I have been planting and harvesting sun root for a few years but I’ve never been able to harvest the actual seeds of the plants, regardless of having the flowers atracting insects.
Has anyone been able to harvest the seeds? If so, how and when? My intention is to try to grow from seed and see if some variation occurs.
My sun roots develop the usual yellow brownish tubers but occasionally I find some which are reddish or even deep purple; the pulp remains white or lightly yellow but the flavour profile changes drastically, with the purple ones having a very pronounced hazel nut hint.
Another difficult feature to breed J. artichoke is that it is hexaploid carrying 3 times more chromosomes than sunflower [34]. It has been shown that J. artichoke is probably auto-polyploid carrying 3 different elementary genomes named H, C and P [35], as other polyploid species, H. tuberosus displays any regular meiosis et is partially female fertile. Moreover, J. artichoke displays a strong self-incompatibility system that prevents a plant to produce seeds after self-pollination. Because S-alleles in J. artichoke have not been identified success or failure of crosses between clones cannot be predicted and several crosses have to be done to ensure some will succeed.
https://www.agrobiology.ru/articles/5-2017kiru.pdf
Translation:
Hexaploidy = produces very little seed on a good day.
Self-sterility = it will not produce seed without a different genetically distinct variety. It is unable to pollinate within the clone.
Most breeding work has been crossing the 6N sun root with 2N sunflowers. This produces a 4N offspring that does produce tubers.
It is essentially close to impossible.
It’s theoretically achievable but would be extremely expensive and time consuming.
Hmmm… Here a quick stab at methodology to achieve your aims.
To start if you have the funds, a full sequence of several lines of J. Artichoke and maybe a few accessions of diplod wild types that can make a viable cross. Then create an extremely high density SNP marker profile of the individuals.
Next generate 6n x 2n crosses to initiate the breeding project. The resulting 4n progeny could be further reduced to 2n via haploid creation techniques. Irradiated pollen parthenogenesis works in the genus. So there’s a possibility it will work.
Once you have it in a 2n state it’s time to figure out the self-incompatability mechanism. With the mechanisms defined, a introgression strategy is possible to get the original 6n genome into three 2n lines using the SNP markers.
From there you can do all of the gene discovery and breeding much easier. You can identify genes of interest and manipulate them by breeding the 2n lines. Seed production should be around 1,000x better than the original.
You can always recreated a 6n line by doubling a 2n plant with colchicine to 4n. Then crossing the 4n x 2n plant to generated a 3n plant. Doubling the 3n plant with colchine creates 6n again.
All together it would cost around $3-5 million USD per year and take around 15 years to accomplish if everything went smoothly.
I’ll return to you after I won the lottery. Or robbed a bank.
Interesting read, informative. Truly unexpected.
The alternative would be to not bother with the plant breeding aspect, just try to create mutations with EMS. It’s been done with other vegetatively propagated species like saffron.
But that wouldn’t answer the OP’s questions about their existing population.
Also…
Have you ever worked with EMS? It’s the last resort of the desperate. You burn money and time searching for a needle in a haystack.
It’s useful for creating variations for narrowly targeted objectives with easy phenotyping. Say a color variation in a flower or a herbicide resistance in grain.
Ploidy also matters a ton for if the mutations will be able express at all. Saffron for example is a sterile triploid. J. Artichoke is a hexaploid- double the number chromosomal copies.
Side note: For Saffron the outlook for breeding looks to be very good. They have identified the parent species Crocus cartwrightianus. It’s also in a 2n diploid state. Converting the 2n to a 4n and then crossing to make new 3n cultivars is theoretically possible.
A quick internet search and reading a couple blogs, brought up that you need multiple varieties for them to be able to go to seed, but also, the easiest way to propagate them is plant the tubers though.
Sun root has no recognized varietes where I live; I’ve contacted a few shops that carry the tubers and none was any knowledgeable regarding varieties. It was sun root and that is it.
Why not just replant your own harvested tubers? Or simply leave some in the ground for next year.
It is what I do. What I would like to do was increase the frequency of the uncommon tubers I mention, which are much more pleasant to eat.
Which would happen easier with the tubers.
How would you get a diverse variety from seeds that are from one variety? You’re asking for something thatd really not possible.
You’ve asked the seed places, they gave you this information from what you mentioned. How many more people need to say the same thing before it hits home?
The tubers enable cloning the same plant, one year after the other; there is no new genetic variation being introduced.
Even with only plants of the same variety crosspolinating, there is room for selection over generations. If I was able to carry true seeds from one year to the next, I could test for new individuals and crosspolinate those which developed greater numbers of uncommon tubers to select towards plants with a higher yield of such tubers.
If there’s no variation, how are you getting it already? The plant has variants in its genes, you can accomplish the same thing with the tubers. It’s why the tubers also have the variations you’re already seeing.
What part of this are you still missing here?
I’ve kept and planted only purple tubers and the plants do not return a higher yield of such tubers. It may return a few purple ones, it may grow only standard tubers.
I’ve even considered it a response of the plant towards soil conditions, sun exposure or amount of watering and it makes no difference.
There is no way, in my limited knowledge, to increase the frequency of such tubers, unless I was able to selectively breed towards such result like what I’ve done with hot peppers.
Lot of plants who spread via rhizomes or other root parts are difficult or impossible to grow via seeds. I suspect they fall under that category. The best way to spread is to use part of the root. I suspect that is what you need to do.
It is what I already do. My intention was to try to increase the frequency of the unusual tubers my plants produce, which are much more palatable.
how do you feel about doing tissue culture? It’s certainly do-able at home, but requires a bit more effort than just collecting seeds and hoping for a useful de novo mutation.
Basically cut the tubers into tiny bits, treat them with EMS and grow them on an agar plate.
Would you mind breaking that acronym down, please?
I won’t say no. Might be an interesting experiment.
EMS is ethyl-methanesulfonate. It’s a compound used to cause random point mutations in organisms. Basically the idea is to treat a whole bunch of plants with the compound and try to cause mutations that might exhibit a trait of interest, like disease resistance or increase crop yield.
What you’d do in this case is take a tuber and dunk the meristematic tissue (i.e the little eyes on the tuber) in a solution of EMS to induce mutation and then grow all the little eyelets on some sort of growth media, usually MS agar or something similar. EMS and the growth media can be ordered online. In the lab you’d typically have access to things like a laminar flow and autoclave, but you can use a plastic box and pressure cooker instead. It’s a bit dodgy, and you might get some plate contamination, but if you’re careful it shouldn’t be unmanageable.
I’ve had rotten seeds thrown on the compost heap sprout and take root. I risk the things will manage.