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Hybrid questions

Posted by treeguy123 AL 7a (My Page) on
Wed, May 9, 12 at 1:04

What do you get when you pollinate a diploid (2n) tree with hexaploid (6n) tree pollen, and vice versa?

What do you get if you then backcross those two resulting hybrids with the original diploid (2n) tree?

Any help would be very appreciated in this, I'm new to hybridizing and very interested.


Follow-Up Postings:

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RE: Hybrid questions

Sorry, let me start over the correct two are:

What do you get when you pollinate a diploid (2n=38) tree with hexaploid (2n=114) tree pollen, and vice versa?
What do you get if you then backcross those two resulting hybrids with the original diploid (2n=38) tree?

I read a little more and I think the hybrids of the above would be (2n=76), right? Would this hybrid have viable seed and pollen? And does it have a name (ie. hexaploid, diploid etc.)?

I guessing the backcross would be (2n=57) right? Same on the backcross, Would this hybrid have viable seed and pollen? And does it have a name (ie. hexaploid, diploid etc.)?

Any help would be very appreciated in this, I'm new to hybridizing and very interested.


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RE: Hybrid questions

This is basically what I'm wondering, fill in the blanks:

The Hybrid: diploid (2n=38) x hexaploid (2n=114) = _________(2n=76)

Backcross: diploid (2n=38) x __________(2n=76) = __________(2n=57)

Also, how does two species with different number of chromosomes cross in meiosis/fertilization? Seems like it won't work, but I know this specific hybrid has crossed before, I just don't know how.
Any help would be very appreciated.


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RE: Hybrid questions

"Also, how does two species with different number of chromosomes cross in meiosis/fertilization?"

Usually because they are the same species**, one is just a polyploid variety, or, in some cases, the chromosome count is different because of a fusion/fission event in one ancestry. Karyotype polymorphism is not overly important compared to other factors.

**species is fluid in some organisms. Say, the mints ;-)


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RE: Hybrid questions

The answer depends on the species involved.

For example, Prunus cerasifera (2x=16) x P. domestica (6x=48) gives a hybrid that behaves like a regular allotetraploid with all bivalents.

In other words, that hybrid is a fertile tetraploid.

Sometimes, a cross between a polyploid and a diploid may give an occasional diploid among the offspring. And sometimes a seedling will turn up with the same chromosome count as the polyploid parent. Both have been reported in crosses between diploid and octoploid strawberries.

Karl

Here is a link that might be useful: Strawberry Hybrids


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