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Duplicated Genomes Helped Grasses Diversify and Thrive
Context:
A new analysis by Penn State biologists examined the genomes of over 350 grass species, reconstructing the ancestral grass genome to understand its early characteristics.
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- Earlier a more complete phylogeny of grasses was built, enabling the tracking of duplicated gene pairs across related species.
- It’s kind of like molecular palaeontology. This approach helps reconstruct the evolutionary history of genome duplications like finding bones from different dinosaurs to reconstruct a more complete picture of the entire skeleton.
Key Highlights:
- Grasses cover about 40% of the Earth’s land surface and include crucial crops such as rice, maize, wheat, and bamboo.
- According to a new analysis, the evolutionary success of the grass family is likely due to a history of whole-genome duplications.
- A whole-genome duplication event referred to as rho, resulted in ancestral grass cells having two copies of their genetic information.
- Discovered additional, more recent whole-genome duplications in specific grass lineages and tracked which duplicated genes were retained or lost in individual species.
- Genes retained from the rho duplication event include those for aquatic adaptation in rice, cold adaptation in wheat and related species, rapid cell growth in bamboo, and drought response in maize.
- Nine previously unknown whole-genome duplication events were identified among individual grass lineages.
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Whole-Genome Duplications:
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How does it work?
- Hybridisation and Duplication: Sometimes, different species of grasses can hybridise and produce offspring. When this happens, the resulting plant inherits two copies of all genes—one from each parent species.
- These duplicated genes may be slightly different due to their origins, but one copy is considered redundant.
- Evolutionary Freedom: Redundant genes provide a unique advantage. While mutations in a single gene can be detrimental, duplicated genes allow one copy to evolve freely without compromising the plant’s function.
- Gene Conversion and Evolution: Over time, various processes come into play. It can make the two copies more similar, while sometimes one copy is lost altogether. Occasionally, one copy evolves a new function, contributing to the grasses’ adaptability.
Implications:
- Understanding these duplications highlights their role in the successful colonisation of diverse environments by grasses.
- Insights from the study could guide selective breeding in crops, leveraging natural adaptations for better resilience and productivity.