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epigenetics

Posted by lundaesundae Zone 6 (lundaesundae@hotmail.com) on
Mon, Mar 3, 14 at 14:33

I have read it before on garden websites (none come to mind at the moment) that tell growing from a seed saved from a plant in a certain geographic area will then grow better in subsequent years. kind of like adapting or evolving to that general region but we all know these take mutations and happen over a long period of time. well i just read an article about epigenetics not applied to gardening that on a cellular level animals and plants will "adapt" so to speak without actually changing dna. i found this interesting because it would then hold true that seeds saved from a parent plant should in theory be better adapted to that geographic region. sorry for my rambling but i remember seeing a question asking if bought seed mattered which geographic region it came from. now i didnt research fully so im not sure how accurate of a science epigenetics was, but i was wondering what you all thought as applied to tomato growing, and if this was true youd be more likely to save seed?


Follow-Up Postings:

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RE: epigenetics

Epigenetics is a very clearly demonstrated phenomenon, and it is definitely real. HOWEVER, I really have no knowledge that it occurs in tomatoes and I have seen no articles or studies that indicate that it occurs in tomatoes.

That being said, I'm not sure why it would not also apply to tomatoes, and I personally expect that it does.

Essentially, Epigenetics is when the expression of certain genes is induced by the environment, then those genes "lock on" so that the organism continues to express those genes when it didn't do so before it "adapted."

Some Epigenetic changes can be passed to offspring,

But the amount of change available through Epigenetics is limited to whatever genetic potential was already innately there in the genome. What makes it important is that the expression of those genes is increased then locked on. So, the organism actually reponds differently in its environment, but it can't keep changing to adapt better and better, without additional mutations.

Now, does this mean that tomatoes grown from seed raised in your own garden area might produce superior results compared to tomatoes grown from seeds that originated "elsewhere?" Quite possibly. Many people think so. I just don't know if there is evidence.


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RE: epigenetics

and if this was true youd be more likely to save seed?

Whether one buys into epigenetics claims or not, and there is much controversy about it, it's testing and documenting methods, and to what it may or may not apply, I just don't see any correlation between it and saving seed.

There are numerous excellent reasons for seed saving if one is interested in doing so. If one isn't interested in seed saving, why would any claims made by epigenetics change their mind?

Dave


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RE: epigenetics

Personally I have my doubts that species with a very short life/reproductive cycles would express genes to any meaningful extent. It might be very harmful if those changes were in response to very short climate cycles or growing conditions. Plants are more likely to spread their seeds as widely as possible to find the habitat that suits them rather than changing to suit the environment. Soil conditions in one spot might be completely different than 100 yards away and a hot and dry year can be cool and wet the next. Just MHO for what it's worth.


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RE: epigenetics

hmmm, love the comments very thought inducing. It would be very hard to actually substantiate claims made because of the differences of every season. i hadnt actually given that much thought. however, i do suppose most gardeners already do this by selecting the seeds from a plant producing the best that season. Still very interesting IMO


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RE: epigenetics

There has been few discussion on this, adaptation issue and I happened to be a proponent if even it is just a theory. But Three are a lot of scattered evidence pointing in that direction.

Adaptation to an environment is not necessarily equal to mutation. We know a lot of plants of the same species and varieties that do be become NATIVE without mutation. Adaptation is a natural ongoing process among living things both in the animals and plants kingdom.

Case in point: Tomatoes have been introduced to outside south America ( the Old world) about 3 centuries ago. I bet that its propagation must have been very limited and slow during the first century or so. But now we witness a lot of NATIVE varieties coming out of Russia, Italy, Germany and other places. Some of those are said to be suitable for certain climates. How did that happen ? My answer is by natural adaptation. This adaptation may have taken place over a life time of one or two generations of gardeners .


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RE: epigenetics

Case in point: Tomatoes have been introduced to outside south America ( the Old world) about 3 centuries ago. I bet that its propagation must have been very limited and slow during the first century or so. But now we witness a lot of NATIVE varieties coming out of Russia, Italy, Germany and other places. Some of those are said to be suitable for certain climates. How did that happen ? My answer is by natural adaptation. This adaptation may have taken place over a life time of one or two generations of gardeners .

WOW! so the plants did it all themselves? No credit to the humans - who, unlike the plants happen to have brains - for figuring out how to grow the plants from South America in their climate?

And if it took them a century to do it they must have been some real Neanderthals. That would make a good B.C. comic strip.

Dave


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RE: epigenetics

Hi Seysonn, what you are describing is selection, not adaptation. Selection is essentially when you propagate the plants with desirable characteristics. During selection desirable characteristics arise randomly due to spontaneous DNA mutations or by crossing different plants with desirable traits. So you can think of selection as a human-guided evolution.

Epigenetics is a very real phenomenon and occurs widely across species. For example, a gene may be silenced by methylation of DNA at the promoter of a gene. In this scenario a methyl group (CH3) is covalently attached to certain DNA nucleotides at the gene without changing the actual DNA sequence. Other epigenetic changes may involve attachment of covalent groups to histone proteins packaging the DNA at certain genes or regions of the genome (aka "histone code"). This is extremely common. Such type of epigenetic modification can be passed down during cell division with two daughter cells inheriting epigenetic state (e.g. cytosine methylation of the said gene promoter). So, if the plant is a clone of a parent, it would be reasonable to expect that it will inherit epigenetic state of a parent plant.

However, only very few epigenetic changes can be passed down to a young plant grown from a seed. Regions of the genome where this occurs are called "imprinted". During fertilization (i.e. formation of a seed) DNA methylation is completely erased genome-wide except for very few specific imprinted regions (this was demonstrated in mice, but probably something similar happens in plants). So it is possible that if an imprinted region controls adaptive traits of a plant, the new seed-grown plant will also have the same useful adaptations.

So to answer the OP question, epigenetic adaptations may very likely occur. I would expect that the clone would be more likely to inherit epigenetic adaptations, compared to a seed-grown plant. That being said, I don't think any of this was scientifically demonstrated in tomatoes.

This post was edited by Starfinder on Tue, Mar 4, 14 at 12:29


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RE: epigenetics

This conversation seems to be dancing around the issue of transposons (transposable elements or also referred to as "jumping genes") which have been know since Barbara McClintock's work over 50 years ago, Science has been discovering more about these since the 1990's.

Link below is to a recent article about 'jumping genes' effecting pepper diversity.

Shout out to Fred Hempel for posting the article over on the less antiquated interwebs.

Here is a link that might be useful: Researchers sequence pepper genome, find jumping genes enhanced diversity


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RE: epigenetics

Hi lundaesundae,
I wanted to add to the responses already given.
Epigenetic changes can affect how much a gene is expressed or not, but not change the information the genes contain (that happens through mutation as you say).
There are epigenetic changes in all our cells (and plant's cells) that is how different cells with different rolls can have the same DNA and yet perform very different rolls.
Additional epigenetic changes can be triggered though the environment and in some cases they can be transmitted to the offspring. I don't know when this happens in plants (in humans these epigenetics changes are during puberty for male and during pregnancy in females).
Hope it helps!

Here is a link that might be useful: epigenetics TED talk


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RE: epigenetics

WOW! so the plants did it all themselves? No credit to the humans - who, unlike the plants happen to have brains - for figuring out how to grow the plants from South America in their climate?
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Whatever the technical terms are and how it comes about, the fact is that Plants do adapt just like animals. Plants even learn how to cope with certain insects and diseases.
How did human races (white, red, yellow, black ) came about ? Not by mutation but by adaption and under environmental influence. Why East Indians ,being Aryans have dark skin and brown eyes but Germans have light skin and blue eyes ? I am sure there were no DNA scientists to do this. So a Russian framer/gardener did not do anything other/more than planting year after year , generation after generation. And eventually the plant adapted itself to the environment and evolved. Now we have tomatoes with Russian origin with cold tolerance.
Now the plants scientist, knowing how this happens, find a shortcut to develop a cold tolerant tomato like SILETZ and LEGEND (in OSU)


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RE: epigenetics

"How did human races (white, red, yellow, black ) came about ? Not by mutation but by adaption and under environmental influence."

This is a bit nonsensical. I'm not sure if there's a language issue, or what?

Evolution happens through two processes - Mutation, and Natural Selection. Mutation introduces new possibilities into the genome, and natural selection weeds out the ones that don't work well. Mutations are constantly happening to your genome.


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RE: epigenetics

For what it's worth, the comment by fcivish matches my amateur readings. It is safe to guess that there is some epigenetic influence, along with other things (like microbiome) that we don't fully understand.

(Or, if we understand them in a controlled experiment, we don't know how it works in our yards.)


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RE: epigenetics

Something tells me, and I am guessing since I don't know anything about it but I would think that most changes occur first through selection. Then adaption would happen, if it actually does,which would be more correct?


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RE: epigenetics

Change doesn't happen through selection.

Change happens through mutation. Selection eliminates poor changes.


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RE: epigenetics

Adaptation is a mechanism to improve the chances to survive ( carry on the survival of the gene) A black rabbit cannot survive near the north pole. Also a white bear might die of hunger, To be white they have a better chance of survival. We are not talking about mutation, not even a major change. Polar bear is just a bear.... a Tomato adapted to Siberia is still a tomato. Call it NATURAL SELECTION or SURVIVAL OF THE FIT(to climatic conditions), it is the same.

Those tomatoes came out of South America and some ended up in Siberia and few learned how to cope and survive. That is what I mean by adaptation.


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