Cytoplasmic Male Sterility in Maize

Study Notes

Cytoplasmic male sterility (CMS) is a condition where plants fail to produce functional pollen.
CMS is controlled by extranuclear genes, meaning it is inherited maternally from the mother plant.
There are two main types of cytoplasm: N (normal) and S (sterile) cytoplasm.
CMS is an important tool for hybrid maize production, as it eliminates the need for detasseling, a labor-intensive process.
CMS-T, the first commercial CMS discovered, was widely used until it became susceptible to southern corn leaf blight, leading to significant yield losses.
CMS types C and S are now used instead, but they are prone to environmentally induced fertility restoration, requiring careful field monitoring.
CMS is caused by the interaction between the mitochondrial and nuclear genomes.
A gene encoded by the mitochondrial genome affects mitochondrial function and regulation of nuclear genes, causing male sterility.
The RESTORER OF FERTILITY (Rf) gene in the nuclear genome suppresses the CMS-causing gene, restoring male fertility.
The CMS/Rf system is valuable for studying the genetic interactions and functionalities of mitochondrial and nuclear genomes in plants.

Iojap is a recessive chromosomal gene that produces green and white striped leaves in maize.
This trait is named after Iowa State University and the striped variety of maize called japonica.
A cross between a normal green-leaved plant (female) and an Iojap plant (male) produces green-leaved offspring.