Maternal Inheritance and Maternal Effects
Genetic Vulnerability
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A uniform genotype exposes a population to diseaster by pathogen attack
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Until 1970, nearly all corn cytoplasm used to provide male sterility was
the Texas or T cytoplasm
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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.
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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.
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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.