phenotypes for beginners

I'm still a beginner myself, but I've been a little confused about the way people use the term phenotypes when talking about seed suppliers. So I did some research for myself and wanted to share.

If any experts would help me along or correct any bad information I would be grateful for that.

So lets start with the most obvious question. What is a phenotype?

Boiled down to an overly simple answer it's basically any distinct trait about an organism you can observe and classify. This includes physically, chemically, behaviorally, and more. More specifically it's narrowed down to a population or set of organisms.

For our specific application of phenotypes we only care about ones that are valid for plants.

Now that we know what a phenotype is why is it important and how does it play into growing Cannabis?

This is where it gets more complex and not as clear cut. Genotypes of your plant will determine all possible phenotypes. Genotypes are the genetic information your plant receives from its parents. It seems to me that most of what people refer to as "phenotype stabilizing" is just selective breeding. The grower just looks for the plants with the best of all traits to breed and removes plants with any undesirable traits in the next generation. This is done over and over again until the phenotypes are consistently the same. The overall point is to remove as many recessive genes out of the pool as possible.

But wait can it be that easy? I'm afraid not.

Seed companies have the money to grow their breeding plants in very stable and consistent environments (or so I would assume). So, who cares? This brings us to another point that needs to be considered. The environment the plant is grown in and how that plays into phenotypes.

This is where things really get less clear. So I think we can assume that even the best selective breeding is only so effective. I doubt you can ever totally isolate recessive traits. It's also well known that environmental factors can influence phenotypes. Environmental factors are pretty much anything that isn't the plant is self and encompasses a huge amount of variables. Water, soil, air, light, temperature, and more are all things that change wildly between growers. So it stands to reason that even the most stable of phenotypes can be made less stable due to these changes.

Hopefully this is a good starting look at the basics of genetics and how they play into your growing. Please feel free to add or correct information as necessary.

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Originally Posted by socket

Genotypes of your plant will determine all possible phenotypes. Genotypes are the genetic information your plant receives from its parents. It seems to me that most of what people refer to as "phenotype stabilizing" is just selective breeding.

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For each trait, there are 2 possible genes, a dominant and a recessive. Combined, there are 3 possible combinations, homozygous dominant expressing the dominant trait, heterozygous expressing the dominant trait also but carrying the potential for recessive in the next generation, and homozygous recessive, expressing the recessive trait. These 3 genotypes are visible as only 2 phenotypes.

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Originally Posted by socket

The grower just looks for the plants with the best of all traits .... The overall point is to remove as many recessive genes out of the pool as possible.

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This is actually incorrect. For example, purple bud is not a dominant trait but it is highly deisrable to breeders, and if you take a recessive gene for purple bud (g) whose dominant counterpart is green bud (G) we will see these possible combos:
GG= green bud
Gg, gG= green bud
gg= purple bud
The trick is to cross the heterozygous ones- simply, you can allow random mating in a large population and see about 25% of the plants show purple bud; those are homozygous recessive and show the phenotype of a trait you WANT.
Don't confuse recessive and undesirable.

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Originally Posted by socket

This is where things really get less clear. So I think we can assume that even the best selective breeding is only so effective. I doubt you can ever totally isolate recessive traits.

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You can, it is done often, and it just takes a little working knowledge of genetics.

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Originally Posted by socket

It's also well known that environmental factors can influence phenotypes. ... So it stands to reason that even the most stable of phenotypes can be made less stable due to these changes.

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Potential for expressing a vertain trait is genetic (for example a plant that turns purple in cold temps). The environmental factors simply allow or prevent expression of a certain trait.
Here I think you are misusing the term 'phenotype'... a stable STRAIN - let's think of it as an isolated population for argument's sake- can show different expressed traits under different conditions. A phenotype is just a distinct set of traits common to certain individuals within that population.

Anyway hopw that sorta helps.

Stinky, you make my brain hurt ;)

I'm sorry, I'll fax you a bong rip. :D

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Originally Posted by stinkyattic

For each trait, there are 2 possible genes, a dominant and a recessive. Combined, there are 3 possible combinations, homozygous dominant expressing the dominant trait, heterozygous expressing the dominant trait also but carrying the potential for recessive in the next generation, and homozygous recessive, expressing the recessive trait. These 3 genotypes are visible as only 2 phenotypes.

This is actually incorrect. For example, purple bud is not a dominant trait but it is highly deisrable to breeders, and if you take a recessive gene for purple bud (g) whose dominant counterpart is green bud (G) we will see these possible combos:
GG= green bud
Gg, gG= green bud
gg= purple bud
The trick is to cross the heterozygous ones- simply, you can allow random mating in a large population and see about 25% of the plants show purple bud; those are homozygous recessive and show the phenotype of a trait you WANT.
Don't confuse recessive and undesirable.


You can, it is done often, and it just takes a little working knowledge of genetics.


Potential for expressing a vertain trait is genetic (for example a plant that turns purple in cold temps). The environmental factors simply allow or prevent expression of a certain trait.
Here I think you are misusing the term 'phenotype'... a stable STRAIN - let's think of it as an isolated population for argument's sake- can show different expressed traits under different conditions. A phenotype is just a distinct set of traits common to certain individuals within that population.

Anyway hopw that sorta helps.

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Thank you for clearing all that up. I had a feeling recessive genes might be desirable in some cases but wasn't sure. But I'm still not completely sure I understand the part regarding environmental factors. So what causes a recessive trait to win out over a dominate one? Is it just randomly programmed into the seed at the time of it's creation?

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Originally Posted by socket

So what causes a recessive trait to win out over a dominate one? Is it just randomly programmed into the seed at the time of it's creation?

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Take a jar of marbles, black and white, with equal numbers of each.
Black is dominant and white is recessive.
Pick out 2.
What you have in your hand is like the embryo- the seed itself- all the other possible combinations are still in the jar. If you are holding 2 of a single color, the other color CAN'T get passed on by that individual! It's just not there!
You only get expression of the recessive gene if you get 2 white ones because the dominant trait will ALWAYS win if it is present.
Well, unless there is another gene that supresses its expression under certain genetic or environmental conditions.... but that is getting into a lot more complicated shit.

Quote:

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Originally Posted by stinkyattic

Take a jar of marbles, black and white, with equal numbers of each.
Black is dominant and white is recessive.
Pick out 2.
What you have in your hand is like the embryo- the seed itself- all the other possible combinations are still in the jar. If you are holding 2 of a single color, the other color CAN'T get passed on by that individual! It's just not there!
You only get expression of the recessive gene if you get 2 white ones because the dominant trait will ALWAYS win if it is present.
Well, unless there is another gene that supresses its expression under certain genetic or environmental conditions.... but that is getting into a lot more complicated shit.

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EXCELLENT analogy ... even I understood that one, very good :thumbsup:

Okay that helps a lot. Thanks!

So in the end my big point, I think, is you can't expect perfect plants from even the best seed banks and best breeding. Because there can be something specific to your grow environment that will cause expression of a negitive trait. Is that a valid assertion?

Might it also be possible for the reverse? Expression of a positive trait based off something different about your grow environment that wasnt true of where it was orginally grown? I assume it is.

That is in my experience so rare as to be a nonissue. Unless we are talking about a general intolerance of some condition like humidity- yes, some strains are MUCH less tolerant of heat, damp, fluctuations in pH, cold, etc. while some seem impossible to kill and can even withstand FROST and light snow! But this isn't what you are talking about- you are more asking if for example I am growing in an environment that has some weird lighting that I will see plants with beaks and claws, no. lol.
I guess the bottom line is, be nice to your plants and keep them healthy so everything you see is a result of genetics, not a result of poor growing technique.

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Originally Posted by stinkyattic

But this isn't what you are talking about- you are more asking if for example I am growing in an environment that has some weird lighting that I will see plants with beaks and claws, no. lol.

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Now that's a great visual. =)