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Octoploid triticale were derived from common wheat (Triticum aestivum L. ‘Mianyang11’) × rye (Secale cereale L. ‘Kustro’), and some progeny were obtained by the backcrossing of triticale with ‘Mianyang11’ followed by self-fertilization. In situ hybridization using rye genomic DNA and repetitive sequences pAs1 and pSc119.2 as probes was used to analyze the mitotic chromosomes of these progeny. Three wheat–rye 1R monosomic addition lines and a wheat line (12FT-1685) containing a 1R and a 1BL.1RS translocation chromosome were identified. Abnormal mitosis was observed in the two lines. During mitosis of a 1R monosomic addition line (3-8-20-1R-2), lagging chromosomes, micronuclei, chromosomal bridges, and the one pole segregation of 1R chromosome were observed. Abnormal mitotic behaviour of chromosomes was also observed in some of the self-progeny plants of lines 12FT-1685 and 3-8-20-1R-2. These progeny contained 1R chromosome or 1R chromosome arm. In addition, 4B chromosomes were absent from one of the progeny of 3-8-20-1R-2. This abnormal mitotic behaviour of chromosomes was not observed in two other 1R monosomic addition lines. These results indicate that a single 1R chromosome added to wheat might cause abnormal mitotic behaviour of both wheat and rye chromosomes and different genetic variations might occurr among the sibling 1R monosomic addition lines.

Chromosomal rearrangements, including reciprocal translocations, may prevent recombinational transfer of genes from a donor genotype to a recipient, especially when the gene is located in an interstitial segment. The effect of trisomy of chromosome arm 1RS on recombination was studied in translocation heterozygote T248W of rye ( Secale cereale ), involving chromosome arms 1RS and 6RS. (Pro)metaphase I configuration frequencies were analyzed. Crossing over, estimated as chiasma parameters, in five genetically different euploid heterozygotes was compared with those of 10 different single arm trisomics. The addition of 1RS greatly altered the crossing over pattern around the translocation break point, with a special increase in the interstitial segment of 6RS and adjoining regions, normally hardly accessible to recombination. Furthermore, there was considerable variation between plants of closely related genotypes. Heterogeneity widens the distribution of crossing overs, including segments normally not accessible to recombination, but decreases average recombination in other segments. The extra chromosome and abnormal segregants are eliminated by using the trisomic as the pollen parent.

A Robertsonian polymorphism resulting in diploid chromosome number ranging from 59 to 61 and constant chromosome arm number (fundamental number = 104) was observed in the albino rainbow trout ( Oncorhynchus mykiss (Walbaum)) from the yellow color strain. In one individual, 90 mitotic chromosomes and 156 chromosome arms were counted, indicating the fish as a triploid. Morphology of the chromosomes, DAPI staining, and the cytogenetic location of 5S rDNA sequences showed sex-related chromosomal heteromorphism in the specimens. Additionally, length polymorphism of the X chromosome was detected in the studied individuals and two morphs of the X chromosome were described, XLand XS, according to the size of its short arm (p). The XSwas observed in the female as well as male albino rainbow trout; however, among females, no XSXSgenotype was found. After primed in situ labeling with 5S rDNA primers, the p-arms of both types of the X chromosome showed similar hybridization signals. On the other hand, fluorescence in situ hybridization with telomeric PNA (peptide nucleic acid) probe exhibited weak hybridization spots on the p-arm of the XSchromosome compared with the distinct hybridization spots observed on the XLp-arm. This could reflect a different telomere length on the p-arm of the XSand XLchromosomes. Partial translocation and deletion of the X chromosome p-arm are considered to be responsible for the p-arm length difference between the two morphological variants of X chromosome.

We have identified all Hordeum bulbosum chromosomes in 2 diploid Hordeum vulgare × Hordeum bulbosum hybrids using suitable probes and fluorescence in situ hybridization. Using the parental idiograms allowed us to carry out a full analysis of chromosome associations among all chromosome arms in the hybrids. Association frequencies were generally lower for the short arms than for the long arms. There were also significant differences among the chromosome arms in association frequencies, partly correlated with the absolute length of the chromosome arm, as well as with the frequency of recombinant lines, which were recovered from partially fertile interspecific hybrids. The H. bulbosum idiogram will be useful for further chromosome association studies and will enable the identification of H. bulbosum chromosomes involved in chromosome addition or substitution lines.Key words: Hordeum vulgare, Hordeum bulbosum, interspecific hybrids, chromosome associations, meiosis, fluorescence in situ hybridization.

The Ph1 gene has long been considered the main factor responsible for the diploid-like meiotic behavior of polyploid wheat. This dominant gene, located on the long arm of chromosome 5B (5BL), suppresses pairing of homoeologous chromosomes in polyploid wheat and in their hybrids with related species. Here we report on the discovery of genotypic variation among tetraploid wheats in the control of homoeologous pairing. Compared with the level of homoeologous pairing in hybrids between Aegilops peregrina and the bread wheat cultivar Chinese Spring (CS), significantly higher levels of homoeologous pairing were obtained in hybrids between Ae. peregrina and CS substitution lines in which chromosome 5B of CS was replaced by either 5B of Triticum turgidum ssp. dicoccoides line 09 (TTD09) or 5G of Triticum timopheevii ssp. timopheevii line 01 (TIM01). Similarly, a higher level of homoeologous pairing was found in the hybrid between Ae. peregrina and a substitution line of CS in which chromosome arm 5BL of line TTD140 substituted for 5BL of CS. It appears that the observed effect on the level of pairing is exerted by chromosome arm 5BL of T. turgidum ssp. dicoccoides, most probably by an allele of Ph1. Searching for variation in the control of homoeologous pairing among lines of wild tetraploid wheat, either T. turgidum ssp. dicoccoides or T. timopheevii ssp. armeniacum, showed that hybrids between Ae. peregrina and lines of these two wild wheats exhibited three different levels of homoeologous pairing: low, low intermediate, and high intermediate. The low-intermediate and high-intermediate genotypes may possess weak alleles of Ph1. The three different T. turgidum ssp. dicoccoides pairing genotypes were collected from different geographical regions in Israel, indicating that this trait may have an adaptive value. The availability of allelic variation at the Ph1 locus may facilitate the mapping, tagging, and eventually the isolation of this important gene.Key words: diploid-like meiotic behavior, genetic control of pairing, Ph1 gene, Triticum turgidum ssp. dicoccoides, wild emmer.

Detailed karyotypes of Lilium longiflorum and L. rubellum were constructed on the basis of chromosome arm lengths, C-banding, AgNO3staining, and PI-DAPI banding, together with fluorescence in situ hybridisation (FISH) with the 5S and 45S rDNA sequences as probes. The C-banding patterns that were obtained with the standard BSG technique revealed only few minor bands on heterologous positions of the L. longiflorum and L. rubellum chromosomes. FISH of the 5S and 45S rDNA probes on L. longiflorum metaphase complements showed overlapping signals at proximal positions of the short arms of chromosomes 4 and 7, a single 5S rDNA signal on the secondary constriction of chromosome 3, and one 45S rDNA signal adjacent to the 5S rDNA signal on the subdistal part of the long arm of chromosome 3. In L. rubellum, we observed co-localisation of the 5S and 45S rDNA sequences on the short arm of chromosomes 2 and 4 and on the long arms of chromosomes 2 and 3, and two adjacent bands on chromosome 12. Silver staining (Ag-NOR) of the nucleoli and NORs in L. longiflorum and L. rubellum yielded a highly variable number of signals in interphase nuclei and only a few faint silver deposits on the NORs of mitotic metaphase chromosomes. In preparations stained with PI and DAPI, we observed both red- and blue-fluorescing bands at different positions on the L. longiflorum and L. rubellum chromosomes. The red-fluorescing or so-called reverse PI-DAPI bands always coincided with rDNA sites, whereas the blue-fluorescing DAPI bands corresponded to C-bands. Based on these techniques, we could identify most of chromosomes of the L. longiflorum and L. rubellum karyotypes.Key words: fluorescence in situ hybridisation, FISH, 5S rDNA, 45S rDNA, C-banding, reverse PI-DAPI banding.

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

New winter wheat (Triticum aestivum L.) × winter barley (Hordeum vulgare L.) hybrids produced using cultivated varieties (wheat 'Martonvásári 9 kr1'(Mv9 kr1) × barley 'Igri', Mv9 kr1 × 'Osnova', 'Asakazekomugi' × 'Manas') were multiplied in tissue culture because of the high degree of sterility and then pollinated with wheat to obtain backcross progenies. Meiotic analysis of the hybrids Mv9 kr1 × 'Igri' and 'Asakazekomugi' × 'Manas' and their in vitro regenerated progenies with the Feulgen method revealed 1.59 chromosome arm associations per cell in both initial hybrids. The number of chromosome arm associations increased after in vitro culture to 4.72 and 2.67, respectively, in the two combinations. According to the genomic in situ hybridization (GISH) analysis, wheat-barley chromosome arm associations made up 3.6% of the total in the initial Mv9 kr1 × 'Igri' hybrid and 6.6% and 16.5% of the total in in vitro regenerated progenies of the 'Asakazekomugi' × 'Manas' and Mv9 kr1 × 'Igri' hybrids, respectively. The demonstration by GISH of wheat-barley chromosome pairing in the hybrids and especially in their in vitro regenerated progenies proves the possibility of producing recombinants between these two genera, and thus of transferring useful characters from barley into wheat. In vitro conditions caused an increase in chromosome arm association frequency in both combinations and in fertility in some regenerants.Key words: wheat, barley, intergeneric hybridization, meiotic chromosome pairing, GISH.

To test assumptions of the autotetraploid chromosome pairing model regarding events during synapsis, whole-mount spreads of synaptonemal complexes (SCs) of Machaeranthera pinnatifida (=Haplopappus spinulosus) (Asteraceae) (2n = 4x = 16) were analyzed by electron microscopy. On the assumption of one synaptic initiation per chromosome arm, each pachytene quadrivalent is expected to have one partner switch (PS), and the frequency of pachytene quadrivalents for each chromosome is predicted to be 2/3 (or 0.67). However, to the contrary, we observed a range of one to four PSs per pachytene quadrivalent with an overall mean of 1.56. This suggests that the number of synaptic initiations is greater than one per chromosome arm (or >two per chromosome), and the predicted frequency of pachytene quadrivalents should be >8/9 (based on a minimum of three initiations per chromosome). However, in close agreement with the model, the observed pachytene quadrivalent frequency from SCs in this study was 0.69. To explain the apparent discrepancy between the observed frequency of PSs and the observed frequency of quadrivalents, the possibility of nonindependent synaptic initiations and presynaptic alignment are discussed in the context of their potential influence on quadrivalent frequency. Recombination nodules (RNs), which were scored in about half the SC spreads, occurred at a frequency (9.6 per nucleus) comparable with the chiasma frequency at diakinesis (9.3 per nucleus). The frequency of RNs as well as their distribution is consistent with the hypothesis that RNs occur at sites of crossing over and chiasma formation.Key words: autopolyploid, Machaeranthera pinnatifida, meiosis, recombination nodules, synaptonemal complex.

Twenty-nine lines with deletions in the Lr19 ('Indis') translocated chromosome segment were used to physically map three Thinopyrum RFLP loci as well as the Sr25 and Sd1 loci. From the data, the relative locations of marker loci on the translocation were determined as: Sd1, Xpsr165, Xpsr105, Xps129, Lr19, Wsp-D1, Sr25/Y. The data confirmed the reported homoeology between the Lr19 segment and chromosome arm 7DL of wheat. Also, it seems that the Lr19 translocation in 'Indis' is very similar to the Lr19 segment in the T4 source and that the former may not derive from Thinopyrum distichum. Key words : deletion mapping, leaf rust resistance.

Dosage effects generated by either loss or gain of a chromosome segment were used to identify chromosome regions associated with morphological and quantitative characters in maize (Zea mays L.). Using B–A translocation stocks introgressed into a B73Ht background, a chromosome arm dosage series in a Mo17Ht × B73Ht F1hybrid background was created for 18 of the 20 chromosome arms. The dosage series was then evaluated for 12 quantitatively inherited characters to associate specific phenotypic changes in a trait with a specific chromosome arm. Not only did our results show the familiar aneuploid syndrome phenomenon, but differential dosage effects among particular chromosome arms were demonstrated. All the quantitative traits measured and all the chromosome arms examined in this study were responsive to changes in chromosome arm dosage. The possible bases behind those differences and their utility in identifying quantitative trait loci, as well as the genetic relationships among the group of quantitatively inherited characters studied, are considered. Key words : corn, chromosome arm, B–A translocations, dosage analysis.

In maize (Zea mays L.), the consequences of aneuploidy have been well documented, however, genetic variation in the responses to aneuploidy has not been examined. Using simple B–A translocation stocks to generate a dosage series involving segments from 14 chromosome arms, we tested for the presence of genetic variation for dosage responses in maize by examining reciprocal and maternal genotype effects on the dosage responses. Reciprocal effects examined whether there were differences between two distinctly different inbred backgrounds, Mo17Ht and B73Ht, in how they responded to loss or gain of a B73Ht segment in the Mo17Ht × B73Ht (TB) F1cross versus a Mo17Ht segment in the B73Ht × Mo17Ht (TB) F1cross. Maternal genotype effects questioned whether different inbred backgrounds, Sc41R, T8, and either Mo17Ht or B73Ht (depending on the male), when used as females responded differently to the loss or gain of a chromosome arm segment from the same male (either B73Ht TB or Mo17Ht TB) in an F1cross. Numerous examples of reciprocal and maternal genetic effects were identified in this study. Most of the genetic effects were due to differences in magnitude of response rather than direction; however, tassel-branch number involving the 5S chromosome segment in the B73Ht male background and the 7L chromosome segment in the Mo17Ht male background showed a trend toward the maternal genotype effects being due to differences in the direction of the response. Key words : quantitative traits, corn, B–A translocations, dosage analysis.

A standard photographic map of polytene chromosomes of Anopheles sundaicus was constructed from ovarian nurse cells and is described herein. Polytene chromosomes of wild specimens collected from 9 different geographical areas in Thailand and Indonesia have been analyzed. Specimens from these populations appear to share banding patterns with standard gene arrangements, except for some specimens from Purworejo, in Central Java, and South Tapanuli and Asahan, both of North Sumatra, which exhibited distinct banding patterns at the tip of chromosome X (Xb) compared with the standard sequence (Xa). Moreover, some specimens collected from Asahan, North Sumatra, consistently showed distinct loosely diffuse bands in zone 19 of chromosome arm 2R (2Rb) compared with the standard banding patterns (2Ra). The existence of the 2Rb pattern correlates perfectly with the presence of an extra block of centromeric heterochromatin in autosome 2 as revealed by mitotic karyotype analysis (2n = 6). These cytological differences have led to the recognition of 3 distinct forms, viz., A, B, and C, within the taxon An. sundaicus. In addition, forms A and C show a normal size for chromosome Y, (Y1), while form B has a relatively larger type of chromosome Y, (Y2). Form A is widely distributed in Thailand and Indonesia, while form B has been found in North Sumatra and Central Java. Form C, however, has been found only in Asahan, North Sumatra. Key words : Anopheles sundaicus, polytene chromosome map, mitotic karyotype, chromosomal differentiation.

A population of Atlantic salmon from the River Dzwina was karyotyped using conventional staining and banding techniques. The chromosome number was 2n = 58, and the chromosome arm number (NF) was 74. Variation in the size of the long arm of the eighth chromosome pair was observed. The presence of constitutive heterochromatin on this arm was confirmed by C-banding. Silver banding revealed variability in the location of nucleolus organizer regions (NORs) on this arm. Four cytotypes and three phenotypes of the NOR-bearing chromosome were found. The polymorphism of the eighth metacentric pair of chromosomes observed in Atlantic salmon was probably due to deletion and paracentric inversion of the arm involved.

Resistance to common root rot and black point, caused by Cochliobolus sativus, was evaluated in alien chromosome substitution and addition lines of the cultivars 'Cadet' and 'Rescue'. Substitution of chromosome 5B in 'Rescue' with 5Ag from Agropyron elongatum decreased root rot susceptibility to a level intermediate between that in the susceptible 'Rescue' and the resistant 'Cadet'. The substitution of 'Rescue' chromosome 5A or 5D with 5Ag, or the addition of 5Ag to 'Rescue' complement had no consistent effect on root rot susceptibility. The root rot resistance of 'Cadet' was unaffected by substitution of chromosomes 5A, 5B, or 5D with 5Ag, or the addition of 5Ag. This indicates that the susceptible allele of the gene Crr is the primary determinant in the reaction of wheat to common root rot. Black point resistance in the susceptible cultivar 'Rescue' was significantly increased by substitution of chromosome 5B with 5Ag, or the addition of 5Ag. No corresponding effect was demonstrated for black point incidence in the moderately resistant cultivar 'Cadet' with substitution of chromosome 5Ag for 5B, or the addition of 5Ag. Chromosome 5Ag apparently carries one or more genes conferring resistance to black point. The identity of these lines was confirmed by restriction fragment length polymorphism analysis using group 5 chromosome arm specific probes. This extends the use of these molecular probes to the Agropyron genome.Key words: Cochliobolus sativus, common root rot, black point, wheat, Triticum aestivum, Agropyron elongatum, restriction fragment length polymorphism, chromosome arm specific probes.

The polytene chromosomes of Drosophila triauraria and D. quadraria, two of the sibling species of D. auraria, were examined. The polytene chromosomes of all three species exhibit very clear homology. Unlike the stock of D. auraria that we studied, D. triauraria and D. quadraria carry heterozygous paracentric inversions. In both species, 2R and 3R are the arms where these inversions are concentrated. In addition, in D. quadraria, the 3L chromosome arm is very complicated because of heterozygous inversions. The mode of inheritance of these rearrangements was studied. A homozygous strain for all chromosome arms of D. triauraria was isolated, while a homozygous strain was obtained only for the arms X, 2L, 3L, and 4 of D. quadraria. Like D. auraria, both species show a large number of inverted tandem duplications in the paired condition, even in the chromosomes of their hybrids. Small deletions were also detected, one of which, in D. triauraria, is homozygous terminal. Hypotheses are discussed concerning the relationships of the species and the existence of inverted tandem duplications.Key words: Drosophila, duplications, inversions, deletions, evolution.

Chromosome 1D homozygous recombinant substitution lines derived from Triticum aestivum 'Chinese Spring' (cross 1) or 'Chinese Spring' double-ditelosomic 1D (cross 2) hybridized with a disomic substitution line of Triticum tauschii chromosome 1D in 'Chinese Spring' were used to investigate the linkage relationships among Glu-D1, encoding subunits of high molecular weight glutenin storage proteins; Gli-D1, encoding gliadin storage proteins; Sr33, conferring stem rust resistance; and the centromere. Based on analysis of 88 and 91 recombinant substitution lines of crosses 1 and 2, respectively, Sr33 is tightly linked to Gli-D1 on chromosome arm 1DS (5.6 and 7.6% recombination) and less tightly to the centromere (29.6%, cross 2) and to Glu-D1 (40.9 and 39.5%). The order of the loci is Glu-D1 – centromere – Sr33 – Gli-D1.Key words: stem rust resistance, seed storage protein, glutenin, gliadin, Triticum aestivum, Triticum tauschii.

Homozygous recombinant substitution lines, derived from a cross of Triticum aestivum 'Chinese Spring' with a disomic substitution line of Triticum tauschii chromosome 1D in 'Chinese Spring', were used to investigate the linkage relationships among the loci Glu-D1, encoding high molecular weight glutenin storage proteins, Gli-D1, encoding gliadin storage proteins, Rg2, controlling glume color, and Lr21, conferring leaf-rust resistance. Gli-D1, on chromosome arm 1DS, is tightly linked to Rg2 and Lr21 (1.4 and 5.6% recombination, respectively). The order of the loci is Gli-D1–Rg2–Lr21. Glu-D1, on chromosome arm 1DL, segregates independently (P = 0.43) of Gli-D1, Rg2, and Lr21. The position of Glu-D1, Gli-D1, Rg2, and Lr21 in the genetic linkage map of chromosome 1D agrees with the position of storage protein, glume color, and rust-resistance loci on chromosomes 1A and 1B.Key words: leaf-rust resistance, seed storage protein, glutenin, gliadin, glume color, Triticum aestivum, Triticum tauschii.

Species of the genus Lophopyrum are closely related to the genus Triticum and have been extensively used in wheat breeding. To facilitate the detection of the Lophopyrum chromatin in wheat, two repeated nucleotide sequences were isolated from L. elongatum (Host) Löve (= Agropyron elongatum Host, Elytrigia elongata (Host) Nevski), which hybridized strongly with the DNAs of Lophopyrum species but weakly (pLeUCD1) or essentially not at all (pLeUCD2) with those of Triticum species. Both sequences were shown to be on all chromosomes of L. elongatum. Each chromosome arm of L. elongatum showed a unique pattern of restriction fragments hybridizing with pLeUCD2. The analysis of chromosomes recombinant between chromosome arm 3AgL of L. ponticum (Podp.) Löve and chromosome arm 3DL of wheat (T. aestivum L.) showed that regional heterogeneity of the pLeUCD2 family occurs also within the arm. It was demonstrated that this heterogeneity can be exploited for identification of Lophopyrum chromatin in wheat and mapping of crossover points in Lophopyrum–wheat recombinant chromosomes by Southern blot analysis.Key words: concerted evolution, Triticum, gene transfer.

Additions of complete and telocentric chromosomes of Elytrigia elongata (Host) Nevski in Triticum aestivum L. 'Chinese Spring' were employed to assign the genes coding for seed storage proteins to chromosome arms in the E. elongata genome. Genes coding for prolamins equivalent to wheat gliadins were found on chromosome arms 1ES and 6Ep. Genes on chromosome arm 1ES, which is presumably the p arm, coded for several components with electrophoretic mobilities (lactate–PAGE) corresponding to those of β-, γ-, and ω- gliadins and those on chromosome arm 6Ep coded for two components with mobilities corresponding to those of β-gliadins. Amino acid sequencing of mixtures of prolamins from E. elongata and from E. pontica (Podp.) Holub, a species closely related to E. elongata, indicated that prolamins of these species correspond to α-type (which includes β-gliadins), γ-type, and ω-type gliadins. Restriction fragments of genomic DNAs from substitution lines of chromosome 6E of E. elongata in 'Chinese Spring' were separated electrophoretically in agarose gels and probed with a cloned α-type gliadin gene from 'Yamhill'. This Southern blot showed that chromosome 6E yields DNA fragments identical in size to those characteristic of the α-gliadin gene cluster that is on chromosome 6A of 'Chinese Spring', 'Cheyenne', and 'Yamhill'. These results indicate that structural genes for prolamins of Elytrigia are similar to those of wheat gliadins and are located on the same chromosome arms as those in Triticum species. A high molecular weight (HMW) protein likely to be a HMW glutenin subunit was located on the long arm of chromosome 1E, which presumably is the q arm; this also is in accordance with the location of HMW glutenin subunit genes in Triticum. It is concluded that the appearance of α-type gliadin genes on chromosomes of homoeologous group 6 in T. aestivum occurred prior to divergence of Triticum and Elytrigia but after the divergence of Secale, Hordeum, and the Triticum–Elytrigia lineages, since neither Secale or Hordeum appear to have α-type genes. It is, however, possible that α-type gliadin genes were deleted from the ancestors of Secale and Hordeum after divergence from the Triticum–Elytrigia lineage.Key words: Elytrigia elongata, gene location, prolamins, gliadins, wheat.

This study considered the effects of three continuous growth temperatures (14, 21, and 28 °C) on apparent genomic structure, apparent chromosome arm ratio, pollen abortion, and meiotic nonreduction in full-sib genotypes of Festuca mairei × F. arundinacea var. glaucescens. Ten genotypes were sampled for meiosis and 20 for pollen. The metaphase I (MI) data for each sampled combination of genotype, temperature, and replication were subjected to a bootstrap algorithm that calculated 95% confidence limits for each class of meiotic figure and for the ratio of ring bivalents to total bivalents, the total number of chromosomes in multivalents per cell, and the mean arm-binding frequency. These confidence limits permitted an evaluation of the significance of differences among genotypes, temperatures, and replications. The MI data were also subjected to two types of numerical models to investigate apparent genomic structure and mean effective chromosome arm ratio, i.e., pairing regulation and extent of chiasma interference across the centromere. The hybrids overall exhibited a 2:2 (AABB) genomic structure, but there were significant differences among genotypes in arm-binding frequency and frequencies of univalents, rod bivalents, and ring bivalents. Except for desynapsis and impaired chromosome contraction in one genotype at 28 °C, temperature had little effect; optimized genomic structure was slightly more 2:1:1 (like AABC) at 14 °C and chiasma interference increased slightly at 28 °C. One genotype was monosomic but meiotically normal. Pollen stainability was significantly depressed at 14 °C, while microspore micronuclei were more numerous. Pollen diameter was least at 21 °C regardless of degree of abortion.Key words: meiosis, meiotic modeling, temperature, pollen fertility, Festuca.

Chromosome pairing in Triticum aestivum cv. Chinese Spring × T. urartu hybrids lacking chromosome arm 5AS or 5BS was shown to be lower than in similar hybrids involving euploid Chinese Spring. Amphiploids were produced from crosses of Chinese Spring, ditelosomic 5AL, and ditelosomic 5BL with a specific strain of T. urartu. The absence of asynapsis in the amphiploids lacking chromosome arm 5AS or 5BS provides evidence that the poor chromosome pairing observed in the corresponding F1 hybrids was due to suppression of homoeologous pairing and not to general asynapsis. This conclusion is supported by the finding that heterogenetic chromosome pairing, as evidenced by the frequency of multivalents, was lower in the ditelo 5BL × T. urartu amphiploids than in the amphiploids from the cross Chinese Spring × T. urartu.

Two intervarietal hybrids of common wheat, Triticum aestivum L., are meiotically analyzed using the C-banding staining method. The C-banding pattern of nine meiotic chromosomes (4A, 7A, and the seven of the B genome) permitted their unequivocal recognition at first metaphase plates. The pairing frequency of each B-genome chromosome arm was scored. Data on the pairing frequency of the arms, separately considered, are applied to calculate expected pairing of whole chromosomes and whole genomes. The application of mathematical models to predict the genome pairing using either equal or different frequencies per chromosome arm is discussed.Key words: meiotic analysis, Triticum aestivum L., C-banding.

Two lines of common wheat cv. Chinese Spring carrying mutant alleles for the Ph2 homoeologous pairing-suppressor gene on chromosome arm 3DS promoting homoeologous pairing in wheat interspecific and intergeneric hybrids have been tested for their mitotic sensitivity to colchicine. Both the ph2a mutation, which corresponds to a fairly long deletion of 3DS, and ph2b, which is either an intragenic change or a very small deletion, as well as the ph2a/ph2b heteroallelic combination and the deficiency for the entire 3DS arm (ditelo 3DL), conditioned a significantly lower sensitivity to colchicine than that determined by the wild-type allele Ph2 (euploid and ditelo 3DS). Observation of both metaphase and anaphse root-tip cell populations, treated with various colchicine concentrations, provided similar results. The degree of spindle disruption in 2 × 10−4 M colchicine, as measured by the percentage of fully affected metaphases (C type), was significantly reduced in ph2 and Ph2− genotypes and, consequently, a larger proportion of cells could proceed toward anaphase and also had a regular segregation pattern at this stage. The differential sensitivity of ph2 genotypes to colchicine is in the opposite direction to that previously found for ph1 genotypes, lacking the homoeologous pairing suppressor on chromosome arm 5BL. The ph2 mutation, while promoting homoeologous pairing as ph1 does, decreases spindle sensitivity to colchicine with respect to the wild-type (ph2) allele rather than increasing it, as ph1 does. The observed alteration of spindle sensitivity to colchicine that mutants for structurally unrelated but functionally related genes (Ph1 and Ph2) condition is interpreted as a highly probable coincidence in their cellular target. It is assumed therefore that these loci affect the equilibrium between tubulin and microtubules. Through this effect they presumably determine chromosome positioning in somatic and premeiotic stages, leading to different pairing patterns at meiosis. Key words: Triticum aestivum, tubulin, pairing suppressors, somatic association.

Two homoeologous-recombination-produced gene transfer lines in which leaf rust resistance genes from Triticum speltoides Tausch were incorporated into the chromosome complement of Triticum aestivum L. emend. Thell. were analyzed. One line, F-7-3, originated from the cross T. aestivum cv. Neepawa × T. speltoides accession F and the other line, E-11-14, originated from the cross T. aestivum cv. Manitou × T. speltoides accession E. The lines were crossed with Chinese Spring monosomics. Segregation of the F2 progenies from monosomic F1's indicated that both genes were on chromosome 1B. The lines were then crossed with Chinese Spring ditelosomics 1BS and 1BL and the F1, plants were testcrossed to Manitou. Meiotic chromosome pairing in the F1 plants and the segregation of the telosomes and resistance in the testcrosses provided evidence that both gene transfers involved chromosome arm 1BL. The exchange points showed 41% and 4% recombination with the centromere in F-7-3 and E-11-14, respectively. Recombination between the transferred alien chromatin and the chromatin of the recipient wheat chromosome is either severely reduced or entirely absent when the wheat diploidizing mechanism is active.

A deletion in the p arm of chromosome 5B of Triticum aestivum L. cv. Chinese Spring was identified by C-banding during the production of disomic substitutions of 6B of Aegilops longissima Schweinf. et Muschl. for chromosome 5B of cv. Chinese Spring. The deletion was terminal with a breakpoint just proximal to the interstitial C-band. The degree of metaphase I chromosome pairing in plants homozygous for the deletion indicated that the chromosome pairing promoting gene known to be in the p arm of chromosome 5B is located in the deleted portion of that arm. Additionally, all of the 5S ribosomal RNA genes known to exist on arm 5Bp were mapped to this deleted portion.Key words: C-banding, 5S rRNA genes, Triticum, Aegilops chromosome aberration.

The genes coding the synthesis of the three major cathodic isoperoxidases a, c, and d in common wheat cv. Chinese Spring, as determined by polyacrylamide slab gel electrophoresis, are located on the chromosome arms 7DS, 4BL, and 7AS, respectively. Transfer lines with Agropyron elongatum can be detected by electrophoretic analysis of peroxidases if the chromosome arm 7AgS is involved in these transfers. Results have also shown a homology between the chromosome 7D of common wheat and the chromosome 7Ag of Agropyron elongatum.

Larvae of the morphospecies Prosimulium onychodactylum collected from two streams in northern Oregon are divided into 11 sibling species based on fixed and polymorphic inversions. The sibling species have differentiated sex chromosomes; each sibling species falls into one of two groups based on the chromosome arm which carries the sex chromosome markers. Males exhibit lack of homologous pairing or inversion heterzygosity and females have complete chromosome pairing or inversion homozygosity. There is a succession of sibling species which mature in the streams from January through September. Mature larvae of each sibling species are present for about 6 weeks; some are synchronic while others are allochronic. Some of the sibling species occur in the same stream and others are in different streams. Sibling species which are both synchronic and sympatric appear to be reproductively isolated. Reproductive isolation may not be complete for sibling species which are normally allopatric or allochronic; small numbers of F1 and backcross hybrids were found between some of these sibling species. The division of the morphospecies into sibling species was also observed in collections from Washington through northern California.

The arrangement of telomeres in eight types of differentiated Allium cepa L. interphase cells was studied to find whether the distribution pattern varies with differentiation as centromere distribution appears to in differentiated cells of mice and Triturus vulgaris L. The results show that telomere positions and groupings in A. cepa are essentially the same in differentiated and meristematic interphase nuclei; telomeres, which are roughly paired, are arranged in a telophase configuration along one side of the nucleus. Thus telomeres appear to maintain the same basic arrangement in differentiated and in meristematic cells. Comparison of chromosome arm lengths and interphase telomere positions suggests that interphase telomere arrangements are a function of chromosome arm lengths at the time the nuclear envelope forms. Such an arrangement would place homologous telomeres in the same latitudinal band of the interphase nucleus.

An aneuploid durum wheat line (Triticum turgidum L. var. durum) having 13 chromosome pairs and 2 unpaired chromosomes at metaphase I of meiosis in pollen mother cells (i.e., monosomic for chromosomes 7A and 7D) was observed to produce some progeny plants with 2n = 40 chromosomes. These aneuploid (triploid) plants were usually weak and sterile. Triploid plants also occurred in the progeny of durum plants monosomic for chromosome 7A, or in progeny of plants that were mono-telodisomic or ditelomonotelosomic for chromosome 7Aq (13 II + 1 t II or 13 II + t II + t I) but not in the progeny of plants ditelomonotelosomic for chromosome 7Ap (13 II + t II + t 1). Therefore, there is a gene(s) on chromosome arm 7Ap that prevents the production of diploid (2n) egg cells in wheat. In the absence of 7Ap, a portion of the egg cells have 26 chromosomes, which when fertilized with a pollen nucleus with 14 chromosomes, produces progeny plants with 2n = 40 chromosomes. The data also indicated that chromosome arm 7Dp probably contains a second gene that is capable of preventing the production of triploid plants. Key words: Triticum turgidum L. var. durum, polyploidy, aneuploid, triploid, monosomic.

Several translocation and translocation-inversion strains were induced in Anopheles albimanus Wiedemann by using X and gamma irradiation. The propoxur resistance allele (prr), located on chromosome arm 2R, was used to screen for T(Y;2R) translocations and In(2R) inversions. Six T(Y;2R) translocations and eight In(2R) inversions are described herein. The strains designated In(2R)[T(Y:2R)3]2 and In(2R)[T(Y;2R)6]4 eliminated 99.8% and 99.7%, respectvely, of the crossing over between the translocation breakpoint and the prr locus. A direct correlation is shown between genetic map units and physical distance (micrometers) of the polytene chromosome. Inversions are shown to eliminate recombinants in excess of the expected value based on physical size of the aberration. The Y chromosome, which is heterochromatic and located in the chromocenter in polytene complements, is visible in two terminal translocations.

This paper extends the known geographic distribution of S. tuberosum siblings recorded in 1962 by R. Landau by analyzing the polytene chromosomes in the larva. Her seven basic IIS arrangements are augmented by the addition of four new types. These were St/A, A/A; CDE-2/CDE, CDE/CDE; Y2/AB, AB/AB; and FGI. These new siblings, like the originals, have fixed differences in chromosome arm IIS. One of these, FGI, distinguished by a high degree of polymorphism, and the presence of fixed differences from the tuberosum standard in arms IS, IL, and IIIL, occurred both in Alaska and Norway. A comparison of the standard tuberosum, the S. venustum, and the FGI sibling chromosome pattern revealed the FGI sibling to be much closer to the venustum standard than any other tuberosum sibling. A second new sibling (Y2/AB) from Norway differed from the standard in the Y chromosome by multiple rearrangements in IIS and two tandem inversions in IIL. The fixed changes on arms other than IIS in the FGI siblings and the Y2/AB sibling are the first to be detected in this complex. There were a number of shared inversions in the populations studied indicating a common ancestor and (or) introgression.

Telocentrics of hexaploid wheat, Triticum aestivum spp. vulgare cv. Chinese Spring, were used to establish the chromosome arm location and crossover distance from the centromere of genes controlling characters introduced into synthetic hexaploid wheat (2n = 42 = AABBDD) from Aegilops squarrosa (2n = 14 = DD). The chromosome arm location and the crossover distance from the centromere of each gene studied are as follows: synthetic hexaploid RL 5404 — brown glumes (Rg2), 1DL, 13.3 ± 3.3%; tenacious glumes (Tg), 2Dα, 39.4 ± 4.9%; inhibitor of waxy foliage (W21), 2Dα, 52.5 ± 5.0%; adult-plant leaf rust resistance (Lr22), 2Dα, 63.6 ± 4.8%; purple coleoptile (Rc3), 7DS, 10.3 ± 2.8%; synthetic hexaploid RL 5406 — Rg2, 1DL, 1.7 ± 1.0%; Tg, 2Dα, 42.9 ± 4.6%; W21, 2Dα, 58.9 ± 4.6%; Rc3, 7DS, 9.8 ± 2.8%. A gene for seedling leaf rust resistance (Lr21) found in RL 5406 is located on chromosome 1D.

The coefficient of concordance between arm-ratio measurement and homoeologous group in two varieties of hexaploid wheat was found to be highly significant. This is taken to indicate considerable cytological stability in the evolution of the wheats. This stability in the evolution of the cultivated forms of the subtribe Triticinae differs from the evolutionary patterns found in other species of the subtribe. It is possible that this difference is related to the artificial selection pressures imposed by cultivation.

Equations relating the effects of an increment and a decrement of a chromosome arm on arm ratio, centromeric index and morphological index were derived. These equations demonstrate that an increment and decrement of the same magnitude alter specific indices by differing amounts. Further, the equations for centromeric index and morphological index with one exception were chromosome dependent. The use of these indices in applied cytogenetics may require reconsideration.

A dicentric chromosome was observed in the F2 progeny of an interspecific wheat cross. It is suggested that: the dicentric arose from breakage and fusion of two nonhomologous univalent chromosomes in the preceding meiosis. Because only a few bridges were observed in root tips, anther wall tissue, and in sectioned ovaries, it was concluded that the dicentric persisted in the plant because of parallel separation of the chromatids. Somatic variation was observed in some root tip cells. At meiosis, the dicentric was invariably paired with its two homologues and both centromeres were effective in orientation on the plate. Chains-of-five and even rings-of-five were formed in one spike. In another, the loss of one chromosome arm prevented such associations but several forms of trivalents occurred. In one spike, internal chiasmata were formed in the intercentric region of the chromosome. On the chiasmatype theory of crossing over this should have caused bridges at succeeding stages. Besides the lack of bridges, in some cells at AI there was definite evidence that the dicentric was breaking apart and forming an extra chromosome. To explain this phenomenon it is suggested that the effect of the one centromere was nullified by the other and the full consequences of chromatid breakage and reunion in chiasma formation were not fulfilled.

Hybridization experiments involving four Canadian populations of E. glandulosum, six Canadian populations of E. alpinum and one Japanese population of E. pyrricholophum produced F1 hybrids which were studied for meiotic pairing and fertility. The meiotic association of 15 bivalents plus one hexavalent was found in hybrids between E. alpinum and E. glandulosum. The single population of E. pyrricholophum has the same chromosome arm arrangement as E. glandulosum.