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  1. #61
    Administrator deluxestogie's Avatar
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    Re: How to Intentionally Cross Tobacco Varieties

    "Cultivated species N. tabacum is an amphidiploid (2n=4x=48) evolved through the interspecific hybridization of the ancestors of N. sylvestris (2n=2x=24, maternal donor) and N. tomentosiformis (2n=2x=24, paternal donor) about 200,000 years ago."

    The numbers below are haploid numbers, what you would see in an ovum or a pollen grain. The plants' diploid chromosome number, what you see in other plant tissues, is double that.


    https://www.ncbi.nlm.nih.gov/pmc/art...01807-0011.pdf

    Both N. rustica and N. tabacum appear to have arisen when the reproductive cells of both of the "parent" species (the male and the female) for each of them failed to segregate during meiosis, during which the diploid number is normally reduced to a haploid set of chromosomes, prior to the pollination event. The result was a double dose of chromosomes from both parents. The surprise is that the resulting offspring was more "fit" than either parent. This tetraploidy in the offspring produced the large-leaf plants of N. tabacum. I don't know much of the detail for N. rustica.

    Bob

  2. #62
    Senior Member ArizonaDave's Avatar
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    Re: How to Intentionally Cross Tobacco Varieties

    Quote Originally Posted by OldDinosaurWesH View Post
    Bob:

    Stop it! you're making me laugh...crossing gasoline and electric cars...Is that anything like crossing a donkey with a horse?...

    On a more serious note. If my memory serves, doesn't modern tobacco have 28 chromosomes. (7 x 4), or was that 32 (8 x 4)? I forget.

    On a less serious note, I always like to say that "God makes the laws of physics, and he doesn't explain them to us."

    Wes H.
    A donkey and a horse is called a mule. Unfortanately for the mule, he can't reproduce offspring. Neither can a hybrid car.
    Amateur Cigar roller, Tobacco enthusiast.

  3. #63
    Senior Member ChinaVoodoo's Avatar
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    Re: How to Intentionally Cross Tobacco Varieties

    Amphidiploid? Is that the same as allotetraploid?
    Now all them things that seemed so important, well mister they vanished right into the air - The Boss

  4. #64
    Administrator deluxestogie's Avatar
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    Re: How to Intentionally Cross Tobacco Varieties

    Quote Originally Posted by Merriam-Webster
    Definition of amphidiploid. :an interspecific hybrid having a complete diploid chromosome set from each parent form — called also allotetraploid.

    https://www.merriam-webster.com/dictionary/amphidiploid
    "Amphidiploid" emphasizes the sources of the doubled diploid set, whereas "allotetraploid" says, "where the hell did these four sets of chromosomes come from?"

    Bob

  5. #65
    Senior Member OldDinosaurWesH's Avatar
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    Re: How to Intentionally Cross Tobacco Varieties

    Bob:

    Stop making me laugh! My back hurts from my hard day in the tobacco fields. It hurts to laugh.

    Wes H.

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