Expression of Two Rye CENH3 Variants and Their Loading into Centromeres

Area of Science:

• Evolutionary biology
• Molecular genetics
• Plant biology

Background:

• Gene duplication is a key evolutionary mechanism driving functional innovation.
• Centromere specification relies on the centromere-specific histone H3 (CENH3).
• Cereal species exhibit varying numbers of CENH3 gene copies, offering a model for studying duplication effects.

Purpose of the Study:

• To investigate the functional activity and evolutionary fate of duplicated CENH3 genes in rye (Secale cereale L.).
• To compare the expression and protein loading of CENH3 in plants with single vs. duplicated gene copies.

Main Methods:

• Analysis of CENH3 locus organization and identification of functional motifs in rye.
• Comparative gene expression analysis across different developmental stages.
• Assessment of CENH3 protein loading into nucleosomes during mitosis and meiosis using extended chromatin fibers.

Main Results:

• Rye possesses two functional CENH3 gene copies with conserved function, showing no signs of neofunctionalization, subfunctionalization, or specialization.
• Negative selection maintained the conserved function of the coding regions.
• The presence of two functional CENH3 genes provides a gene-dosage advantage.

Conclusions:

• The duplication of CENH3 genes in rye is maintained through negative selection, preserving conserved function.
• The primary benefit of CENH3 gene duplication in rye appears to be a gene-dosage effect, enhancing functional output.