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Messages - bill

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Plant Breeding / Re: Transform tetraploid into diploid?
« on: 2021-05-02, 01:13:37 PM »
In general, with a triploid, you are going to get a distribution of gametes ranging from x to 2x, concentrated around 1.5x, but not making up something as predictable as a normal distribution.  Depending on the species and what other sanity checks it performs against gamete configurations, you might find that only the euploid (x and 2x) gametes function in crosses with partners of equal ploidy, that some aneuploid (x+1 to 2x-1) gametes function, depending on which chromosomes they contain, or all of the aneuploid gametes work at least well enough for fertilization.  Whether or not the seedlings produced in aneuploid crosses will be viable is another matter, but they commonly survive in some species.

In species that have an EBN system (I don't know if sorghum does), most aneuploid gametes will be rejected because they don't have the required EBN chromosomes.  In species that lack this check, any extra chromosomes from aneuploids may still be dumped in the remarkable process of genome elimination.  So, either only euploid gametes make it to fertilization or only euploid zygotes come out of fertilization.  In other cases, aneuploids make it all the way through and manage to produce a viable progeny, although it seems that the extra chromosomes most often get lost in the next generation if the plant is fertile.  In short, nature finds a way.

My expectation would be that you would get haploids reliably from triploid x diploid crosses when the 2x gametes produced by the triploid are fully incompatible with the x gametes from the diploid for whatever reason and perhaps the aneuploid gametes are all resolved by genome elimination.

I really love this stuff.  It is neat to see how nature makes rules and then immediately sets about finding ways to break them.

Potatoes / Re: Potato Tomato Hybrid
« on: 2021-03-22, 05:10:14 PM »
In the paper that you referenced, they produced the hybrids by somatic fusion.  That is a laboratory process in which the cells of the two species are dissolved and then re-fused together.  It is indeed possible to make many wide "crosses" this way, but it doesn't indicate that the species are sexually compatible.  Backcrosses typically dead-end, if they are possible at all, as in this case.  Presumably, genetic engineering will make it possible to fuse genomes less haphazardly and produce fertile progeny in the future, if it hasn't already.

While colchichine is dangerous and difficult to obtain, oryzalin is widely available and is nearly as effective at doubling most species.

Potatoes / Re: Potato Tomato Hybrid
« on: 2021-02-25, 09:08:18 PM »
I think it might be a lot easier than anyone expects.  I have tasted quite a few potato berries and they are often non-bitter when fully ripe, which means that they must be pretty low in at least the most common glycs.  Short day diploids can produce plants with hundreds of fairly large (1 inch or better) berries.  A plant like that could certainly compete at the cherry tomato size.

The hardest part as an amateur would be getting to a sufficient level of certainty that the plants produce low enough glycs at all levels of maturity and under varying conditions.  That would be a lot easier and more reliable with laboratory TGA testing and that is neither easy to do at an amateur level nor commonly available commercially.

Burbank had an edible fruited potato at one point that he called a "pomato."  He thought that it was a hybrid with S. maglia, but he was probably wrong and it was just a domesticated potato with large berries.

There are also a few wild species with berries that have been eaten traditionally, S. demissum for example.  It seems that a lot of Solanum berries that are toxic when green become non-toxic when ripe.  The only problem is figuring out which is which without repeatedly poisoning yourself.

OSSI / Re: Pledging variety?
« on: 2021-01-19, 11:52:03 AM »
You may or may not be able to breed with a patented variety, depending on the type of patent and the license offered by the patent holder.  A standard utility patent on a variety forbids breeding with it.  A utility patent on a trait may forbid recreation of that trait even from other genetic sources, although that is not something that we generally consider.  You can breed from a PVP, unless what you breed from it is "essentially derived," which is generally considered to include sports.  And systems outside of US law vary in their details.  Also, varieties are increasingly bag-tagged or come with a separate contract that can specify almost any restriction that is valid under contract law.

So, we have to take some care in evaluating new varieties.  Overall though, the more common problem is that people submit varieties that don't involve a clear case of breeding.  For example, growing a variety for multiple generations for local adaptation without ever intentionally crossing it.  When there was an intentional cross and the phenotypic change is evident, it is a lot easier to make the case for breeding than when the phenotypic change is small and likely within the normal range of expression for a given variety.

Increasingly, people are breeding from OSSI pledged varieties, which makes all the progeny automatically OSSI pledged.  That may be the bazaar that you are looking for, Nicollas.

OSSI / Re: Pledging variety?
« on: 2021-01-19, 01:45:17 AM »
You can declare your varieties open source without pledging; they just won't be OSSI open source.  The OSSI requires official acceptance of varieties in order to ensure that they are defensible.  We take a breeding history, determine that real breeding has been done and that there were not patented or protected varieties in the background of the variety, and document it on the website.  It is a higher standard than simply public domain or open source.  Without review, we would have a big mess of undefensible varieties and, if OSSI varieties were widely regarded as indefensible, then there would be nothing to stop people from using them in patented/protected breeding work.

OSSI / Re: Pledging variety?
« on: 2021-01-19, 12:42:15 AM »
I am a member of the variety revew committee and would be happy to help anyone get their variety pledged, but it is best to email me at

Potatoes / Re: Potato Tomato Hybrid
« on: 2021-01-19, 12:36:00 AM »
I think that you would have an easier time selecting potatoes for larger and more edible fruits than you will hybridizing them.  There has been a lot of work to try to cross members of section Petota with more distant relatives and even the closest section, Etuberosum, is virtually impossible to cross naturally.

Potatoes / Re: List of fertile potato varieties
« on: 2021-01-19, 12:30:28 AM »
Based on the progeny and the fact that I got berries on isolated plants, I do believe that Pink Fir Apple is self-fertile.  It does have a very poor berry set for me though.

Plant Breeding / Re: Seed or ovule culture contracting
« on: 2020-09-06, 07:58:37 PM »
Check out the book "Plants from Test Tubes."  It is an introduction to tissue culture with amateurs in mind.  You don't need a fancy lab (although it is nice).  I worked for several years using a glove box (a plastic bin with holes in the side for hands) and it was sufficient.  There are also some additives like Plant Preservative Mixture that help to keep media free of contamination when working in less than ideal circumstances.

OSSI pledged varieties / Re: Perennials and the OSSI Pledge
« on: 2020-09-02, 12:07:03 PM »
The board has discussed this a few times and always comes to the conclusion that "seed" is sufficient, even for other kinds of propagules, but, speaking only for myself, I don't see any reason why your change would be a problem.

Potatoes / Re: Working with wild potatoes & breeding by clade
« on: 2020-08-19, 03:51:35 PM »
Clade 3 mostly contains lesser known species that haven't been used much in potato breeding.  They are mostly diploid species, about 2/3 with 2EBN and 1/3 with 1EBN.  The difference in EBN will be a barrier to easy crossing, but I expect that the two EBN groups will mostly be compatible for crossing within group.  In general, species with the same ploidy, EBN, and nuclear genome can be expected to cross to some degree.  You can find a list of clade 3 species here and each profile notes in the Breeding section if there have been reported crosses with other species.

Solanum chomatophilum seems to be the most studied species in clade 3 and has been crossed with many other species in clade and out.

I have had berries with a single seed.  For that matter, I have had entirely seedless berries fairly commonly from some crosses, so I don't know what effect the number of embryos has on berry development.

A good understanding of EBN is the most important tool when it comes to predicting the results of crosses with wild species:

Potatoes / Re: Viruses in Certified Seed Potatoes
« on: 2020-02-17, 03:37:55 PM »
That makes sense.  GB is one of the few widely available varieties that is male fertile.  I plan to cross yellow flesh diploids to it, but that will now have to wait a year.

Potatoes / Viruses in Certified Seed Potatoes
« on: 2020-02-17, 01:15:09 PM »
Certified seed potatoes are the most disease free option available to potato growers (other than TPS), but they are not disease free.  There are tolerances for various diseases.  For some, the tolerance is zero (most bacterial diseases), but for viruses, there is generally an allowance.  So, you can get any of the common potato viruses from certified seed.  The most common virus that I see in certified seed is Potato Virus S (PVS).  Most programs don't have an upper limit for PVS infection.  PVS is generally considered to be a virus of minor importance, but is has a number of undesirable effects, particularly if you are saving your own tubers year on year.  PVS, in my experience, makes potatoes much less likely to hold flowers.  It also amplifies the symptoms of other viruses and can reduce resistance to late blight.

The picture shows test results for the variety 'German Butterball,' received from a major certified seed supplier this year.  As far as I could tell, the whole lot was infected with PVS.

Potatoes / Re: TPS 2019
« on: 2020-02-17, 01:07:40 PM »
As far as this post goes, I don't have a strong opinion.  We could start a new thread or lop of the 2019 and keep going.

Potatoes / Re: TPS 2019
« on: 2020-02-17, 01:04:33 PM »
Clancy is the latest try at "uniform" tetraploid TPS.  There have been several of these over the years, including Explorer, Zolushka, and Catalina.  And those were preceded by a bunch of Soviet varieties, some of which are still available from a seller in Ukraine.  These have always been pretty disappointing compared to tuber grown potatoes, but I can only see mass market TPS as a good thing, since it will introduce more people to the idea.  I was sent a promotional packet this year and I plan to grow them out and review.

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