Maternal Inheritance and Maternal Effects

A uniform genotype exposes a population to diseaster by pathogen attack
Until 1970, nearly all corn cytoplasm used to provide male sterility was the Texas or T cytoplasm
In 1970, a fungal disease (Southern corn leaf blight) appeared that preferentially attacked plants with the T cytoplasm. Thus, all of the hybrid corn was at great risk the following year.
Other seed stocks were developed that had to be manually detasseled, and its hybrid performance was not as good as the previous T-cytoplasm material, but it did provide a source of seed that was resistant to the disease and saved
the United States from losing the entire hybrid corn harvest that year.
Since that time though sources of the T cytoplasm have been developed that are resistant to the disease, and hybrid seed production utilizing cytoplasmic male sterility has resumed.