Male Sterility /CMS

Nursery bought F1s and Male Sterility

Shao S 2022-10-13T07:00:00Z
Right now I have a range of F1s of brassicas from a nursery which initially I had chosen because I liked the idea that they already had 2 different parents and a wider genetic gamma, but after learning that many commercial F1 are sterile due to a sterile parent, I’m a bit lost.

Is there any where to check if these plants and/or seeds are sterile other than planting out their seeds? Will leaving them to seed in my garden cause sterility in other brassicas they cross with?

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Note: the October zoom call discusses this topic. Add link and timestamp. List of hybrids to avoid.

Mark R
They probably are male sterile because of the large numbers of small individual flowers; it would be near impossible to make an F1 without using male sterility. Same is true for about any other species with lots of very small flowers.

Since they don’t make pollen, they cannot pass the trait to other non-sterile varieties. However, they can make seeds if pollinated by the fertile ones. The danger of accidentally getting the seeds mixed up or not knowing the status of any volunteers is why I banned F1 of those species completely from my garden.

Julia D
So if it were you, would you toss everything and start with new seeds?

Shao S
Thanks for the amazing and concise information! I have been googling for hours trying to figure out the answer to no avail… Welp… I’ll have to stop them from flowering then… A shame… That purple cauliflower trait looks so cool!

Mark R
Yes, for my purposes I probably would discard them.
@Shao Sanchez
, growing them but not letting them flower would be fine. No danger there.

Ray S
I’m with Mark there. I wouldn’t have them in the mix. Alright to eat them though.

Shao S
That being said… Should I assume the F1s of other plants with less numerous flowers to be ok? They seem like an easy way to introduce more genetics into the pool… Melon, tomato, beans, peppers, etc?

Mark R
I think most other F1s are fine. I have genetics from lots of F1s in my crops. Corn, tomatoes, melons, and so on. I think in the case where hand pollination of a single flower is easy and produces a lot of seeds, like with a tomato, or like with corn where it’s easy to detassel a plant and pollinate with another CMS is not used, at least that I know of.

We should double check that with Joseph, especially about your peppers, I’m not much familiar with them. Beans are mostly self-pollinated; crosses show up in my garden now and then, but I don’t think I’ve ever seen an F1 bean offered for sale by a seed company.

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Cytoplasmic male sterility is relatively easy to see, even from a distance. The flowers either don’t make anthers at all, or the anthers are shriveled and lack pollen.





I’d love to add some brassica genetics that I can only find in commercial F1s, such as this Clementine cauliflower. It’s my understanding that if I planted this with a non-CMS variety and saved the seeds from the F1 that I could then select against CMS in the F2 generation.

Do you know how quickly CMS can be weeded out of the gene pool? If I cull all F2s with CMS, with I still be dealing with it in F3 and on or will it be more or less gone?

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Cytoplasm carries the organelles, which are things like mitochondria, chloroplasts, etc. They are inherited only from the mother. If there is a genetic defect in the organelles, then the plant can’t produce pollen. Therefore, Mendelian inheritance doesn’t apply. The offspring will carry the defective organelles in each generation. Sometimes, the deficiency is due to a disharmony between the organelles and the nucleus DNA, and rarely getting the right pairing can resolve the CMS. But it’s rare, and can’t be expected.

In brassicas, the CMS is due to the organelles being from a different species than the nuclear DNA. They are essentially GMO.


Drats! I’ll cross the F1 brassicas off my shopping list.


If the male sterility is passed on by the mother through the cytoplasm, but if the plants are not 100% male sterile, then logically, it should be worth trying to gather pollen from the male F1 to give to a healthy female, right? Like, maybe get loads of that cauliflower’s flowers and tap every last bit of pollen you can get out of them and use that for making crosses? If it’s just that most flowers produce no pollen or even like 98% reduction or whatever, that pollen harvesting should fix that, and if it’s a case of what little pollen it does make, being mostly unviable, then even if it’s 98% unviable, then using lots of it to shower lots of female flowers of what you’re crossing it with, should work, right? I mean, even if only 1 in 10 get fertilised that way, or even way less, it should still be doable right?


Ahhhh! Okay, I read the other thread where we’re talking about CMS before this one. Okay, yeah, if CMS brassicas are inherently genetically engineered, and not something that showed up as a mutation in nature, that’s not great. I don’t think it’s the end of the world, but it’s probably not something that’s a great idea to perpetuate.

Especially since brassicas are self-incompatible anyway, so it’s not like CMS confers a possible advantage of self-incompatibility that wouldn’t be there.

This is excellent knowledge to have - the actual practice of making this hybrid seed sounds dreadful and unnecessary. This thread has changed my thinking on the subject of induced CMS. I’m not sure how I imagined it was being done, but certainly not like this.

How can it be legal for these seeds to be distributed without the GMO label - - because the nuclear DNA has not been tampered with?

It’s because of issues like this, that i choose to grow what i love, rather than fuss about how other people do things.


[the following are slightly out of order because they are moved from another thread]

Ryder T
2022-12-23T08:00:00Z [response to a CMS comment]
For CMS, I wonder about this often as well, as I have grown fond of planting strange cabbages after we have eaten most of them. I just put the base and inner leaves of a local bok choy into a critter-dug hole a few days ago when temps were above freezing. Now they’re subzero. It looked happy enough this morning with what looked to be still-pliant leaves. I’ll check on it again soon.

Anyway, most of what I read from the internet and experienced breeders seems to make the case that you should take care not to introduce CMS. On that note I think Lowell is favoring scratching a year of development to keep CMS out of his onions.

Personally I’m considering doing it. Not intentionally putting CMS into my brassicas, mind you, but allowing for it.

The way I look at it, if I’m going to breed plants for more than one season going, I’m inevitably going to introduce off traits. At that point I’ll be reaching for one or the other or a combination of a likely-or-known-good reset state and removing the undesirable trait.

I’ve got a rudimentary handle on understanding CMS that basically goes like this. It’s a maternal trait that is counteracted by nuclear restorer-of-fertility genes. I’m not worried (perhaps I should be?) that it’ll muck up my whole landrace. It would make CMS-manifesting plants mandatory outcrossers, in some ways an advantageous trait. If the entire landrace got like that it’d be inconvenient, but if it’s just half (let’s say) that seems fine to me as long as any seeds I share come with an appropriate disclaimer. I’m more interested in seeing what happens with my cabbage transplants than I am in maximizing seed production. Breeding CMS out might also make for an interesting (if contrived and self-imposed) project.

Here’s a thought, if you don’t mind CMS in your landrace, and you think most other landrace gardeners may. You could mark your best plants that don’t have CMS to save extra seeds from, and keep all the extras you don’t need for yourself in a separate bag (or packet, or whatever you use to store seeds) for sharing. If it’s exclusively maternally inherited, the trait wouldn’t be showing up as a recessive trait in the next generation of the seeds with male fertility, so you could distribute those seeds to anybody.

Am I correct about that?

If so, that seems like a very simple way to have plenty of seeds to share, and to also not mind CMS in your landrace. It also seems like it would be easy to select against in only one generation if you ever decided you had enough genetic variability in the male fertile plants to only save seeds from those that year.

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Huh, really? It seems like it ought to be. I mean, if the plants are only female-fertile, they won’t be contributing pollen to a landrace, so it seems like it ought to be easy to eliminate that trait just by not saving seeds from the plants that are male-sterile.

The only way I could see it popping up afterwards is if there’s a Mendellian component. For instance, if it’s a recessive trait, and so some of the male-fertile plants you save seeds from might be carrying one allele for it, so it would keep on popping up occasionally. If that’s the case, and it’s also always inherited from a mother who has both recessive alleles, then yikes, yeah, that would be hard to remove.

It’s also possible there are other genetic systems I don’t know about now.

Does anyone know precisely how CMS works on a genetic level in brassicas? This is one of those times when knowing exactly how the genetics work would be very helpful in making plans for the future.

As an example, with brassicas, brocolli cytoplasm was removed from the cell, and replaced with radish cytoplssm. That is a drastic change, which broke the brocolli’s ability to make anthers.

It’s easy to eliminate CMS, by selecting against deformed anthers. But you can’t expect to convert a CMS family into a non CMS family. Pollen goes into a CMS family, but it doesn’t come out.

I was growing a carrot landrace that was 70% CMS. It grew fine. The plants with perfect flowers provided enough pollen. I made a philosophical choice to not grow plants that can’t produce pollen. What if one year, every plant that I saved seed from happened to be CMS? Or what if I share seeds with people that grow small populations for seed saving?


Oh, wow. Was CMS in brassicas genetically engineered? I thought it was a deleterious mutation that some humans decided they liked and wanted to keep.

Hmm, yeah, I see what you mean. I was kind of missing the obvious. If a plant has CMS, and you don’t save seeds from it, you won’t be keeping anything from its genetics in the landrace, anyway. In which case, why introduce it in the first place? Even if it’s easy to select against, if you’re planning to select against it eventually, introducing it in the first place won’t increase your post-selection genetic diversity.

Which of course is fine for a person who doesn’t mind having a bunch of male-sterile plants in their landrace long-term.

It sounds like the main difference between male sterility and gynoeciousness is whether something is broken or working as intended. Which may make all the difference philosophically, but may not make much difference other than that. Am I correct about that?

I’m personally planning to introduce some gynoecious squash varieties into my pepo landrace next year. I have ten times more male flowers than female right now, and I’d rather have more fruit. (I may be a bit greedy. :stuck_out_tongue:) I figure some gynoeciousness would be a great way to get more female flowers in my landrace.

The way I read what Joseph said there was that it’s critical to avoid only the female. But it seemed to me that if there is any fertile pollen available from the males, then using that should completely avoid the problems. No-one fed back on that but if anyone knows if it is possible to gather viable pollen from CMS plants, then that should be useful information. I was kind of guessing that they might not all be 100% sterile? In fact this to me implies I was on the right track:

So, supposing you want to get that orange cauliflower into your landrace, and supposing my first idea doesn’t work, you can’t even manage to get any pollen from them, let’s say they happen to be 100% male sterile (if that’s even a thing). So then, my logic is telling me,

  1. Cross the orange CMS ones with one of your regular male candidates.
  2. Get offspring that then have x% male sterility (like Joseph’s landrace had). So you now have a population which includes 100-x% male fertile cauliflower.
  3. So, now select from that male fertile group, the ones that have the trait you want - that orange colour I guess. And use their pollen to fertilise flowers of other candidates that have not been crossed at all with any of the CMS population, i.e. regular healthy females. Just make sure that you have isolated that CMS population and that you make the crosses manually, or cull all the CMS population before it sets any seed.

If I have understood Joseph correctly, this should pose zero problem regarding CMS, and you have now likely introduced your desired orange trait to your population, can discard all the CMS population, and can continue selecting for your newly introduced orange trait in the next season, either on the plants from the seed resulting from the above planted on their own, or by adding that seed directly to your regular landrace if you have one already going.

Or did I misunderstand something?

In case anyone wanted a visual for male sterility, here’s one from a paper I was just reading (they used this plant to introduce CMS to domesticated European radishes it seems, which sounds pretty immoral!):

Ogura cytoplasmic male sterile (left) and fertile (right) flowers found in a population of Japanese wild radish. Arrows show male sterile (left) and fertile (right) anthers. Scale bar = 1 cm

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I just can’t see an upside to messing with CMS. Especially with my briccol-ish which I envision someday becoming feral like some of my other crops, I don’t want male sterile seeds being dispersed to sprout volunteer.

From what I understand if a plant is CMS then all of its offspring will be as well. It also sounds like there are no advantageous heritable traits, even if by some chance a CMS plant did make a little pollen. For me the whole idea of it falls into the category of more trouble than it’s worth.

I think that if I became aware of a CMS variety that had traits I wanted, I would track down the non-CMS origin of those traits.