Deletion Mutagenesis and Identification of Causative Mutations in Maize

Area of Science:

• Plant genetics and genomics
• Crop improvement
• Maize breeding

Background:

• Developing maize mutants with desirable traits like opaque endosperm and reduced kernel fill is crucial for understanding kernel development.
• Efficient methods are needed to map mutations and identify causative genes in large mutant populations.

Purpose of the Study:

• To describe a gamma irradiation method for generating maize mutants with opaque endosperm and reduced kernel fill phenotypes.
• To present novel functional genomics platforms (BSREx-seq and BSEx-seq) for mapping mutations and identifying candidate genes.
• To demonstrate the utility of these methods by identifying causative deletions in two maize mutants.

Main Methods:

• Gamma irradiation of mature maize seeds to induce mutations.
• Development of a population of 1788 M2 families and 47 F2s for phenotypic screening.
• Utilizing Bulked Segregant RNA and exome sequencing (BSREx-seq) for mutation mapping.
• Employing exome capture sequencing of F2 mutant and normal pools (BSEx-seq) for mapping without RNA-seq.

Main Results:

• A stable population of maize mutants with viable kernel phenotypes was generated.
• BSREx-seq identified a 6203-bp deletion in the Opaque-1 gene in mutant 937.
• BSEx-seq showed a tight mapping interval and deletion in mutant 1486 on chromosome 10.

Conclusions:

• The described gamma irradiation and screening methods effectively generate maize mutants for functional genomics.
• The BSREx-seq and BSEx-seq platforms provide powerful tools for rapid mutation mapping and gene identification.
• These approaches accelerate the understanding of gene function in maize kernel development.