Author Topic: Working with wild potatoes & breeding by clade  (Read 36 times)

bill

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Working with wild potatoes & breeding by clade
« on: 2018-11-03, 05:26:10 PM »
For the past few years, I have been growing every wild potato species that I could lay my hands on.  The goal of this project has primarily been to enhance my own knowledge, although I am documenting everything as I go here: Wild Potato Project.

There are three main clades of potatoes: clade 4 is S. tuberosum and its close relatives, most of which are diploid, 2EBN and A genome; clade 3 is mostly South American diploids with 2EBN and P genome, and clade 1+2 is mostly North American diploids with 1EBN and B genome.  Most breeding efforts focus on identifying resistance genes in other species and then trying to find ways to cram them into S. tuberosum.  This is often a difficult task due to ploidy and EBN barriers between the three clades, although there are polyploid species that bridge the different genomes as well.

It seems to me that there is an opportunity here for at least two more domesticated species, with one nucleus in each clade as S. tuberosum is for clade 4.  This isn't a new idea.  There has been a lot of attention in recent years on the 1EBN species, with the possibility of breeding domesticated 1EBN diploids from species like S. cardiophyllum, S. ehrenbergii, S. jamesii, and S. commersonii.  Some of these species have been used as food, including S. cardiophyllum and S. commersonii.  The tubers are small, the stolons are really long, and some have high glycoalkaloids, but there is definitely potential to select something better and these 1EBN species have a much better pool of resistance genes easily available.

The bigger surprise to me was the possibility of breeding another domesticate out of clade 3.  These South American species are probably the most poorly known of all the wild potatoes and many of them have really weird features like moniliform tubers, but many of them seem to have low glycoalkaloids and good disease resistance, most of which has been untapped.  The problems are those common to all wild potatoes - small tubers and long stolons.  One species that I grew this year, S. acroscopicum, had reasonable tuber size, short stolons, low glycoalkaloids, and short day tuberization.  It could potentially serve as a nucleus for work in clade 3.

I think there is a lot of potential for doing interesting work from mixed gene pools of diploids within each clade.  It isn't likely that we will ever see a serious competitor to the domesticated potato from these species, but I think it should be possible to select perfectly acceptable edible varieties with potentially superior pest and disease resistance.

The attachments show a large S. acroscopicum tuber and a very impressive USDA selection of S. ehrenbergii.  Most tubers are much smaller and most plants have a much lower average size, but you can see the potential.
« Last Edit: 2018-11-03, 05:52:20 PM by bill »