Self Pollination and DNA

[AJ Drew]

For the sake of discussion, lets pretend you have a single pepper plant in perfect isolation. That sucker is growing on the moon in an air tight bubble.  No possible chance of anything cross pollinating with it.  Would its offspring have the same exact dna like a clone, or does the dna get recombined over and over again in different ways?  I have not a clue, but it does seem like offspring will very from their parent. 

If the DNA gets shaken up, I wounder if that might not account for what people seem to think are random mutations.  From what I understand, an actual mutation is incredibly rare.  However, have seen myself on a few occasions really odd things coming from seed that whose parent was isolated by itself.  Also, consider things like the CPR by Mr. Taylor.  Was new dna introduced or maybe there was a recessive gene for chocolate all the time.  Could mixing up the same plants dna bring something like that out?

I honestly havent a clue.  Want to add that when this seems to happen, I very much appreciate the seedmen who say just that: I havent a clue.

 

[Neel]

I believe self polinating will cause some weakness as the genetics get less varied every generation, like inbreed. Quick search led me to this site: http://www.superhotchilli.com/info2.html suggesting to keep throwing a f1 and/or f2 in the mix for more genetic variety.
 
Edit. So I'd say the DNA gets recombined everytime but the gene pool does get smaller and smaller

 

[cruzzfish]

I believe self polinating will cause some weakness as the genetics get less varied every generation, like inbreed. 

That's the entire point of doing it in the first place. People want to know how the plant is going to grow.
 

If the DNA gets shaken up, I wounder if that might not account for what people seem to think are random mutations.  From what I understand, an actual mutation is incredibly rare.  However, have seen myself on a few occasions really odd things coming from seed that whose parent was isolated by itself.  Also, consider things like the CPR by Mr. Taylor.  Was new dna introduced or maybe there was a recessive gene for chocolate all the time.  Could mixing up the same plants dna bring something like that out?

The DNA does get recombined the same way as if that pepper plant were to breed with an exact clone of it. That being said, there's a bit more too it. A pepper hybrid that's in the early generations will display a lot of variance in self pollinated offspring, while a stable one should display none if it's been done fully. Say pepper AaBbCcxSelf happens, you could get any eight(technically sixty four results, but most of them are going to be the same thing) combinations anywhere from  AABBCC to aabbcc. If pepper AAbbCCxSelf happens though, only AAbbCC will come out of it. As for random mutation, they really aren't that rare. They just have to actually do something before anyone knows about it, and a lot of mutation becomes more apparent when it happens during reproduction. There's also that a lot more mutations that occur in meiosis, so it's definitely a pretty common factor. And with recessive genes, it's very possible not to find out about them for a long time.

 

[Peter S]

This might be a little off topic, but curious, as I never tried to make my own crosses yet. If you have say an f1 hybrid that has features you want to persist in future generations, would it be better to cross the f2 seeds produced from it back against the original f1 parent? What would that be classified as? Would seeds produced from those pods be considered f1 again? Would the genepool for it be more stable at that point than the original f2 seeds? I hope the question makes sense. Thanks.

 

[cruzzfish]

This might be a little off topic, but curious, as I never tried to make my own crosses yet. If you have say an f1 hybrid that has features you want to persist in future generations, would it be better to cross the f2 seeds produced from it back against the original f1 parent? What would that be classified as? Would seeds produced from those pods be considered f1 again? Would the genepool for it be more stable at that point than the original f2 seeds? I hope the question makes sense. Thanks.

That would just be another f1 and no more stable than the f2. It wouldn't necessarily be less stable though. Better just to get a lot of seeds, grow them out, and pick the ones you like.

 

[Malarky]

it can be said as well that "mutations" happen more than you think...they just tend to form offspring that don't survive. the mutation effects a gene necessary for life...so your seed may just not germinate. The chances of a beneficial mutation are slim to none.
 
that and most traits are non-medelian

 

[cruzzfish]

it can be said as well that "mutations" happen more than you think...they just tend to form offspring that don't survive. the mutation effects a gene necessary for life...so your seed may just not germinate. The chances of a beneficial mutation are slim to none.
 

No. Most mutations don't kill the offspring. They're just absolutely inconsequential and there's no way of knowing that they even happened. It's very rare, especially in plants, for a mutation to actually be fatal.

 

[mrgrowguy]

Cruzzfish is on fire! I just read the responses and I agree with him all around. Thanks for sharing your knowledge!!
 
I've done my own research for the past few years and have come up with just about the same info he has already mentioned. There is a lot more to the art of breeding than just this topic, but as for answering the question at hand... bravo.
 
 
 
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[AJ Drew]

it can be said as well that "mutations" happen more than you think...they just tend to form offspring that don't survive. the mutation effects a gene necessary for life...so your seed may just not germinate. The chances of a beneficial mutation are slim to none.
 
that and most traits are non-medelian

I should have said viable seed from mutation is rare.  I forget what variety of apple it is.  Maybe yellow delicious.  But there is a variety of apple tree which all came from the same branch.  If I am remembering what I read correctly, there was a random mutation that changed the apples on a single branch.  The seed of that fruit did not produce the same fruit.  So the owner cloned a cutting of the branch, took cuttings of what followed, and on and on until you can buy the thing at any garden supply.

Not sure if cloning is the right term here.  They grafted it onto another tree.  I am fairly sure the roots are always from another tree variety.  Something about resisting pests or disease. 

 

[Tarzan]

The gene recombination makes DNA of the self pollinated mother plant's seedlings unique. In an infinite number of self pollinated generations, you could actually get a plant, that could give you genetically identical offspring, but if you include the mentioned small mutations, even the infinite generations would not be enough.
 
When you try to stabilize a new variety, you do just that, you self pollinate a plant with whole bunch of different DNA, which makes various combinations in every new generation. By selecting the best plants and 'inbreeding' them further, you eliminate some of the unwanted parts of DNA with each generation. When you self pollinate a  plant with 'good gene' and 'unwanted gene', you eventually get to a plant which holds both possible combinations of 'good gene'.

 

[cruzzfish]

Cruzzfish is on fire! I just read the responses and I agree with him all around. Thanks for sharing your knowledge!!
 
I've done my own research for the past few years and have come up with just about the same info he has already mentioned. There is a lot more to the art of breeding than just this topic, but as for answering the question at hand... bravo.
 

Someone get Hybrid Mode in here. He knows more than me, so he can check everything.

 

[AJ Drew]

I dont remember the title, but back in the day read a science fiction short story.  Kind of a long short story.  Instant transportation / teleportation was being marketed.  What they did not tell the public was that you were not really being transported.  Instead, you were being scanned, destroyed and then rebuilt based on the scan.  This included your dna. People started noticing changes.

First it was a little bit of your older memories, the ones that were replicated over and over again more often.  Then physical things started to fail.  With each replication, there were tiny errors.  Kind of like a photo copy of a photo copy of a photo copy starts to become blurry.

From what he said, I can tell I am not nearly as versed in this as Tarzan.  But I have to wonder if a self pollinating plant were to be made completely stable, wouldn't it eventually get fuzzy around the edges like the photo copy of the photocopy of the photocopy?

Have been working on some things for a bit, trying to get them stable, horrible luck.  So tipping my hat to folk with much more knowledge and hoping to learn.

P.S. - Tons of experience (as a younger self) with cloning and yes, clones of clones of clones wind up having problems.  I ran into it at about 8.  But keeping a single mother plant, or turning clones into mother plants to put it off helps a great deal.  Today my cloning is usually limitted to something that seems special, plants with emotional attachment, and because I am a cheap bastard who doesnt like paying a dollar a seed.

 

[Hybrid Mode 01]

This might be a little off topic, but curious, as I never tried to make my own crosses yet. If you have say an f1 hybrid that has features you want to persist in future generations, would it be better to cross the f2 seeds produced from it back against the original f1 parent? What would that be classified as? Would seeds produced from those pods be considered f1 again? Would the genepool for it be more stable at that point than the original f2 seeds? I hope the question makes sense. Thanks.

 
 
 
     Cruzz pretty much nailed the response to this. I just want to add that something else you might consider is a backcross to one of the parents. Say you have a variety you really like like a Scotch bonnet, but you want it to be way hotter. You could cross it to a moruga and grow out all the crossed seeds into mature plants. From that cross, you could select the offspring that most closely resemble the bonnet, but also have the heat of the Moruga. 
     Now with those offspring, you could cross this new f1 back to the Scotch bonnet parent, instead of self pollinating. Then from these offspring, you could again select plants that even more closely resemble the desired Scotch bonnet parent while still being Moruga-hot. Over and over again until you just end up with a bonnet that is almost indistinguishable from the parent bonnet, except for capsaicin production. You just kind of keep filtering out all the Moruga traits, except for the desired higher capsaicin production.
     Backcrossing to a stable parent can make it much faster and easier to introduce a desired trait (in this case, capsaicin production) into a preexisting variety or cultivar. A lot of time this technique is used to create "improved" varieties for traits like disease resistance, productivity, dwarf habit, etc...
     I used to do a lot of work with certain soybean PIs (Plant Introductions) that were all but useless as a field crop. No disease resistance, non-uniform pod ripening, poor germ rates, weak plants... Just garbage genetics. Except that each one had a certain gene involved in nematode resistance. Crossing these PIs with robust, good-producing soybean varieties can be used to introduce  Soybean Cyst Nematode resistance into a good cultivar that otherwise would succumb to nematode infestation. 
     That's one reason why big seed banks exist. There are all kinds of species out there that are going extinct all the time. Some of these species and biovars have potentially useful genes that could be used to introduce desired traits into other useful, but otherwise flawed, plants. 
 
 
edit: Disclaimer - This gets more complicated when more than one gene is responsible for a phenotypic trait. Capsaicin production is the result of a whole concert of genes working together. 
     Think of it this way. Plant leaves produce sugar as a metabolic raw material. That sugar might be used (indirectly) in a fruit cell to give energy to an enzyme that creates a certain chemical from some other chemical raw material. Another enzyme might form another chemical via a separate pathway. Yet another enzyme might come along and combine these two chemicals into something else altogether. Then another enzyme might convert this new chemical into a capsaicin precursor... 
     Each one of these enzymes in this (horribly oversimplified) metabolic pathway is a potential control point in the synthesis of capsaicin. It gets complicated really fast. And that's not even considering all the enzymes that are needed to regulate or locate the actual enzyme catalysts in the pathway. 
     So yeah. What was I saying?... Oh yeah - biochem is hard. 
 
 
 

Someone get Hybrid Mode in here. He knows more than me, so he can check everything.

 
 
     It's been years since I studied all this stuff. Now I just try to remember the basics and the rest I just make up.  Don't tell anyone, though.