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      Camila Fonseca

      Hi, I was uncertain about what would be the correct alternative on a question I have to answer, regarding male sterility in maize. Below, I’ll insert the problem and what I have thought so far (also, my apologies if the sentence is not well formulated, I’m translating it from my native language).

      In maize, a plant has both male and female flowers. Male sterility can occur: the plant is uncapable of producing pollen, although it produces female gamettes. When these plants are crossed with normally-fertile plants, the entire offspring has male sterility. This type of inheritance indicates that male sterility is determined by a mutation which is:
      a) Dominant, in a nuclear gene, expressing restrictively to the male flower. Therefore, this explains its transmission to the entire offspring, maternally.
      b)in a mitochondrial gene, expressing restrictively to the male flower, not being possible its transmission paternally.
      c) in a nuclear gene, because a mitochondrial mutation cannot cause male sterility, since the mitochondrial genes aren’t present in the pollen and are transmitted maternally, exclusively.
      d) in a mitochondrial gene, which explains its maternal transmission, exclusively, to all offspring, an event that would happen even if it didn’t cause male sterility.
      e) dominant, in a nuclear or mitochondrial gene, since it causes male sterility, its transmission is always always maternally, to all offspring.

      I’ve discarded alternative A because it excludes the mitochondrial inheritance possibility, which is discussed on Griffths’ and Snustad’s books. Also, I’ve disconsidered C, since it doesn’t include that a mitochondrial mutation could be responsible for such event. I thought alternative B would be more plausible, because it didn’t seem to show incorrect concepts, but I´m not sure whether it is incomplete or not, hence I considered E to be possible (because maize can also go through nuclear mutations that cause such phenotype). Nonetheless, I’ve been struggling with this question for some days now, if anyone can help me, thank you!

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