[AxB] x [BxA]

[chappie]

Suppose out of a populations of 100 plants of strain A we pick 1 male and one female. Same for B.

We make two crosses, AxB and BxA.

- Is [AxB] x [BxA] still just a "F2"?

- What would this type of crossing be called?

It involves more variation and instability I suppose, but it also allows females to be selected for each strain, ensuring that floral considerations are part of the inputs.

I might be babbling, but does anyone have thoughts on this mode of hybridization?

 

[burningfire]

-f2 sounds right.. but that's up to interpretation, I think some of the terms, such as F1 should only be applied when the parents are true breeding

-double cross hybrid

 

[chappie]

For the sake of argument, lets say A and B are both true-breeding landraces.

 

[Baba Ku]

If it is a hybrid cross, no matter what the parent plants are, it's important to know that the first cross is indeed the first filial generation, or F1.
If only crossing within a stable line, it is less important to know.

 

[burningfire]

Mendell coined the term F1 but he used true-breeding plants for all his experiments.

technically, yes, it is a f1.. but that alone does not determine uniformity.

 

[The iD]

A x B = F1

B x A = F1r

A/B x B/A = F2

B/A x A/B = F2r

if i also produced A/B x A/B &/or B/A x B/A F2, my labelling would certainly be different, but they would all be considered as F2 progeny resulting in differing lines, imo. i would get into F2r1, F2r2, etc.

"r" = reciprocal

it is inbreeding. F1 x F1 = F2. i would consider it a partial diallel cross. i would say the label is dependant on the number of lines i am running. if i only had one line i would not need to denote a reciprocal, imo.

variation in F1, imo, would be minimal w/ like homozygous, "true breeding" P1 in this instance, w/ the exception of sex-linked traits. see: T.H. Morgan; sex linkage.

variation between sexes of the same variety in cannabis is dependant on specific plant genotype & its interaction w/ the environment. if both varieties/lines being worked are "true breeding" or homozygous for the traits we are selecting for then there should be little to no difference between males and females w/i the same variety. there would likely be differing variation in the F2 generations between lines depending on the number of F1 P that were chosen and selection. bred wide enough, this variation should diminish.

ime, diallel crosses are quite useful w/ QTL mapping. once again, it is difficult to convey specifics w/ vague questions. this is the best i can do, and may not be correct for all instances, so buyer beware. stay frosty,

-iD

 

[chappie]

Excellent info, iD, thanks!