Vic Highs Braintease...breeding for vigour

[devout]

Vic High
Breeder


Registered: Oct 1999
Location: Beautiful BC
Posts: 3269 Brain tease - breeding for vigour.
Here's something for those getting started in breeding and those who feel they know what they are doing to ponder and hopefully debate

We all want to breed for improved vigour which in turn usually translates in easier to grow plants that yield more. But vigour can come from two sources.

1) vigour can be the result of nothing more than heterosis (hybrid vigour).

2) the plant may actually have genes that code for increased vigour. Polyploids are a common used example. But even certain diploid genetic combinations may result in increased growth as well.

My assumption is that the breeder would be more interested in the second source of vigour when making his/her selections. Any other thoughts?

This also leads to the question, how does a breeder distinguish between the two sources of vigour when selecting breeding stock?

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October 24th, 2000 02:39 AM



SATICA
Junior Member


Registered: Sep 2000
Location:
Posts: 3
I like to use 2 stable IBL's that are known/reported to have excellent vigor for the mother and father, then inbreed that hybrid to my satisfaction. I also figure if i use 1 stable IBL (again known for vigor) and cross it with something decent (like a true f1 hybrid, meaning bred from IBL's), then backcross it's siblings 2 times i can achieve a steady increase in vigor. Of course all this is based on growing enough plants to have a good selection to choose from. I am definitely a beginner, so to speak, and these are just my thoughts. Peace...

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October 24th, 2000 04:16 PM



Vic High
Breeder


Registered: Oct 1999
Location: Beautiful BC
Posts: 3269
Satica - thanks for biting and helping get the ball rolling. I'll just ask one overall question to address your first sentence. This question isn't just to you but everyone who follows the same fundamental logic.

When choosing the two IBLs reported to have good vigour, how do you determine if that IBL's vigour is the result of reduced homozygosity (less inbreeding) or if it actually contains genes for improved growth? What I mean is does the IBL's aparent vigour necessarily get transferred to hybrids proportionately to how much vigour is displayed by the IBL?

Like say we took a cubed seedline and F2'd it to select the homozygous individuals to create an IBL of that cubed seedline. The resulting IBL would more than likely have more vigour than my heavily inbred blueberry. But I ask, which would create the most vigorous hybrids?

I know one person who holds the answer to this, but haven't seen him around lately so not sure if he is lurking.

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October 24th, 2000 07:54 PM



brownthumb
Huge member



Registered: Aug 2000
Location: North of 62 degrees
Posts: 89
My $.02

First off, you have to have a definition of vigor. Here is the definition I would use.
Vigor: is the expression of a phenotype that is able to make maximum use of a specific environment. Notice that when the environment is changed, the parameters of what is "vigorous" changes. A great desert plant won't do much in the jungle, and vice versa.

From the above, I would infer that part of hybrid vigor comes from an expanded range of environments the phenotype can adapt to. Each of the heterozygous alleles would be better adapted to different environmental conditions. The combination has an increased range of conditions that it will be "vigorous" in.

In some cases hybrid vigor comes from alleles that are very good partners, but not impressive on their own. Hybrid corn crops are an example of this. In many corn hybrids neither of the parent lines are useful crop plants in their own right. It is only when the alleles are paired that the desirable traits are expressed. In hybrids, desirable results from pairing of alleles don't require the alleles to show desirable traits alone (in the IBLs).

Pot breeders are stuck in a position of not being able to screen large enough trials of potentially desirable F1 combos because of security concerns. Pot breeders in general have to start out with alleles that show desirable traits in their own right, as homozygous IBLs. Maybe someday we'll be able to run 100,000 seed plant trials like ADM does with hybrid corn seed. Until that day pot breeders are handicapped in searching for combinations with maximum hybrid vigor.

I don't think that polyploidy is a useful trait for improved vigor. It is unreliable to induce it, and polyploidy is too easily lost, strains revert to the natural diploid condition to easily.

I think the best a small time breeder can do now is to choose whether the interest is in developing a desirable true breeding strain, or a desirable F1 hybrid line.

If the object is to create a desirable hybrid, the selection criteria should be almost entirely the performance of the F1. The vigor of the parent lines isn't as important, it is only important that the parent lines be homozygous for the chosen traits. Homozygousity of the parents is proven by the lack of variability in the F1 progeny. Parent lines are culled based on the performance of the progeny alone, not on their own “vigor”.

That's about all I think I know

bt





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October 24th, 2000 11:20 PM



Lucas
Cannabist


Registered: Mar 2000
Location:
Posts: 1493
Thanks for the invitation Vic, allow me to reveal my ignorance.

>1) vigour can be the result of nothing more than heterosis
(hybrid vigour).

why "nothing more"? do you mean not repeatable in the offspring? isnt hybrid vigour an inheritable trait?

> 2) certain diploid genetic combinations may result
in increased growth as well.

that is what I mean above, inherited gene combinations for vigour, which can be cubed and inbred further. I have no use for polyploidy btw, too freaky for me. Just call me mr natural rotfl.

>My assumption is that the breeder would be more
interested in the second source of vigour when making
his/her selections.

thanks for indicating your presumption. I do not share it, probably because I dont get your meaning, yet. I guess my problem is not understanding what is different between hybrid vigour and "certain diploid genetic combinations". isnt hybrid vigour exactly that, a diploid genetic combination (of dominant traits of course).

> This also leads to the question, how does a breeder
distinguish between the two sources of vigour when
selecting breeding stock?

I suppose by observing how reliably the trait for vigour is inherited. iow, if it is only occasionally expressed in the F2 generation, then you are working with hybrid vigour and mixed pools, if the vigour is inherited consistently, then you are working with a stable gene pool, at least for the vigour trait.

I am sure I dont really get your question, since I am sure you anticipate my answers.

please elaborate. I love to apply theory to specific examples. Are we talking cindy, bb, gf, what?

peace
Lucas

This message has been edited by Lucas on October 24, 2000 at 07:56 PM


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sharrina
Senior Member


Registered: Nov 1999
Location:
Posts: 272
I don't think you'll get much of a response from the seedbreeders because i don't think the majority can answer the question,ican't answer either,but i'm not a breeder so it don't matter,i was reading a book on breeding dogs [same methods apply]that if you cube a male and a female dog of the same breed,and then breed the 2 cubed offspring together,hydrid vigour will be expressed.


peace...

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October 25th, 2000 04:48 AM



Oz
Junior Member


Registered: Oct 2000
Location:
Posts: 15
Vic,

The fact that your Blueberry creates hybrids that are well known for their vigour, suggests to me, that BB already has a fixed gene or genes for increased vigour, but is missing some other important, more basic dominant gene, that most other strains have. Any time you make a cross with a strain that can compliment this defect, it allows the vigour traits to really show their stuff and may be the reason BB dominates the crosses. If you wish to increase the vigour of BB, it would seem that all you need to do, is backcross the missing gene into your line, using a very vigorous BB hybrid as a starting point.

As far as vigour goes, I think most mj growers consider a vigorous plant to be one that grows bigger, faster, stronger, and better, under a wide range of growing conditions. As many have stated before, "you just throw some dirt at 'em and they grow". So if you are trying to increase vigour, it seems to me that the best way is to grow plants under less than optimal conditions, and select for the few plants that still do well.

As far as differentiating between hybrid vigour and "stable" vigour, you probably have to inbred to find out. I know of several inbred strains that are very vigorous (my NL#2 has been inbred for nearly a decade, but is still extremely vigorous), so it certainly appears that increased vigour can be stable and not just the result of hybridization. Hmmm, maybe I should cross my NL#2 with BB and see what happens.

Just my morning rambling,

Oz




October 25th, 2000 06:04 PM



Vic High
Breeder


Registered: Oct 1999
Location: Beautiful BC
Posts: 3269
Brownthumb, you made the comment <<I think the best a small time breeder can do now is to choose whether the interest is in developing a desirable true breeding strain, or a desirable F1 hybrid line.>>

- I just want to ask how these two goals can be mutually exclusive? Like how does the breeder create new unique F1s without first creating quality IBL?

As to the main topic at hand, Lucus is getting close but I'm not sure if he realizes it. I'll use Brownthumb's corn example to offer another hint. In the case of the hybrid vigour coming from the hybridization, is the vigour a result of pairing of vigour genes or is it mearly the breaking up of paired negative recessive alleles? You see, the genome is loaded with mutant recessive genes, many of which are either lethal or have a negative effects on plant health and vigour. By creating the IBL, we end up pairing up many of these negative genes, thus reducing vigour. Hybridization (and therefore heterozygosity) prevents these from being paired up.

So vigour can be achieved by:

1) selecting AGAINST the frequency of the negative alleles, which on the surface would seem to mean selecting for heterozygosity. This kinda conflicts with the goals of creating homozygous IBLs.

2) selecting FOR specific genes that actually do code for improved vigour. This is where true genetic gain can be realized, but how does the breeder both identify it and isolate it?


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October 25th, 2000 06:09 PM



Vic High
Breeder


Registered: Oct 1999
Location: Beautiful BC
Posts: 3269
Oz - you made the comment <<So if you are trying to increase vigour, it seems to me that the best way is to grow plants under less than optimal conditions, and select for the few plants that still do well.>>

- but what really are you selecting for then? Plants that are genuinely more vigorous under a wide range of conditions? Or just ones that have adapted or are climatized to the new non optimal conditions? My UVb work is an example. The most vigorous plants in the presence of UVb tend to be the most potent. However, by using the UVb in my selection of breeding stock, am I selecting for more potent plants under a wide range of environments? Or just ones that will do well in the presence of UVb?

Another example is the difference between indoor and outdoor strains. There have been some strains adapted to the canadian outdoor environment that are probably the best and most vigorous for this area. But are they also the best indoors, or in the california sun? Usually not.

Sharina - dog breeding is an excellent place to start because like cannabis, dogs are sexually dimorphic and dog breeders need to work with relatively low numbers. There is some excellent books on breeding plants, but their main downfall for us is that they are slanted more towards self pollinating field crops. By studying both perspectives, a new breeder could gain a more complete understanding.


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October 25th, 2000 06:33 PM



Lucas
Cannabist


Registered: Mar 2000
Location:
Posts: 1493
> In the case of the hybrid
vigour coming from the hybridization, is the vigour a result
of pairing of vigour genes or is it mearly the breaking up of
paired negative recessive alleles?

Both breaking and dominance (dont trust that "merely" term, so I'm hedging my bets <g> ).

In the case of blueberry, it seems breaking negative pairs fits as an explanation. So my answer would be that hybrid vigour is the result of breaking negative pair bonds, thereby allowing the expression of positive dominance. In english, the good part of the blueberry comes through in the hybrid because it is not being inhibited by the negative recessive pairs acquired by inbreeding. This is why parallel IBL's, as OZ mentioned, can be recrossed to each other to renew vigor.

It seems therefore that inhibition of vigour by negative pairs is the factor at work (where "negative" is defined by grower vision). Similarly, the flowering response itself is inhibitory in nature. iow the plant wants to bloom, but photochemistry produces an inhibitory effect. It is kind of like building a car to go fast, with the engine always revving, but using braking power reduction to make the car go. You have to think backwards.

If all this is true, then the way to increase vigour, is to reduce braking, or vigour inhibition. Hence, the best way to reduce negative pairs in IBL's will be to outcross to parallel lines. Outcrossing to unrelated strains also works, but defeats the intent of producing true breeding lines in the offspring.

How'd I do Vic?:-), and thanks for the very educational quiz. Could you please fill in the blanks on parallel outcrossing?

Lucky Lucas


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brownthumb
Huge member



Registered: Aug 2000
Location: North of 62 degrees
Posts: 89

Brownthumb, you made the comment "I think the best a small time breeder can do now is to choose whether the interest is in developing a desirable true breeding strain, or a desirable F1 hybrid line."
- I just want to ask how these two goals can be mutually exclusive? Like how does the breeder create new unique F1s without first creating quality IBL?

How are you going to determine “quality"

[devout]

Vic High
Breeder


Registered: Oct 1999
Location: Beautiful BC
Posts: 3269
Ahhh, some excellent input since I was here yesterday. Pnwfriend, ya nailed it dude as I was hoping you would I hope you don't mind me trying to spell out the relevance and significance for others here, I already know you got it I'm having a tough time explaining this without getting too technical, my approach feels clumbsy. If you feel I've given an erroneous impression, please feel free to correct or clarify.

As I've said before, I believe selection is the cornerstone of breeding. It can have positive, neutral, or negative effects on your breeding program depending upon your perspective. A breeder must be aware of all the overall effects of whatever criteria he/she uses in his/her selection methods. This applies to ALL breeders whether they are hobby or professional.

So like I started out saying in this thread, the breeder can acquire vigour through 2 means. The most common method is to select against the pairing of recessive negative alleles. This is accomplished by keeping both parental lines as unrelated as possible. But even amongst related breeding populations, chance will cause this form of vigour to be observed within individuals. An important point here is that although there is a commercial significance to this type of vigour (as Brownthumb illustrates), all that's being done is that the current genetic potential is being revielled. The breeder is simply selecting against the negatives and not really selecting for anything new. There really isn't any significant genetic gain occurring, IMO.

However, as has been mentioned earlier, vigour can also be improved by joining new genetic combinations that actually code for improved health, growth rate, yields, etc. By fixing this new combination whether they be dominant alleles or new mutant recessives, something new and potentially better is being created. Genetic gain is ocurring, IMO. It is through this venue that steady increases are still being made in many food crops. This kind of vigour can be achieved in both related and unrelated lines, although it may be harder to see in both extreme cases of relatedness and unrelatedness. Being masked by inbreeding depression or hybrid vigour respectively.

Which again brings up my question, how can the breeder identify and distinguish between the two sources of vigour when creating new hybrids? This is a fundamentally important question for most breeders to tackle, or at least understand. The answer will usually lie with test crosses which in turn serves to direct the selection process. Pnwfriend offers one such way of accomplishing that goal.

You see, if his A and B lines are unrelated, chances are that he is going to see vigour expressed by crossing the two lines whether he does the reciprocal test crosses or not. This increase in vigour will most like be nothing more than hybrid vigour. However, any improvement beyond that will most likely come from the selection of positive genes, and not be the result of hybrid vigour. So if the reciprocal test crosses can result in a hybrid of even greater vigour, the breeder can easily assume that a good portion of the extra vigour will indeed be the result of genetic gain, and not just hybrid vigour.

I hope this makes sense, I felt clumbsy writing it. It's much easier to explain in technical talk. There were many interesting points and questions raised by others here, any number of which would have made an interesting discussion. I only avoided them because I was trying to remain focussed.


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October 26th, 2000 06:06 PM



~D~
Member


Registered: Oct 2000
Location:
Posts: 37
Wow, outstanding information. I copied much of it into my files for future reference.

Wanted to bring up an interesting side issue. I recently obtained a product called Messenger, it's a complex targin protein which activates natural plant defense and growth systems without altering the plant?s DNA. http://www.edenbio.com/

Messenger received approval from the EPA in April and has been demonstrated to activate natural plant systems to:
Protect against a broad array of viral,fungal and bacterial diseases, including some diseases for which no effective treatment is currently available;
Reduce damage caused by a variety of pests; and
Improve plant growth, crop yield and quality;
Effectiveness across a wide array of crops;
Improved food safety;
Reduced risk of environmental damage;
Increased worker safety; and
Reduced likelihood of pest resistance.

The topical application of this protein has had a marked effect on my control group of increasing the size of the plants and shortening the flowering period by about 1 week. I'm not seeing all of the incredible benefits that the field trials demonstrated on some food crops, but faster flowering, more vigor and about a 10% yeild improvement is nothing to complain about.

It is likened to flipping a genetic switch in the plant, which goes to a point made earlier on vigor.

I didn't want to sidetrack the thread, but I thought it might be important to mention.

[country boy]

Correct me if i'm wrong, but didn't vic have a change of heart concerning 'Polyploids' ?

On a completely different note: Messenger is great, except for storage issues-seems to go 'bad' if exposed to air and not mixed immediately.

cb

[suzy cremecheese]

Whats your view on polyploids Country boy?

[Cuzin_Dave]

Heterosis is almost always assumed to be the case with cannabis, hence the relentless outcrossing that goes on continously. Unfortunately with cannabis there is no actual body of empirical evidence to suggest that outcrossing is beneficial. For example do the offspring of supposed F1 crosses always, sometimes or never outperform either the mid -parent or best parent from selection? Heritability is almost always ignored when it comes to breeding cannabis it would seem.

[country boy]

Good points Cuz,
Seems inbreeding, selection, and ruthless culling is used in most other plants/animals used by humans...

cb

[Cuzin_Dave]

Another term used to define hybrid vigour is over dominance. That is the phenotypic expression being more pronounced in the heterozygote than in the homozygote. For example the heterozygote intermediate phenotype AaBbCcDdEe being superior to the homozygote AABBCCDDEE or aabbccddee for any pairings of alleles.

[Schip]

hello cw!

This is a great topic, and one that is still vigorously debated in the field.

The biggest indication that inbreeding is deleterious to cannabis is the fact that the male and female organs are on separate plants. If inbreeding wasn't a problem, hermies would have a selective advantage and would increase in the populaiton. I am using 'inbreeding' here to refer to the loss of alleles from the genepool, which will always happen but will happen much slower in large populations.

In fiber hemp, F1's generally outperform the midparent, but it is difficult to create seedstock on a field level. Hemp breeders tend to use open-pollinated lines, making some selections during the season but allowing each female to be seeded by many males and saving seed from many females. This preserves the total allelic diversity, more or less, and is basically the way plants have been bred since the dawn of agriculture.

Re: heritability, it tends to be rather high for agronomic traits such as fiber yield, seed yield, and disease resistance but rather low for organoleptic traits such as aroma or psychoactivity.

As far as I'm concerned, nobody knows anything solid about cannabis polyploids. People get fucked-up mutants all the time and say 'oh, it must be a polyploid' but it's not nearly that simple. Many times, polyploids are indistinguishable from their diploid ancestors, and it is the benefit of having extra copies of the DNA that allows mutations to persist in the population, which at some point may become beneficial to the carrier.

There is also the fact that vigor can be inversely correlated to resistance, flavor, etc. Many modern tomatoes are very vigorous, but taste like paste. This is because they are using their entire metabolism to build biomass, but not to build interesting flavor compounds (terpenes etc.) to fill them with. Grapes are the same way, if you have a season where your vines grow very vigorously, you're going to be making midgrade wine at best. Selecting for the most vigorous plants in a climate-controlled, insect-protected growroom will produce seeds that will be very vigorous, in the environment where they were selected. But, if you consistently have spider mite, PM, or botrytis problems, selecting for resistance will do you more good in the long term than selecting for vigor. Finally you have the problem of determining what the nature of the vigor is... are the plants vigorous because they are efficient at building new cells, or are they vigorous because they do a good job repelling pathogens?

In short, I think the hobby breeder needs to focus on one trait that is most important, and select for only that trait. With population sizes under 100, to try and select for multiple traits does nothing but perpetuate the polyhybrid mish-mash that passes for breeding in most seed catalogs.

[suzy cremecheese]

Thanks for coming by schipp. Good to see you. Great post.

[tiedye420]

Oh yes food for thought..
So
What if say, someone were to have a couple of IBl's one with high mutations of quad nature (two stems ,four leaves, four nodes) and another with rare "sport" Type mutations. Strange growth and flowering patterns with extreme vigor, Funky leaves at youth clearing up, normal amount of nodes, but possibly a branchier growth than the 'parent strain" it comes from.
I was looking at a plant given to my friend, a couple actually. Two phenotypes of a strain im working. It seems the calyx's on the one that was "mutated at birth" and "cleared up later" are the size of peanuts.
clustered together they look strange, and well i had to see. I picked a couple pieces, ripped open one of those huge calxy's. There was a bud forming inside every single little calyx, little white hairs inside them. But the calyx is wrapped around it like a blanket.
Looked ready for harv with them huge frosty calyx's. But it's just ready to get it's freak on... Seems Like this old afghani im working is just a freak of nature strain- no wonder the clones are so controversial. They are sports.
Im working with two generations of afghani and both produced sports.
I have just assimilated this information over the past few days.
Ground breaking news actually , at leats for me.
So this thread got me thinkin, and well, i been doing this type thinkin.
So like, thanks for helping me get my thinking cap on...
Robert mentions using mutations to increase vigor from within a genepool, and that's the route im contemplating going with my old afghani,
Normal reproduction has been done- now time to include the mutant.
It was so slow growing at birth she never made it to the first breeding sessions.... But i still got another sport on the second run of beans i made.
I used five males and two females....Im freaking