Steady-state transposon mutagenesis in inbred maize

Area of Science:

• Plant Genomics
• Functional Genomics
• Transposable Elements

Background:

• High-copy transposons are powerful tools for genome analysis.
• The Mutator system in maize offers potential for mutagenesis but requires controlled behavior.

Purpose of the Study:

• To implement a novel strategy for functional analysis of the maize genome using high-copy transposons.
• To characterize the behavioral features of the Mutator system in a uniform inbred background.
• To establish a unique UniformMu population and database for high-throughput molecular analysis of Mu-tagged mutants.

Main Methods:

• Developed the UniformMu maize population with controlled Mutator (Mu) element copy number.
• Utilized a bz1-mum9 marker for selecting stable lines and inhibiting further transpositions.
• Employed Mu Transposon Amplification-mediated Insertion site Ligation (MuTAIL) PCR and sequencing to identify Mu insertion sites.
• Bioinformatic analysis to subtract ancestral elements and identify unique insertions.
• In silico mapping to assess insertion distribution.

Main Results:

• Achieved high mutation frequencies (7% independent seed mutations) with moderated copy number (approx. 57 total Mu elements).
• Identified new insertions targeting low-copy, gene-rich sequences with random genome distribution.
• Demonstrated that controlled MuDR copy number is a key determinant of Mu population differences in insertion hotspots and mutation frequency.
• Created a public database with pedigree, phenotypic, and MuTAIL sequence data for over 2000 mutants.

Conclusions:

• The UniformMu population provides a robust platform for high-throughput functional genomics in maize.
• Controlled Mutator element copy number is crucial for predictable transposition and efficient gene tagging.
• The developed database facilitates comprehensive analysis of Mu-tagged mutants and gene knockouts.