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A total of 139 triticale × wheat progenies (including recombinant inbred lines and doubled haploids) were developed indigenously. Screening at cytogenetic level using genomic in situ hybridization and fluorescence in situ hybridization revealed maximum progenies (48%) carrying 1RS.1BL translocation. D-R genome substitution ranging from 1 to 7 chromosomes of rye showed significantly more biological yield (9.29 g), 1000 grain weight (48.26 g), number of tillers per plant (6.67) and plant height (106.06 cm) than other progenies depicting the contribution of rye chromatin towards plant yield. Thirteen per cent of lines were found without rye chromatin. Screening of all progenies against yellow rust pathogen revealed about 85% lines to be resistant with varying levels of resistance. In vitro testing for drought tolerance showed non-significant difference among progenies carrying variable rye introgressions. The progenies developed in the present study may present novel germplasm and utilized in the future wheat improvement programmes. [ABSTRACT FROM AUTHOR]

Chromosome identification is essential for linking sequence and chromosomal maps, verifying sequence assemblies, showing structural variations and tracking inheritance or recombination of chromosomes and chromosomal segments during evolution and breeding programs. Unfortunately, identification of individual chromosomes and chromosome arms has been a major challenge for some economically important crop species with a near-continuous chromosome size range and similar morphology. Here, we developed oligonucleotide-based chromosome-specific probes that enabled us to establish a reference chromosome identification system for oil palm (Elaeis guineensis Jacq., 2n = 32). Massive oligonucleotide sequence pools were anchored to individual chromosome arms using dual and triple fluorescent in situ hybridization (EgOligoFISH). Three fluorescently tagged probe libraries were developed to contain, in total 52,506 gene-rich single-copy 47-mer oligonucleotides spanning each 0.2–0.5 Mb across strategically placed chromosome regions. They generated 19 distinct FISH signals and together with rDNA probes enabled identification of all 32 E. guineensis chromosome arms. The probes were able to identify individual homoeologous chromosome regions in the related Arecaceae palm species: American oil palm (Elaeis oleifera), date palm (Phoenix dactylifera) and coconut (Cocos nucifera) showing the comparative organization and concerted evolution of genomes in the Arecaceae. The oligonucleotide probes developed here provide a valuable approach to chromosome arm identification and allow tracking chromosome transfer in hybridization and breeding programs in oil palm, as well as comparative studies within Arecaceae. [ABSTRACT FROM AUTHOR]

The interest in Robertsonian fusion chromosomes (Rb fusions), sometimes referred to as Robertsonian translocations, derives from their impact on mammalian karyotype evolution, as well from their influence on fertility and disease. The formation of a Rb chromosome necessitates the occurrence of double strand breaks in the pericentromeric regions of two chromosomes in the satellite DNA (satDNA) sequences. Here, we report on the fine-scale molecular analysis of the centromeric satDNA families in the Rb(1;29) translocation of domestic cattle and six antelope species of the subfamily Bovinae. We do so from two perspectives: its occurrence as a chromosomal abnormality in cattle and, secondly, as a fixed evolutionarily rearrangement in spiral-horned antelope (Tragelaphini). By analysing the reorganization of satDNAs in the centromeric regions of translocated chromosomes, we show that Rb fusions are multistep, complex rearrangements which entail the precise elimination and reorganization of specific (peri)centromeric satDNA sequences. Importantly, these structural changes do not influence the centromeric activity of the satellite DNAs that provide segregation stability to the translocated chromosome. Our results suggest a common mechanism for Rb fusions in these bovids and, more widely, for mammals in general. [ABSTRACT FROM AUTHOR]

Molecular characterization of germplasm is important for sustainable exploitation of crops. DNA diversity was measured using inter-retrotransposon-amplified-polymorphism and inter-simple-sequence-repeat markers in 203 Ethiopian landraces and reference varieties of linseed (flax, Linum usitatissimum) and wild Linum species. Molecular diversity was high (PIC, 0.16; GD, 0.19) compared to other reports from the species. Genotyping separated reference from landrace accessions, and clustered landrace accessions from different altitudes and geographical regions. Collections showed evidence for recent introduction of varieties in some regions. The phylogeny supported L. bienne Mill. as the progenitor of domesticated L. usitatissimum. Markers developed here will be useful for genetic mapping and selection of breeding lines. The results show the range of characters that can be exploited in breeding lines appropriate for smallholder and commercial farmers in Ethiopia, producing a sustainable, secure, high-value crop meeting agricultural, economic and cultural needs. [ABSTRACT FROM AUTHOR]

Satellite DNA (satDNA) is a major component of genomes but relatively little is known about the fine-scale organization of unrelated satDNAs residing at the same chromosome location, and the sequence structure and dynamics of satDNA junctions. We studied the organization and sequence junctions of two nonhomologous satDNAs, pBuM and DBC-150, in three species from the neotropical Drosophila buzzatii cluster (repleta group). In situ hybridization to microchromosomes, interphase nuclei and extended DNA fibers showed frequent interspersion of the two satellites in D. gouveai, D. antonietae and, to a lesser extent, D. seriema. We isolated by PCR six pBuM × DBC-150 junctions: four are exclusive to D. gouveai and two are exclusive to D. antonietae. The six junction breakpoints occur at different positions within monomers, suggesting independent origin. Four junctions showed abrupt transitions between the two satellites, whereas two junctions showed a distinct 10 bp tandem duplication before the junction. Unlike pBuM, DBC-150 junction repeats are more variable than randomly cloned monomers and showed diagnostic features in common to a 3-monomer higher-order repeat seen in the sister species D. serido. The high levels of interspersion between pBuM and DBC-150 repeats suggest extensive rearrangements between the two satellites, maybe favored by specific features of the microchromosomes. Our interpretation is that the junctions evolved by multiples events of illegitimate recombination between nonhomologous satDNA repeats, with subsequent rounds of unequal crossing-over expanding the copy number of some of the junctions.Heredity (2009) 102, 453–464; doi:10.1038/hdy.2009.9; published online 4 March 2009 [ABSTRACT FROM AUTHOR]

The DNA hypomethylation effect of 5-azacytine (5-AC; a cytosine analog) is widely known. This agent has been used for rRNA gene expression studies of Triticeae amphiploids and hybrids regarding rye rRNA genes suppression caused by the wheat nucleolar dominance phenomenon. However, this situation is reverted by 5-AC treatment which activates rye rRNA gene expression as it has been intensively observed in triticale. For nucleo|ar dominance studies, we produced F1 multigeneric hybrids (AABBRHCh; 2n=6x=42) from crosses between the triticale cultivar 'Corgo' (AABBRR; 2u=6x=42) and the tritordeum cultivars HT9 and HT31 (AABBHchHch; 2n=6x=42). The hybrid seeds were germinated in a low concentration of 5-AC (treatment) and in distilled water (nontreated control plants). Silver nitrate staining performed in one 5-AC-treated F1 hybrid revealed a reduced number of interphase cells with seven nucleoli, metaphases with eight Ag-NORs, and neocentromeres in the long arm of three wheat chromosomes. Nontreated hybrids presented six Ag-NORs per mitotic metaphase cell and a maximum of six nucleoli per interphase because of the 1R Ag-NOR suppression. No neocentromere was found in the control F1 hybrid plants. Both treated and nontreated seedlings were subsequently evaluated by fluorescent in situ hybridization performed with genomic and repetitive DNA probes to identify Hch and rye genomes, to confirm Ag-NORs location, and to detect inactive rDNA loci. DAPI counterstaining was also helpful for the detection of neocentromeres in the lung arm of three wheat chromosomes. This study allowed us to suggest that 5-AC treatment specifically induced wheat neocentromeres in the F1 multigeneric triticale x tritordeum hybrids. [ABSTRACT FROM AUTHOR]

The morphological, yield, cytological and molecular characteristics of bread wheat x tritordeum F1 hybrids (2n = 6x = 42; AABBDHch) and their parents were analysed. Morphologically, these hybrids resembled the wheat parent. They were slightly bigger than both parents, had more spikelets per spike, and tillered more profusely. The hybrids are self-fertile but a reduction of average values of yield parameters was observed. For the cytological approach we used a double-target fluorescence in situ hybridization performed with total genomic DNA from Hordeum chilense L. and the ribosomal sequence pTa71. This technique allowed us to confirm the hybrid nature and to analyse chromosome pairing in this material. Our results showed that the expected complete homologous pairing (14 bivalents plus 14 univalents) was only observed in 9.59% of the pollen mother cells (PMCs) analysed. Some PMCs presented autosyndetic pairing of Hch and A, B or D chromosomes. The average number of univalents was higher in the wheat genome (6.8) than in the Hch genome (5.4). The maximum number of univalents per PMC was 20. We only observed wheat multivalents (one per PMC) but the frequency of trivalents (0.08) was higher than that of quadrivalents (0.058). We amplified 50 RAPD bands polymorphic between the F1 hybrid and one of its parents, and 31 ISSR polymorphic bands. Both sets of markers proved to be reliable for DNA fingerprinting. The complementary use of morphological and yield analysis, molecular cytogenetic techniques and molecular markers allowed a more accurate evaluation and characterization of the hybrids analysed here. [ABSTRACT FROM AUTHOR]

Human myeloid leukemia cell lines are induced to terminal differentiation into monocyte lineage by 1,25-dihydroxyvitamin D3 (1,25D3) or its analogs (deltanoids). However, translation of these findings to the clinic is limited by calcemic effects of deltanoids. Strategies to overcome this problem include combination of deltanoids with other compounds to induce differentiation at lower, noncalcemic, deltanoid concentrations. We previously showed that either carnosic acid, an antioxidant, or SB202190, a p38 MAPK inhibitor, increase the potency of 1,25D3 in the HL60 cell line. Here, we report that simultaneous addition of both these agents further increases differentiation potency of deltanoids in this cell line and in freshly obtained leukemic cells ex vivo. Activity of MAPK pathways showed that increased differentiation was associated with enhanced activity of JNK pathway in all responding cell subtypes. Our studies suggest that patients with CML or AML subtypes M2 and M4, but not M1, M3 or M4eo, are particularly suitable for this combination therapy. We conclude that the established cell line HL60 presents a good model for some, but not all, subtypes of myeloid leukemia, and that the JNK pathway plays an important role in monocytic differentiation of human leukemic cells ex vivo, as well as in vitro.Leukemia (2005) 19, 1812–1817. doi:10.1038/sj.leu.2403916; published online 18 August 2005 [ABSTRACT FROM AUTHOR]

The abundance and genomic organization of six simple sequence repeats, consisting of di-, tri-, and tetranucleotide sequence motifs, and a minisatellite repeat have been analyzed in different gymnosperms by Southern hybridization. Within the gymnosperm genomes investigated, the abundance and genomic organization of micro- and minisatellite repeats largely follows taxonomic groupings. We found that only particular simple sequence repeat motifs are amplified in gymnosperm genomes, while others such as (CAC)5 and (GACA)4 are present in only low copy numbers. The variation in abundance of simple sequence motifs reflects a similar situation to that found in angiosperms. Species of the two- and three-needle pine section Pinus are relatively conserved and can be distinguished from Pinus strobus which belongs to the five-needle pine section Strobus. The hybridization pattern of Picea species, bald cypress and gingko were different from the patterns detected in the Pinus species. Furthermore, sequences with homology to the plant telomeric repeat (TTTAGGG)n have been analyzed in the same set of gymnosperms. Telomere-like repeats are highly amplified within two- and three- needle pine genomes, such as slash pine (Pinus elliottii Engelm. var. elliottii), compared to P. strobus,Picea species, bald cypress and gingko. P. elliottii var. elliottii was used as a representative species to investigate the chromosomal organization of telomere-like sequences by fluorescence in situ hybridization (FISH). The telomere-like sequences are not restricted to the ends of chromosomes; they form large intercalary and pericentric blocks showing that they are a repeated component of the slash pine genome.Conifers have genomes larger than 20000 Mbp, and our results clearly demonstrate that repeats of low sequence complexity, such to (CA)8, (GA)8, (GGAT)4 and (GATA)4, and minisatellite- and telomere-like sequences represent a large fraction of the repetitive DNA of these species. The striking differences in abundance and genome organization of the various repeat motifs suggest that these repetitive sequences evolved differently in the gymnosperm genomes investigated. [ABSTRACT FROM AUTHOR]

The genomic organization and chromosomal distributions of two abundant tandemly repeated DNA sequences, dpTa1 and pSc119.2, were examined in six wild Hordeum taxa, representing the four basic genomes of the genus, by Southern and fluorescence in situ hybridization. The dpTa1 probe hybridized to between 30 and 60 sites on the chromosomes of all five diploid species studied, but hybridization patterns differed among the species. Hybridization of the pSc119.2 sequence to the chromosomes and Southern blots of digested DNA detected signals in Hordeum bulbosum, Hordeum chilense, Hordeum marinum and Hordeum murinum 4x, but not in Hordeum murinum 2x and Hordeum vulgare ssp. spontaneum. A maximum of one pSc119.2 signal was observed in the terminal or subterminal region of each chromosome arm in the species carrying this sequence. The species carrying the same I-genome differed in the presence (Hordeum bulbosum) or absence (Hordeum spontaneum) of pSc119.2. The presence of pSc119.2 in the tetraploid cytotype of Hordeum murinum, but its absence in the diploid cytotype, suggests that the tetraploid is not likely to be a simple autotetraploid of the diploid. Data about the inter- and intra-specific variation of the two independent repetitive DNA sequences give information about both the interrelationships of the species and the evolution of the repetitive sequences. [ABSTRACT FROM AUTHOR]

Three lines of the tetraploid wheat Aegilops ventricosa Tausch (2n=4 x=28), which contains good resistance to eyespot, were analysed using fluorescent in situ hybridization. Probes used included rDNA, cloned repeated sequences from wheat and rye, simple-sequence repeats (SSRs) and total genomic DNA. The banding patterns produced could be used to distinguish most chromosome arms and will aid in the identification of Ae. ventricosa chromosomes or chromosome segments in breeding programmes. All lines had a single major 18S-25S rDNA site, the nucleolar organizing region (NOR) in chromosome 5N and several minor sites of 18S-25S rDNA and 5S rDNA. A 1NL.3DL, 1NS.3DS translocation was identified, and other minor differences were found between the lines. [ABSTRACT FROM AUTHOR]

The physical locations of the 5S and 18S-25S rDNA sequences were examined in nine wild Hordeum species and cytotypes by double-target in situ hybridization using digoxigenin-labelled 5S rDNA and biotin-labelled 18S-25S rDNA as probes. H. vulgare ssp. spontaneum (2n=2 x=14; I-genome) had a similar composition of 5S and 18S-25S rDNA to cultivated barley ( H. vulgare ssp. vulgare, I-genome), with two major 18S-25S rDNA sites and minor sites on four of the other five chromosomes; three chromosomes had 5S rDNA sites. The closely related H. bulbosum (2 x; also I-genome) showed only one pair of 5S rDNA sites and one pair of 18S-25S rDNA sites on different chromosomes. Four wild diploid species, H. marinum (X-genome), H. glaucum and H. murinum (Y-genomes) and H. chilense (H-genome), differed in the number (2–3 pairs), location, and relative order of 5S and the one or two major 18S-25S rDNA sites, but no minor 18S-25S rDNA sites were observed. H. murinum 4 x had three chromosome pairs carrying 5S rDNA, while the diploid had only a single pair. Two other tetraploid species, H. brachyantherum 4 x and H. brevisubulatum 4 x (both considered to have H-type genomes), had minor 18S-25S rDNA sites, as well as the major sites. Unusual double 5S rDNA sites – two sites on one chromosome arm separated by a short distance – were found in the American H-genome species, H. chilense and H. brachyantherum 4 x. The results indicate that the species H. brachyantherum 4 x and H. brevisubulatum 4 x have a complex evolutionary history, probably involving the multiplication of minor rDNA sites (as in H. vulgare sensu lato), or the incorporation of both I and H types of genome. The rDNA markers are useful for an investigation of chromosome evolution and phylogeny. [ABSTRACT FROM AUTHOR]

In a search for repetitive DNA sequences in the sugar beet genome, two sequences with repeat unit lengths of 143 and 434 bp were isolated and characterized. The pSV family showed an unusual conservation of restriction sites reflecting homogenization of the analyzed repeats. Members of the family are organized as tandem repeats as revealed by PCR and sequencing of dimeric units. The pSV satellite occurs in large intercalary arrays which are present on all chromosome arms of sugar beet. The pSV sequence family is present in different abundance in the sections Beta, Corollinae and Nanae but is not detectable by Southern hybridization in the section Procumbentes. The pDRV family is characterized by an interspersed genomic organization. The sequence is detectable in all sections of the genus and is amplified in species of the section Beta but was also detected, although at lower abundance, in the remaining three sections. Fluorescent in situ hybridization has shown that the pDRV sequence family is dispersed over all chromosomes of the sugar beet complement with some regions of clustering and centromeric depletion. [ABSTRACT FROM AUTHOR]

Molecular cytogenetic methods have been used to study the controversial phylogenetic relationships between the species Dasypyrum villosum (L.) Candargy (2 n=2 x=14) and D. breviaristatum (Lindb. f.) Frederiksen (2 n=4 x=28). Using total genomic DNA from the two species as probes for in situ hybridization to chromosomes, we found that the pericentromeric regions of the chromosome arms of both species are similar, while distal regions show substantial differences. Two dispersed repetitive DNA sequences were isolated: pDbKB45 is distributed along the chromosomes but amplified in the subtelomeric regions of D. breviaristatum chromosomes, while pDbKB49, in both species, is less amplified in terminal regions. Size-separated restriction enzyme digests of DNA showed many repetitive fragments, but few in common between the two species. After probing Southern transfers with D. breviaristatum genomic DNA, all lanes showed similar hybridization patterns although one extra small band was evident in the D. breviaristatum lanes. In contrast, probing with D. villosum DNA showed very substantial differences between the two species. Genomic in situ hybridization to meiotic metaphases from an interspecific hybrid showed seven bivalents of D. breviaristatum origin and seven univalents from D. villosum. We also analysed the physical organization of 5S rDNA, 18S-25S rDNA and a tandemly repeated sequence from rye. Our data support an autotetraploid origin for D. breviaristatum, but its genome and that of D. villosum show extensive differences, so the tetraploid is unlikely to be directly derived from D. villosum. [ABSTRACT FROM AUTHOR]

Eleven wheat- Ae. umbellulata recombinant lines involving chromosome 1U, including an important high-molecular-weight glutenin locus, were characterized by protein and RFLP markers. Four 1U-1A recombinants, one 1U-1B recombinant, two 1U deletions with either nullisomy for chromosome 1A or 1B and a 1U ditelosomic addition line were detected, while 3 recombinant lines involved 1U and non-homoeologous wheat chromosomes. Similar recombination events were found in independent lines, and no small segmental translocations of Ae. umbellulata chromatin were detected. Correlation of the markers with physical maps of the wheat- Ae. umbellulata breakpoints obtained using in situ hybridization enabled the marker order to be established on chromosomes 1A, 1B and 1U. The short arm of chromosome 1A probably differs from both 1U and 1B by one inversion. As now being found to be universal in the Triticeae, clustering of the genetical map in the distal physical regions of the group 1 chromosomes was found. [ABSTRACT FROM AUTHOR]

Ensete ventricosum (Musaceae, enset) is an Ethiopian food security crop. To realize the potential of enset for rural livelihoods, further knowledge of enset diversity, genetics and genomics is required to support breeding programs and conservation. This study was conducted to explore the enset genome to develop molecular markers, genomics resources, and characterize enset landraces while giving insight into the organization of the genome. We identified 233 microsatellites (simple sequence repeats, SSRs) per Mbp in the enset genome, representing 0.28% of the genome. Mono- and di-nucleotide repeats motifs were found in a higher proportion than other classes of SSR-motifs. In total, 154,586 non-redundant enset microsatellite markers (EMM) were identified and 40 selected for primer development. Marker validation by PCR and low-cost agarose gel electrophoresis revealed that 92.5% were polymorphic, showing a high PIC (Polymorphism Information Content; 0.87) and expected heterozygosity (He = 0.79–0.82). In silico analysis of genomes of closely related species showed 46.86% of the markers were transferable among enset species and 1.90% were transferable to Musa. The SSRs are robust (with basic PCR methods and agarose gel electrophoresis), informative, and applicable in measuring enset diversity, genotyping, selection and potentially breeding. Enset SSRs are available in a web-based database at https://enset-project.org/EnMom@base.html (or https://enset.aau.edu.et/index.html, downloadable from Figshare). [ABSTRACT FROM AUTHOR]

Grass pollens lack a dormancy period, remaining in a partly hydrated state at maturation with the contents of the vegetative cell continuing in active motion thereafter. The polysaccharide-containing wall-precursor bodies, derived mainly from previous dictyosome activity (P-particles), move randomly throughout much of the vegetative cell, but at the apertural pole of the grain many follow tracks related to actin fibrils focused on the single aperture. Isolated P-particles are shown by immunofluorescence localization using an antimyosin antibody to be associated individually with myosin. This, together with the fact that movement in the vegetative cell is arrested reversibly by cytochalasins, indicates that their motility is actomyosin based. [ABSTRACT FROM AUTHOR]