Golden Sweet x Bijou

[Galina]

Last year I made a cross between Golden Sweet (as the mother) and large green mangetout Bijou was the pollen donor. The F1s are now ready, see photo. This is the correct photo, sorry to upload the wrong one initially.

All plants look alike and have produced identical pods. As any F1 should of course, but after last year's surprises with the CEGxShiraz crosses, not something I take for granted anymore.

Again the aim is to create a very large yellow mangetout. The F1 is not particularly long with a pronounced blunt end. .

[jayb]

Golden Sweet are very narrow aren't they. Hopefully something that will be able to be selected away from. Looking forward to your progress on this one too
Yes if an F1 isn't pretty identical, then my understanding is it's either an unstable parent or an addition of stray pollen. It was a bit odd with CEGxShiraz.

[templeton]

OK, Let me stick my neck out. based on this F1, long pod is dominant, wide pod recessive. So F2 should give 3/4 long, 1/4 short, and 1/4 of the F2 should be wide. Caveat: If long and wide are single genes, and there is no pleitropy, and no co-dominance, or linkage. Or I could just be wrong...
T

[Galina]

There is the v linkage group associated with the gp yellow gene. I may still not understand linkage groups correctly, but there are pod shortening and pod narrowing genes associated with gp. Which is why it was such a lovely happenstance that CEG is a wide-podded pea (and also a bit longer than Goldensweet but no giant length). I am trying to breed from CEG and get one of the really long types as well as wide, with the various crosses I made. Please put me straight if I got all this linkage group business wrong.

My cross with Golden Sweet is narrow, but my crosses with Court Estate Gold don't look narrow in the F1 generation.

[Galina]

Additional comment to qualify the above: I repeated the cross that was the origin for Court Estate Gold (Golden Sweet x Schweizer Riesen) and I got w i d e pods in the F1 generation, not narrow like the F1 pods of the Golden Sweet x Bijou cross.

[Silverleaf]

The linkage group thing is basically what chromosome the locus is on. If two loci are in the same linkage group, they are on the same chromosome. That's a bit simplified, but good enough. Linked genes are less likely to get separated during the pollen/egg-producing process so they tend to get inherited together.

Practically, what this means is if you're looking at two genes that are linked, you won't see the usual 9:3:3:1 ratio. You'll get more "parental" types than you expected.

A made-up example, to see if this makes things clearer. (My genetics lecturer used to talk about dragon genetics because he could then created "model" examples rather than finding imperfect real examples, so I'm going to do that too). Let's say that purple scales, P, are dominant over red ones, p. Black claws, B, are dominant over white ones, b. We mate a homozygous purple-scaled white-clawed dragon with a red-scaled black-clawed one.

PP bb x ppBB ---> Pp Bb (F1 all purple-scaled, black-clawed)

We'd expect the following in the F2:
9/16 P_ B_ (purple, black)
3/16 P_ bb (purple, white)
3/16 pp B_ (red, black)
1/16 pp bb (red, white)

But if the genes are linked, we'll see more of the parental types than we'd get with unlinked genes. Here the parental types are P_ bb and pp B_, (what the original parents were). If a baby dragon gets P from its mother, it's likely to get b as well, because the genes are physically close together and thus hard to separate.

I haven't explained that very well, but it's a hard concept. :/

When it comes to CEG and pod width genes, linkage is actually on your side since you already have the combination of wide pod and yellow pod together and those two traits will have an increased chance of staying together. How much it's increased depends on how closely linked they are (I don't know), but it'll mean you'll see more plants with wide yellow pods than you would if the genes were unlinked.

[Galina]

I am a little confused (doesn't take much! ): If narrow podded genes are linked to yellow pods and preferentially stay with yellow pods, has this link been broken with the wider podded Court Estate Gold? If the link has been broken, why is there an increased chance that yellow and wide will stay together if I breed with CEG? You mention pod width genes, but there are no genes for wide pods in this linkage group. http://data.jic.ac.uk/cgi-bin/pgene/...Search=linkage. When I look at pod genes in general http://data.jic.ac.uk/cgi-bin/pgene/...earch=SubClass I cannot find any wide-pod genes.

[Silverleaf]

The link is reformed, is the short answer.

It isn't that narrow is associating with yellow, it's that pod width (whether wide or narrow) is associating with pod chlorophyll (whether green or yellow). It's the loci that are linked, not the actual alleles.So if your original pod is yellow and narrow, those two alleles will be inherited together more often than they "should". Similarly if you have narrow green pods, narrow and green will be more common than you'd expect from unlinked genes.

What's happened with CEG is that you've recombined the original pair of traits to make what is now a new parental type. Yellow is now associating with wide pods and will continue to do so. This of course doesn't mean that you won't see the original yellow/narrow pairing getting passed on to CEG's offspring, t'll just happen at a reduced rate. That's what I mean by linkage working for you now.

And when I said "wide pods" I meant "not narrow". Sorry to be confusing!

[Silverleaf]

Oh good, I was wondering if I'd need to make a little video about linkage and crossing over. Much easier to explain by speaking!

[jayb]

I'm not sure I get it, but maybe when I go over it again.

[Silverleaf]

Do you think a video would help?

[Galina]

Oh dear! I've done it now. I feel like such a dork, you would not believe! So the peas are growing fairly tightly packed, That's a given considering the numbers I am growing this year. And there was a lost label and a skipped row because of it. Yesterday I did a proper 'stock-take' - 'Where are the Serpette Guilloteau I planted according to the garden note book?' Right adjoining to the Golden Sweet x Bijou according to the book. I have gone right down to bottle level and separated all plants to be absolutely sure which is which. And duh! the above is n o t GS x Bijou but a lovely curved Serpette Guilloteau. I feel such a numpty. How can I replace the photo above? Sorry everybody. I will upload the correct photo as soon as I discover how to remove the wrong one. And it is not as interesting as the lovely shape of Serpette. My apologies again.

[jayb]

How can I replace the photo above?

Click on edit at the bottom of your post, select the picture and delete it, you can then replace it with the one you want.

[Galina]

Still can't do it, I'm afraid. Jayb, could you please sort the above mess out. The picture of the peas on the pink carpet is the correct one, but we don't need it twice and it is too large. I can't make the wrong picture go away whatever I try.

[Admin]

I hope it's how you wanted it, I'm not sure why it was such a fiddle, the pictures were not behaving!

[Galina]

Perfect, thanks muchly

[Galina]

Well I have 4 plants growing in the F2 (second generation in 2015). I have another 3 but they are not planted out because they germinated later. #1 is mildewed, but still growing, a couple of mid-size dark green mangetout pods. #2 started off at an amazing rate of knots, a well branched plant, extremely quick growing and has a dozen pods, slight mildew. A couple of doubles. Huge light green mangetout pods, very similar to Bijou. #3 has yellow mangetout pods, smaller plant, pods like golden sweet, #4 not yet podding - no yellow on foliage, guess it will have green pods (but probably too late for this year).

[Galina]

3 F2 plants this year. And to save space they are all jumbled together on an 8ft support. Not to worry. Just looked them over, retied them because the wind and their tendrils had caused a little disorder. But in the end it was easy to look at them separately.

One plant too small yet, another medium long, wide green mangetout pods and the joy of the bunch! - a very wide and very long yellow mangetout. Haven't tasted them yet, but just exactly what I had hoped to get from this cross. Photo to follow. And the big yellow was the earliest and is on the tallest plant too. Very happy! Son (who is not usually observant when it comes to things in the garden), was amazed to see a long and wide mangetout last year. Guess I have to name this one after him and the first decent red I am happy with after daughter.