Author Topic: Removing male sterility in CMS hybrids  (Read 615 times)

Ocimum

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Removing male sterility in CMS hybrids
« on: 2018-10-17, 09:42:42 AM »
“Normal” hybrids (emasculated or based on self-incompatibility) can be used to breed new or OP varieties, but cytoplasmic male sterile (CMS) cannot.
What are the ways to induce fertile pollen in CMS hybrids?

1) Environmental stress induces pollen in some CMS varieties.

2) In some species, restorer genes are present in wild populations, allowing a CMS plant with this (nuclear) genes to produce pollen.

3) In the labs, fusion of protoplasts is used to get the CMS into species not having it naturally. In short, a nucleus of CMS-free species A is put into a CMS cell without nucleus of species B, grown out, it gives the male sterile plant A. Theoretically, it could be reversed: How easy is it? Can I give seeds to biology student and a he can do it?

Are there other ways to remove CMS in plants with otherwise useful properties?

Joseph Lofthouse

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Re: Removing male sterility in CMS hybrids
« Reply #1 on: 2018-10-17, 10:02:57 AM »
When I first started making my carrot landrace, more than 70% of the plants were male sterile. While I didn't do breeding with those plants, they were easy to eliminate from the population, just by looking at the flowers.

In onions, CMS, Cytoplasmic Male Sterility, seems to require a nuclear component, and a matching cytoplasmic component. So changing the pollen donors can disable the CMS. 

One of the squash lines I work with is male sterile. Fertility can be restored by pollinating with other varieties. It segregates normally, so some of the offspring are also male sterile.

bill

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Re: Removing male sterility in CMS hybrids
« Reply #2 on: 2018-10-17, 12:35:29 PM »
I would add a tentative #4, which is graft transformation.  I am still a skeptic about this, but there are some reports of exchange of nuclear and cytoplasmic material, particularly in the graft zone, when two varieties are grafted together.  If that is true, it would be possible to tissue culture material from the graft zone and potentially get the right combination of nucleus and cytoplasm to restore fertility.  It is at least theoretically easier than protoplast fusion to accomplish the same reversal.

Nicholas Locke

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Re: Removing male sterility in CMS hybrids
« Reply #3 on: 2018-10-18, 05:24:16 PM »


In onions, CMS, Cytoplasmic Male Sterility, seems to require a nuclear component, and a matching cytoplasmic component. So changing the pollen donors can disable the CMS. 


This makes sense, as my father planted a few different varieties of commercial onion bulbs, and let them go to seed, The onions bulbs came from a large local onion grower which would have been F1's for sure as none of them use OP seed anymore. I was sure they wouldnt produce seed ,which I stated to him thinking I had superior knowledge of this CMS thing he had never heard of . of course they all set copious amounts of seed of which he has saved for the last 3 years! Had me scratching my head! 
"Maybe" said the farmer...