Golden Sweet x Absolute Zero

[Silverleaf]

Another cross that I made just because I'm curious about what a particular combination of alleles will look like. When I was researching genes in 2014 I was interested to find out that the dp allele darkens pod colour, so green becomes dark green. It also darkens yellow pods, so I immediately decided I wanted to see what dark yellow pods would look like.

Enter Absolute Zero, an accession from GRIN. It's a short pea with flowers that are described as "muddy wild" and I can see what they mean. It's a little darker and less "pure" than the ordinary purple. I can't see that the pods are very much darker to be honest, as there's lots of variation in green pods anyway, but the information on the website says this one has the dp allele. It's quite short but it's been the first to flower both years I've grown it.

And of course my old friend Golden Sweet has yellow pods, due to the gp allele.

As expected, the F1 had ordinary green pods and wild type purple flowers.

The F2 should have four phenotypes:
9/16 Dp_ Gp_ Green
3/16 Dp_ gpgp Yellow
3/16 dpdp Gp_ Dark green
1/16 dpdp gpgp Dark yellow

I need 71 plants to be 99% sure of seeing dark yellow, so I'll grow 100, because about 25 will be short and I'll cull them.

[Galina]

Very interested to see how big the difference is between yellow and dark yellow and of course the flower colours too.

[Galina]

You say there is a lot of variation in green pods anyway, which reminds me to ask you whether this is genetic or environmental or for some obscure reason. I am particularly interested in the green that is light green with a silvery sheen, what Jayb called icy green. Is there a different gene involved? I have this occasionally in the CEGs. I called them C E Silver and grow some very occasionally, haven't really followed this up much. And last year we saw it in the three-coloured mangetout, which had yellow background, silvery green overlay and red spots. Other crosses with CEG have normal green pods (or yellow or part red) and few have this type of green. Is there a recessive gene involved? Amish Snap also has that colour and it gets more prominent on the older pods. Sorry, slight side-track Silverleaf.

[Silverleaf]

Hmm, I haven't seen that before (or at least haven't noticed it). I wonder if that silvery sheen is a difference in the amount of wax on the surface of the pod? Is it kind of a bloom, like you get on plums? There are several genes that control wax.

As for different greens, there are also several genes that affect that. I'll check my gene list and get back to you.

[Galina]

Thank you, I appreciate that.

Yes wax may well be a factor here, although 'wax' conjures up something dull, rather something silvery and shiny. But this occurs with pods which are much paler green than normal. With 'wax' I also think of a surface layer rather than a different colour altogether. And the colour is definitely pale green and not normal green and just coated with waxy stuff, which dulls a brighter green. Hope this makes sense. I wish I had photos to hand atm.

[Galina]

http://www.growingfoodsavingseeds.co...h?photoid=3077
This is the photo of the three-coloured mangetout (and a yellow one for comparison). This is the green (over yellow background) that is pale green. A pea like Amish Snap has that pale green but not the red and yellow that this particular pea has. It is different from standard 'green' peas.

I apologise for hi-jacking your thread even more, but wanted to clarify what I mean by pale, icy, silvery green.

[Silverleaf]

I don't mind being hijacked in the slightest! This is fascinating and I wish I could be more helpful...

After consulting the gene list, I've come to the conclusion that there are so many genes involved in foliage and pod colour it's going to be impossible to tell exactly what's going on. There are literally dozens that affect the amount and type of chlorophyll. :/

I'm thinking the kind of wax that you can see on grapes sometimes, that makes them look grey.

The pod in the picture does look a very light green, I'm thinking it has some number of genes that lighten the colour, and then maybe some extra wax gives it a silvery sheen?

I think the antho spots are caused by rup and rups alleles together.

[Silverleaf]

Just found a picture from last year, of some pods that had antho spots. The lighter ones are drier. There's also an antho stripe, which looks quite interesting!

Did your spots look like these?

Annoyingly I don't remember which of my projects these pods came from.

[Galina]

I had both 'random' spots and spots that highlight the outline of the seeds inside and also an example where the spots were dense enough to be called a 'stripe'. I don't think it was an actual continuous antho stripe though. Spots that highlight on the outside of the pod where the seeds are on the inside I have definitely seen and I will go check up on the rup and rups genes - thank you.
Also grateful for the description of wax as the bloom on plums and grapes. If it get this right it is a surface layer on top of the pod and could be wiped away. A bit like a layer of mildew that can befall late pods? I wish I had a CE Silver in front of me right now to check.

[Silverleaf]

Yes, a surface layer. I notice a very slight bloom on mangetout pods sometimes, where you can almost leave darker fingerprints as you pick them.

Kind of like mildew, yes, but a shiny-ish even layer.

[Galina]

More off-piste stuff (my bad) - this time about the antho stripe you mentioned.

There is of course an antho stripe at the 'seam' of some pea pods. This is a solid antho stripe. I noticed this with Elisabeth peas a few years ago. So I saved seeds from those pods separately and grew seeds from striped pods separately - and the stripes did not return as a feature the following year. This was one of the checks I did with Elisabeth after Jayb reported near-white flowers. I checked out each and every feature that seemed to be 'different' including flower colour with seeds from Jaybs near white flowers. Red seams (antho seams) happen occasionally with Elisabeth, but don't repeat predictably. I wanted to know whether Elisabeth was uniform (like it had always been for me) and that the white flower colour was not due to a cross. I now put it down to environment rather than genes, both the changes in flower colour - pink, redder pink, near white - and also the antho stripe or lack of it on the seam of pods. There is possibly an external trigger that enables the expression of a different phenotype and we may never know precisely what that is. .

[Silverleaf]

Yes, I meant the seam stripe. Fascinating to hear that it's variable! It does sound likely that Elisabeth's carrying something that makes it respond to certain environmental factors. I guess we just have to enjoy it when it happens!

Actually, now you come to mention it, my spotty pods might be my Elisabeth x Tachyon test cross - the one that I did to see if Elisabeth was b. If so, that might be the reason why I didn't note that observation, as I didn't intend to continue that line.

[Galina]

The dp allele darkens pods, but there is probably no corresponding simple, opposite allele that lightens pod colour. We know that lighter green pods happen, but the causes are not as straightforward as what causes the darkening of pods and flowers with dp. It will be very interesting to see all the effects you will get - as always, chances are that all sorts of other effects materialise as well as the intended.

[Silverleaf]

There are some that lighten green to a yellowish green, some of which affect the pods. But like you say, it's not a simple "this single allele makes light pods" deal, unfortunately...

That's part of the beauty of crosses though I think, you never know what's lurking away in the background ready to show up in later generations!

[jayb]

Fascinating stuff, just boggles the mind - in a good way.
You are introducing me to all sorts of new genes!

Do you have an example of a dark yellow?

I do love that icy green, so lovely, cool and tranquil!

[Silverleaf]

The icy green is pretty.

No, I've never seen dark yellow and haven't been able to find pictures of it. That's most of the reason why I wanted to do this cross...

[jayb]

Ahhh, that's why I couldn't find any pictures! Well I'm very interested to see how this turns out and hopefully glimpse 'dark yellow'.
Do you think any hints will be given in the leaves/axils or will you have to wait until they pod?

[Silverleaf]

Well you can tell Golden Sweet is going to be yellow well before it pods, so I guess that's quite likely.

[Galina]

Yes yellower stems and yellower foliage, especially at the growing points of the plant, new growth is the most yellow, greener later. Also there can be red in mature foliage. Almost like autumn colours on peas.

[Silverleaf]

I know what you mean! I often see red/purple on the edges of older leaves. Very pretty.

[jayb]

So cool, perhaps from an early age then, yayyyy!

[Silverleaf]

I'll keep you posted!

[Silverleaf]

These were sowed 1/4/16, and I spotted the first flower yesterday, at 62 days after sowing. It's on a yellow plant which is one of the taller ones - unfortunately I had problems with all my experimental peas this year as a lot of the young plants were munched to death by slugs, but I do have some which are doing well, now at that stage where they suddenly start shooting up very quickly. Wonder if the flower will be muddy or standard wild?

[Galina]

you should know by tomorrow? Photo please.