Continuing the discussion from Potatoes: What I Have & What I'll Try:
You might say the prior thread was me exploring the general world of Potatoes & similar tubers. On this thread, I’ll be focusing on breeding Solanum tuberosum & closely related plants. So, we start with a recap…
Planting the store-bought potatoes was a disaster. The red ones turned out scabby… I might have peeled them if they weren’t so tiny at senescence. Clearly it didn’t like the heat. I planted a blue-skinned one the same season, and though unblemished by scab, the insides were blackened with blight. I don’t intend to try that again any time soon.
Regarding the in-vitro & True Potato Seed (TPS) material I got through GRIN from NR6, the story is much more interesting… Firstly, my initial plans never would’ve worked, as I was treating the different potatoes as one and the same when in fact, they were quite different at the cellular level (differing ploidy levels, cytoplasm types and Endosperm Balance Numbers or EBN) – as you can see, potato breeding isn’t always simple, and certain quirks (unreduced gametes, haploid inducers, self-compatibility, sterility, etc.) can complicate it further. Secondly, I killed off the first set of clones with excess moisture, after which I educated myself on the broad strokes of potato cellular compatibility, and ordered a wider arrange of in-vitro clones, seeds & tuber-based accessions. I killed off the second set of clones through premature exposure, with only one tetraploid tuber-based accession surviving to the present (either DTO-2 or DTO-28, I mixed them up). I shelved the project for about a year, until a few months ago, when I started reading really in-depth into potato breeding again. Armed with this knowledge, I ordered a more carefully-researched group of in-vitro clones and seed-based accessions. With my siblings’ help, I also managed to acquire several diploid and tetraploid TPS from Cultivariable, as well as tubers of the diploid Skagit Valley Gold (and for next year, the tetraploid S. acroscopicum Twanoh). The adventure begins!
The TPS accessions have all been placed into cold storage for the time being, as I want to get TPS from my current live plants before I start germinating new ones. Once this generation’s TPS goes into storage to eliminate the dormancy, the other TPS will come out for planting. I’m trying out several promising wild accessions, disease-resistant tetraploids, and a wide range of diploids, mostly Colombian as they’re the most heat & disease-tolerant types. I’m focusing on resistance to Scab, Blight and Verticillium Wilt.
The tubers are currently growing, with DTO-* in a container, and Skagit Valley Gold now flowering in a raised bed. How exciting! With the right varieties, you really can bloom potatoes in the tropics (trust me, this winter is barely making a dent in the heat). Most diploids are self-incompatible (and incompatible with tetraploids), so I don’t expect seed from Skagit just yet, but the fact that it’s blooming is very promising.
A pic of DTO-*, prior to planting it in a much larger container:
Pics of Skagit Valley Gold:
And as for the in-vitro accessions, for once I have success! I started out with 23 accessions (10 diploids, 13 tetraploids), and so far I’ve only lost 2! Diploid Cuchipa Ismaynin (chosen for pigment & tuber traits) succumbed quickly, while a numbered feral Venezuelan tetraploid lingered in a weakened state from the start, and succumbed yesterday to damping off (it might have bounced back had I not watered from overhead). The rest have remained relatively strong, with every indication that they’ll survive to tuberize, if I keep up the gentle care. I’m currently acclimating them to sun exposure, and they’re getting stronger every day. They used to look pitiful when wilting, now they look like they can take the hot sun and bounce back with little issue. A few more weeks, and I’ll be able to give them a full day of sun.
Here’s some pics of them after planting from the test tubes:
And some more recent pics of some of the more vigorous plantlets:
Among the diploid in-vitro accessions, I chose RN27.01 for pigment and probable heat tolerance, Guincho Negra for pigment, Pirampo for probable heat tolerance, M10 for blight resistance and genetic diversity (wild-based stock), GS 422 for russeting, GS 427 for pigment, BS 291 for diploid self-compatibility, BS 281 for scab resistance, and BS 288 for viral resistance and wild-based diversity.
For the tetraploids, I chose Yuguima for resistance to Tuber Moth & Blight, Canasta for Tuber Moth & Scab, Elmer’s Blue & Bora Valley for pigment (the latter is edible raw, interestingly enough), Sarpo Mira, Unica & Fripapa for Blight resistance and agronomic traits, LT-2, C89.315 & Igorota for heat resistance (all 3 are tropical lines), M17 for Scab resistance, BR03 for Blight resistance, and both for wild-based diversity. The 3 tropical clones should form the base of my tetraploid breeding stock, with the 3 agronomic clones adding blight resistance and other desirable qualities. I can cross Yuguima & Canasta to double up on Tuber Moth resistance while combining Scab & Blight resistance. Likewise, M17 & BR03 to combine Scab & Blight resistance. Elmer’s Blue + Bora Valley would make for a good blue line. The best of each line would go into the core breeding stock.
My plans for the diploids aren’t quite so centralized, as I’ll mainly combine varieties into multiple parallel breeding lines and hope each one bears useful strains. I’ll be doubling up on certain traits to strengthen their genetic basis, and combining complementary traits to cover all weak spots. Anything that succumbs to pest or disease pressure weeds itself out automatically, and the survivors must pass my own criteria to make it into the long-term breeding lines.
And that’s pretty much it for now. I’ll try to update as circumstances progress. Between the tuber plants, the in-vitro clones and especially the stored TPS, I have a legitimately insane amount of diversity for the founding stock of this project. I was wondering whether to include Haploid Inducers (to get diploids out of tetraploids), but I decided to keep it simple and leave the fancy stuff for later. For now, my challenge will be to get every live plant to tuberize. If I can get tubers out of them, I can plant them out next season and start the second challenge: getting them to flower and set fruit. Once that hurdle is passed, I’ll start the long process of breeding them and saving seed. The diploids will be easy to cross due to self-incompatibility, but the tetraploids will require emasculation & isolation if I want the different lines to cross.
All this work just to tickle my inner mad scientist, and get some potatoes that can handle the tropics. If I get anything good, I hope to send it out to NR6, for other growers to play around with.
Edit: forgot to add some sources: