Using CMS at home for breeding ?

[nicollas]

I have a question about CMS for breeding project. If i've understood correctly CMS are not cool because the male sterility is transmited to all following generations. But there are some restorers to restore fertility, although i dont know why.

I'm thinking about CMS for the breeding project involving an interspecific cross between Phaseolus lunatus and P. polystachios. During my researches i've seen that at least one CMS cultivar for the lima bean as been found (but i dont know if it will be accessible), and i'm wondering if it can be of any use for the project, because of the difficulty of the cross. I could plant the CMS with the polystachios and screen for any pods on the lunatus. The offsprings will be sterile anyway due to some differences in chromosomes (?) so it needs to double the chromozomes to create a polyploid. Could this polyploidy restore the male fertility ? If not, could i use a restore if i've made an interspecific cross and doubled chromosome meanwhile ?

thanks for any clarification !

[oxbowfarm]

I'd say it would over complicate a bean interspecific cross. With bean crosses you are usually hand pollinating each flower anyway, so the benefits of the CMS is hard to see? My understanding of CMS is the primary benefit to agribusiness is how much cheaper it makes the production of hybrid seed. For a home-scale hobbyist, cost is irrelevant, likewise intellectual property value.

[nicollas]

The problem with this interspecific cross is that it could be very difficult to make it. It has been made only two times, and onlywith one lunatus accession (and not the one i'd like cause of smaller seeds and annual type). Attempts have been made with other lunatus and failed (0 crosses over ~400 pollinations). And the crosses with the Fordhook cultivar was made with 7% success and 0.7% success (this one from the same study reporting the 0/400) which could suggest different compatibility with the polystachios accessions (if not the methodology). So why not letting nature rolls some dices while i'm hand pollinating some plants elsewhere ?

[billw]

If you are talking about naturally male sterile lines, it should be easy, but the difficulty will be restoring fertility later. With naturally sterile lines, unless the cause of the sterility has been worked out, you may end up with sterility that can't be reversed.

If you are talking about using somatic fusion techniques to induce and later reverse CMS, then you will need pretty good lab skills and equipment. I've been looking into reversing CMS by fusion and it isn't trivial. It is hard to isolate protoplasts, successfully fusing them by chemical process (which is about the only option for a home-scale lab) is a low probability event, and determining whether or not you have been successful without growing out plants to maturity may be impossible unless the cells that you are working with have visible differences in key organelles.

But, where there's a will, there's a way.

[nicollas]

I think it was a natural male sterility. i was wondering if doubling chromosomes could reverse the sterility but i'm not qualified enough to understand if it is a possibility

[karl]

CMS is cytoplasmic male sterility. "Cytoplasmic" being the key word. Chromosome doubling is unlikely to affect this type of sterility.

Karl

[nicollas]

Well it seems not a good idea afterall, thanks to all