Overcoming self-incompatibility

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Carbo
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Overcoming self-incompatibility

Post by Carbo »

I've been searching the internet for hours on methods that can be used on cacti to promote self fertilization in self-incompatible species but I found nothing. Does anyone have any resources or knows of any methods that might work? I've tried cutting the stigma at a sharp angle and then dusting the open wound with pollen, but it didn't work. Treating the stigma with 4% salt solution also didn't work. I've yet to try another method which supposedly can work and that's heat treatment.

Anyone tried something that worked?
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One Windowsill
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Re: Overcoming self-incompatibility

Post by One Windowsill »

I haven't tried it but I have read that mentor pollen from a compatible plant will elicit the necessary response from the stigma, allowing the plant's own pollen to also enter. This may only be true of some plants as the barriers to selfing do vary.

You can just mix them and then separate the seedlings if they are sufficiently different.

You can kill the mentor pollen, the simplest method I have seen mentioned is to freeze and thaw the pollen in a dry plastic bag. Simpler than gamma irradiation, anyway. The only details I have are "successively frozen for 5 min at -4°C and thawed for 30 min for a period of 105 min."
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gemhunter178
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Re: Overcoming self-incompatibility

Post by gemhunter178 »

I was curious about this as well when it came up here a while ago, I think it's this thread:
https://www.cactiguide.com/forum/viewto ... 23&t=29268

Personally I think I've used the cement method and on the second try on a Copiapoa hypogaea did get me 5 or so seeds, but unsure about viability since I haven't sown them. They look like normal, ripe seeds though.

Edit: just noting the language used on the external link in that thread is not quite family friendly/uses triggering words for some
A cactus and succulent collector who especially likes Aricarpus. ...Though I have a bit of everything! Want some pictures? See my flickr! I also do art and such.
LateBloomer
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Re: Overcoming self-incompatibility

Post by LateBloomer »

calcium carbonate or other alkaline powder mixed with the pollen. Don’t need much as it will burn the flower but I’ve had success in the past... same technique as cement
DaveW
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Re: Overcoming self-incompatibility

Post by DaveW »

I have heard various methods discussed in the past, even of wetting your finger with saliva and touching it on the stigma before pollinating the stigma. However whether these actually worked or if the plant had not crossed already is open to question. Since unfortunately few do these things under regulated scientific conditions of isolation, often still with the plant in the open greenhouse. Also few have enough individual plants in the test to prove it was that that caused self pollination. Also of course a method that may work with one genus, or even species, may not work with another.

Anyway searching the web for overcoming stigma incompatibility I found these:-

https://www.biologydiscussion.com/palyn ... %20More%20

https://www.biologydiscussion.com/palyn ... logy/64552

To do a proper scientific test the plant needs isolating from all the other cacti in your greenhouse before the buds open, (brought into the house provided no flowering cacti there either). You cannot do anything meaningful with the plant left in the greenhouse with the rest of your collection since self sterile plants will always outcross with anything compatible given the chance, and it only needs a few flies in the greenhouse to do so. The same applies to supposedly self fertile plants since as nature abhors non-sexual reproduction so they will always outcross first before as a last resort they self fertilise.

You will notice in many cases the stigma protrudes from the flower before the pollen is ripe to aid outcrossing. In some cases the stigma will protrude from the bud before the flower itself opens. Therefore for all such experiments the golden rule is to isolate away from any other flowering species before the bud opens or stigma protrudes.
nes
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Re: Overcoming self-incompatibility

Post by nes »

LateBloomer wrote: Mon Jul 05, 2021 5:10 pm calcium carbonate or other alkaline powder mixed with the pollen. Don’t need much as it will burn the flower but I’ve had success in the past... same technique as cement
I'm going to try this method but I don't wanna purchase calcium carbonate. I'm grinding up an tums pill crushing it up instead. Trying this on C. Tenuissima.

Edit: all flowers failed
LateBloomer
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Re: Overcoming self-incompatibility

Post by LateBloomer »

nes wrote: Thu Mar 17, 2022 5:09 pm
LateBloomer wrote: Mon Jul 05, 2021 5:10 pm calcium carbonate or other alkaline powder mixed with the pollen. Don’t need much as it will burn the flower but I’ve had success in the past... same technique as cement
I'm going to try this method but I don't wanna purchase calcium carbonate. I'm grinding up an tums pill crushing it up instead. Trying this on C. Tenuissima.

Edit: all flowers failed
try even less calcium carbonate... don't need much but also not 100%
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jerrytheplater
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Re: Overcoming self-incompatibility

Post by jerrytheplater »

Nes

Question/Comment regarding grinding up Tums for Calcium Carbonate. I'm wondering how pure the tum tablet is. I suspect there are other compounds in the tablet to allow it to be formed into a tablet. You could check by weighing the tablet and comparing it to the weight of Calcium Carbonate the Tums tablet contains-assuming they tell you.
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nes
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Re: Overcoming self-incompatibility

Post by nes »

jerrytheplater wrote: Fri Apr 22, 2022 8:07 pm You could check by weighing the tablet and comparing it to the weight of Calcium Carbonate the Tums tablet contains-assuming they tell you.
Didn't put much thought into it, just smashed up the pill took a paintbrush to it.

And there are many ingredients in tums, I doubt calcium carbonate is a big one but it's certainly in there.

Might buy some calcium carbonate and do a more careful, legit, CaCO3 self pollination on my S. rauschii
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7george
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Re: Overcoming self-incompatibility

Post by 7george »

I have tried diluted honey (= nectar) or pollen from other distant species of cacti, some time before application of own pollen on the stigma lobes. It can work for some self-sterile species. This way I've got some seeds from my only F. latispinus that is considered incompatible otherwise.
If your cacti mess in your job just forget about the job.
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jerrytheplater
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Re: Overcoming self-incompatibility

Post by jerrytheplater »

Just thought of this question: if a plant is normally self incompatible, and by various chemical means one is able to overcome the self incompatibility, are the plants resulting in any way weaker or atypical in form or in any other way different from a plant pollinated by another plant?
Jerry Smith
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45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
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7george
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Re: Overcoming self-incompatibility

Post by 7george »

jerrytheplater wrote: Sat Apr 23, 2022 9:13 pm Just thought of this question: if a plant is normally self incompatible, and by various chemical means one is able to overcome the self incompatibility, are the plants resulting in any way weaker or atypical in form or in any other way different from a plant pollinated by another plant?
That is maybe a theoretical question. I think self-incompatible plant species just have a different breeding strategy that became successful at some point of their life (еvolution) history. My observations over offspring of different self-pollinating Rebutia do not found any disadvantages or weakness but I haven't compared those with cross-pollinated specimens of the same species. Lower genetic variability may occur after after several or many generations of such propagation but this will also happen even with cross-pollinating of limited number of parent plants in culture within collections.
If your cacti mess in your job just forget about the job.
°C = (°F - 32)/1.8
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