CHARACTERIZATION OF CENTROMERIC HISTONE H3 VARIANTS IN ALLOPOLYPLOIDS OF WHEAT AND RYE

Area of Science:

• Plant genetics
• Genomics
• Cell biology

Background:

• Chromosome elimination in interspecific hybrids, a common issue in remote hybridization, hinders successful development.
• Centromeres, crucial for chromosome segregation, rely on specialized histone H3 modifications (CENH3).
• CENH3's N-terminal tail (NTT) is vital for its loading into centromeric chromatin.

Purpose of the Study:

• To comparatively analyze CENH3 variants expression in wheat-rye allopolyploids and their parental species.
• To investigate the role of CENH3 N-terminal tail (NTT) sequence variations in hybrid genomes.
• To understand the contribution of parental CENH3 to the stability of allopolyploid genomes.

Main Methods:

• Comparative sequence analysis of CENH3 N-terminal tail (NTT) coding sequences.
• Identification of single nucleotide polymorphisms (SNPs) and deletions in NTT sequences.
• Analysis of CENH3 variant expression in parental wheat (Triticum aestivum L.) and rye (Secale cereale L.) varieties and their allopolyploids.

Main Results:

• Identified full-length NTT CENH3 copies and copies with 21 bp or 66 bp deletions in wheat and rye.
• Rye NTT CENH3 copies with 66 bp deletions showed specific SNPs also present in wheat-rye allopolyploids.
• Full-length rye NTT CENH3 sequences with specific SNPs were detected in all analyzed wheat-rye allopolyploids, with higher frequency in secalotriticum.

Conclusions:

• Expression of CENH3 copies from both parental species occurs in hybrid genomes.
• NTT CENH3 copies with deletions were absent in secalotriticum.
• Preferential synthesis of full-length rye NTT CENH3 copies in secalotriticum suggests their importance for genome stability.