Rubus Breeding

For those interested in creating a fertile cross between raspberries and strawberries my educated opinion would be that one should use octoploid Fragaria ×ananasa as the seed parent and find a tetraploid Rubus idaeus to use as the pollen parent.

The most likely result for offspring would then be hexaploid with two sets of raspberry chromosomes that can pair wth eachother along with four sets of strawberry chromosomes that can pair with eachother. These resulting plants could then potentially be fertile enough to bear fruit themselves.


If I recall, the garden strawberry genome has more than two different sets of chromosomes from multiple diploid and/or tetraploid strawberry ancestor species. The different sets aren’t necessarily homologous with each other, that’s why they’re having trouble matching the chromosomes of interspecific strawberry crosses. Crosses outside the genus will be even more difficult. That isn’t to say it can’t be done.

Some links that might be of interest


Above poster what about A wild one with 10 chromosomes , and not a hybrid?

What would be good for that new Wild Strawberry (2012) being a decapoloid 2n-70 be good to cross
(fragaria cascadenesis
(has USDA ID NUMBER) D2877-1)

Staalmannen and others
(something for research)


I would not think a decaploid to be ideal for intergeneric hybridizing if you want the offspring to be fertile. Since the hybrid offspring would then have five sets of chromosomes from the strawberry parent that will leave one of those sets trying to pair with a set of raspberry chromosomes which would not work out well. It would interfere with meiosis which would make fruit set pretty difficult.

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The main challenge with my suggested cross of octoploid strawberry with tetraploid red raspberry is that most red raspberries are diploid so you may have some trouble finding a tetraploid red raspberry.

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How about a synthetic tetraploid? They used one in the creation of Tayberry. 2x raspberry x loganberry should yield tetraploids.

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Above poster (Johanns) Can you explain exaptive breeding, and unreduced gametes
(even though I do not see exaptive breeding being brought on by selective pressure
(if it has been used what I read is it hasn’t only came about naturally by changing environment over time)

Not sure If I understand this
So maybe if the cascade strawberry goes to another location long enough it will adapt
(edit I think you know what I mean — I meant the sterile hybrid might have a deletion)
(I took a avocado and stressed it badly for years I think I created mutant --)


Berry Allen I know what your saying about seeds probably not harboring disease,

but if yuo really want to be careful could put some powdered diatomaceous earth with seeds
(like I thought from the store I found a grub in tamarind seed
(bean/pea family) but not sure if it was living still.

I also agree with Clark as well people should be responsible , and not spread soil
(or even cuttings in different countries especially if you want to travel there, but still.)
some nurseries in California have to get inspected for sudden oak death in all the plants
(not sure if you could get a prison term for spreading that,
but if some lumber Jack saw the article of you spreading it you may have to leave USA anyways.)

for sharing pollen I plan to use diatomaceous earth.


I’m not aware of any naturally occurring tetraploid R. idaeus. As far as I know they only exist in breeding programs where they were created by doubling diploids into tetraploids via colchicine.

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I’ve never heard the term “exaptive breeding” before.

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(modify statement ( What about unreduced gametes )

Unreduced gametes most commonly arise through meiotic defects. Meiosis is a specialized cell division that is essential for sexual

I am trying to make sense of this also ( that is why I am asking if anyone knows)
I used to have a breeding book science text book , (from thrift store)
but it may be gone now (or misplaced ) (some go for $100 to 300 so not bought another)

I forgot most the stuff I leaned maybe 2016 or so.


  • The ability to produce unreduced gametes facilitates polyploid speciation.

Unreduced gamete production is under genetic control.

Stress and interspecific hybridisation increase unreduced gamete production.

Unreduced gamete production may comprise an evolutionary mechanism for speciation.

Unreduced gametes (gametes with the somatic chromosome number) are known to facilitate polyploid formation. Unreduced gametes result from a plethora of different mechanisms across different taxa, suggesting that the ability to produce unreduced gametes has evolutionary utility. Heritable genetic variation for unreduced gamete production has been observed, thereby providing an evolutionary substrate. Unreduced gametes are also frequently involved in interspecific hybridisation events as well as being produced by interspecific hybrids, facilitating allopolyploidisation. Environmental stress often triggers unreduced gamete production, suggesting that unreduced gametes may facilitate polyploid speciation in response to changing environments. Thus, although unreduced gamete formation may be a meiotic mishap, we suggest that unreduced gametes can be more explicitly considered as a mechanism for evolutionary speciation that should be measured and tested across and within lineages for exaptive evolution (a feature with evolutionary utility that has not arisen under conventional selective pressure) and evolvability (the capacity to generate adaptive genetic variation).,unreduced%20gametes%20has%20evolutionary%20utility.

Any good things to start understanding this
A guild or book from A through Z
I should go back, and read some Cannabis breeding stuff
they do not try to make things complicated for the Average Joe (without a degree)

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Heat stress during pollen formation is known to increase the occurrence of unreduced gametes in roses. F1 hybrids between different species also tend to produce a higher amount of unreduced gametes.


I need to catch up, but not sure If I could not understanding the whole thing from point A to b through Z
but AS I understand naturally A plant could mutate being in wrong soil even (over time)

The Equivalent to have a plant Mutate itself , and it’s genes by being exposed to chemicals
(not colchicine )
(I am not for GMO, and transferring genes but if a Chemical changes the plants make up in the plants Own doing then in my opinion it is just adapting, and changing it’s own genes.)

I can explain more but wondered on peoples opinions since to some it’s a touchy subject
So If I grow acidic loving Blueberries (Vaccinum) on alkaline soil,
and it mutates on it’s own devise I am playing God?

I am talking about EMS chemical by the way to mutate them
(not to cross but to shuffle the genes around )
Even Inbreeding depression eventually shuffles the genes around
(according to a 100 year old article about WILD persimmon
or a lone persimmon with no other way to change it’s genes except adaption of the inbreeds different then itself.)

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Not to difficult to find a strawberry selection at the ploidy level you need. Just request a accession from USDA GRIN

Strawberry’s by Ploidy

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Speaking of… I’ve requested strawberries from GRIN three years in a row and have yet to get any.

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I think I might have my first new rubus hybrid this year.

I hand pollinated some purple flowering raspberry(rubus odoratus) flowers with different raspberries last summer. Two flowers developed into berries, which had to carry hybrid seed since the mother plant is self sterile. A few weeks ago this seedling sprouted:

Unless the birds planted it I believe this is rubus odoratus x idaeus. I should know more when the next pair of leaves has opened up.

The strawberry seedlings in the picture are also hybrids. Wild Canadian f. virginiana x f. ananassa.


its was about 3 years ago i requested strawberries from GRIN. I received them. The request period is still open to Jun 1. try try again i suppose.

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US only I presume?

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hello, greetings from europe.
Lots of interesting posts here :slight_smile:
I bought a polarberry recently, hopefully it will set some fruits.

Since there seem to be many rubus breeders here, do you think
it would be doable to cross a yellow raspberry eg fallgold with the polarbery
I’ve read that most raspberries are diploid, same as the polarberry,
so a small chance of success should be there ?

I’m still trying to grab some understanding of the basics
Like if there a major differences in gene pool, if I take the polarberry as the main plant
and use pollen from the fallgold instead of doing it the other way around?

Or if there are any gene differences in the offsprings of multiple seeds
that come from the same berry, or if I can assume that that only the seeds of different berries that I’ve pollinated with
e.g fallgold pollen come with a different set of genes ?

I know I should probably not be too hopeful of anything fertile or tasty coming out, since crosses between raspberries and blackberries are
very hard to do from what I’ve read and breeding in general takes a few hundred
plants were only a low percentage with desired traits get selected. Then comes backbreeding etc to get
things more stable.
But still, some experiments would be fun, maybe I’ll get lucky.

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Yes its possible. it has been accomplished many times. Of course it can be difficult. first of course is bloom time. My Polar and Snowbank are the first to bloom in my yard. Fallgold is only going in the ground this year but its a primocane so you get two chances to try. But your likely collecting pollen from your polar.

On the other hand Polar has had terrible fruit set for me. I would say its only partialy self fertile at best. if you save and use raspberry pollen next season and the berry actualy develops fully you could be confident there hybrids seeds.

This year I am hopeing i get good fruit set now that both my Polar and Snowbank are mature.

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