Chromosome complement and nucleoli in the Festuca pallescens alliance from South America

1991 ◽  
Vol 69 (12) ◽  
pp. 2756-2761 ◽  
Author(s):  
Jorge Dubcovsky ◽  
Arturo J. Martínez
Keyword(s):  
South America ◽  
Key Words ◽  
Chromosome Pairing ◽  
Chromosome Complement ◽  
Meiotic Behaviour ◽  
Root Tips ◽  
Festuca Pallescens ◽  
Secondary Constrictions

The karyotypes, chromosomes with secondary constrictions, and maximum number of nucleoli of 14 hexaploid (2n = 42) species of Festuca native to South America are described to complete the cytological characterization of the Festuca pallescens alliance. The species analyzed were Festuca acanthophylla E. Desv., Festuca argentinensis (St.-Yves) Türpe, Festuca chrysophylla Phil., Festuca circinata Griseb., Festuca cirrosa (Speg.) Parodi, Festuca gracillima J. D. Hook, Festuca kurtziana St.-Yves, Festuca monticola Phil., Festuca pallescens (St.-Yves) Parodi, Festuca scabriuscula Phil., Festuca scirpifolia (Presl.) Kunth, Festuca thermarum Phil., Festuca tunicata E. Desv., and Festuca ventanicola Speg. They have symmetric and uniform karyotypes but differed (p < 0.01) in arm ratio values. The species had similar maxima in the number of nucleoli in the root tips (9–12), microspores (5–7), and chromosomes with secondary constrictions (10–14). The arrangement of chromosomes in homomorphic pairs and their meiotic behaviour suggest that the species are allohexaploids. The size, shape, and number of chromosomes bearing secondary constrictions confirm that these species are members of the same alliance. Key words: Festuca, karyotype, nucleolus, chromosome pairing.

Chromosome pairing affinity and quadrivalent formation in polyploids: do segmental allopolyploids exist?

Genome ◽  
1996 ◽  
Vol 39 (6) ◽  
pp. 1176-1184 ◽  
Author(s):  
J. Sybenga
Keyword(s):  
Key Words ◽  
Chromosome Pairing ◽  
Meiotic Behaviour ◽  
Homoeologous Pairing ◽  
Preferential Pairing ◽  
Multivalent Formation ◽  
Well Differentiated ◽  
Quadrivalent Frequency ◽  
Segmental Allopolyploid ◽  
Clear Cases

When polyploid hybrids with closely related genomes are propagated by selfing or sib-breeding, the meiotic behaviour will turn into essentially autopolyploid behaviour as soon as the affinity between the genomes is sufficient to permit occasional homoeologous pairing. An allopolyploid will only be formed when the initial differentiation is sufficient to completely prevent homoeologous pairing (in some cases enhanced by specific genes), or when segregational dysgenesis prevents transmission of recombined chromosomes. A new polyploid hybrid may be considered a segmental allopolyploid and may show reduced multivalent formation as a result of preferential pairing between the least differentiated genomes. An established polyploid is either an autopolyploid or an allopolyploid. In exceptional cases it is thinkable that a stable segmental allopolyploid arises, in which some sets of chromosomes are well differentiated and behave as in an allopolyploid, whereas other sets are not well differentiated and behave as in an autopolyploid. No clear cases have been found in the literature so far. Key words : chromosome, pairing affinity, quadrivalent frequency, segmental allopolyploidy.

scholarly journals Alien introgression and morpho-agronomic characterization of diploid progenies of Solanum lycopersicoides monosomic alien addition lines (MAALs) toward pre-breeding applications in tomato (S. lycopersicum)

2021 ◽  
Author(s):  
Puneet Kaur Mangat ◽  
Junghyun Shim ◽  
Ritchel B. Gannaban ◽  
Joshua J. Singleton ◽  
Rosalyn B. Angeles-Shim
Keyword(s):  
Chromosome Complement ◽  
Introgression Lines ◽  
Addition Lines ◽  
Solanum Lycopersicoides ◽  
Drought Tolerant ◽  
Use Efficiency ◽  
Tomato Breeding ◽  
Chromosome Segments ◽  
Alien Addition Lines

Abstract Key message Alien introgressions that were captured in the genome of diploid plants segregating from progenies of monosomic alien addition lines of S. lycopersicoides confer novel phenotypes with commercial and agronomic value in tomato breeding. Abstract Solanum lycopersicoides is a wild relative of tomato with a natural adaptation to a wide array of biotic and abiotic challenges. In this study, we identified and characterized diploid plants segregating from the progenies of monosomic alien addition lines (MAALs) of S. lycopersicoides to establish their potential as donors in breeding for target trait improvement in tomato. Molecular genotyping identified 28 of 38 MAAL progenies having the complete chromosome complement of the cultivated tomato parent and limited chromosome introgressions from the wild S. lycopersicoides parent. Analysis of SSR and indel marker profiles identified 34 unique alien introgressions in the 28 MAAL-derived introgression lines (MDILs) in the genetic background of tomato. Conserved patterns of alien introgressions were detected among sibs of MDILs 2, 3, 4 and 8. Across MDILs, a degree of preferential transmission of specific chromosome segments was also observed. Morphologically, the MDILs closely resembled the cultivated tomato more than S. lycopersicoides. The appearance of novel phenotypes in the MDILs that are lacking in the cultivated parent or the source MAALs indicates the capture of novel genetic variation by the diploid introgression lines that can add commercial and agronomic value to tomato. In particular, screening of representative MDILs for drought tolerance at the vegetative stage identified MDIL 2 and MDIL 11III as drought tolerant based on visual scoring. A regulated increase in stomatal conductance of MDIL 2 under drought stress indicates better water use efficiency that allowed it to survive for 7 days under 0% moisture level.

scholarly journals Chromosomal Map of the Model LegumeLotus japonicus

Genetics ◽  
2002 ◽  
Vol 161 (4) ◽  
pp. 1661-1672 ◽  
Author(s):  
Andrea Pedrosa ◽  
Niels Sandal ◽  
Jens Stougaard ◽  
Dieter Schweizer ◽  
Andreas Bachmair
Keyword(s):  
Repetitive Sequences ◽  
Lotus Japonicus ◽  
Chromosome Complement ◽  
Linkage Groups ◽  
Closely Related Species ◽  
F1 Hybrid ◽  
Bac Clones ◽  
Genomic Regions ◽  
Chromosomal Map

AbstractLotus japonicus is a model plant for the legume family. To facilitate map-based cloning approaches and genome analysis, we performed an extensive characterization of the chromosome complement of the species. A detailed karyotype of L. japonicus Gifu was built and plasmid and BAC clones, corresponding to genetically mapped markers (see the accompanying article by Sandal  et al. 2002, this issue), were used for FISH to correlate genetic and chromosomal maps. Hybridization of DNA clones from 32 different genomic regions enabled the assignment of linkage groups to chromosomes, the comparison between genetic and physical distances throughout the genome, and the partial characterization of different repetitive sequences, including telomeric and centromeric repeats. Additional analysis of L. filicaulis and its F1 hybrid with L. japonicus demonstrated the occurrence of inversions between these closely related species, suggesting that these chromosome rearrangements are early events in speciation of this group.

Chromosome pairing in female and male diploid and polyploid anurans (Amphibia) from South America

1983 ◽  
Vol 25 (5) ◽  
pp. 487-494
Author(s):  
I. M. Rahn ◽  
A. Martinez
Keyword(s):  
South America ◽  
Genetic Control ◽  
Chromosome Pairing ◽  
Diploid Males ◽  
Terminal Chiasmata

Chromosome pairing in females and males of diploid (2n = 22) and tetraploid (2n = 44) Odontophrynus americanus and diploid Ceratophrys cranwelli (2n = 26) and tetraploid C. ornata (2n = 104) showed that diploid females formed more chiasmata per paired arm than diploid males and polyploids of both sexes. There was a reduction in the level of recombination in female polyploids by forming multivalents with terminal chiasmata. The reduction reflected a change in the genetic control of pairing in females after polyploidization.

CHROMOSOME RELATIONSHIPS BETWEEN THE CULTIVATED OAT AVENA SATIVA (6x) AND A. VENTRICOSA (2x)

1970 ◽  
Vol 12 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Hugh Thomas
Keyword(s):  
Chromosome Pairing ◽  
Avena Sativa ◽  
Diploid Species ◽  
Meiotic Behaviour ◽  
Hexaploid Species ◽  
C Genome

Chromosome pairing in the F1 hybrid between the cultivated oat Avena sativa and a diploid species A. ventricosa, and in the derived amphiploid, shows that the diploid species is related to one of the genomes of the hexaploid species. The amount of chromosome pairing observed in complex interamphiploid hybrids demonstrates further that A. ventricosa is related to the C. genome of A. sativa. However, the chromosomes of the diploid species have become differentiated from that of the C genome of A. sativa and this is readily apparent in the meiotic behaviour of both the F1 hybrid and the amphiploid.

Molecular characterization of Ph1 as a major chromosome pairing locus in polyploid wheat

Nature ◽  
2006 ◽  
Vol 439 (7077) ◽  
pp. 749-752 ◽  
Author(s):  
Simon Griffiths ◽  
Rebecca Sharp ◽  
Tracie N. Foote ◽  
Isabelle Bertin ◽  
Michael Wanous ◽  
...  
Keyword(s):  
Molecular Characterization ◽  
Chromosome Pairing ◽  
Polyploid Wheat

Persisting demibivalents: a unique meiotic behaviour in Cuscuta babylonica Choisy

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 63-66 ◽  
Author(s):  
Batia Pazy ◽  
Uzi Plitmann
Keyword(s):  
Key Words ◽  
Chromosome Segregation ◽  
Meiotic Behaviour ◽  
Chromosome Behaviour ◽  
Chromosome Movement ◽  
Pollen Mother Cells ◽  
Key Words Meiosis ◽  
Mother Cells ◽  
Telomeric Association

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.

Synthesis and characterization of the binuclear diamido titanium chalcogenides [(Ar)NCH2CH2CH2N(Ar)]2Ti(µ-E)2 (E = Se, Te)

2002 ◽  
Vol 80 (11) ◽  
pp. 1524-1529 ◽  
Author(s):  
Tianle Zhang ◽  
Warren E Piers ◽  
Masood Parvez
Keyword(s):  
Solid State ◽  
Key Words ◽  
Synthesis And Characterization ◽  
Catalyst Precursor ◽  
Tellurium Atom ◽  
Titanium Complex ◽  
X Ray ◽  
X Ray Crystallography ◽  
Atom Source

Reaction of McConville's chelating amido titanium complex [(Ar)NCH2CH2CH2N(Ar)]Ti(CH3)2 (Ar = 2,6-i-Pr2C6H3) with either elemental Se or the tellurium atom source Te=PBu3 resulted in the formation of bis-µ-chalcogenido dimers [(Ar)NCH2CH2CH2N(Ar)]2Ti(µ-E)2 (E = Se, 2; Te, 3) with concommitant loss of EMe2. The dimers 2 and 3 were characterized spectroscopically and via X-ray crystallography. The two compounds are isostructural in the solid state. The tellurido dimer 3 may also be synthesized by reduction of the diamido dichloride [(Ar)NCH2CH2CH2N(Ar)]2TiCl2 with Na–Hg amalgam followed by treatment with Te=PBu3. This dimer is unreactive toward further Te=PBu3 or stannanes such as HSnBu3. Unlike decamethyltitanocene derivatives, the diamido complex is not an effective catalyst precursor for the heterohydrodecoupling of Te=PBu3 and HSnBu3.Key words: diamido titanium complexes, selenides, tellurides.

scholarly journals KARAKTERISTIK AKAR BEREKTOMIKORIZA PADA Shorea pinanga, Pinus merkusii DAN Gnetum gnemon

PERENNIAL ◽  
2010 ◽  
Vol 6 (1) ◽  
pp. 11
Author(s):  
Melya Riniarti ◽  
Irdika Mansur ◽  
Arum Sekar Wulandari ◽  
Cecep Kusmana
Keyword(s):  
Key Words ◽  
Ectomycorrhizal Fungi ◽  
Host Plants ◽  
Clamp Connection ◽  
The Other ◽  
Branching Pattern ◽  
Root Tips ◽  
Hartig Net ◽  
Gnetum Gnemon ◽  
Pinus Merkusii

Morphology and anatomy characteristics often used to identify ectomycorrhizal fungi. We used three Scleroderma spp. (Scleroderma columnare, S. dictyosporum), and S. sinnamariense) and inoculated to Shorea pinanga, Pinus merkusii, and Gnetum gnemon. After 6,8, and 10 months, each root tips were collected to determined hyphae colour, branching pattern, clamp-connection, hartig net and mantle. This result revealed that S. sinnamariense did not form association with S. pinanga and P. merkusii but form association with G. gnemon. On the other hand, S. columnare and S. dictyosporum could form association with all the host plants. S. columnare and S. dictyosporum formed white hyphae while S. sinnamariense formed yellow hyphae with monopodial branching pattern. The depth of hartig net and mantle was increased by timed. Key words: ectomycorrhizal fungi, hartig net, mantle, Scleroderma

scholarly journals Karyotype and meiotic behaviour in Zephyranthes (Amaryllidaceae) from south America.

CYTOLOGIA ◽  
1989 ◽  
Vol 54 (2) ◽  
pp. 269-274 ◽  
Author(s):  
Julio R. Davña ◽  
Aveliano Fernández
Keyword(s):  
South America ◽  
Meiotic Behaviour
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