Genetic Screening for EMS-Induced Maize Embryo-Specific Mutants Altered in Embryo Morphogenesis

Area of Science:

• Plant genetics
• Developmental biology
• Maize genetics

Background:

• Previously identified embryo-specific (emb) mutations in maize using Robertson's Mutator stocks.
• Transposon mutagenesis yielded abnormal embryos with normal endosperm.

Purpose of the Study:

• To induce and screen for embryo-specific (emb) mutations using ethyl methane sulfonate (EMS) mutagenesis.
• To achieve a higher frequency and greater ease of mutation induction compared to transposon mutagenesis.

Main Methods:

• Screened for embryo-specific mutations in progeny of EMS-treated maize pollen.
• Assessed germination capacity and embryo phenotypes of induced mutants.
• Performed complementation tests on a subset of mutations.

Main Results:

• Achieved a nearly threefold higher EMS-induced emb mutation frequency compared to transposon stocks.
• 45 EMS-induced mutants were identified, most were lethal.
• Mutant embryos exhibited developmental retardation and morphological abnormalities, with distinct developmental blockages.

Conclusions:

• EMS mutagenesis is an efficient method for generating maize embryo-specific mutations.
• Identified mutations likely affect nuclear genes controlling plastid proteins and shoot apical meristem development.
• Results support the existence of numerous embryo-specific loci in the maize genome.