State II dissociation element formation following activator excision in maize

Area of Science:

• Plant genetics
• Molecular biology
• Transposable elements

Background:

• Active Activator (Ac) elements in maize can spontaneously mutate into nonautonomous Dissociation (Ds) elements.
• Understanding the mechanism of Ac to Ds conversion is crucial for gene tagging and genome manipulation.

Purpose of the Study:

• To develop high-throughput genetic and molecular screens for identifying rare Ds derivatives from Ac insertions.
• To elucidate the molecular mechanisms underlying the formation of Dissociation (Ds) elements from Active Activator (Ac) elements in maize.

Main Methods:

• Development of novel high-throughput genetic screens.
• Application of molecular assays to characterize Ac-derived Ds elements.
• Analysis of DNA sequences at deletion junctions and flanking regions.

Main Results:

• Identification of 15 new Ds elements derived from Ac insertions at eight different maize loci.
• Characterization of filler DNA at deletion junctions in approximately half of the identified Ds elements, originating from Ac sequences.
• Observation that several Ds elements lack direct repeats flanking deletion junctions, contrary to previous reports.

Conclusions:

• A slip mispairing model during error-prone repair synthesis is proposed to explain the formation of state II Ds elements.
• The developed methods and identified Ds elements provide valuable tools for studying somatic Ds transposition in Ac/Ds tagging systems in maize.