Oca crosses

[ottawagardener]

At the risk of seeming like an uneducated dork, has anyone ever tried a wide cross with Oxalis tuberosa and some other Oxalis or is this goofy? Feel free to laugh.

[starry]

Interesting idea...if I have success this season with growing oca I will put it on my list of crosses to try next year.

[billw]

I've thought about it and done a bit of research looking for likely partners, but haven't been inspired to try anything yet. It is not a particularly promising idea, at least as far as theory goes. First, what do you hope to get out of it? It seems unlikely that tubers production will be improved, since oca has been bred for large tubers for a very long time. It might be a route to day neutrality or better heat or cold resistance, though, and any of those could be quite useful. Since there hasn't been a lot of work done on any of these problems within the constraints of the existing oca genome, it seems more sensible to start there and only resort to inter-specific crosses if those efforts don't produce.

Second, finding a suitable partner for oca could be difficult. Oca is octoploid, apparently via multiple alloploid stages. Basically, it appears to be the union of three different genomes. So, you have two problems: finding a chromosome number match and getting useful results if you do. Most other oxalis are not octoploids. In fact, most are not even tetraploids. With the tetraploids, you could potentially intervene to get an unreduced gamete from the tetraploid to cross with oca and end up with a success. With the diploids, which are probably where you would want to turn, since they are the more diverse lot, you would need to potentially work out an intermediate step by doubling the diploid. And, once you have done that, you still have the problem that the oca genome is unusually diverse and that it may not be possible to get useful pairings.

Regardless of outcome, it would be a really interesting project!

[ottawagardener]

Thanks for your thoughtful answer billw. The daynuetrality or at least change in day length requirements and/or cold hardiness is what intrigued me but I'm content to start with selecting within oca. However, in the future, who knows

[philip]

I tried grafting oca this year just for fun. It didn't work for me but i only tried it on two plants. I think it could be done. Last year i tried grafting oca on to oxalis stricta and vice versa. It didn't work either.
From having read Mitchurin's books i know that a wide cross is much more likely to succeed after having grafted both candidates on to eachother. When those grafts then flower you attempt the cross.
It seems logical that an oca cross with northern wood sorrel may result in day-neutrality but achieving a successful cross appears impossible or very difficult.
I got the idea while flicking through an organic gardening book and seeing a picture of oca. It turned out it wasn't oca but oxalis stricta. At first glance they quite resemble eachother but stricta doesn't have the fleshy stems. The flowers are also quite alike. I did all this before i learned that oca was an octoploid. But then again when Mitchurin did his crosses it was considered impossible by the scientific community to cross plants from different genera and he did it successfully.

[darrenabbey]

Feb 7, 2014 13:54:34 GMT -5 billw said:

First, what do you hope to get out of it? It seems unlikely that tubers production will be improved, since oca has been bred for large tubers for a very long time.

Other tuberous Oxalis species may have alleles which would be useful in increased tuber formation in the genetic context of Oca. That the other species haven't been improved in respect to tuber size isn't necessarily a factor. Though I can't find the references right now, I recall cases in dog and chicken breeding where alleles introduced from the other/larger breeds resulted in strong improvement in the desired characteristic in the breeding program (miniaturization in both cases).

[nicolas]

That is an interesting graft/cross to try