Maternal Inheritance and Maternal Effects

Genetic Vulnerability

• 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.