I wanted to start a thread about 1EBN potato crosses after learning about S. jamesii and then reading about some of Bill’s work with these species. There are many interesting resistances among them. To make it agronomically useful, the challenges are primarily finding and then linking together domesticated traits such as short stolons, low glycoalkaloids, and decent size. It’s been exciting seeing some of Bill’s preliminary progress in this regard. I personally just really enjoy the learning that can come from this kind of project, even if the actual progress toward a new domesticate is small and slow.
So far, it seems that you get get tuber size from S. commersonii and S. ehrenbergii, short stolons from S. bulbocastanum, and palatability from S. cardiophyllum, S. ehrenbergii, and maybe S. jamesii. Whether or not it will be possible to concentrate them all in one hybrid is anybody’s guess. And, of course, the 1EBN species don’t appear to have been extensively evaluated for these traits, so it is possible that there are additional and better sources.
The super low glycoalkaloids of some accessions of cardiophyllum and ehrenbergii is very attractive. It seems like you have found many 1EBN species seedlings have some degree of palatability. If I understand correctly, cardiophyllum and ehrenbergii are the most likely to be non bitter, and sometimes with unusually low glycoalkaloids. Jamesii having some CPB resistance is also very attractive. I have mixed feelings about the tuber freeze tolerance of jamesii, but maybe it wouldn’t be a nuisance with LB resistance and crossed into a short stolon type. Commersonii just seems interesting—history of cultivation in Europe for food, called purgative potato in its native land, freeze tolerant leaves, and sometimes big tubers.
I’m thinking I’ll start with 2 or 3 species this season, depending on what’s available in the store this spring.
Is it possible that you could have a 1EBN hybrid function as a perennial crop? I had to wonder after learning that the native Americans didn’t plant jamesii so much as they just harvested it. What if you could breed a larger, short stolon version? In a multi resistant 1EBN hybrid, could growing it as a perennial be much more workable than with tuberosum? Any crop will inevitably get loaded down with time, so I guess the question is a matter of degree. Maybe the crucial difference is that in wild populations like jamesii, they are periodically refreshing themselves by seed.
Whether native Americans planted jamesii is uncertain. I think it is most likely that they did plant it, especially in locations close to settlements. The USDA germplasm collecting trips have found a surprising amount of diversity in areas they did not expect it. That, to me, likely means they collected some tubers and moved them around to other areas.
Potatoes are perennial as long as you don’t dig them up and you have soil that is sufficiently warm and dry for them to persist in good condition. That’s how they grow in nature, after all.
This is a topic that I have thought about a lot. I am a grad student that has worked a lot with 1EBN species and both John Bamberg (the head of the potato genebank) and I have talked about this topic specifically and we think there is some potential to create a domesticated group within the 1EBN species, but lack of time and resources has prevented us from making much progress in this area. I would say that when it comes to species to use, I think that S. ehrenbergii has to be a large part of that effort.
From what I understand many of the low glycoalkaloid and large tubered S. cardiophyllum are actually S. ehrenbergii. There isn’t a very clear delineation between these two species which complicates things.
I have some populations of 1EBN hybrids that I have been working with and in my experience S. pinnatisectum and S. jamesii cross very easily in both directions. And S. stenophyllidium, S. ehrenbergii, and S. tarnii are fairly easy to cross with as well.
S. bulbocastanum, S. cardiophyllum, and S. clarum have been difficult for me. I havent been able to make hybrids with these three species except for one family where S. jamesii is the female and S. bulbocastanum is the male.
As for S. commersonii, I think that there is a lot of value in this species but I have not been able to cross any of the north/central American species with S. commersonii. As I have done research on Endosperm Balance Number and its implications, the EBN classification seems to be an oversimplification of the crossing interactions between species. I would not assume that just because two species have the same EBN number that they are able to cross. In fact It is possible that the barriers that prevent south american 1EBN species form crossing with 2EBN species are an entirely different set of genes than the set that prevents north/central American 1EBN species from crossing with 2EBN species.
I agree that the South American 1EBN species are hard to cross to NA 1EBN and it seems pretty likely that they have a different genome. I’ve been surprised by how little research has been published about the genetics of the SA 1EBN species.
S. bubocastanum is very difficult to cross with anything that I have tried, but I got seeds from S. x sambucinum x S. bulbocastanum and S. bulbocastanum x S. cardiophyllum. Just a few though.
Large tubered S. ehrenbergii seems like a good nucleus for a 1EBN project, but it really doesn’t like wet soil and has performed poorly here, unfortunately. I get much nicer tubers from S. bulbocastanum, but also extreme bitterness.
Have you all ever noticed more openness to crossing among the interspecies F1s? In some genera, a difficult to cross species can sometimes be crossed to a hybrid. Maybe you could more easily cross bulbocastaneum to say a (jamesii x ehrenbergii).
That’s kind of what I am working on right now. My jamesii x bulbocastanum family is getting ready to bloom and we will see what I can cross it too. I think that it is important to recognize unilateral incompatibility in some of these crosses. For example I have never had success in interspecific crosses when bulbocastanum is the female. So, I would expect that I may see that in the jamesii x bulbocastanum family I have. It may cross easily as a male to ehrenbergii but not in the other direction.