What is an F1 hybrid?
Posted by Vic High on February 13, 1999 at 22:09:27 PT:
This page isnāt about ego trips and pissin contests to see who knows the most. Itās meant to be about sharing info and furthering our understanding of cannabis genetics. So hereās a step in the right direction. Anyone else want to join in?
What really is an F1 cross?
Well defining the terms P1, F1, F2, homozygous, and heterozygous can be a simple task, however, applying them to applied genetics can often create confusion. Depending on your point of reference, a plant could be described as any of these terms. For our specific field of interest itās important to further define these terms to reduce confusion and protect the consumers. First Iāll provide the classic scientific definition of these and other related terms and then Iāll dive into each term into detail.
Heterzygous - a condition when two genes for a trait are not the same on each member of a pair of homologous chromosomes; individuals heterozygous for a trait are indicated by an āAaā or āaAā notation and are not true breeding for that trait.(Clarke)
Homozygous - the condition existing when the genes for a trait are the same on both chromosomes of a homologous pair; individuals homozygous for a trait are indicated by āAAā or āaaā and are true breeding for that trait. (Clarke)
- Now the heterozygous and homozygous terms can be applied to one trait or a group of traits within an individual or a group of individuals. Depending on your point of reference, an individual or group can be considered both homozygous or heterozygous. For instance, say you have two individuals that are both short (S) and have webbed leaves (W) and have the following genotypes.
#1 = SSWW #2 = SSWw
They are both homozygous for the short trait but only individual #1 is homozygous for the webbed leaf trait. Individual #2 is heterozygous for the webbed leaf trait and would be considered a heterozygous individual. As a goup, they would be considered heterozygous in general by some and homozygous by others. It would depend on your point of reference and the overall importance you place on the webbed leaf trait. Most would consider it to be heterozygous.
For example, the blueberry cannabis strain is considered a true breeding homozygous seed line because as a whole the many offspring have a similar look and produce a similar product.
However there are often subtle differences between the plants of characters such as stem colour and potency. When taking a close look at blueberry, you will find heterozygous traits, but because of the whole overall look, we still generally consider them homozygous for the purpose of breeding programs. Using dogs is another way to explain this, take a dobie for example, you can tell the difference between dobies, but you can tell a dobie from another breed. Ya follow?
Hybrid - An individual produced by crossing two parents of different genotypes. Clarke says that a hybrid is a heterozygous individual resulting from crossing two seperate strains.
- For the purpose of seedbanks, a hybrid is in general, a cross between any two unrelated seedlines. ANY HYBRID IS heterozygous and NOT TRUE BREEDING.
F1 hybrid - is the first generation of a cross between any two unrelated seedlines in the creation of a hybrid. F1 hybrids can be uniform or variable depending on the P1 parent stock used.
F2 hybrid - is the offspring of a cross between two F1 plants (Clarke). What Clarke and other sources donāt make clear is do the two F1ās need to be from the same parents? By convention they donāt. As well, german geneticists often describe a backcross of an F1 back to a P1 parent as a F2 cross.
OK lets say we take blueberry and cross it with romulan (both relatively true breeding of their unique traits) to create the F1 hybrid romberry. Now lets cross the F1 romberry with a NL/Haze F1 hybrid. Some could say this is a F1 cross of romberry and NL/Haze. Others could argue that it is a F2 cross of two F1 hybrids. Gets confusing doesnāt it? Now lets cross this Romberry/NL/Haze(RNH) with a Skunk#1/NL#5 F1 hybrid to create RNHSN. Now some would argue that RNHSN is an F1 hybrid between RNH and SK/NL seedlines. Others would call it an F2.
So what does this mean to the consumer? It means that a seed bank can call a cross whatever it wants until the industry adopts some standards. This is what this article will attempt to initiate. Clarke eludes to standardising these definitions but never really gets around to it. Fortunately other plant breeding communities have (Colangelli, Grossnickle&Russell, Watts, &Wright) and adopting their standards makes the most sense and offers the best protection to the seedbank consumer.
Watts defines an F1 as the heterozygous offspring between two homozygous but unrelated seedlines. This makes sense and gives the F1 generation a unique combination of traits; uniform phenotype but not true breeding. This is important in the plant breeding world. This means that when a customer buys F1 seeds that they should expect uniform results. It also means that the breederās work is protected from being duplicated by any other means than using the original P1 (true breeding parents). [There are exceptions to this by using techniques such as repeated backcrosses (cubing the clone)]
F2 crosses are the offspring of crossing two F1 hybrids. This means that they will not be uniform nor will they breed true. However, F3, F4, F5, etc will also share these characteristics, so to simplify terminology for the seedbanks and seedbank merchants, they can all be classified as F2 seeds in general.
What does this mean for the preceeding example? Well, the blueberry, romulan, skunk#1, NL#5, and haze were all P1 true breeding seedlines or strains (another term that needs clarification). Romberry, NL/Haze, and SK/NL were all F1 hybrids. Both the Romberry/NL/Haze and the RNHSN would be F2s. Within each group the consumer can know what to expect for the price they are paying.
Few cannabis seedbanks (if any) and their breeders are following these definitions and are subsequently creating confusion within the cannabis seedbuying community. This is a change that needs to happen.
Note: this is a rough draft to be published to the internet. Hopefully in time it or something similar will be used to help establish an industry standard. Any comments and critism is welcome to aid in the production of the final draft. Small steps like this can only benefit the cannabis community over the long haul.
REFERENCES:
Clarke RC. 1981. Marijuana Botony Ronin Publishing, California
Colangeli AM. 1989. Advanced Biology notes. University of Victoria, BC
Futuyma DJ. 1986. Evolutionary Biology Sinauer Associates, Inc. Massachusetts
Klug & Cummings. 1986. Concepts of Genetics 2nd ed. Scott, Foresman, & comp. Illinois
Grossnickle & Russell. 1989. Stock quality improvement of yellow-cedar. Canada-BC Forest Resources Developement Agreement (F.R.D.A.) Project 2.40
Watts. 1980. Flower & Vegetable Plant Breeding Grower Books, London
Wright JW Introduction to Forest Genetics Academic Press, San Francisco
Re: What is an F2 hybrid? - longer post
Posted by MrSoul on February 14, 1999 at 08:02:30
In Reply to What is an F1 hybrid? - longer post posted by Vic High.
Vic_~
Some folks may find the development of your points a bit difficult to follow due to some typos that cause contradictionsā¦but I knew what you meant {8o)_~
I agree thereās a need for all cannabis aficionados to have a standard glossary. I agree with the terminology you suggest and have always used it.
The subtlety of the F2 definition needs a bit more clarification IMO. I suggest the convention that an F2 be the offspring of members from the same F1 generation. Using your F1 Romberry example, an F2 Romberry is the offspring of two F1 Romberry parents. Your mixed F2 hybrids are what most of us have been simply referring to as a āmulti-wayā hybrid. But technically youāre right that itās an F2 because it is a generation created by two F1 generations.
The recombination potential of these two types of F2 should be emphasized. While an F2 Romberry may exhibit traits ranging over all the possibilities inherent in the genetic palette of Romulan and Blueberry, the āmixed F2ā has almost infinitely more possible genetic recombinations due to the larger genepool of NL, SK#1, Haze, Romulan and Blueberry.
Having made the above clarifications to your comments, Iād like to expand on the subject of F2ās just a bit. More people should be aware of the IMPORTANCE of the F2 generation in breeding.
Itās easy to be confused by terms that have more than one interpretation, depending on the context. F2 seeds are generally considered by the seed-buying public to be an inferior product. This may be a true statement for example, in the case of a seed bank selling Jack Herer seeds WITHOUT STATING that they were created by crossing two Jack Herer plants from Sensi Seed Bankās F1 stock. These seeds are an F2 generation of Jack Herer in the classic definition of the term. The F2 generation is NOT going to produce the same results as the F1 in terms of the similarity of the plants in the groupĆthey will vary in their characteristics rather than all of them being essentially identical. Such a scam rips off the buyer expecting a uniform crop of Jack Herer.
Now hereās the ākickerā because of the negative connotation of the example of an F2 above, some have the mistaken impression that any member of the F2 generation is undesirable as a plant. This is NOT necessarily true. Quite the contrary; the F2 generation is a treasure trove of possibilities. The recombination of genes produces a variety of different plants, among which there may be individuals of great value. This is actually the source for future true-breeding strains. A breeder who recognizes an outstanding and unique individual from an F2 group can work with it to create a true-breeding hybrid strain such as was done with classics like Skunk #1 and Northern Lights. The methods to accomplish this task vary, but back crossing to the original unique plant is typically a part of a process which ultimately must accomplish the goal of creating a strain which breeds true for all the important traits which made the unique individual so valuable.
I hope the above will enlighten.
Re: Soul - thanks for the F2 additions
Posted by Vic High on February 14, 1999 at 10:40:34
In Reply to Re: What is an F2 hybrid? - longer post posted by MrSoul.
I too wanted to expand on the subject of pros and cons of the F2 but didnāt want to further complicate the original post. This is all going towards a genetics section at the BCGA webpage. Mind if I add your additions? I think your points are very important.
Now your Jack Herer example brings up an interesting point that I was trying to make. Jack Herer is a multi-way cross between a skunk/NL and a haze wasnāt it? We talked about this in the the past but I can exactly remember the concenses on which way it was created. Was the skunk/NL a stabilized inbred line at the time of the cross? If I remeber right the initial feedback of Jack Herer was that it was variable but that there were excellent individuals within the mix. If this was the case, then it would seem that the Skunk/NL was a hybrid and not a true breeding seedline. (If Iām wrong about this particular example lets just assume otherwise for the sake of argument since many new āstrainsā are from hybrid parents.)
Even though Jack Herer was technically an F1 hybrid of the SK/NL and haze, it could also be said to be an F2 seedline. For the purpose of the seedbuyer, which term would be more useful? By calling it an F1, is the consumer being mislead into what to expect from the seeds? But then calling them an F2 makes it hard to distinguish them from the more variable knock offs.
I think creating a standard where all seedlines coming from unstabilized parents should simply be considered to be F2 in general. This would help seperate the serious breeders from the not so serious. It would also put pressure on the breeders to slow down and take their time when making new strains.
Your princess is a good example of this. Itās a killer clone and you could have simply made crosses with it and called them F1s even though they would behave like F2s. But instead you are taking the time to stabilize her genetics by cubing. You have created a sound building block for the developement of new true F1 hybrids.
Once the designation of F1, F2, and IBL (inbred line=true breeding) is standardized, it would make it easier to standardize pricing structures and bring them in line. Now both F1s and F2s are valuable in their own ways, but generally speaking one would need less F1 seeds than F2 seeds to find what they are looking for. Therefore F2 seeds should be priced lower than F1s. Also, anyone under the sun could make quality F2s from a relatively small number of F1s so this should also affect the pricing by lowering it.
But what about the IBLs? Well these can be the most valuable of all the seedlines so at first one would expect them to be the highest price. However, because of their true breeding nature, if they are priced too high, it would make it easy for someone to create a less expensive knock off as I have with blueberry. Many breeders simply donāt release the IBLs to protect their investment and will instead rely on creating F1 hybrids for market.
Itās a tough call to decide what should be priced higher but supply and demand will probably dictate that a true F1 will be the highest priced seeds. Then the IBLs, followed by the F2 seedlines. I suspect that there should be a further breakdown in the F2 catagory to distinguish between original F2s (technically F1s or mixed hybrids) and their knock-offs.
Keep it up, we really appreciate it. 
Hope that helps