Developmental and genetic aspects of Mutator excision in maize

Area of Science:

• Genetics
• Molecular Biology
• Plant Science

Background:

• The regulation of Mu elements, a family of maize transposable elements, is not well understood.
• Somatic instability of Mu receptor elements provides a method to study Mu element excision dynamics.

Purpose of the Study:

• To investigate the frequency and timing of Mu element excision in various maize tissues.
• To identify genetic factors influencing Mu element excision timing.

Main Methods:

• Monitoring somatic instability of Mu receptor elements at the Bronze 1 and Bronze 2 loci.
• Analyzing spot size variation in aleurone cells to infer excision timing.
• Investigating Mutator activity in tassel sectors and pollen shedding stages.
• Characterizing germinal revertants using Southern blot analysis.

Main Results:

• Mu element excision in aleurone cells begins eight divisions before differentiation and continues until after the final division.
• Excision timing is biased towards late events across studied tissues.
• A chromosome 5 locus was identified that potentially alters Mu excision timing.
• Mutator activity showed localized changes in tassel sectors but no overall change during pollen shedding.
• Germinal revertants of bz1::mu1 and bz2::mu1 alleles were recovered, with one characterized as similar to the progenitor allele.

Conclusions:

• Somatic instability of Mu elements offers a valuable assay for studying transposition dynamics.
• The timing of Mu element excision is a regulated process influenced by specific genetic loci.
• Understanding Mu element regulation is crucial for maize genetics and breeding applications.