DNA content, repeatome composition and origin of the Zea mays micronuclei

Area of Science:

• Genetics
• Molecular Biology
• Plant Science

Background:

• Micronuclei are indicators of DNA damage from clastogenic and aneugenic effects.
• Previous studies identified centromere, telomere, and rDNA sequences in plant micronuclei.
• The full genomic composition and DNA content of micronuclei remain incompletely understood.

Purpose of the Study:

• To investigate the DNA content, genomic composition, and origin of micronuclei induced by methyl methanesulfonate (MMS) in Zea mays.
• To characterize the diversity of micronuclei generated by genotoxic agents.
• To explore the potential of micronuclei analysis in mutagenesis research.

Main Methods:

• Induction of micronuclei in Zea mays using methyl methanesulfonate (MMS).
• Analysis of DNA content distribution in micronuclei.
• In situ probing of micronuclei with specific DNA sequences (5S and 18S rDNAs, 180-bp knob, Grande LTR-retrotransposon) and DAPI staining.
• Construction of probe pools from microdissected micronuclei for hybridization analysis on Zea mays chromosomes.

Main Results:

• Micronuclei exhibited a wide range of DNA content, indicating diverse genomic origins.
• In situ probing revealed the presence of specific DNA sequences, with potential hotspots for MMS damage identified in guanine-rich regions.
• Hybridization of probe pools demonstrated that individual micronuclei possess distinct genomic compositions, originating from various chromosomes.

Conclusions:

• Micronuclei in Zea mays induced by MMS display significant genomic diversity in content and composition.
• The study illustrates the extent of genotoxic damage to the nuclear genome.
• Micronuclei represent a valuable tool for further research into mutagenesis and genotoxicity.