VARIABILITY OF CENTROMERIC HISTONE H3 VARIANTS AND PHYLOGENETIC RELATIONSHIPS IN SECALE

Area of Science:

• Plant genetics
• Molecular evolution
• Epigenetics

Background:

• Centromeric histone H3 (CENH3) is crucial for centromere identity and function.
• Understanding CENH3 variation provides insights into plant evolution and adaptation.
• Rye (Secale) species exhibit diverse life histories and breeding systems.

Purpose of the Study:

• To investigate nucleotide sequence variation in CENH3 across fifteen rye species and subspecies.
• To compare genetic diversity within the N-terminal tail (NTT) and histone fold domain (HFD) of CENH3.
• To explore the relationship between CENH3 diversity and rye life history traits.

Main Methods:

• Sequencing of the CENH3 gene in fifteen diverse rye taxa.
• Estimation of nucleotide diversity (p) and number of segregating sites (S).
• Comparative analysis of diversity levels between NTT and HFD, and across different rye groups.

Main Results:

• Nucleotide diversity was consistently higher in the CENH3 N-terminal tail (NTT) compared to the histone fold domain (HFD).
• Perennial rye (Secale strictum) showed similar NTT diversity to annual rye (S. cereale), with higher diversity in ancient species (S. silvestre).
• Patterns of nucleotide polymorphism were similar between self-pollinating and cross-pollinating rye subspecies.

Conclusions:

• Higher nucleotide diversity in the CENH3 NTT suggests potential functional or evolutionary flexibility.
• Lower CENH3 nucleotide diversity in some wild and cultivated rye may be linked to ecological niche, evolutionary age, or breeding system.
• These findings contribute to understanding the evolutionary dynamics of centromeric histone genes in plants.