Homoeolog expression bias and expression level dominance in allopolyploid cotton

Area of Science:

• Genomics
• Evolutionary Biology
• Plant Science

Background:

• Allopolyploidy involves merging and regulating diverged genomes.
• Understanding gene expression changes post-hybridization is crucial for polyploid evolution.

Purpose of the Study:

• To investigate gene expression patterns in cotton hybrids and allopolyploids.
• To determine how expression level dominance and homoeolog bias change during polyploidization and evolution.

Main Methods:

• RNA-Seq analysis of leaf transcriptomes from F(1) hybrids, synthetic, and natural allopolyploid cotton.
• Quantification of expression level dominance and homoeolog expression bias.

Main Results:

• Genome-wide expression level dominance showed A-genome bias in hybrids/natural allopolyploids, reversed in synthetic allopolyploids.
• Altered homoeolog bias and dominance occurred upon genome merger, driven by regulatory and epigenetic interactions.
• Expression bias and dominance increased over time, with natural allopolyploids exhibiting higher rates of novel expression and homoeolog silencing.

Conclusions:

• Natural selection acts on regulatory mismatches in allopolyploids, generating new expression patterns.
• Evolution at the polyploid level leads to increased complexity in gene expression regulation.