Breeding related siblings/Parents

M

manpan

Member

• Sep 16, 2018

• #1

Hello all -
I have a question related to inbreeding IBLs.

Here's the scenario. I have 2 plants, from an IBL line, brother and sister. P1 & P2, male and female respectively

So: P1 x P2 = F1 (female)

Is there any value in producing the following pairing?

P1 x F1 = F2

Or would the best outcome, in terms of producing the best genetic be to produce from the P1 x P2 paring?

 

C

CrushnYuba

Well-known member

• Sep 16, 2018

• #2

I'm confused. Are you just talking about a bx?
I don't think it should be an f1 if the parents were from an inbred line.

 

M

manpan

Member

• Sep 16, 2018

• #3

Ok, yes, a back cross.

If the parents are already an IBL, theres' really no value in doing a back cross, right? I guess that's the question.

 

troutman

Seed Whore

• Sep 16, 2018

• #4

Crossing a sister and brother together is what they call full-sib mating which results in F2's.

Crossing a sibling to it's parent is called parent-offspring mating or backcrossing which results in a BC1 and not an F1.

They are both forms of inbreeding. F2 are only created by crossing two F1's together.

https://en.wikipedia.org/wiki/F1_hybrid

https://en.wikipedia.org/wiki/Backcrossing

What mating system you should do depends on what your trying to achieve.

Good Luck

 

D

djonkoman

Active member

Veteran

• Sep 16, 2018

• #5

manpan said:

Ok, yes, a back cross.

If the parents are already an IBL, theres' really no value in doing a back cross, right? I guess that's the question.

Click to expand...

no, it's the opposite.
purpose of a backcross is to get just 1 trait/gene from one parent, and all the rest from the other. each backcross the amount of genes from the donorparent halves, but by selecting for that 1 trait/gene you keep it in. for example usefull when one parent does have one really usefull thing, but also a lot of 'bad' genes you don't want to keep(like with tomatoes using a wild relative to bring in a certain desease resistence gene).

however if you backcross with a recurrent parent that isn't stable, you'll just get a mess with all the heterozygous genes of the recurrent parent segregating. and if you would try to stabilize in between backcrosses, each backcross you would bring back heterozygosity/unstableness, doing away with the work you just did.

 

Lost in a SOG

GrassSnakeGenetics

• Sep 16, 2018

• #6

Wouldn't the IBL already be an F7 anyway, assuming the person that made it knows what an IBL is, so Imo it would just be an F8

A BX would be hitting back to a specific parent.. crossing siblings is not a BX..

 

Fuel

Active member

• Sep 16, 2018

• #7

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however if you backcross with a recurrent parent that isn't stable, you'll just get a mess with all the heterozygous genes of the recurrent parent segregating. and if you would try to stabilize in between backcrosses, each backcross you would bring back heterozygosity/unstableness, doing away with the work you just did.

Click to expand...

[/FONT]
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[/FONT]
[FONT=Arial, Helvetica, sans-serif]Well it's true for a "one shot" without any further selection[/FONT]. But the heterozygosity can be hitted at each pass with a decent selection.


In BX projects, the deleterious homozygotes are more frequent in fact than a reference's cut enough strong to recombine each time the genotype.

 

MJPassion

Observer

ICMag Donor

Veteran

• Sep 16, 2018

• #8

Are you assuming the line is IBL because that what the package (somebody else) said or because you worked the line to IBL?

To be a true IBL, the variety MUST have some sort of true breeding trait(s).
Somebody doing sib matings for 7 generations without any goals does not an IBL make.
Just saying...

If you are working with a real IBL line you should see uniformity for one or more traits in both an F2 breeding as well as a Back Cross.

If your goal is to not to have to buy those seed again your best option, IMO, is an open pollination using several males & females keeping the line pure but opening up the genome a bit more for exploration via possibly thousands of seeds.

Doing this would definitely let you know how IBL'd that particular line is.

 

C

CrushnYuba

Well-known member

• Sep 16, 2018

• #9

They could never be f2s since parents were not f1s to start.
There can definitely be value in it, but it would depend on your goals.
Just because the person who gave you a line said it was an ibl, doesn't mean it's true breeding and it doesn't mean it's true breeding for traits that you want. If you found traits in p1 you wanted to preserve, and different traits in p1xp2 you wanted to preserve, then yea, there would be value in doing that back cross.

 

M

manpan

Member

• Sep 16, 2018

• #10

I'm growing the Sour Diesel IBL and Chemdog IBL from Reservoir. I was just wondering if there's value to be had by backcrossing the parents with the offspring.

Based on the responses here - and thank you all - a better approach may be to just allow multiple males to pollinate my females.

To my thinking, if they are stable IBLs then it wouldn't matter, right? And if they are not, it may be of interest to have as varied potential phenotypes and possibly develop a line using a desirable one.

 

C

CrushnYuba

Well-known member

• Sep 16, 2018

• #11

That's a good idea. Yea, the rez IBLs are worked lines but maybe not really ibl's.
Maybe instead of doing an open pollination, you use all off the plants and make as many pairings as you can but label the work and do it a little more deliberately. If recources allow of course.

 

MJPassion

Observer

ICMag Donor

Veteran

• Sep 17, 2018

• #12

If you can do as CrushnYuba says you will, in effect, have the same exact seeds as an open pollination but the fathers would also be separated one from another.