raspberryfool: (The wind changed...)
[personal profile] raspberryfool
All six of the hybrid pea seeds from last year's pea cross-breeding experiment, Bijou x Golden Sweet, have germinated; touch wood I'll have my cross. I can't wait to see what they produce! I'm expecting:

Anthocyanin (red colouration) in the stems and leaf axils (dominant, both parents, confirmed),
Tall plants (dominant, both parents),
Green pods (dominant, one parent (yellow is recessive)),
Small pods (unsure whether it's dominant or recessive, one parent),
Edible (mangetout) pods (recessive, both parents),
Purple flowers (dominant, linked to Anthocyanin production, both parents).

My aim is a large, yellow-podded mangetout type, and I'm hoping the recessive genes I need to make those will express themselves in the next (F2) generation. The F1 plants should be genetically identical, so pod size and colour will be the signs that my jiggery-pokery has worked; if I get anything different from the above I'm just growing the parent varieties!

(no subject)

15/3/15 18:48 (UTC)
ext_15862: (Default)
Posted by [identity profile] watervole.livejournal.com
What am I missing? I'm expecting 1/2 mangetout from two mangetout recessive parents, not identical plants.

(no subject)

17/3/15 00:18 (UTC)
Posted by [identity profile] raspberryfool.livejournal.com
Hello Judith, It's good to see you're still on LJ. ;-)

This is my understanding on fibreless pod characteristic inheritence; it's possible I've missed something! :-)

In peas, the presence or absence of a fibrous layer in the pod is controlled by two independent genes. The dominant forms, P and V, produce an inedible layer of fibre between the peas and the pod's skin. The recessive forms, p and v, reduce or eliminate this layer, which makes the pod a mangetout. Both of my cross's parent varieties have at least one of these recessive genes.

When two pea varieties are cross-polinated, the resulting seeds get half their genes from the mother variety and half from the father. These genes are either recessive or dominant. In the first generation after the cross—the F1 generation—unless two recessives have been inherited only dominant genes will show themselves, so if my cross inerits Pp and Vv, only the dominant genes will be expressed, giving fibrous pods.

With two mangetout parents, each having matched pairs of p and/or v, we should see the recessive genes p and/or v express themselves in the F1 generation. Because dominant genes don't hide themselves, I know I already have at least one matching pair of pp or vv, and even if the PP or VV are inherited, the other recessive matched pair should express itself, giving mangetout pods.

It's possible that my cross doesn't have a matched pair of recessives, and that one parent is PP and vv, and the other parent is pp and VV, which might give me Pp + Vv, leading to fibrous pods. The dominant gene will hide the recessive one.

This blog post from Rebsie Fairholm (http://daughterofthesoil.blogspot.co.uk/2008/02/pea-breeding-project-golden-yellow.html) will explain it much more clearly!
Edited 17/3/15 00:21 (UTC)