Hybrid Incompatibility Caused by an Epiallele. Blevins, T.; Wang, J.; Pflieger, D.; Pontvianne, F.; and Pikaard, C. S. 114(14):3702–3707.
Hybrid Incompatibility Caused by an Epiallele [link]Paper  doi  abstract   bibtex   
[Significance] Deleterious mutations in different copies of a duplicated gene pair have the potential to cause hybrid incompatibility between diverging subpopulations, contributing to reproductive isolation and speciation. This study demonstrates a case of epigenetic gene silencing rather than pseudogene creation by mutation, contributing to a lethal gene combination on hybridization of two ecotypes of Arabidopsis thaliana. Our findings provide direct evidence that naturally occurring epigenetic variation can contribute to incompatible hybrid genotypes, reducing gene flow between subtypes of the same species. [Abstract] Hybrid incompatibility resulting from deleterious gene combinations is thought to be an important step toward reproductive isolation and speciation. Here, we demonstrate involvement of a silent epiallele in hybrid incompatibility. In Arabidopsis thaliana accession Cvi-0, one of the two copies of a duplicated histidine biosynthesis gene, HISN6A, is mutated, making HISN6B essential. In contrast, in accession Col-0, HISN6A is essential because HISN6B is not expressed. Owing to these differences, Cvi-0 × Col-0 hybrid progeny that are homozygous for both Cvi-0 HISN6A and Col-0 HISN6B do not survive. We show that HISN6B of Col-0 is not a defective pseudogene, but a stably silenced epiallele. Mutating HISTONE DEACETYLASE 6 (HDA6), or the cytosine methyltransferase genes MET1 or CMT3, erases HISN6B's silent locus identity, reanimating the gene to circumvent hisn6a lethality and hybrid incompatibility. These results show that HISN6-dependent hybrid lethality is a revertible epigenetic phenomenon and provide additional evidence that epigenetic variation has the potential to limit gene flow between diverging populations of a species.
@article{blevinsHybridIncompatibilityCaused2017,
  title = {Hybrid Incompatibility Caused by an Epiallele},
  author = {Blevins, Todd and Wang, Jing and Pflieger, David and Pontvianne, Frédéric and Pikaard, Craig S.},
  date = {2017-04},
  journaltitle = {Proceedings of the National Academy of Sciences},
  volume = {114},
  pages = {3702--3707},
  issn = {1091-6490},
  doi = {10.1073/pnas.1700368114},
  url = {https://doi.org/10.1073/pnas.1700368114},
  abstract = {[Significance]

Deleterious mutations in different copies of a duplicated gene pair have the potential to cause hybrid incompatibility between diverging subpopulations, contributing to reproductive isolation and speciation. This study demonstrates a case of epigenetic gene silencing rather than pseudogene creation by mutation, contributing to a lethal gene combination on hybridization of two ecotypes of Arabidopsis thaliana. Our findings provide direct evidence that naturally occurring epigenetic variation can contribute to incompatible hybrid genotypes, reducing gene flow between subtypes of the same species.

[Abstract] Hybrid incompatibility resulting from deleterious gene combinations is thought to be an important step toward reproductive isolation and speciation. Here, we demonstrate involvement of a silent epiallele in hybrid incompatibility. In Arabidopsis thaliana accession Cvi-0, one of the two copies of a duplicated histidine biosynthesis gene, HISN6A, is mutated, making HISN6B essential. In contrast, in accession Col-0, HISN6A is essential because HISN6B is not expressed. Owing to these differences, Cvi-0 × Col-0 hybrid progeny that are homozygous for both Cvi-0 HISN6A and Col-0 HISN6B do not survive. We show that HISN6B of Col-0 is not a defective pseudogene, but a stably silenced epiallele. Mutating HISTONE DEACETYLASE 6 (HDA6), or the cytosine methyltransferase genes MET1 or CMT3, erases HISN6B's silent locus identity, reanimating the gene to circumvent hisn6a lethality and hybrid incompatibility. These results show that HISN6-dependent hybrid lethality is a revertible epigenetic phenomenon and provide additional evidence that epigenetic variation has the potential to limit gene flow between diverging populations of a species.},
  keywords = {*imported-from-citeulike-INRMM,~INRMM-MiD:c-14332948,arabidopsis-thaliana,constraints,diversity,epigenetic-variation,genetic-diversity,hybrid-incompatibility,hybridisation,niche-limits,non-linearity,vegetation},
  number = {14}
}
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