First flowers

Well like everyone else I've been suffering a lot of slug damage what with the mild winter we had and the wet weather we've been having recently. But my peas are mostly doing well. Sugar Ann here won the race for first to flower. It's a standard widely-available dwarf sugarsnap type with as you can see, white flowers. Nothing terribly exciting, but it's here to provide me with the n allele.

Snap peas are those ones with the edible fat pods. Great raw or in stirfries and they cost an absolute fortune from the supermarkets and they taste much better fresh anyway. All snaps have two copies of n, which makes the pod walls thick. They also have two other alleles which together make the pods free of inedible fibre, p and v.

I'm going to cross Sugar Ann with Golden Sweet in the hope of creating a yellow snap. Golden Sweet's already most of the way there - it has edible snow (mange tout) type pods so all I need to do is introduce n and we're all good.

Only slightly behind flower-wise is one of my experimental lines, W6 15097, which I've nicknamed Absolute Zero. The flowers are described on its page at the Germplasm Resources Information Network as "muddy wild", wild meaning the "default" colour that the flower would normally be in a wild pea plant (maroon/purple). This one looks almost brown.

Apart from the strange flower colour, Absolute Zero's going to give me an allele called dp, which makes the pods a dark blue-green. If I combine this with the gp that gives Golden Sweet its yellow pods, I should get dark yellow pods.

I can't wait to see other flowers! It's also be nice to have some decent weather for crosses...

Epistasis and the D gene

I don't know the exact details of the genetics of all my pea plants. Many of the experimental varieties have their own pages on the website of the organisation that I got them from, which lists the genes the researchers know they have, but many others do not. I'm attempting to fill in the gaps by observing all the plants myself.

With this aim in mind, I went out with a notepad and assessed my plants with respect to the D gene. This controls whether pigment is deposited in the axils.

This is Purple Podded. And here's a little plant anatomy - the two leaf structures attached directly to the stem are called stipules, and that dark pink bit is the axil.

To be fair, the axil colour isn't really relevant or at all since I'm mostly interested in pod and flower colour, but it's going to illustrate an important genetic concept.

Purple Podded there has a single axil ring, caused by an allele of D called Dco. Pretty, isn't it?

And Golden Sweet has a double ring due to its Dw allele, which I think is even more attractive.

Sometimes you can get information about other genes from the axil pigmentation, for example in Salmon Flowered, which has only a little pigment. I suspect this is the result of something like the b allele modifying the anthocyanins from a deep red-purple to a paler pink, but I don't know yet whether Salmon Flowered carries b or something else entirely.

Finally these baby Telephone plants don't have any axil pigmentation at all, because of the d allele (no axil pigmentation), right? Right?

Well, not necessarily.

There's another gene that could be at work here - a. The dominant allele, A, makes the plant produce anthocyanins. The recessive a means the plant can't produce any anthocyanins at all, ever, no matter what other genes it has for where to put them.

Imagine it like a factory line building the plant. Department A is responsible for turning on the anthocyanin-making machine, and Department D is responsible for delivering that pigment it to the axil specifically. Other departments deal with delivering it to the flowers, and some to the pods (i.e. the Pu and Pur alleles I talked about in the last post). The B Department along with some others control the exact recipe that makes the pigment, changing its colour. Some will distribute pigment in a specific pattern.

None of these other alleles can do their job if the anthocyanin machine isn't switched on in the first place, because there's no anthocyanin to work with at all.

The effects of these genes are essentially hidden by a, and this is called epistasis - a is epistatic to all those other genes that do something with anthocyanin.

So my Telephone pea might have no axil pigment because of d, or no anthocyanin at all because of a. I can't tell by looking at them right now, but I know it has white flowers and green pods so a is likely.

The easiest way to tell would be to make a cross with a pea I absolutely definitely know is aa but also has anthocyanin-depositing alleles like Pu and Pur (purple pods) and Dco or Dw (axil colour) and the ones that allow flower colour. If Telephone has aa the offspring will all also be anthocyanin-less. If it has A but all the other genes are the recessive non-delivering types, we'll see pigment in the offspring. I don't have the necessary breeding material to do this but to be fair, right now it doesn't matter much to me anyway.

And it might all become clear as a result of other crosses I'm planning to make.

More about red pods and crosses

Although I started late, my peas are doing well. The tall varieties are about 2ft tall (of course the short ones are shorter!) now and they all look absolutely beautiful, and it probably won't be too long before they think about flowering, and then I can start to actually make crosses.

The first one I'm going to talk about is Golden Sweet x Purple Podded. I've mentioned this before, but in order to get red pods I need yellow pods with purple/red anthocyanin pigments laid over it - Golden Sweet has the yellow, and Purple Podded of course has the purple.

What I'm growing

I currently have seeds of 42 different types of peas. I don't have the room to grow everything this year, so some decisions had to be made prioritising the material I have.

Peas to eat
Golden Sweet, which I got from The Real Seed Catalogue. It's an old yellow-podded snow pea (i.e. you eat the flat young pods) and it's delicious. It's tall, and had purple flowers.

Purple Podded, which Celia kindly sent to me a few years ago. Like the name says it has purple pods, and it makes a good soup pea. I love the contrast of the purple pods and flowers against the green foliage too.

Telephone, also from The Real Seed Catalogue. Another tall pea, this one an old shelling-type with green pods. This is new to me this year, so I don't know much about it other than the description on the site.

Sugar Ann, a short snap-type pea (like a snow pea in that you eat the pods too, but the pods are thick and fleshy rather than flat). It has green pods and white flowers and is apparently very early for a snap.

Sugar Bon, which I bought because it was extremely cheap from Lidl. I assume it's similar to Sugar Ann but I haven't tried it before.

Peas for seed saving and breeding
 All of the above, plus:

Salmon Flowered, from Galina at Allotments4All. An unusual variety which has fasciated stems (they are thick and ridged as if many stems have fused together and the flowers and pods are all at the top of the plant giving it an "umbrella" effect. They look very interesting and apparently taste nice too. New to me.

Elisabeth, also from Galina. She discovered a single plant of this pea mixed in with something else. It's a pink-flowered snow pea with green pods, which I also haven't grown before.

Waverex, a popular petit pois pea. Short, white flowers, and very sweet tasty peas. Should be good for adding flavour into my project if necessary.

Also some experimental material, which is carrying various genes (mostly for flower colour) that I'd like to add. Most have codes instead of proper names, so I've given them nicknames of characters from my favourite superhero board game to make them easier for me to remember.

Absolute Zero, bluish-green pods.

Bunker, bluish-green pods, darker purple flowers.

Fanatic, pink flowers, some leaf weirdness.

Haka, bluish-violet flowers.

Legacy, cerise flowers.

Ra, pale pink flowers.

Scholar, brick/rose red flowers.

Tachyon, pink flowers, extremely weird leaves.

Tempest, purple pods.

Unity, crimson flowers.

Visionary, blue flowers, dark bluish-green foliage.

Wraith, yellow pods.

That's 20 different types. I must be mad. ;)

Pod colours, and some genetics

There's a surprising amount of variety in the colours of pea pods. We all know the standard green ones, but it's possible to get the following as well:

*Purple (courtesy of the Guardian)


*Yellow (grown by me, years ago)


*Red (courtesy of the lovely Rebsie Fairholm)


*Bluish-green (no picture, sorry, but I am growing a couple of types with this colour so I can show you later in the year)

Breaking down the plan

This project is going to to take literally years.

I can grow one generation of peas every year (you can squeeze in a second one, but a second sowing may well not be as successful and might waste my precious breeding material).

This year, I plan to do basically two things.

1) Grow out my breeding material, and save as many seeds as possible for next year. For some of the peas I'm growing, I only have 4 or 5 seeds so I'll need to increase their numbers.

2) Make some crosses with the material I have. Hopefully I can perform each cross 5 times. I haven't decided on all the crosses yet, but my plants are only small so far and not even close to flowering, so I have plenty of time to think about it.

Next year I'll grow out and increase some more varieties, as well as the results of my crosses. Those crosses won't start to show me what I'm actually looking for until the year after that, and may require a few more years to get the exact combination I want.

Once I have what I want, it will require seven generations to stabilise it and basically get rid of all the traits I don't want. Like I said, it's going to take a while.

So why peas?

So why have I chosen to focus my attentions on peas, when I could be working on any other vegetable or fruit? What's so special about them? Why on earth am I planning to spend time cross-breeding them and collecting different varieties?

Well to understand that, you need to know The Plan (which I talked about briefly in my last post). I want pretty vegetables so that people (especially those with small gardens) can grow them in the flower garden where they can look nice but still provide useful and healthy food. Really I had to choose one species because I have neither the time nor the space to work with more. Peas win for the following reasons:

* Peas are already pretty. The flowers are beautiful, just like sweet peas (except they don't smell).
* Peas already have a lot of variety in flower, pod and foliage colour genes, much more than you'd usually see in the standard garden pea which has white (or sometimes purple) flowers, green pods, and green foliage.
* They climb, and come in different heights from maybe 60cm up to 3m, so you can basically pick the height you want. I prefer tall ones, but many people prefer the short ones because supporting the plants is easier.
* They are easy to grow, and well adapted to the coolish environment of my suburban English garden.
* Growing legumes increases the amount of plant-available nitrogen in the soil, improving it for my nitrogen-hungry brassicas which will grow in that space next year.
* Peas and their genes have been studied by geneticists for hundreds of years, which is very helpful when you're trying to work out what genes you're dealing with and how they're going to interact with each other.
* Peas are convenient to breed because they naturally self-pollinate - you don't have to worry about different varieties getting "mixed up" with each other. This is a helpful shortcut for some of the work I'm planning to do.
* It's also relatively easy to make crosses between plants. I'll talk about that when I get to the stage of actually doing it.
* They can be grown very close together, saving me precious space for more varieties. I can squeeze 36 pea plants into a 1' square, the same space needed for one tomato plant or about 1/4 of a squash plant!
* Peas also taste great, and come in 3 basic types - ordinary shelling peas, fat snap peas where you eat the pods too, and flat snow peas where the crunchy pod is the main event. The shoots are also delicious, but I'd rather let the plants grow up into proper plants.

Basically, I love peas. Peas are perfect for my experiments.

The ultimate aim? To create a rainbow mixture of beautiful ornamental peas with varied flower, pod and foliage colours. Peas that are pretty enough for the flower garden, and tasty enough for the vegetable plot. And I'm going to share these with whoever is interested in growing them, because if they make someone else happy, that's payment enough for me.