Author Topic: Is male sterility in brassicas dominant?  (Read 146 times)

Gilbert Fritz

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Is male sterility in brassicas dominant?
« on: 2018-12-11, 05:16:18 PM »
I've been thinking about male sterility in brassicas. When seed is saved from a male sterile F1 (which by definition myst have been pollenated by a male fertile plant) what will happen in the F2? As I understand it, all the plants will be male sterile. Why would this be?

Joseph Lofthouse

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Re: Is male sterility in brassicas dominant?
« Reply #1 on: 2018-12-11, 06:12:08 PM »
There are two types of genetic inheritance in plants: Nuclear DNA, and cytoplasmic DNA. The nuclear DNA is inherited equally from each parent. The cytoplasmic DNA is typically inherited only from the mother, and is contained in things like mitochondria, chloroplasts, and other organelles. So if a plant has a defective organelle, it is typically inherited unchanged by the offspring. If the defect causes male sterility, it may be a permanent condition for all of the offspring.

I say "may be permanent", because sometimes, the defect is with the interface between the nuclear DNA and the organelle, and some alleles might work while others fail. Therefore in some cases,  fertility may be restored by pollinating with a suitable variety. Then it's just a matter of re-selecting for fertility.   

"Restorer Genes" exist in some varieties of brassicas. I haven't studied them enough to know how wide spread they are. In my own work, restorer genes seem pretty common in open pollinated onions, but lacking in carrots.
« Last Edit: 2018-12-11, 06:17:21 PM by Joseph Lofthouse »

Richard Watson

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Re: Is male sterility in brassicas dominant?
« Reply #2 on: 2018-12-11, 09:35:19 PM »
But then how would you know if a certain variety of brassica has the 'restorer Gene'

Joseph Lofthouse

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Re: Is male sterility in brassicas dominant?
« Reply #3 on: 2018-12-12, 12:57:06 AM »

Restorer genes are trade secrets of the highest order. I don't see any way for me to gain access to restorer genes other than by trial and error. Since I grow landrace style, I get to do plenty of trial and error with minimal added effort.

I'm not much interested in restorer technology on my farm. I tend to simply select against plants that are missing expected flower parts such as anthers or pollen.


Gilbert Fritz

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Re: Is male sterility in brassicas dominant?
« Reply #4 on: 2018-12-12, 08:03:56 AM »
Thanks, that makes sense.

Klaus Brugger

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Re: Is male sterility in brassicas dominant?
« Reply #5 on: 2018-12-24, 03:20:21 AM »
Presence of restorer genes in CMS cultivars also depends on the crop. CMS rapeseed typically has restored fertility, otherwise you need additional pollinator lines for a seed crop.
Cole crop cultivars might as well be infertile from the perspective of seed companies and most growers. For the widely used Ogu-CMS there wasn't even a restorer gene available in Brassica oleracea at least until recently. They've been working on it (compare Yu et al. (2016)) but I'm not sure if any commercial breeder already works with Ogu-CMS fertility-restored B. oleracea. And even if so, I doubt that the restorer gene will find its way into released cultivars.

Yu, H., Fang, Z., Liu, Y. et al. Theor Appl Genet (2016) 129: 1625. https://doi.org/10.1007/s00122-016-2728-9

Andrew Barney

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Re: Is male sterility in brassicas dominant?
« Reply #6 on: 2018-12-24, 08:48:37 AM »
So apparently CMS can be transferred via grafting. I had the idea that maybe you could restore good mitochondria via grafting to get around CMS, but I have yet to find any articles that say it can be done.

Also I find it unlikely that restorer lines are not published somewhere in scholarly articles, or databases because how would these big companies find them too.
« Last Edit: 2018-12-24, 10:00:17 AM by Andrew Barney »

Andrew Barney

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Re: Is male sterility in brassicas dominant?
« Reply #7 on: 2018-12-24, 10:03:11 AM »
In addition,  though very rare, mitochondria can be passed from farther germ cells to the offspring and recombination between mitochondria can occur,  even in humans. So statistically speaking if just lots and lots of crosses occurred,  then perhaps fertility would be restored anyway.

Also back mutation can also occur, so randomly cms lines may become fertile by random chance as well.