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Maintaining Heterokaryosis in Pseudo-Homothallic Fungi

Summary

This research explores how certain fungi maintain two different types of nuclei in their cells, allowing them to reproduce both by self-fertilization and by mating with others. This unusual ability helps these fungi survive and adapt in various environments. Impact on everyday life: – Improved understanding of fungal reproduction could help in developing better mushroom cultivation methods – Knowledge of fungal genetics aids in biotechnology applications – Better comprehension of evolution and adaptation mechanisms in organisms – Potential applications in crop breeding and agricultural improvements – Insights into biological diversity maintenance in nature

Background

Fungi have developed various dispersal strategies including pseudo-homothallism, where self-fertile mycelium contains two genetically-compatible nuclei. This allows reproduction without finding a compatible partner while maintaining the ability to cross with other mates. Pseudo-homothallic species can be found in many groups of ascomycetes and basidiomycetes, with three well-studied examples being Neurospora tetrasperma, Podospora anserina, and Agaricus bisporus.

Objective

To examine and summarize the mechanisms involved in creating and maintaining heterokaryosis in pseudo-homothallic fungi, particularly focusing on how sexually-compatible nuclei end up in the same spore after meiosis and how heterokaryosis is maintained throughout the life cycle.

Results

Different mechanisms for achieving heterokaryosis were found in each species. In P. anserina, the mating type locus undergoes Second Division Segregation in 99% of cases with perpendicular post-meiotic spindles. N. tetrasperma shows First Division Segregation with overlapping meiosis II spindles. A. bisporus exhibits preferential migration of non-sister nuclei into basidiospores. Recombination is inhibited around the mating type locus in both P. anserina and N. tetrasperma, though through different mechanisms.

Conclusion

Pseudo-homothallic fungi have evolved multiple sophisticated mechanisms to create and maintain the dikaryotic state, operating during both sexual reproduction and vegetative growth. These adaptations allow them to maintain genetic diversity while enabling both selfing and outcrossing capabilities.
  • Published in:Communicative & Integrative Biology,
  • Study Type:Review,
  • Source: 10.4161/19420889.2014.994382
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