The pachytene checkpoint and its relationship to evolutionary patterns of polyploidization and hybrid sterility

  title={The pachytene checkpoint and its relationship to evolutionary patterns of polyploidization and hybrid sterility},
  author={X C Li and Brian C. Barringer and Daniel A. Barbash},
Sterility is a commonly observed phenotype in interspecific hybrids. Sterility may result from chromosomal or genic incompatibilities, and much progress has been made toward understanding the genetic basis of hybrid sterility in various taxa. The underlying mechanisms causing hybrid sterility, however, are less well known. The pachytene checkpoint is a meiotic surveillance system that many organisms use to detect aberrant meiotic products, in order to prevent the production of defective gametes… 

Meiosis in Polyploid Plants

A more relaxed control of pairing and segregation in polyploids might be an important contribution to evolution and adaptation potential, especially under drastic or frequent changes in environmental conditions.

MAT heterozygosity and the second sterility barrier in the reproductive isolation of Saccharomyces species

It is found that the allospecific MAT heterozygosity repressed MAT switching and mating in the hybrids and in the viable but sterile spores produced by the cevarum hybrids that had increased (allotetraploid) genomes.

Polyploidy‐associated genomic instability in Arabidopsis thaliana

It is demonstrated that the ploidy increased for two consecutive generations due to unreduced but viable gametes in the Arabidopsis cyclin a1;2‐2 (also named tardy asynchronous meiosis‐2) mutant, but the resultant octaploid plants produced progeny of either the same or reduced ploids via genomic reductions during meiosis and pollen mitosis.

A High Incidence of Meiotic Silencing of Unsynapsed Chromatin Is Not Associated with Substantial Pachytene Loss in Heterozygous Male Mice Carrying Multiple Simple Robertsonian Translocations

It is proposed that a low stringency of the pachytene checkpoint could help to increase the chances that spermatocytes with synaptic defects will complete meiotic divisions and differentiate into viable gametes, explaining the multitude of natural Robertsonian populations described in the mouse.

desynaptic5 carries a spontaneous semi-dominant mutation affecting Disrupted Meiotic cDNA 1 in barley

An exonic insertion in the positional candidate ortholog of Disrupted Meiotic cDNA 1 (HvDMC1) on chromosome 5H of des5 is identified, indicating the value of non-knockout mutations for dissection of the control of recombination in the early stages of meiosis.

Karyotype variation, spontaneous genome rearrangements affecting chemical insensitivity, and expression level polymorphisms in the plant pathogen Phytophthora infestans revealed using its first chromosome-scale assembly

Light is shed on diverse phenomena affecting variation in P. infestans and relatives, helps explain the prevalence of polyploidy in natural populations, and provides a new foundation for biologic and genetic investigations.

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If transposable elements in the seed are not targeted by small RNA from the pollen, or vice versa, this could lead to hybrid seed failure, in a mechanism reminiscent of hybrid dysgenesis in Drosophila.

Ploidy Dictates Repair Pathway Choice under DNA Replication Stress

This study reports an unusual ploidy-specific response to replication stress presented by a defective minichromosome maintenance (MCM) helicase allele in yeast and uncovers a fundamental difference between haplophase and diplophase in the maintenance of genome integrity.

Starvation-Associated Genome Restructuring Can Lead to Reproductive Isolation in Yeast

This model provides direct genetic evidence that reproductive isolation can arise frequently in stressed populations via genome restructuring without the precondition of geographic isolation.



Studies on Hybrid Sterility. II. Localization of Sterility Factors in Drosophila Pseudoobscura Hybrids.

It remains possible that suppression of meiotic pairing may be caused by different mechanisms in different cases, and that sometimes there is no cause and effect relation between the failure of paking and the sterility.

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  • Biology
    Plant Molecular Biology
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Insight into genome function gained from the study of allopolyploidy may be applicable to hybrids of any type and may even elucidate positive interactions, such as those responsible for hybrid vigor.

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It is suggested that duplicate genes, and more generally any kind of genomic redundancies, provide a powerful substrate for the origin of genomic incompatibilities in isolated populations.


The results indicate that the triploid bridge pathway can contribute significantly to autopolyploids formation regardless of the mating system, and to allopolyploid formation in outcrossing taxa.

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It is found that recessive hybrid incompatibilities outnumber dominant ones and that hybrid male steriles outnumber all other types of incompatibility, consistent with the dominance and faster-male theories of Haldane's rule.

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The results suggest that nuclear fusion requires dynamic microtubules, similar to Saccharomyces cerevisiae, C. reinhardtii mating-type functions necessary for nuclear fusion are not nuclear limited and can act through the cytoplasm.

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  • Biology, Medicine
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Comparative linkage mapping is used to demonstrate extensive genomic reorganization in the hybrid species Helianthm anomalus, relative to its parents H. annuus and H. petiolaris, and satisfy genetic models for speciation through hybrid recombination.

‘why polyploidy is rarer in animals than in plants’: myths and mechanisms

The evidence for and against some of the traditional views on polyploidy is reviewed, with an attempt to synthesize factors promoting evolution through genome duplication in both groups.