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Abstract Hybridization in plants is often accompanied by nuclear genome doubling (allopolyploidy), which has been hypothesized to perturb interactions between nuclear and organellar (mitochondrial and plastid) genomes by creating imbalances in the relative copy number of these genomes and producing genetic incompatibilities between maternally derived organellar genomes and the half of the allopolyploid nuclear genome from the paternal progenitor. Several evolutionary responses have been predicted to ameliorate these effects, including selection for changes in protein sequences that restore cytonuclear interactions; biased gene retention/expression/conversion favoring maternal nuclear gene copies; and fine-tuning of relative cytonuclear genome copy numbers and expression levels. Numerous recent studies, however, have found that evolutionary responses are inconsistent and rarely scale to genome-wide generalities. The apparent robustness of plant cytonuclear interactions to allopolyploidy may reflect features that are general to allopolyploids such as the lack of F2 hybrid breakdown under disomic inheritance, and others that are more plant-specific, including slow sequence divergence in organellar genomes and preexisting regulatory responses to changes in cell size and endopolyploidy during development. Thus, cytonuclear interactions may only rarely act as the main barrier to establishment of allopolyploid lineages, perhaps helping to explain why allopolyploidy is so pervasive in plant evolution.
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Genome‐wide patterns of homoeologous gene flow in allotetraploid coffee
Abstract PremiseAllopolyploidy—a hybridization‐induced whole‐genome duplication event—has been a major driver of plant diversification. The extent to which chromosomes pair with their proper homolog vs. with their homoeolog in allopolyploids varies across taxa, and methods to detect homoeologous gene flow (HGF) are needed to understand how HGF has shaped polyploid lineages. MethodsThe ABBA‐BABA test represents a classic method for detecting introgression between closely related species, but here we developed a modified use of the ABBA‐BABA test to characterize the extent and direction of HGF in allotetraploidCoffea arabica. ResultsWe found that HGF is abundant in theC. arabicagenome, with both subgenomes serving as donors and recipients of variation. We also found that HGF is highly maternally biased in plastid‐targeted—but not mitochondrial‐targeted—genes, as would be expected if plastid–nuclear incompatibilities exist between the two parent species. DiscussionTogether, our analyses provide a simple framework for detecting HGF and new evidence consistent with selection favoring overwriting of paternally derived alleles by maternally derived alleles to ameliorate plastid–nuclear incompatibilities. Natural selection therefore appears to shape the direction and intensity of HGF in allopolyploid coffee, indicating that cytoplasmic inheritance has long‐term consequences for polyploid lineages.
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- Award ID(s):
- 2145811
- PAR ID:
- 10568645
- Publisher / Repository:
- Applications in Plant Sciences
- Date Published:
- Journal Name:
- Applications in Plant Sciences
- Volume:
- 12
- Issue:
- 4
- ISSN:
- 2168-0450
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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