval tubercle-colour polymorphism in Hyalophora Columbia of northwestern Ontario (Lepidoptera: Saturniidae)
Authors: Kohalmi Lester , Moens Peter B.
Published: April 2011

A fifth instar larval colour polymorphism in H. Columbia from northwestern Ontario had been previously indicated indirectly from the progeny of interspecific matings. The polymorphism has been confirmed directly by a recent collection of larvae from the vicinity of Kenora, Ontario. Results from six different mating classes suggest that the dorsal thoracic tubercle colours are determined by a pair of codominant autosomal alleles such that TRTR produces a red colour, TRTy a reddish-orange colour, and TyTy a yellow colour. Epistatic interaction with abdominal tubercle determining factors is hypothesized to cause larvae with white instead of yellow abdominal tubercles to have dorsal thoracic tubercles that are pinkish red, pale pinkish red, and pale yellow.Key words: Hyalophora, tubercle colour, polymorphism.
Reversal of dominance in a gene on chromosome 5A controlling frost resistance in wheat
Authors: Sutka J. , Veisz O.
Published: April 2011

The genetic effects on frost resistance, when chromosome 5A from wheat (Triticum aestivum L.) cultivars with varying degrees of frost resistance (Cheyenne, Hope) and T. spelta were substituted into an identical genetic background ('Chinese Spring') were analysed using the parents and the F1, F2, and BC progeny generations. In the crosses CS/Ch 5A × CS/Ts 5A and CS/Ch 5A × CS/H 5A, the parents differed from each other only with respect to chromosome 5A. In the first experiment, the F1 hybrids and the parents were frozen at temperatures of −10, −11, −12, −13, and −14 °C and in the second experiment at −10, −12, and −14 °C. Chromosome 5A of 'Cheyenne' was found to carry a gene controlling intense frost resistance and that of T. spelta and of 'Hope', a gene controlling weak frost resistance. For both pairs of parents and at all freezing temperatures the additive gene effect was greater than the dominant gene effect. The additive to dominant ratio changed from one freezing temperature to the other. At a high (−10 °C) freezing temperature frost resistance was dominant; as the temperature decreased, the direction of dominance was reversed and at the lowest (−14 °C) freezing temperature frost sensitivity became dominant.Key words: Triticum aestivum, wheat, chromosome substitution 5A, frost resistance, dominance.
Differential rates of genic and chromosomal evolution in bats of the family Rhinolophidae
Authors: Qumsiyeh M. B. , Owen R. D. , Chesser R. K.
Published: April 2011

Data for nondifferentially stained chromosomes from 10 species of Rhinolophus (Chiroptera: Rhinolophidae) suggest a conserved chromosomal evolution. G-banded chromosomes for three well differentiated species (Rhinolophus hipposideros, Rhinolophus blasii, and Rhinolophus acuminatus) corroborate a low level of gross chromosomal rearrangements. Additionally, a comparison between G-banded chromosomes of Rhinolophus (Rhinolophidae) and Hipposideros (Hipposideridae) suggests extreme conservatism in chromosomal arms between these two distantly related groups. On the other hand, we report extensive genie divergence as assayed by starch gel electrophoresis among these 10 species, and between Rhinolophus and two hipposiderid genera (Hipposideros and Aselliscus). The present chromosomal data are not sufficient for phylogenetic analysis. Phylogenies based on electrophoretic data are in many aspects discordant with those based on the classical morphological criteria. Different (and as yet not clearly understood) evolutionary forces affecting chromosomal, morphologic, and electrophoretic variation may be the reason for the apparent lack of concordance in these independent data sets.Key words: Rhinolophidae, chromosomes, electrophoresis, phylogeny.
Homozygous and heterozygous homologous chromosomes: effects on preferential pairing and recombination frequency in wheat
Authors: Suárez E. Y. , Gorgoschidse L. , Sacco F. , Saione H.
Published: April 2011

Trisomics for chromosomes 1A and 6B of wheat backcrossed to euploids showed progeny with unexpected segregation frequencies (cytological and genetical) that can be attributed to preferential pairing between homologues. Recombination frequency between the centromere and a gene for mildew reaction of chromosome 1A showed an increase from the first to the second backcross that could be attributed to a positive correlation between homozygosity and the degree of pairing between homologous chromosomes. The use of wheat trisomics for genetic analysis is also discussed.Key words: preferential pairing, trisomic segregation, wheat cytogenetics, recombination frequency, pathogen reaction.
Cytological differences and chromosomal rearrangements in four members of the Anopheles dirus complex (Diptera: Culicidae)
Authors: Baimai V. , Poopittayasataporn A. , Kijchalao U.
Published: April 2011

A reference photomap of the larval salivary gland, polytene chromosomes of the Anopheles dims complex (species A) is presented. Samples of species A, B, C, and D from natural populations in Thailand were compared to this standard map using the larval progeny of wild-caught females. All species show differences in their chromosome banding patterns involving band size, number, and shape, particularly at the free ends of the X, 2R, and 2L. These differences provide useful diagnostic characters for separating members of the species complex. However, overall banding patterns are conservative in the group: species A, B, and C are virtually homosequential. Species D is highly polymorphic for a single paracentric inversion in each of the four autosomal arms and has a fixed inversion on the X chromosome. This same X chromosome inversion occurs at low frequency in species A.Key words: Anopheles dirus, larval polytene chromosome, inversion polymorphisms.
Synaptonemal complex spreading in Allium cepa and Allium fistulosum. II. Pachytene observations: the SC karyotype and the correspondence of late recombination nodules and chiasmata
Authors: Albini S. M. , Jones G. H.
Published: April 2011

Pachytene synaptonemal complexes and recombination nodules were analysed, by surface spreading, in the closely related species Allium fistulosum and Allium cepa (both 2n = 16), which show highly contrasting patterns of chiasma distribution. Pachytene observations show that all eight pairs of homologues are fully paired in both species, despite the pronounced localisation of chiasmata in A. fistulosum. Synaptonemal complex karyotype analysis reveals similar marker complexes in both species. These are presumed homoeologues, which, possibly due to the uneven distribution of the higher DNA amount found in A. cepa, rank in slightly different positions in the two karyotypes. Darkly staining ellipsoidal late recombination nodules were observed associated with PTA stained pachytene synaptonemal complexes. The positional distribution of late recombination nodules along synaptonemal complexes corresponds almost exactly to the distribution of chiasmata along metaphase I bivalents in the two species. These observations strongly support the proposal that late recombination nodules are involved in reciprocal meiotic recombination. The frequencies of late recombination nodules at pachytene showed deficits (30% in A. fistulosum, 70% in A. cepa) compared to metaphase I chiasma frequencies. It is suggested that the greater deficit of late recombination nodules in A. fistulosum could be related to a longer duration of meiosis in this species resulting from its greater genomic DNA content.Key words: synaptonemal complex, recombination nodules, Allium.
Meiotic behaviour of extra chromosomes in fertility restored Polima CMS Brassica napus plants
Authors: Tai William , McVetty Peter B. E.
Published: April 2011

Crosses were made between Brassica napus (2n = 38) with the 'Polima' cytoplasmic male sterile system and variety 'Zem' of B. juncea. Fertility was partially restored in backcross progeny with an extra chromosome (2n = 39) that was believed to be a member of the B genome of B. juncea. Among more than 40 self-pollinated offspring plants studied, fertility restoration was transmitted only through those plants with two extra chromosomes (2n = 40). Anthers of these plants were either full or shriveled with small swollen protrusions. Full and round pollen grains were found in full anthers and in the swollen portion of shriveled anthers. These pollen grains were stained darkly with I2-KI solution and full seed set was obtained from bagged flowers. Meiotic studies in plants with 2n = 40 showed 18 bivalents + 1 quadrivalent at diakinesis in most of the pollen mother cells analyzed. The chromosomes segregated equally at anaphase I and behaved normally at other meiotic stages. The presence of a single quadrivalent in the backcross progeny was highly consistent and occurred in very high frequencies. It is believed that the extra chromosomes belong to the B genome of B. juncea and take part in the quadrivalent formation.Key words: Brassica napus, cytoplasmic male sterility, aneuploidy, Polima, Brassica juncea, rapeseed cytogenetics.
Incomplete bivalent pairing in dihaploids of Brassica napus L
Authors: Tai William , Ikonen H.
Published: April 2011

Twenty five polyhaploid plants (2n = 2x = 19, genome formula AC) of Brassica napus (2n = 4x = 38, AACC) were cytogenetically studied. Seven of these were found among field populations and the rest were derived through anther culture of B. napus cv. Regent. Meiotic behaviour at diakinesis and metaphase I revealed nine bivalents and one univalent in more than 40% of the more than 400 pollen mother cells analyzed. However, when the chromosome number of the polyhaploids was doubled using colchicine, 19 bivalents were observed. These doubled plants (2n = 4x = 38, AACC) also had normal behaviour identical to a regular B. napus at other meiotic stages. Quadrivalent associations were observed when the chromosome numbers were doubled to the octaploid level (2n = 8x = 72, AAAACCCC). It is suggested that A and C are homoeologous genomes. If homologous partners are present, chromosomes would pair within the same genome to form bivalents as occurred in the allotetraploids and to form quadrivalents as occurred in the allooctaploids. However, when a homologous partner is not available, the homoeologous chromosomes would then pair to form bivalents in those polyhaploids.Key words: Brassica napus, polyhaploids, genome relationship, meiotic behaviour, homoeologous pairing.
Restriction endonuclease digestion of meiotic and mitotic chromosomes in Pyrgomorpha conica (Orthoptera: Pyrgomorphidae)
Authors: López-Fernández C. , Gosálvez J. , Suja J. A. , Mezzanotte R.
Published: April 2011

Mitotic and meiotic chromosomes of the grasshopper Pyrgomorpha conica were treated with the restriction endonucleases (REs) AluI, MboI, and HaeIII. Two important results were obtained. First, REs successfully acted to produce linear differentiation not only in mitotic but also in meiotic chromosomes. Second, the changes in pycnosis that occur in the chromatin from first prophase to first metaphase in meiosis, as revealed with orcein or Giemsa, do not affect the digestion capability of REs. This suggests that it is the presence of restriction sites, rather than chromatin condensation itself, that is critical in the production of the linear differentiation obtained.Key words: insect cytogenetics, restriction endonucleases, mitosis, meiosis, heterochromatin.
Giemsa C-banded karyotypes of Avena species
Authors: Fominaya A. , Vega C. , Ferrer E.
Published: April 2011

Giemsa C-banding was used to identify individual somatic chromosomes in eight diploid species of Avena. Two patterns of heterochromatin distribution were found. The chromosomes of five A genome species (A. strigosa, A. hirtula, A. longiglumis, A. damascena, and A. canariensis) possessed mainly telomeric bands, whereas those from three C genome species (A. clauda, A. pilosa, and A. ventricosa) were characterized by higher chromatin condensation and several intercalary heterochromatin bands. The divergent evolution between the two groups is confirmed after C-banding. The unique C-banding patterns of several chromosomes in each species will be a useful tool for the study of meiotic behaviour in interspecific hybrids among Avena spp.Key words: C-banding, Avena, heterochromatin.
Chromosome pairing in hybrids of ph1b mutant wheat with rye
Authors: Naranjo T. , Roca A. , Giraldez R. , Goicoechea P. G.
Published: April 2011

Metaphase I pairing was studied in five ph1b mutant wheat × rye hybrids to verify the presence of translocations between homoeologous chromosomes in ph1b mutant wheat and to establish the pairing homoeology between wheat and rye chromosomes. Three 5B-deficient ABDR hybrids with standard chromosome structure were used as controls. Chromosomes 1R and 5R of rye and most wheat chromosomes, as well as their arms, were identified by means of C-banding. The presence of 5BS in ph1b hybrids raised the overall pairing level. The pattern of pairing between wheat chromosomes in ph1b hybrids, as in 5B-deficient hybrids, was characterized by the occurrence of preferential pairing between chromosomes of the A and D genomes in most homoeologous groups. The existence of a double translocation involving 4BL, 5AL, and 7BS in common wheat was confirmed. Deviation from the standard pairing pattern suggested the existence of a translocation involving 1BL and 1DL in one ph1b ABDR plant and another translocation involving 3AL and 3DL in three other ph1b hybrids. In ph1b hybrids, wheat – rye pairing was relatively frequent for 1RL, 5RL, and an arm of a metacentric rye chromosome, probably 2R, that is homoeologous to 2BL, and the homoeologous arms of 2A and 2D. The existence of a translocation involving 5RL and 4RL in rye was confirmed.Key words: homoeologous, homologous, 5B-deficient, translocations, C-banding.
The effect of restriction enzyme digestion of human metaphase chromosomes on C-band variants of chromosomes 1 and 9
Authors: Hedemann Ute , Schürmann M. , Schwinger E.
Published: April 2011

Human metaphase chromosomes, fixed on slides, have been treated with 8 different restriction endonucleases and 29 combinations of 2 restriction enzymes prior to staining with Giemsa. The endonucleases AluI and DdeI and the combinations AluI + DdeI, AluI + HaeIII, AluI + HinfI, and AluI + MboI have then been used to digest metaphase chromosomes of nine individuals with C-band variants of chromosomes 1 or 9, obtained by the CBG technique. The restriction enzyme resistant chromatin of the paracentromeric regions of chromosomes 1 and 9 has been measured and compared with the corresponding CBG-bands. The size of the enzyme resistant chromatin regions depend upon the type of enzyme(s) used. Treatment with AluI + MboI was the only digestion that acted differently on different chromosome pairs. However, within one pair of homologous chromosomes, all digestions revealed the same variations as conventional C-banding.Key words: C-band variants, heterochromatin, human chromosomes, restriction endonucleases.
Synaptic mutants in potato, Solanum tuberosum L. I. Expression and identity of genes for desynapsis
Authors: Jongedijk E. , Ramanna M. S.
Published: April 2011

For tuber-bearing Solanum species, six monogenic recessive synaptic mutants, designated sy-1, sy-2, sy-3, sy-4, ds, and dsc have been reported in the literature. In the present investigation no indication for the existence of the mutant sy-1, affecting megasporogenesis only, was found. The mutant ds was confirmed to display typical desynaptic behaviour in microsporogenesis and shown to similarly affect megasporogenesis. It furthermore proved to be allelic to the mutants sy-3 and dsc. It is proposed that the mutants sy-3, ds, and dsc be uniformly designated ds-1, whereas the remaining mutants sy-2 and sy-4 (possibly identical) may be designated simply as synaptic mutant until their actual identity has been established. The observed F1 segregations generally support monogenic recessive inheritance of ds-1. However, in one cross progeny the expected mutant phenotype was not clearly expressed in contrast with its reciprocal, which might indicate cross-specific influence of the cytoplasm on ds-1 expression. The potential value and limitations of desynaptic (ds-1ds-1) mutants for potato breeding and true potato seed production are discussed.Key words: Solanum, (de)synaptic mutants, microsporogenesis, megasporogenesis, 2n gametes.
Apparent sources of the A genomes of wheats inferred from polymorphism in abundance and restriction fragment length of repeated nucleotide sequences
Authors: Dvorak Jan , McGuire Patrick E. , Cassidy Brandt
Published: April 2011

Four hundred random DNA fragment clones of wild diploid wheat Triticum monococcum ssp. aegilopoides (syn. T. baeoticum) were screened for clones of repeated nucleotide sequences. Seven DNA fragments were isolated that were more abundant by one order of magnitude or more in the genome of diploid T. monococcum ssp. aegilopoides (genome A) than in the genome of diploid Triticum speltoides (genome BS). These clones were then used to determine which of the two wild diploid wheats, T. m. ssp. aegilopoides or T. urartu, was the ancestor of domesticated diploid wheat T. m. ssp. monococcum, wild tetraploid wheats T. turgidum ssp. dicoccoides and T. timopheevii ssp. araraticum, domesticated tetraploid wheat T. turgidum, and hexaploid bread wheat T. aestivum. Three of the seven cloned repeated nucleotide sequences differentiated the genome of T. m. ssp. aegilopoides from that of T. urartu in repeated sequence abundance, restriction fragment length polymorphism, or both. The same distinctions were observed between the A genome of T. m. ssp. aegilopoides and the A genomes of polyploid wheats. From this it was concluded that the species from which T. m. ssp. monococcum was domesticated was T. m. ssp. aegilopoides but that the A genomes of the polyploid wheats are equivalent to that of T. urartu. The results presented here demonstrate the utility of polymorphism in repeated nucleotide sequences in the investigation of the origin of genomes in polyploid plants.Key words: RFLP, Triticum, wheat phylogeny.