Author Topic: Talk nerdy to me... crossing custard apples and the odds of diploids  (Read 905 times)

dytandme

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Howdy all! I found myself here while researching a pawpaw / cherimoya cross. I see I'm far from the first.  ;)

It would appear the different chromosome count would be an issue with haploid hybridization. So is anyone aware of specific studies that provide a percentage of haploid and diploid pollen and ovule cells in each particular species? I believe I've seen them referenced but I don't have a link on hand right now.

I'd like to approximate my odds of successful hybridization before I worry about the chances of self abortion, nevermind the later stuff-stratification, germination, survival, etc...

SoCal2warm

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Re: Talk nerdy to me... crossing custard apples and the odds of diploids
« Reply #1 on: November 03, 2023, 03:40:40 PM »
From what I understand, the pollen from triploids usually tends to be sterile, or has lower chances of fertility (at least fertility caused by sexual recombination, though clonal seeds can often happen in many species and hybrids). However, if the pollen is able to be successful in sexual recombination, the vast majority of the time it will result in normal diploid offspring. (Though sometimes sterile pollen can trigger clonal seed production, in some species)

When the triploid parent undergoes meoisis, the odd number set of chromosomes typically causes problems, so there is a higher chance of the gamete (ovule or pollen cells) only getting one chromosome set, which is the same that happens from a normal diploid parent. In rarer cases, sometimes the triploid gamete fails to undergo meosis, and will include the full triploid set. This triploid set then sexually combines with the normal single chromosome set from another gamete resulting in a tetraploid offspring. This will typically happen around less than 1 to 5 percent of the time, from what I remember.

Do custard apples and cherimoyas have the same chromosome number set, 14 ?

Diploid is normal. Perhaps you mean chance of spontaneous tetraploid offspring?
« Last Edit: November 03, 2023, 03:47:51 PM by SoCal2warm »

mikkel

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