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deluxestogie

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"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.

Nicotiana_ChromosomeNumbers_Goodspeed1933.JPG

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1086129/pdf/pnas01807-0011.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
 

ArizonaDave

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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.
 

deluxestogie

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Merriam-Webster said:
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
 

deluxestogie

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Regarding the original post, Bob. The paper tape. How do you protect it from the rain?
The paper masking tape needs to adhere for only a week or so, which it seems to survive well. We're just trying to keep away bugs from that specific blossom while it is fertile. My experience was that the tape fell off only when the maturing pod would otherwise have shed its dead blossom. I suspect that even Scotch cellophane tape would survive long enough.

Bob
 

skychaser

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Regarding the original post, Bob. The paper tape. How do you protect it from the rain?

What is this "rain" you speak of? .04 inch for July at the weather bureau. None here. 90's all week and heading for 100 degrees by the weekend.

I have a tobaccum / rustica cross growing this year. No idea what was crossed. The seed is from the old FTT seedbank and all it said is T x R tobacco rustica cross. Any ideas where it came from originally or what was crossed? It has a plant form like a tobaccum, but the leaves look very rustica like.
 

ChinaVoodoo

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What is this "rain" you speak of? .04 inch for July at the weather bureau. None here. 90's all week and heading for 100 degrees by the weekend.

I have a tobaccum / rustica cross growing this year. No idea what was crossed. The seed is from the old FTT seedbank and all it said is T x R tobacco rustica cross. Any ideas where it came from originally or what was crossed? It has a plant form like a tobaccum, but the leaves look very rustica like.

Very cool. That was before my time. I would certainly like to see the plants. Can you please take some photos?
 

deluxestogie

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I've searched the FTT seed bank data as of JAN 2015, and find no reference to a tabacum X rustica cross. There are, of course, numerous entries for "TRn", in which "n" represents a numerical digit or two. So, I have come up empty on that.

Bob
 

skychaser

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The sprinklers were on in this section of the field when I took these. They plants are about 2' tall now.
 

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deluxestogie

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Looks like a rustica to my old eyes. A nickel says the blossoms are stumpy and yellow. [Maybe somebody collected seed from an un-bagged rustica plant growing near his tabacum, and just thought that meant it was a cross. If the procedure required any notable effort, then the grower surely would have commented on at least one of our discussions of the subject over the past 7 years.]

Bob
 
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