Cytonuclear interplay in auto- and allopolyploids: a multifaceted perspective from the Festuca-Lolium complex

Area of Science:

• Plant genetics
• Evolutionary biology
• Cell biology

Background:

• Restoring cytonuclear stoichiometry is crucial following whole-genome duplication (WGD) and hybridization in plants.
• Understanding these mechanisms is key to comprehending early polyploid and hybrid generation development.

Purpose of the Study:

• Investigate cytonuclear stoichiometry restoration in Festuca-Lolium auto- and allopolyploids.
• Examine processes balancing nuclear and organelle genomes after WGD.

Main Methods:

• Comparative analysis of diploids and autopolyploids (new and established).
• Quantification of chloroplast and chloroplast genome copy numbers.
• Assessment of nuclear and organelle gene expression.
• Evaluation of allele expression in allopolyploid hybrids.

Main Results:

• Newly established and established autopolyploids showed increased chloroplast and chloroplast genome copy numbers.
• Chloroplast genome copy number expansion compensated for nuclear genome doubling.
• Nuclear and organelle gene expression changes were minimal.
• Biased maternal allele expression played a limited role in Festuca × Lolium hybrid cytonuclear stabilization.

Conclusions:

• Cytonuclear stoichiometry is restored in polyploids, primarily through chloroplast genome amplification.
• Potential structural conflicts exist in allopolyploid hybrids, with limited evidence for biased allele expression in stabilization.
• Further research into post-transcriptional regulation is needed for a complete understanding of cytonuclear gene expression stoichiometry.