Broad bean / Fava bean flower colour?

[jayb]

Most varieties have white and black flowers, a few I think are all white and then there are Crimson flowered. Are there any other stable flower colours?
Why do red x white produce such a variety of colours as they segregate, can any of these colours/ shades be captured?

[Silverleaf]

I'd be interested to know too. Should be easy-ish to do some tests.

As far as I can work out, white x red makes pink. This would suggest incomplete dominance to me - red colour requires the plant to be homozygous for red. Heterozygotes only produce half as much red pigment so they are pink. I'm just theorising here!

If red shows incomplete dominance then pink will never be stable. If you had a population of pink plants, when they selfed or crossed with other pinks then half the offspring would be pink, 1/4 red, and 1/4 white. Even if you rogued out the reds and whites every time you'd still see them in every generation after the F1. The best you could hope for would be a mixed population.

Of course I'm just throwing the idea out there, but that's how it looks to me with my minimal knowledge.

How I'd test this: grow reds and whites in an insect-proof cage. Hand pollinate reds with whites, and vice versa. Save all hand-pollinated seeds. Sow saved seeds. If there's incomplete dominance, the F1 will (hopefully) have some pinks. Again, insect-proof, but this time hand self-pollinate only the pinks and save from those. The F2 should be about 1/2 pink.

If we see anything we're not expecting, it'll still be useful information.

I do have some crimson-flowered beans growing but I don't think I'll be able to use them for this test because they were sowed much later than the white/black ones and won't flower at the same time.

[jayb]

The crosses I've had in the past are a mix of browns and light and dark pink some have brown shading. So these are all variations on the pink? I never got to grow them out properly they just all got saved and sown, so not possible to track.

Pinkish and brown Broad bean flowers


Two tone purple broad bean flowers


Chocolate broad bean flowers


Have I got it right, none of the above colours could have been stabilised? But if left to self/cross pollinate, then saved seed the following year would give plants with over half pink/brown types and the remainder whites? What about a back cross to a white? Also if red has incomplete dominance, would there not be more red flowered bean varieties about? Sorry I might not be getting this at all.


I look to have some x plants this year from previous mixes I've grown, plus the Russian Black and an Aztec Yellow that looks to have a wonky flower, though not overly coloured. I can mark these plants to save them for seed though they would be open pollinated, unless I get in gear and do a bit of hand pollinating. I could hopefully get enough seed saved for growing next year.

One of the crosses I wondered about

[Silverleaf]

Honestly, I don't know. Just making an educated guess really, based on the fact that a red crossing with a white throws up pinks. It immediately rang a bell in my head - if the F1 has types that are intermediate to the two parents, then incomplete dominance us the first thing I'd check for.

I'd suspect that the brown colour is a completely different gene, so what you're seeing is various combinations of red and brown/black pigments. There are probably some other genes that modify anthocyanins into different shades of red/purple, which is why there are purple flowers as well as red ones.

The chocolate ones have obviously had their black pigment modified into brown. I know that the normal black is unusual because it's a true black, rather than very dark blue or purple, which is what black colour in plants usually is. The chocolates are absolutely gorgeous, where did you get them from?

If I'm right about red being incompletely dominant (i.e. all the pinks are homozygous), the pinks won't ever stabilise. If there was a modifier gene (like the b gene in peas) changing the antho colour to pink, that could be stable.

I am making quite a lot of assumptions here though!

If we go with the assumption that red is codominant, this is why pink will never be stable. Let's call red R, and white r. A red (RR) plant crosses with a white (rr) plant. The F1s are all pink (Rr). Great! Now if you let the pinks self or cross with each other, the F2s will segregate as usual, except you'll see an unusual ratio of phenotypes - 1/4 RR (red), 1/2 Rr (pink) and 1/4 white (rr). Every time a pink crosses with a pink or selfs, you'll see that same pattern, no matter how many generations you grow out.

Crossing a pink with a white won't help either. Half the offspring will be pink, half white.

I'm totally prepared to be wrong about the incomplete dominance though!

[templeton]

Well, you could get pure pink line if you found a male sterile plant, like CMS in carrots, for example. Wouldn't matter if it was red or white. Grow it next to the alternate colour as the pollen donor, and then all the seed will always be heterozygous red ie pink phenotype. Can't really think of a use for this apart from the culinary flower trade - a microherb farm near me was well pleased when I told them about chocolate flowered. They grow a big row of broadies every winter just to harvest the flowers for high-end restaurant plate decoration.
T

[jayb]

- a microherb farm near me was well pleased when I told them about chocolate flowered.
T

Is chocolate flowered a stable variety?


Found this https://www.diggers.com.au/shop/edib...lowered/s0082/

[jayb]

The chocolate ones have obviously had their black pigment modified into brown. I know that the normal black is unusual because it's a true black, rather than very dark blue or purple, which is what black colour in plants usually is. The chocolates are absolutely gorgeous, where did you get them from?

The Chocolate one and the others above are from a few years ago, Crimson Flowered crossed with Red Epicure. I was looking for a red flowered, red seeded bean. The growouts ended up going into the mix I'm growing at the moment.

[templeton]

J, I only grew them one year, but yes, I believe they are - tho take anything Diggers say with a grain of salt - don't have a great reputation in my circles. The Chocolate flowered were pretty wimpy compared to a good broady - weak plants, small pods. Hope they have ended up in my broady mix, which is just emerging from the soil.
T

[jayb]

Great, gives me hope on getting a more varied colour pallet of beans here I'm not interested in looking for and adding in a male sterile variety, as much as I love the pink flowers.

Not great for you the were weak plants, but I'm sure you will improve them if they made it into your mix.

[jayb]

Thanks Silverleaf, I'm just trying to take on board what you have said about the different colours. I'm excited by the news that a chocolate brown has been stabilized, I'm hoping the ones I'm growing have the right combination to as well.

Thsi one from my SeedMix 2013 seems to have purpley colour on the outside of the buds before they open.

Dark chocolate


The same plant

[jayb]

This one is quite striking, not sure how to describe the colour, Deep plum perhaps? The buds look almost black, do you think it is another mix of the red and black colours, but with something added or subtracted, so it doesn't look brown? Not the same I know, but tomato fruit either have a clear epidermis or a yellow one which affects fruit colour, red/pink, brown-black/purple-black etc. I've been having a look at the Crimson flowered I'm growing and they don't look as uniformed as they use to, some look red red and others purply red. I know I've sown a mix of saved and bought seed, which might account for a bit of crossing but most of the earlier sown were bought seed. I wonder if more than one strain of Crimson Flowered are going around?

Deep Plum 2013 mix

[Silverleaf]

I'd suspect that those have black overlaid with red, yes. I think when the plants have brown, it's when the black pigment has been completely modified (kind of like the way the b gene in peas modifies the purple anthocyanins into pink). So I doubt you'd get both brown and black pigment in the same plant anyway.

They all look absolutely gorgeous anyway!

[Silverleaf]

Oh and yes, welcome to degree level genetics.

[Silverleaf]

One of my broadies has pink flowers!

I'll grab a picture later, but this is definitely supporting the idea of incomplete dominance for the antho pigments. I only grew ordinary white/black plants last year with a couple of crimsons, so the pink is almost certainly a cross.

I didn't label my plants though, so I don't know for certain, but I'm pretty confident it's a cross.

[Silverleaf]

Definitely much lighter in colour than the crimsons.