Variation in hybrid fertility among the disjunct populations and species of Sullivantia (Saxifragaceae)

1981 ◽  
Vol 59 (7) ◽  
pp. 1174-1180 ◽  
Author(s):  
Douglas E. Soltis
Keyword(s):  
Interspecific Hybrids ◽  
Chromosomal Rearrangements ◽  
Geographical Distance ◽  
Viable Seed ◽  
Hybrid Fertility ◽  
Gross Chromosomal Rearrangements ◽  
Disjunct Populations ◽  
Intraspecific Hybrids ◽  
Meiotic Aberrations ◽  
Made In

Crosses were made in all combinations between the four allopatric taxa of Sullivantia. Artificial hybridizations between any two Sullivantia plants almost invariably yielded viable seed that produced vigorous F1 hybrids. The observation that Sullivantia species are highly interfertile is in agreement with similar findings for many other north temperate perennial plants. In most cases, the average pollen fertility of interspecific hybrids is reduced compared with the fertility of parental plants and intraspecific hybrids. Since no meiotic aberrations were observed in hybrids, gross chromosomal rearrangements apparently are not responsible for the reductions in hybrid fertility. Within Sullivantia there is a general correlation between geographical distance separating parental populations and reduction in hybrid fertility. Similar correlations have been reported for several other angiospermous species, but the present study is the first report of such a geographical distance – fertility correlation within an entire genus.

Relationship in annual spceies of Medicago. III. The complex M. littoralis Rhode-M. truncatula Gaertn

1967 ◽  
Vol 15 (1) ◽  
pp. 35 ◽  
Author(s):  
JP Simon ◽  
AJ Millington
Keyword(s):  
Interspecific Hybrids ◽  
Seed Set ◽  
Chromosomal Rearrangements ◽  
Chromosome Translocation ◽  
Pollen Sterility ◽  
Multivalent Formation ◽  
Structural Differences ◽  
Intraspecific Hybrids ◽  
Adult Plants ◽  
Cytological Behaviour

A programme of interspecific hybridization, involving species from subsections Pachyspirae, Leptospirae, and Rotatae of section Spirocarpos, resulted in only one successful combination out of the 20 attempted. Viable hybrids were obtained with ease in crosses between different accessions of M. littoralis and M. truncatula. The morphology, fertility, and cytological behaviour of interspecific hybrids involving seven strains of M. truncatula and three strains of M. littoralis was compared with intraspecific hybrids of each species. With the exception of those with N.2829, which was differentiated from the other strains by one chromosome translocation, intraspecific hybrids of M. truncatula were fully fertile. Considerable pollen sterility and reduced seed set were observed in intraspecific crosses of M. littoralis, but there was no evidence of chromosomal rearrangements. The morphology of the hybrids between M. littoralis and M. truncatula was intermediate between the parents. Chlorophyll deficiency in seedlings and adult plants, dwarfism, and other morphological irregularities were observed in F2 plants. In some FT1s failure of pairing, multivalent formation at metaphase I, and other irregularities at meiosis indicated chromosome rearrangements. Up to three independent translocations and one inversion in the hybrid combinations and pronounced sterility were observed in both FT1s and FT2s. The pollen sterility of the hybrids could be explained in several instances by structural differences, but these do not account completely for the results obtained. Inheritance studies of three possible strain markers indicated simple monohybrid segregation in most intraspecific crosses, but in the interspecific and partially fertile intraspecific crosses, ratios were disturbed and phenotypes abnormal. The agronomic implications of these studies are discussed.

SINE-B1 Distribution and Chromosome Rearrangements in the South American Proechimys gr. goeldii (Echimyidae, Rodentia)

2021 ◽  
pp. 1-8
Author(s):  
Naiara P. Araújo ◽  
Radarane S. Sena ◽  
Cibele R. Bonvicino ◽  
Gustavo C.S. Kuhn ◽  
Marta Svartman
Keyword(s):  
Transposable Element ◽  
Genome Evolution ◽  
Significant Role ◽  
Sex Chromosomes ◽  
Chromosomal Rearrangements ◽  
Evolutionary Relationship ◽  
Chromosome Rearrangements ◽  
South American ◽  
Gross Chromosomal Rearrangements

<i>Proechimys</i> species are remarkable for their extensive chromosome rearrangements, representing a good model to understand genome evolution. Herein, we cytogenetically analyzed 3 different cytotypes of <i>Proechimys</i> gr. <i>goeldii</i> to assess their evolutionary relationship. We also mapped the transposable element SINE-B1 on the chromosomes of <i>P.</i> gr. <i>goeldii</i> in order to investigate its distribution among individuals and evaluate its possible contribution to karyotype remodeling in this species. SINE-B1 showed a dispersed distribution along chromosome arms and was also detected at the pericentromeric regions of some chromosomes, including pair 1 and the sex chromosomes, which are involved in chromosome rearrangements. In addition, we describe a new cytotype for <i>P.</i> gr. <i>goeldii</i>, reinforcing the significant role of gross chromosomal rearrangements during the evolution of the genus. The results of FISH with SINE-B1 suggest that this issue should be more deeply investigated for a better understanding of its role in the mechanisms involved in the wide variety of <i>Proechimys</i> karyotypes.

RELATIONSHIP OF TAXA IN THE GENUS MEDICAGO AS REVEALED BY HYBRIDIZATION. I. M. STRIATA × M. LITTORALIS

1968 ◽  
Vol 10 (2) ◽  
pp. 263-275 ◽  
Author(s):  
K. Lesins ◽  
A. Erac
Keyword(s):  
High Mortality ◽  
Genetic Factor ◽  
Genetic Factors ◽  
Chromosomal Rearrangements ◽  
Cytoplasmic Factor ◽  
Reciprocal Crosses ◽  
Gross Chromosomal Rearrangements ◽  
Coiling Direction ◽  
Chlorophyll Deficiencies ◽  
Relationship Of

In crosses between the two taxa Medicago striata Bast, and M. littoralis Rohde a high mortality of gametes and seedlings, and sterility of some plants were noted which were not related to gross chromosomal rearrangements. Although the F1, F2 and F3 generations from reciprocal crosses differed in chlorophyll deficiencies (indicating a cytoplasmic influence) a genic cause became evident from segregations for chlorophyll characters in the F2 and F3. Transference of the cytoplasmic factor by the pollen is indicative.Segregation for pod coiling direction indicated that the character was determined by one or two genetic factors of which the clockwise coiling direction is recessive. The spininess appeared to be determined by one genetic factor, of which the spineless allele is recessive.On the basis of genetic differences (especially on the built-in repulsion systems for normal chlorophyll development of opposite species) the two taxa should be considered two different species.

scholarly journals Meiosis-specific recombinase Dmc1 is a potent inhibitor of the Srs2 antirecombinase

2018 ◽  
Vol 115 (43) ◽  
pp. E10041-E10048 ◽  
Author(s):  
J. Brooks Crickard ◽  
Kyle Kaniecki ◽  
Youngho Kwon ◽  
Patrick Sung ◽  
Eric C. Greene
Keyword(s):  
Chromosome Segregation ◽  
Single Molecule ◽  
Atp Hydrolysis ◽  
Potent Inhibitor ◽  
Chromosomal Rearrangements ◽  
Motor Protein ◽  
Product Formation ◽  
Gross Chromosomal Rearrangements ◽  
Strand Annealing ◽  
Hydrolysis Activity

Cross-over recombination products are a hallmark of meiosis because they are necessary for accurate chromosome segregation and they also allow for increased genetic diversity during sexual reproduction. However, cross-overs can also cause gross chromosomal rearrangements and are therefore normally down-regulated during mitotic growth. The mechanisms that enhance cross-over product formation upon entry into meiosis remain poorly understood. In Saccharomyces cerevisiae, the Superfamily 1 (Sf1) helicase Srs2, which is an ATP hydrolysis-dependent motor protein that actively dismantles recombination intermediates, promotes synthesis-dependent strand annealing, the result of which is a reduction in cross-over recombination products. Here, we show that the meiosis-specific recombinase Dmc1 is a potent inhibitor of Srs2. Biochemical and single-molecule assays demonstrate that Dmc1 acts by inhibiting Srs2 ATP hydrolysis activity, which prevents the motor protein from undergoing ATP hydrolysis-dependent translocation on Dmc1-bound recombination intermediates. We propose a model in which Dmc1 helps contribute to cross-over formation during meiosis by antagonizing the antirecombinase activity of Srs2.

Patterns of genome duplication within the Brassica napus genome

Genome ◽  
2003 ◽  
Vol 46 (2) ◽  
pp. 291-303 ◽  
Author(s):  
I A.P Parkin ◽  
A G Sharpe ◽  
D J Lydiate
Keyword(s):  
Brassica Napus ◽  
Genome Duplication ◽  
Chromosomal Rearrangements ◽  
Centric Fusion ◽  
Linkage Groups ◽  
Gross Chromosomal Rearrangements ◽  
A Genome ◽  
C Genome ◽  
Homologous Locus ◽  
Duplicate Loci

The progenitor diploid genomes (A and C) of the amphidiploid Brassica napus are extensively duplicated with 73% of genomic clones detecting two or more duplicate sequences within each of the diploid genomes. This comprehensive duplication of loci is to be expected in a species that has evolved through a polyploid ancestor. The majority of the duplicate loci within each of the diploid genomes were found in distinct linkage groups as collinear blocks of linked loci, some of which had undergone a variety of rearrangements subsequent to duplication, including inversions and translocations. A number of identical rearrangements were observed in the two diploid genomes, suggesting they had occurred before the divergence of the two species. A number of linkage groups displayed an organization consistent with centric fusion and (or) fission, suggesting this mechanism may have played a role in the evolution of Brassica genomes. For almost every genetically mapped locus detected in the A genome a homologous locus was found in the C genome; the collinear arrangement of these homologous markers allowed the primary regions of homoeology between the two genomes to be identified. At least 16 gross chromosomal rearrangements differentiated the two diploid genomes during their divergence from a common ancestor.Key words: genome evolution, Brassicaeae, polyploidy, homoeologous linkage groups.

scholarly journals Heterochromatin suppresses gross chromosomal rearrangements at centromeres by repressing Tfs1/TFIIS-dependent transcription

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Akiko K. Okita ◽  
Faria Zafar ◽  
Jie Su ◽  
Dayalini Weerasekara ◽  
Takuya Kajitani ◽  
...  
Keyword(s):  
Chromosomal Rearrangements ◽  
Gross Chromosomal Rearrangements

Analysis of Gross‐Chromosomal Rearrangements in Saccharomyces cerevisiae

2006 ◽  
pp. 462-476 ◽  
Author(s):  
Kristina H. Schmidt ◽  
Vincent Pennaneach ◽  
Christopher D. Putnam ◽  
Richard D. Kolodner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosomal Rearrangements ◽  
Gross Chromosomal Rearrangements
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