Don't get too excited, this one looks very pretty but it's actually a yellow mangetout (snow) and only has one of the two recessive genes I'm looking for
There's been so much happening with the Yellow Sugarsnap Project, and so much else happening in the rest of my life, I haven't had a hope of blogging up all their progress. One issue is that I'm collecting huge amounts of data which I'm then having to type up and spend ages staring at, in addition to all the usual seasonal garden activity. So this is the best I can do for the moment. At least it'll give you a glimpse of what is happening with the project, which has reached its most exciting stage now.
A couple of years ago on this blog I claimed that naturally inbreeding plants such as peas don't show much hybrid vigour, if any. Well I'm having to eat humble pie now as my yellow sugarsnap F2 hybrids soar beyond a height of 7ft and show no interest in slowing down. They've massively outgrown the frame I made for them and are beyond the tops of the support sticks. This project is a cross between a 5ft variety and a tiny dwarf one which barely reaches 1ft in height, so I wasn't expecting anything quite like this. D'oh!
The original cross was Golden Sweet x Sugar Ann and this is the F2 generation.
Some things have turned out just as predicted ...
Flower colour is usually pretty simple in peas. Purple is dominant over white. So if you cross a white-flowered variety with a purple-flowered variety, the first season's progeny (F1 hybrid) should all have purple flowers ... and that's exactly what happened when I grew the F1 generation last year. In the F2 generation the genes are recombined, and approximately a quarter of them end up with the pair of recessive genes which enable white flowers to express themselves. So I expected to get purple flowers on three quarters of my plants and white on the others. And that's not far off what I've got. Hurrah!
I already showed you the first flower, which was purple (when I say purple, I mean the mauve and maroon bicolour which is common to many heritage varieties). The next four were all purple too, and then the next four were whites. A majority of the early flowers were white, but overall the ratio is 24 whites to 39 purples, which is not quite a Mendelian ratio but is not wildly far off it.
The joy of F2 variability. Sometimes they're white-flowered with a cream calyx and yellow stems ...
Sometimes they're purple-bicolour flowered with green calyx and stems ...
And sometimes it's the other way around.
Yellow pods are a recessive trait in peas, and again the inheritance is pretty simple because it's all down to a single gene. In a cross between a yellow-podded pea and a green-podded pea, all the first generation (F1) plants should be green-podded (and indeed they were). In this F2 generation the recessive yellow gene has a chance to assert itself and so roughly one in four plants should have yellow pods ... and so far that's pretty much what I've got. 19 yellows to 44 greens is as near as dammit the predicted Mendelian ratio.
It's quite odd to see these yellow and green pods all growing together, and to think that they're siblings from the same batch of seeds. Gene segregation in action!
Snap pods are another recessive class, so again I'm only expecting about one in four. In some cases it's still too early to tell which are sugarsnaps and which are mangetouts. Many of the mangetouts are obvious because the pods are already large and flat, but I haven't finished collecting data on this yet so there's no point drawing any conclusions. But at a glance I'd say the ratios are looking about right.
Tall plants outnumber dwarf plants considerably, which consist of 6 true dwarfs and 7 intermediate types (13 altogether). The expected ratio is three talls for every one short, because once again it's a trait which usually shows simple dominance.
Yellow tendrils grow alongside green tendrils, another variable trait in the F2 plants
Some new things I discovered, but they weren't huge surprises ...
There is a correlation between axillary pigmentation and purple flowers. All the plants with a deep pink splodge in the leaf nodes (whether it was a tiny smudge or a big blotch) went on to produce purple (bicolour) flowers, while all the plants with no trace of pigmentation went on to be white-flowered, no exceptions. Not entirely unexpected, although theoretically I can't see why these traits shouldn't be inherited independently because they're controlled by different genes. Maybe it's gene linkage, but I don't know to be honest. The genes controlling purple/pink colouring in peas are numerous and sometimes interrelate in funny ways.
A trait common to all purple bicolour pea flowers is that they turn a beautiful blue as they fade
There is a correlation between cream or yellow colouring on the plants and yellow pods, so all the plants showing any trace of yellow colour are turning out to be yellow-podded. No exceptions so far. The surest sign is when the first flower buds begin to form, because the buds have a very distinctive pale cream calyx (that's the leafy bit round the outside of the flower that looks like a pixie hat) which is easily recognisable even while they're still tiny. It's interesting that there appears to be just one gene controlling yellow colour, and it's an all-or-nothing kind of thing. Not like purple, which has separate genes (or even pairs of genes) for colouring different parts of the plant. It seems that if the yellow gene is there, you can expect to see yellow consistently in the stems, tendrils, calyx, pods and young leaves.
Pods per node is variable, as in many other pea varieties. Some bear their pods singly, some in pairs, and some show a mixture of both on the same plant.
And some things which were a pleasant surprise ...
New phenotypes are the most exciting aspect of breeding your own plants. Crossing any two varieties, especially those with a healthy bit of genetic diversity, is likely to throw up a few new traits not seen in either parent. It happens because genes interact with each other in a variety of ways and some can only express themselves when they hit just the right combination. While it's nice when all your predictions and ratios come out correct, it's not as exciting as seeing something totally wacky and unexpected show up in the F2.
So you can imagine how delighted I was to be presented with this:
New pink and white flower phenotype, which is essentially a white flower overlaid with pinky-mauve, giving a veined and mottled effect
This is the rear view ...
... and they age very gracefully too, producing more colours as they're going over.
Six plants out of the 63 are showing this new phenotype. What appears to be happening here is that the standard petal (the big one at the back) is white but the pinky-purple is trying to assert itself over the top. As the pink is stronger in the middle it gives this beautiful mottled two-tone effect. The same is true of the wing petal, where the maroon is spattered over a creamy white base. The overall effect is absolutely beautiful, and looks more like something you'd see in sweet peas than culinary ones. I really like this new type and would love to have a new variety like this, even though it's nothing to do with the original purpose of the project (distractions and sidelines are part of the fun).
The burning question is whether I can actually preserve this new phenotype in future generations and make a true-breeding stable variety out of it. The reason I'm uncertain is that I don't know what genetic factors are responsible for it. Maybe if I save seed from all the pink-and-white plants they will happily produce offspring with the same attribute, in which case I will be hopping up and down with joy. If, on the other hand, the unusual colour is created by co-dominance between two opposing colour genes then I'm stuffed ... because the genes will recombine and segregate out into pure white types and purple types. I would still get some of the pink-and-white types, but they would decrease with each generation and no amount of careful selection would be able to fix those colours.
There's more interesting stuff about these pink-and-whites. You may recall that when I sowed the seeds I separated them out into different seed types, according to their colour, wrinkliness and whether they had purple speckles. I did this so that I could look out for any correlation between seed type and plant traits. For the most part there hasn't been anything obvious, but ... four out of the six pink-and-whites are from Group 2, which was "smooth, green seeds with purple speckles". The other two are in a group which were selected for size rather than colour, so it's not possible to know what colour seed they came from, but they both came from the "small seeds with indeterminate markings" group.
And that's not all ... I'm intrigued to find that all six of the pink-and-whites have the sugarsnap pod type. Given that the sugar pod gene is recessive, it seems unlikely that it's simply down to chance. But I don't know what the explanation is. The most obvious is gene linkage. That's something which happens when genes are positioned close together on the same chromosome ... they tend to stick together rather than being inherited separately. The closer together the genes are on the chromosome, the less independent they tend to be. So it may be that one or more of the genes which make pink-and-white flowers (and of course I don't know anything about these genes yet) is on the same chromosome as the sugarsnap gene. And I have no complaints about that. I prefer sugarsnaps to mangetouts anyway, so if this is going to turn out to be a pink-and-white flowered sugarsnap by default, well, suits me.
There are other new phenotypes too, even if not quite so exciting. Here's another of the very pretty ones, a dwarf plant with exceptionally intense yellow colour. It's even got yellow leaf veins. The bicolour flowers have an unusual rolled tube shape. Pods are yellow mangetouts.
And the yellow sugarsnap itself? At the moment it looks like I have only one plant which is a true yellow sugarsnap (others may become apparent later, but I think that's the lot). This isn't entirely surprising ... there is only a one-in-four chance of a plant having yellow pods, and of those, only one in four are likely to have the recessive sugar-type pods. So overall that means a 1 in 16 chance of a yellow sugarsnap. Out of 63 plants I might have hoped to get more than one, but when you look at it from a statistical point of view it's not that wide of the mark. Better one than none at all!
The holy grail of this particular breeding project, a Yellow Sugarsnap.
For those who want to see the actual data I'm collecting on these plants I'm compiling them into a huge table and making it available online (on what will eventually be an extension-website to this blog but it's very much a work in progress). I'm still collecting data so the table isn't yet complete.
If you're inspired by what you've seen here but still thinking "what the heck is she talking about?" I heartily recommend a read of Carol Deppe's book, which is where I learned half of what I know (the other half coming from the garden itself). There would be no Daughter of the Soil without Carol Deppe!
Saturday, 31 May 2008
Don't get too excited, this one looks very pretty but it's actually a yellow mangetout (snow) and only has one of the two recessive genes I'm looking for
Posted by Rebsie Fairholm at 11:29 pm
Thursday, 8 May 2008
A diversity of beans. I grew all these varieties in the garden last year. Top row, left to right: Coco Bicolour, Nun's Belly Button, Early Warwick.
Middle row: Purple Queen, Purple Prince, Mrs Fortune's.
Bottom row: Spagna Bianco, Vermont Cranberry, Caseknife.
Beans are a joyous thing to grow. They make such a big fanfare when they emerge from the ground. Huge fat fleshy cotyledons which don't look like leaves at all. And then a slightly prehistoric appearance as the true leaves unfold from inside. You can't miss 'em. And neither can the slugs, unfortunately.
I'm having serious problems with the slugs at the moment, as a lot of other Brits probably are. We've had a lot of alternating heavy rain and bright sunshine, which has brought the plants (and weeds) on a treat. Lots of fresh new growth = gastropod party time. After a drawn-out and very dry spring season, a dousing of rain has suddenly brought them all out of hibernation and they are hungry. All my breeding projects are under assault. Ulluco, razed at ground level every time a shoot emerges. I've lost my entire crop of onions, which included some rare and hard-to-get varieties, and it's too late to start again. Nurtured since January, wiped out in a single night.
Young bean plants are very vulnerable when first planted out. Some snails like to work their way up the stem stripping off the outer layer, and then pointlessly chomp through a leaf stalk so the whole leaf falls off. Other times the slimy little sods don't bother with all that and just shin up the bamboo cane to mangle the leaves directly.
I've been planting out loads of beans this week and I'm doing my best to keep them alive. I have had to sow a few replacements, but hopefully if we have a few days of dry weather the survivors will get properly established and the slugs will cease to bother them. I've collected rather more beans than I've got room to grow but I'm managing to find space for most of them, and the rest can wait till next year.
French beans in Rootrainers. The emerging seedling is Poletschka (thanks Celia) which grows from amazingly beautiful indigo-black glossy seeds ... and the pink stems beside it belong to Jo's Purple Podded, an ongoing breeding project distributed by the Irish Seed Savers Association.
Most of the varieties I'm growing are climbers. I don't grow very many dwarf beans because of the slug problem ... the low-slung pods are easy pickings for them. I also find the yields very poor for the amount of space they take up and they often give back barely a handful more beans than I sowed to start with. But there are some interesting varieties which don't have any equivalent among the climbing types, so I make an exception for those.
Two new dwarfs I'm trying this year are Black Valentine, a variety from the 1850s with small but pretty black kidney beans, and Comtesse de Chambord with even smaller shiny white beans. Indeed Comtesse de Chambord is something very different, as it's what's known as a rice bean ... the white beans are tiny enough and elongated enough to look a bit like rice grains (pudding rice, anyway). Actually they aren't quite that small but they're pretty tiny as beans go. They're reputed to have an excellent flavour but they're not grown commercially because their tiny size and delicate plants make them uneconomic. So if you want them you have to grow your own. I got my seeds from Association Kokopelli.
Newly emerged seedlings of Comtesse de Chambord, which look a bit like little bug-eyed monsters while they still have their yellow cotyledons. They grow into small, delicate plants of a very bright green and the pods can be used for green beans or left for shelling.
By way of contrast, these are the emerging seedlings of a supersize Australian climbing variety called Purple Giant. This one is mainly grown for its purple pods and the seeds are flat and fairly small. With the weather being so clement they've grown rapidly in the last few days but I can't plant them out yet because I don't have any tall enough poles. I can only buy bamboo canes of a maximum of 7ft because anything bigger than that won't fit in my car. I'm having to borrow some extra-long poles from my neighbour. He has a bigger car.
Purple Giant emerges. The one on the right is more strongly purple than all its siblings, though otherwise it looks true to type.
I'm always on the lookout for natural variations and mutations in beans, because breeding them the same way I do peas is not convenient ... the anatomy of the flowers makes them incredibly difficult to hand-pollinate. However, some of the most dramatic variations are no use for breeding because they're not genetic.
That includes the curious phenomenon of occasional bean colour reversal, or "day for night" to give it a more romantic name, where (for example) a batch of tan beans with purple markings has the occasional purple bean with tan markings. Many heirloom varieties seem to display this trait. Last year I picked out all the "day for night" beans from a batch of Mrs Fortune's and sowed them separately. The result was exactly the same as if I'd sown any normal Mrs Fortune's beans, i.e. the usual colour and a few with reversed colours. Afterwards I spoke to a couple of other bloggers who had had the same experience, picking out the reversed beans from other varieties only to find they grew into the same plants regardless. So something other than genes much be responsible for the colour reversal, but what? Moisture levels inside the pods and exposure to light and air during harvest might be factors, but in all honesty I've no idea.
More bean diversity. Top row, left to right: Jo's Purple Podded, Black Valentine, Lazy Housewife.
Middle row: Canadian Wonder, Dog Bean, Poletschka.
Bottom row: Pea Bean, Kew Blue, San Antonio.
Posted by Rebsie Fairholm at 10:44 pm
Sunday, 4 May 2008
Well, it is for me anyway.
Pictured above is the first flower bud on one of my F2 peas, in this instance Golden Sweet x Sugar Ann, my yellow sugarsnap project. The only other pea in the garden currently producing buds is Alaska, whose synonym is Earliest of All. So this one is very early. Both the original varieties in this cross are fast maturing, Sugar Ann particularly so, but it's likely I'll see a bit of variability in these F2s.
This project is a hybrid between a white flowered and a two-tone purple-flowered variety, so the F2 plants are likely to segregate into different flower colours (the F1 generation were all purple as that's the dominant gene). It's too early to tell what colour this flower will be, but so far it looks very, very like a Golden Sweet flower. It has a yellow penduncle and a creamy-yellow calyx, which are both Golden Sweet traits, as well as the obvious yellow tinge to the young leaves. I can see a tiny bit of pink colouration on the inner petals of the bud, so I think this one is going to go purple.
I have just today seen two other plants in this F2 batch producing tiny flower buds. Not like this one though, they both have a green calyx and look more like Sugar Ann flowers. The creamy-yellow calyx is a recessive trait so most of the plants will probably have the green ones.
Can't wait to see this flower open!
Posted by Rebsie Fairholm at 10:00 pm