Can a plant change its climate DNA? (Can we grow lemons?)

Answer

Dear Kurt,

The answer to your question is: yes, the DNA of a lemon plant changes
continuous. But it’s not the lemon plant itself that targets changes
to the genetic code to adapt to the new environment.

Four phenomena are important to understand the answer to this question:
mutagenesis, heredity, epigenetic modification and evolution.

1) Mutagenesis.
All organisms continuously undergo mutations (changes) throughout their lives
in their DNA (their genetic code). This can have all kinds of causes. By people
are some typical causes of UV radiation on the skin, smoking, burns
eating food (e.g. meat from a BBQ) and acrylamides (which, for example,
can occur during the frying of fries). So there are both human
as natural causes of mutagenesis.

Then there is also spontaneous mutagenesis. These are changes that arise
during cell division. Both plants and humans are made up of billions of cells,
and billions of ‘worn’ cells are replaced in humans every day
by new ones. Even during our growth from child to adult (or before
a plant from seed to adult) billions of cells are created.
Each cell carries a complete copy of all hereditary material (all DNA
code) in it. This means that the DNA of an organism during its
life course is copied many billions of times. This copying process is unfortunately
not perfect and often there are errors in the copy that were not present in the
original. This is called spontaneous mutagenesis.

Both causes of mutagenesis therefore cause changes in the DNA and consequently
also for changes in the organism. Usually a mutagenesis has no or
a negative effect (such as cancer), but occasionally has mutagenesis
also a positive effect (e.g. better resistance to a certain
disease). The organism undergoing this mutagenesis has no way
to direct this process, i.e. whether an organism becomes stronger or weaker due to
mutagenesis depends purely on chance.

Both we humans and lemon plants undergo mutagenesis every day in a large
part of our cells. Fortunately, we have a mechanism in our body that
cells with a ‘bad’ mutagenesis die, so that we live here every day
not really bothered. But sometimes our body doesn’t manage to make such a
mutated cell to die, and then a tumor can develop. Sometimes
mutagenesis takes place in sperm cells or eggs, and then this new
mutation can also be passed on to our offspring.

2) Heredity.
Every organism that reproduces passes on its own DNA to its
offspring. In organisms that reproduce asexually, such as
bacteria and also some plant species, the parent passes on 100% of its DNA.
In organisms that reproduce sexually, such as a lemon plant and also the
In humans, 50% of DNA is passed from each parent to an offspring.
Since that 50% is chosen randomly, you get with every offspring
a different combination of DNA from both parents, and so each offspring
different and unique (with the exception of identical twins). By new
combinations of DNA from both parents can also be made in the offspring
new traits arise that were not present in either parent.

3) Epigenetic modification.
The DNA is the ‘building plan’ of every organism. But many organisms have the
possibility of not executing parts of this construction plan if the
circumstances are not favorable for this. They do this through pieces of this
construction plan (the DNA) ‘forbidden to use’. This changes it
building plan (the genetic code) itself is not. It only covers part of it
construction plan so that it cannot be read. This process is called epigenetic
modification.

This is the only mechanism organisms have for targeted adaptation
to a new environment during their life cycle (such as your lemon plant).
Nearly all organisms also have the ability to produce at least one
pass on part of that epigenetic modification to offspring.

4) Evolution.
After reading the above text you may be wondering how it is possible
that animal and plant species are able to adapt themselves to a
new environment. The answer to this is ‘evolution’ or ‘survival of the fittest’
as the famous scientist Charles Darwin called it.

Every time an organism gives birth to offspring, they have
offspring new traits thanks to their unique DNA. This DNA is unique
thanks to mutagenesis and, if sexual reproduction is involved, the
randomly throwing together pieces of DNA from both parents. Very occasionally goes
this new unique DNA may have benefits for one of the offspring. In that
case, that offspring has a better chance of surviving until the self again
can make offspring. The ‘beneficial’ DNA of this offspring is
passed on to the next generation. This mechanism, where
‘DNA well adapted to the environment’ provides ‘a greater chance of
offspring’ ensures that mainly advantageous traits are
pass on to new generations. If you let this go on long enough
(thousands to millions of years) then you get an accumulation of sufficient
‘new properties’ that a new plant species or animal species arises.

Now back to the lemon plant:
Maybe you’re lucky and your lemon plant happens to have the right thing
DNA to survive well at typical Belgian room temperature. This is
possible because your lemon plant is unique, with a unique DNA
that has never existed before. This is thanks to sexual reproduction
and mutagenesis.

But this is probably not the case and your plant is still adapted to
a tropical climate. Your plant can adapt a bit during its
life course through pieces of DNA that are only important in a tropical climate
to be marked as ‘not usable’, through the mechanism of ‘epigenetic’
modification’. It is possible that your plant has some epigenetic
passes on modification to his offspring, but this differs per species
organism and I cannot say for sure to what extent this is in lemon
planting happens.

Then a footnote:
Before Charles Darwin came up with the evolutionary theory of ‘survival’
of the fittest’ they were not sure how new animal species could arise.
A theory that was popular before Darwin’s discoveries was the
‘Lamarckism’, a theory of ‘Jean-Baptiste de Lamarck’. This theory
states that an organism has acquired characteristics during its lifetime
passes on to posterity. And it’s very similar to that theory you have
suggested in your question.

This passing on of acquired properties therefore only occurs in very limited circumstances
extent via epigenetic modification. Traits we actively acquire
are almost always not passed on. For example, a woodcutter who
strong muscles developed by exercising his profession will therefore not
have stronger children. It is true that people who are born with a
strong physique may be more likely to become a woodcutter, as their
naturally strong body allows this. And if those people have children go
which are also naturally stronger, not thanks to all the wood chopping, but thanks to
the naturally strong physique of the parent.

Hopefully my explanation is a bit clear and not too long,

Best regards,

sam