Point Mutations in Centromeric Histone Induce Post-zygotic Incompatibility and Uniparental Inheritance.

Area of Science:

• Genetics
• Molecular Biology
• Epigenetics

Background:

• The centromeric histone H3 variant (CENH3) is crucial for accurate chromosome segregation during cell division.
• Understanding CENH3's functional constraints is key to deciphering its role in genome stability.

Purpose of the Study:

• To investigate the functional impact of specific amino acid substitutions within the conserved histone fold domain of CENH3.
• To explore the potential of CENH3 mutations in generating haploid inducers for crop improvement.

Main Methods:

• Complementation of a null CENH3 allele in Arabidopsis with various mutant alleles.
• Analysis of growth, fertility, and inheritance patterns in transgenic and wild-type crosses.
• In silico identification of existing point mutations in CENH3.

Main Results:

• Missense mutations in the CENH3 histone fold domain can lead to post-zygotic lethality and uniparental inheritance.
• These mutations mimic genome elimination syndromes observed with chimeric or diverged CENH3.
• A single point mutation (A87V) was identified as sufficient to create a non-transgenic haploid inducer line in Arabidopsis.

Conclusions:

• Specific alterations in the CENH3 histone fold domain disrupt centromere function, causing genome instability.
• Single point mutations in CENH3 provide a simple, effective method for generating haploid inducers.
• This approach facilitates the identification of haploid inducers in existing mutagenized collections, accelerating crop breeding.