Reshaping epigenomic landscapes facilitated bread wheat speciation

Area of Science:

• Plant Genomics
• Epigenetics
• Evolutionary Biology

Background:

• Polyploidization is crucial for wheat (Triticum aestivum) evolution and speciation.
• The precise impact of polyploidization on epigenetic regulation and gene expression in wheat is not fully understood.

Purpose of the Study:

• To construct a high-resolution epigenetic landscape of wheat and its relatives.
• To investigate how epigenetic modifications and sequence variations influence gene expression and trait development during wheat evolution.

Main Methods:

• High-resolution epigenetic profiling across different tissues (leaves, spikes, roots) of diploid, tetraploid, and hexaploid wheat.
• Analysis of gene expression patterns, chromatin accessibility, and histone modifications (H3K27ac, H3K4me3).
• Identification and characterization of distal cis-regulatory elements (dCREs) and their role in gene regulation.

Main Results:

• Stably expressed genes show conserved sequences, while dynamic genes are linked to species-specific adaptation.
• Hexaploidization suppresses D-subgenome homoeolog expression through epigenetic modifications.
• Distal cis-regulatory elements (dCREs) exhibit high dynamism and are regulated by H3K27ac and H3K4me3.
• Sequence variations in dCREs, like in the TaDEP-B1 region, cause differential gene expression and affect spike morphology.
• Coevolution of transcription factors (e.g., ERF family) and their binding sites influences spike development.

Conclusions:

• Epigenetic modifications and sequence variations interact to shape transcriptional regulation during wheat speciation.
• Understanding these mechanisms provides insights into wheat genetic improvement and trait development.