Rapid GC content evolution in rice through GC-biased gene conversion and selection for translation efficiency

Area of Science:

• Genomics
• Molecular Evolution
• Plant Biology

Background:

• GC-biased gene conversion (gBGC) is a mechanism that increases GC content during recombination.
• gBGC's role in plants is less understood compared to yeast and animals.
• gBGC is generally more effective in outcrossing species.

Purpose of the Study:

• To investigate the presence and impact of gBGC in rice (Oryza sativa).
• To understand the factors shaping GC content in rice's coding and noncoding regions.
• To evaluate the influence of outcrossing on GC content in rice.

Main Methods:

• Analysis of GC content in coding and noncoding sequences of rice.
• Correlation of GC content with recombination frequency.
• Assessment of GC content changes in relation to outcrossing levels.

Main Results:

• GC content in rice noncoding sequences correlates with recombination frequency.
• GC content in coding regions is influenced by recombination and selection for GC-rich codons.
• Both rice and its wild progenitor show declining GC content.
• No evidence suggests full outcrossing leads to increased GC content in rice.

Conclusions:

• Mutations appear to be a more dominant force than gBGC in altering GC content in rice.
• GC content is predicted to continue declining in rice and related species.
• The effectiveness of gBGC in plants may be less significant than previously thought, or other factors are overriding its effect.