Everything's happening so fast in the garden at the moment I'm barely able to upload my photos onto the computer before they're out of date (however did I manage in the days when I had to send films to Bonusprint?) so I'm just going to chuck a few pictures of my Luna Trick F4 peas up here to show you how they're getting on.
I'm very happy with the way things are going with this variety. You may recall, dear reader, that I have two separate batches of F4 plants because last year's Luna Trick F3 segregated into mangetout (snow) types and sugarsnap types, and as I'm intending to develop them as different varieties I'm growing the two types separately. Or I thought I was. As it turns out I have sugarsnaps among the mangetouts and mangetouts among the sugarsnaps, so balls to that idea. The former situation was entirely expected - I knew some of the mangetout-podded plants I saved seed from last year would've sneakily closeted away the recessive n allele in their genome, ready to spring forth unbidden in future generations. This recessive allele singlehandedly creates the sugarsnap type simply by thickening the pod wall, transforming a wide flat pod into a slim, round, plump and juicy one. I love both types, so I'm open minded about what I get. But the recessive nature of this gene means that it will be hiding itself in a proportion of the mangetout plants for a generation or two yet, and I won't know which ones until I grow their offspring.
Upside down flowers? Well why not.
The most promising F3 plant I had last year was one called LT10. (There's nothing arcane about this name, it was simply the 10th plant in my Luna Trick trial to get a label stuck on it.) It was a tall mangetout-podded plant with a divine flavour. And the gene gods were smiling on me, because when I started growing out the F4 it turned out to be the only one of my mangetout lines which was true-breeding for tallness, which is what I want. All the others had hidden recessive dwarfing genes lurking in them. If I save seed only from LT10's offspring and not from the other lines I should have no more trouble with dwarves. I supposed it would be too much to expect LT10 to be true-breeding for mangetout pods as well, and indeed it has presented me with a goodly smattering of sugarsnaps. They may well be good enough to contribute to the development of my sugarsnap line, but in the breeding of a stable mangetout line they are a pain in the backside.
While I was expecting to get sugarsnaps in the mangetout batch, I certainly wasn't expecting to get mangetouts out of the sugarsnaps - that was a complete surprise. A recessive trait is by definition true-breeding. It can only express itself when a matched pair of recessives get it together and there are no dominants involved to spoil the party. As the mangetout-pod trait is dominant it couldn't possibly be present, hidden, in any of the sugarsnap plants I saved seed from last year. So I was intrigued to see not one but several of the F4 sugarsnap plants developing mangetout pods. How could this be? Is there some other gene at play which suppresses the sugarsnap gene? Did the faeries dig my plants up and move them in the night? The solution became obvious when I looked at the identification tags of the plants concerned. They were all from the same parent plant, LT2. I'm growing ten of LT2's offspring, and the majority of them have mangetout pods, with a few sugarsnaps. While I hesitate to declare a Mendelian ratio on such a small sample size, it seems obvious that there is one and I made a mistake in classifying LT2 as a sugarsnap when it was nothing of the sort. Sometimes mangetout pods look a bit sugarsnappy. It's a relief to find such a simple explanation, and it's one of the reasons I number my plants at the F2, F3 and sometimes F4 stage - as laborious as it is, it enables me to track the pedigree of each individual, to find patterns in weirdness and resolve mistakes.
The first Luna Trick F4 pod, still with its little petal nosebag on. This one is a sugarsnap type (honest).
The same pod five days later, now with a beautiful luna crescent shape.
In the last couple of days I've managed to do the first couple of taste tests, and so far they've all been very nice. Flavour is the most important thing I'm selecting for, apart from healthy vigorous plants which goes without saying. But I'm also looking out for crescent moon shaped pods, particularly among the sugarsnaps. I'm also mindful of the colour intensity. For the most part Luna Trick has a stronger and longer-lasting yellow colour than its yellow parent, Golden Sweet, but in last year's batch I did have some which faded to pale washy green a bit more quickly than I would like.
I'm also busy with the scalpel using Luna Trick for various hybrids, particularly as it represents a superior alternative to Golden Sweet, so rather than doing backcrosses to Golden Sweet in my Peachy and Red-Podded lines, I'm using Luna Trick instead. I'm making these crosses with both the mangetout and the sugarsnap types, which I'm hoping will give me a red sugarsnap as well as the decent flavoured red mangetout I've been coveting. I've also made some crosses with Salmon Flowered (the antique umbellatum pea) which is more of an experimental endeavour. What I have in mind is to extract the gene which makes the rosy pink flowers, which would look lovely on a yellow-podded pea. But my weird imagination also conjures up a vision of a yellow-podded umbellatum, crowned by a giant clump of sticky-outy golden sugarsnaps. What a spectacle that would be.
Luna Trick F4 plants all tagged up and ready to plant out
Well both my F4 Luna Trick batches are now planted out in the garden - the standard version and the sugarsnap version. They were sown a couple of weeks apart, in the hopes that their development will be staggered somewhat and I will be less overwhelmed by the workload. Growing peas is not in itself much of a workload … they are independent little dears. But breeding projects have a habit of being very time-consuming, especially this one, because I'm being very careful about collecting individual data on each plant. It takes a lot of effort to label and track every single plant in the project and write down detailed notes for all of them. But it will save me time in the long run because I will be able to select more precisely for the traits I want - and it will teach me a lot about the genetics involved, and pea genetics generally. By labelling every plant with its own number, which includes a code for its specific pedigree, I can identify which lines are true-breeding for dominant traits such as tallness. I'll be able to see which pedigree lines are entirely made up of tall plants and save seed only from those, which should eliminate unwanted recessives very quickly. If I pooled the F4 seed and selected from the whole group, I wouldn't know which of the tall ones were hiding unwanted recessives. So although it would save me a lot of note-taking for this year, I'd be weeding out unwanted dwarf types for years to come.
Luna Trick F4 plant, photographed today. This one is the offspring of LT10, which so far looks to be the only line which is true-breeding for tallness.
As these plants are so important to me, I take extra care with them. They have been raised in rootrainers, which in my experience are far more reliable than any other method for producing strong seedlings and healthy plants. The expense of rootrainers doesn't necessarily make them a good option for pea cultivation generally, but for me they are a worthy investment. The next important thing is soil preparation. I don't bother with fertilisers because peas don't really need them … they have a unique mechanism for producing their own. But what they do benefit from is a digging in of organic matter of some kind. Compost is good. Horse manure is excellent, but in the light of the disgraceful aminopyralid poisoning of Britain's grasslands, I'm not using manure in my garden at the moment. Removal of perennial weeds such as couch grass root is also important, because it's difficult to weed around peas once they get established.
The other special care I provide them with is protection from the weather. Peas are hardy, and I'm not at all worried about the April frosts. The cold nights we're getting at the moment are bringing out some lovely red colour in the leaves of peas capable of producing red colour (which Luna Trick isn't) but it's not harming them in any way. What peas do suffer with though is the cold blustery winds that are so common at this time of year. Having said that, this year has been astonishingly warm and settled, so it hasn't been an issue. They are only really vulnerable to this when they're young and first planted out … the cold winds wither and damage the young growing tips. Once they've got established after a couple of weeks, they are a lot more robust. So what I do for precious peas when first planted out is set up a netted fabric screen round them. Horticultural fleece is the conventional choice, but the lovely old lady who lived in my house before me has saved me ever having to buy any. The house was festooned with about 30 miles of net curtains, which do an admirable job in taking the edge off the winds without losing too much sunlight. I'm growing Luna Trick in a frame made of bamboo canes, so it's the work of a moment to attach the net curtains round it with clothes pegs. I do have to be careful to lay a few unwelcoming heavy twigs around the outside as well, because my cat finds it amusing to charge into the net curtains at high speed.
Doesn't that look grand? Well all right, it looks bloody awful, but old net curtains are very effective at filtering the English spring breezes while the seedlings get established. I make no apology for the state of my garden ... the breeding and heritage conservation work is so time consuming I don't have time to make it look pretty as well.
I keep each of my breeding projects in their own personal filing containers, made from ultra high-tech re-used cat food boxes. When I picked up an empty box the other day for a new project I'm starting, it turned out not to be empty. Rattling around inside were about a dozen lovingly sorted and labelled bags of Luna Trick seed from the best of my F3 lines, and three unmarked whole pods left loose in the box. I'm afraid I do have this bad habit of failing to label things and then forgetting what the hell they were. These seeds were all harvested earlier in the season, when I was selecting the best plants and harvesting the pods as they matured. I remember harvesting them but don't remember shelling them and boxing them up, which serves me right for smoking too much weed in my youth. There were about twelve pedigree lines in labelled bags, including a load of extra seed from my best plant LT10 … so I've sown another fifteen of those. You can never have enough LT10 as far as I'm concerned. And by starting off another batch of them now, in addition to the ones sown about a month ago, I'm greatly increasing my window of opportunity to make crosses with them.
The loose pods were something of a mystery, but there had to be a good reason I kept them separate instead of bagging them up like I did the others. According to my pollination records, which can also be a bit sporadic when I'm busy, I did some crosses between the best Luna Trick F3 plants and one of the trial varieties I grew in 2009, Buerre Cosse Rouge. This latter is quite a special little variety because it has red-sploshed pods … not quite the deep consistent crimson I got in my red-podder project, but reasonably close to it. And it's a sugarsnap type. It does have some frustrating weaknesses though. The plants (in my trial at least) were tiny and not very strong, and the yields absolutely miniscule. It produced miniscule pods that have about three peas in them, and more often than not they withered and fell off before they reached maturity. I didn't even get to taste Buerre Cosse Rouge, because I was struggling to scrape together enough seed just to regrow it this season. In doing these crosses, I had in my head the idea that I might get some red-pod gorgeousness into the voluptuous sweet abundance of Luna Trick. There is a chance - only a chance mind - that these loose pods had been kept separate because they were hybridised ones.
Fortunately for me and my slack incompetence, I should be able to find out fairly quickly. My old friend gene A will help me out. It's the gene which switches on the colour pigment in peas. Luna Trick doesn't have it - it's true-breeding for the recessive a a genotype which cannot produce anthocyanin pigment. Buerre Cosse Rouge presumably has the dominant A A type, because it has lots of anthocyanin colour. Crossing the two will give me the a A genotype, in which the recessive colourless gene gets elbowed out. In other words, if the seedlings show any trace of red colouring, I will know they are from a cross. If they turn out to be the normal unpigmented Luna Trick type, then I'll know they weren't from a cross. Thus nature sometimes forgives us for poor labelling.
(The seedlings have now emerged and so far are not showing any obvious traces of anthocyanin. Arse!)
This post comes with a little explanatory video (12 minutes running time) as an introduction to my Luna Trick pea project. It's the first time I've made one of these, so do let me know if it's useful.
Luna Trick is a new pea variety I'm working on. It's an exquisitely tasty edible-podded pea with pale golden yellow moon-shaped pods - named for my music partner Daniel Staniforth who has a music project called Luna Trick.
The project originally started as an attempt to breed a yellow sugarsnap pea. In 2007 I crossed Golden Sweet, a unique heritage golden-podded mangetout pea, with a modern sugarsnap pea, Sugar Ann. The result was a spectacular range of unexpected colour and flavour diversity - but sadly no yellow sugarsnaps. My chance of getting a yellow sugarsnap in the F2 generation was one in sixteen (a double recessive combination), but none showed up in that particular batch. I had yellow mangetouts and green sugarsnaps, but that was it. However one mangetout plant did stand out from all the rest for its elegant beauty, high yields, juicy golden yellow pods and truly exquisite flavour. This plant, which was numbered YSS 25, became the prototype for Luna Trick.
In 2009 I grew out 35 seeds from this one plant. I was hoping to get more plants of a similar type. And so I did - and a lot more besides!
The first Luna Trick yield. Golden yellow moon pods, exquisitely sweet and completely fibreless.
Hybrid vigour in peas is something I've often wondered about. I've often heard it said that hybrid vigour exists only in outbreeding plants, if indeed it exists at all, which is still a subject of debate. Peas are inbreeding plants - very inbreeding - and so you might expect them not to gain much vigour from being hybridised. However my experience is that peas do have a bit of a wahey in their size and growth when you hybridise them. It varies, but it's usually apparent in one way or another. And it may be the reason why Luna Trick turned out a lot taller than expected.
The parent varieties were 5ft tall and 1ft tall respectively. Under normal circumstances, I would expect most of the offspring to be around 5ft tall, as that's the dominant form - with about one in four defaulting to the recessive 1ft size, and maybe the odd intermediate. As it turned out, the dwarf types were nearer 2ft, and voluptuously chunky. Whereas the tall types - well frankly they didn't want to stop.
Daniel, in whose honour the peas are named, is a big bloke. He's 6' 4". I never thought the plants would get as tall as him, but they did.
The F3 crop reaches the same height as Daniel. I wasn't able to measure it after this point because my arms aren't long enough.
Most of the plants weren't going to stop there either. They just kept going, way beyond the 5ft tall frame I'd optimistically provided for them. I had to ram some extremely tall and sturdy poles into the ground all around the frame and wrap masses of garden twine around them to hold everything together. And still the plants kept growing. I couldn't even reach the tops. They were probably a good 8ft by the time they started slowing down.
But apart from this, they behaved very well and did everything I hoped they would do. I'm very optimistic indeed that they will turn out to be a wonderful variety. Not only that, they are TWO wonderful varieties. The original YSS 25 protoype plant was a mangetout type - but growing its offspring revealed the presence of a hidden recessive sugarsnap gene, and a large number of the F3 plants turned out to be sugarsnaps. Beautiful, crescent-podded, golden yellow sugarsnaps! So I got exactly what I had wanted when I made the original cross - in addition to developing Luna Trick as a mangetout type. A wonderful, beautiful and very much appreciated gift.
The key trait in Luna Trick is flavour. I'm aiming for it to have the same flavour as YSS 25, which stood out from every other plant in the F2 batch and was among the most refined mangetout flavours I've ever tasted. Very sweet and juicy, but there's a lot more to it than that - it had a rich and refined complexity to its flavour and no trace of bitterness. YSS 25 was good enough that you would want to eat its full size pods straight off the plant. A salad mangetout, effectively, because it tastes so good raw you really would have no incentive to cook it. I think a yellow mangetout which tastes good enough to include in a salad, even at full size, would be a very nice thing to have.
At the moment I'm getting a mixture of single pods and double pods - some plants produced one or the other but in many cases there was a mixture of both on the same plant. I'm not quite sure how this trait works - it is clearly partly genetic but I'm not sure whether there are environmental factors involved too, or a complex interaction of genes, because it doesn't follow normal patterns and ratios. Consequently I'm just not worrying about it for the moment. Two pods per node is often deemed more desirable but I tend to find that the two pods have fewer peas in them compared to the single ones, so I'm not convinced it actually matters that much either way.
A single flower bud. This is an unusual colour combination in peas - a white flower with a creamy blond calyx (the pixie hat bit).
To summarise the F3 characteristics ...
Luna Trick is stable (true-breeding) for:
Yellow pods - a very simple recessive gene is responsible for this, called gp. In order to express yellow pods, the Luna Trick prototype must have had the stable gp gp genotype. Which is fine by me. It holds only gp genes, so all its offspring will be gp gp too.
There is, however, some variability in how persistent the yellow colour is. One of the weaknesses of the parent variety Golden Sweet is that its pods tend to green up as they reach maturity, so only the young pods are truly yellow. Some of the Luna Trick F3 plants shared this tendency, but others were notable in their ability to stay yellow right up to the time they were harvested for seed. Presumably this is a genetic variable - though I don't yet know how it works - and I will select for it at the F4 stage.
Edible pods - a slightly more complicated trait, as there are two genes involved in the reduction of fibre in the pod, p and v, both recessive. They work in slightly different ways, and you need both of them to get a really good fibreless pod. I have my suspicions that Golden Sweet only has one of them, as it tends to go a bit gristly at maturity. However, Sugar Ann has them both - and now Luna Trick has them both too. There was no trace of fibre in any of the pods in the Luna Trick F3. Hurrah!
White flowers - peas need a dominant gene called A in order to "switch on" anthocyanin production. Without it, they cannot produce any purple pigment in the leaves, stems, flowers, seeds or anywhere else. Luna Trick has inherited the recessive a a genotype from Sugar Ann, and therefore cannot produce colour pigments. White flowers it is then.
Cream calyx - the flowers all have a cream calyx (sometimes with green mottling) rather than the more conventional green. This is a true-breeding trait because it's directly related to the yellow pods. It looks absolutely gorgeous with the white flowers and really gives this variety an extra beauty factor in the garden, adding to its luna blondness.
Luna Trick is still segregating for:
Height - I'm selecting for tallness, which is the work of a dominant gene called Le (internode length). The cross with Sugar Ann will have introduced the recessive type le into the mix. Although the Luna Trick prototype was tall, it had the recessive shortie gene lurking in its genome … and by a simple Mendelian ratio I ended up with dwarf types in about a quarter of the F3 plants. With a bit of luck the F4 generation should take care of this. By growing out several plants from each of several lines, I'm hoping to be able to identify the lines which produce only tall plants, and which are therefore likely to have the desired Le Le genotype.
Pod type - the prototype Luna Trick had large mangetout type pods, which represent the dominant form. However, squirrelled away in its genome was the recessive gene n, inherited from Sugar Ann, which gives sugarsnap type pods. Consequently about a quarter (or just over actually) of the F3 plants were sugarsnaps. I was overjoyed by this, as yellow sugarsnaps were the original intent when I made the cross. The way this gene works is to thicken up the pod wall, giving it its chunky and succulent 'snap' characteristic. To compensate for this thickening, sugarsnap pods tend to be slimmer. Although this genetic difference is simple and made by a single gene, it effectively creates a separate new variety.
The recessive nature of gene n means that any sugarsnap lines I follow up will be true breeding for sugarsnap pods, as they will be genotype n n. The mangetout Luna Trick, on the other hand, will continue to throw up the odd sugarsnap from recessive genes hidden away, and I'll have to eradicate those through repeated selection.
Even within the mangetout type, differences in pod size and shape are apparent. The ideal I'm looking for is a fairly wide crescent shaped pod, but some are narrower and some are extra wide, and some are not quite so crescent-shaped.
Flavour - this is the most important factor, and I would have liked it if all the offspring had tasted as good as the prototype - but only some of them did. I know very little about the genes involved in pea flavour. The combinations are very varied, and so I assume a number of genes have a bearing on it. Sugar content obviously is a major factor, but it's not the be-all and end-all. Some peas taste very sweet but are still quite bland, others have a rich and interesting flavour but aren't particularly sweet. There is also a kind of 'soapy' taste which peas are prone to which seems quite independent of the other flavour variables. The flavour variability in the Luna Trick F3 was quite considerable. They ranged from something akin to nectar of the gods to something bordering on bitterness. Some were just bland. Overall though, the vast majority tasted substantially better than Golden Sweet - and the best ones were truly exceptional. So I'm confident of creating a flavour benchmark with Luna Trick - it's just going to take a bit of careful selection.
Seed colour - the Luna Trick prototype was heterozygous for seed colour, producing both the dominant cream seeds and the recessive green ones. Some of the resulting F3 plants were homozygous for green seeds, but the lines I'm most interesting in following up happen to be heterozygous ones, so the variability will continue in this coming generation. I'm not too bothered about this. I might select one colour or the other if it becomes easy to do so, but I don't see any harm in having the variability. It would be unacceptable in a commercial variety to have mixed cream and green seed, but I don't see why not. One of the compensations of public domain plant breeding is that you're not bound by rules and conventions.
Sugarsnap version of Luna Trick. I will develop this type separately and make a new variety with a different name.
Luna Trick does have a potential weak spot which may be genetic or environmental or a combination of the two. The peas have a tendency to split their skins when ripe - much as ripe tomatoes do when they're over-watered. This isn't a problem when you want to eat them, but verily 'tis a bugger when you are saving them for seed. In the F3 crop, some plants suffered badly from it and some had no problem with it at all. So I am selecting the ones that didn't have the problem - kind of by default, because the ones that have split will not make good seed for replanting. If it's a genetic issue, selecting against it should soon eradicate it. If it's environmental (affected, for example, by how much water the plants get at a particular time) then no amount of selecting will make any difference. So far this seems to be the only flaw though in an otherwise wondrous variety.
Rain on Luna Trick blossom.
So what now? The F4 crop in 2010 I've already sown 100 seeds for this year's selection work - 50 mangetouts and 50 sugarsnaps - and these are the ones shown in the video above. Germination was 100%.
I'm working on the mangetout and sugarsnap versions as completely separate varieties, and at some point the sugarsnap one will get its own name. Some sugarsnap types will continue to show up among the mangetouts in this generation. I'm also seeing height variability, which is apparent even at the seedling stage.
I've chosen F4 seed from the best six plants of the mangetouts and the best six plants of the sugarsnaps. In the F3 there was one plant, called LT10, which stood out from all the others - it was the tallest, highest yielding, most beautiful and had the holy grail flavour I was looking for. So I'm growing more of those than any other, hoping that I can stabilise it pretty much as it is. But by growing out a few other good lines alongside it, I'm hedging my bets in case LT10 turns out to have any unexpected flaws - and also learning more about the genetics involved, by observing the ratios for different traits in different lines.
With the sugarsnaps, there was no obvious standout plant in the F3. Some were better for flavour, some for pod shape or colour, some for stringlessness ... so I've just selected the six that looked most promising and will see what I get.
All in all though, I'm very excited and optimistic about Luna Trick.
Last year's F2 plant which became the prototype for Luna Trick
I have at least three or four plant breeding projects which will be ready for naming in 2009.
This is the first ... a new mangetout (snow) pea called Luna Trick.
Named in honour of my friend and music collaborator Daniel Staniforth, a shining inspiration who plays cello for me along with a seemingly endless range of other instruments; Daniel releases his own alt-rock music under the name of Luna Trick, so this beautiful moon-like pea is for him.
Prototype, photographed 2008
Luna Trick was bred from a cross of Golden Sweet x Sugar Ann. It was one of the obvious stand-out phenotypes in the F2 generation in 2008, producing a beautiful and abundant plant, though its greatest asset is its outstanding flavour (which must be carefully selected for in future generations). This is what the variety should look like when it's stabilised:
Growing vigorously to 6ft, it has distinctive yellow-green stems, and bears single rounded moon-white flowers on pale yellow stems so curvy they sometimes turn right over and bloom upside-down. The calyx is cream when young but at maturity turns moon-white with green mottling. Pods are pale yellow, quite large and succulent. As they mature they take on a porcelain-like translucence and the small peas can be seen inside, 8 or 9 per pod. Being a mangetout type, Luna Trick is completely fibreless and the pods are edible at all stages. The absence of fibre helps give it its translucence but it also means that the pod cannot keep its flat shape at maturity ... the peas bulge through and the pod buckles and twists, taking on a crescent shape. The really special feature is the pod flavour, which is exquisitely sweet, and a major improvement on its yellow-podded parent. The flavour has a full and rounded character as well as being sweet, and the thickish pod walls are unusually juicy. Even at a large size they can be eaten straight off the plant with no trace of bitterness. The peas themselves are not huge but very abundant, and sweet enough to be worth eating in their own right, raising the possibility of this being a dual-purpose variety. The one fault the peas have is a tendency for the skins to split if watered too heavily or erratically (either by me or the English weather).
The absence of any fibre inside the pod makes it impossible for it to stay flat. It's a bit weird-looking, but I rather like it. The pods also turn porcelain-translucent as they mature, so you can see the peas inside.
Although this pea has got its name this year, that doesn't mean it's ready for general release ... it will probably need at least another year's work. The basic format of a breeding project goes like this: two varieties are crossed together to make an F1 hybrid. The F1 seeds are all mixed together and don't get a name or a number ... there's no point, as they all look pretty much the same. The only purpose of the F1 generation is to provide as much F2 seed as possible. The F2 generation is where the magic happens ... as all the genes in the lottery get re-shuffled randomly and create enormous differences between siblings. So I treat each F2 seed as a unique individual and give it its own identifying number. Once I've decided which of the resulting F2 phenotypes are worth pursuing, the number is then applied to all subsequent generations so I can keep track of its lineage. In this instance, the plant I wanted to keep was one called YSS 25 - quite simply plant number 25 in my Yellow Sugar Snap project (which so far has produced just about every imaginable phenotype except a yellow sugar snap, but never mind). So at the end of last season I collected all the seeds from YSS 25, and these are now F3 seeds. Although they will display a certain amount of variability they should mostly follow the blueprint set in the previous generation, so they don't get their own individual numbers ... they are collectively labelled YSS 25 F3, and are now the basis for a new variety. It needs to keep its number so I don't lose track of its pedigree, but you can see why I prefer to call it Luna Trick.
2009: new seedlings just starting to sprout. This is the F3 generation
It's still early days on this project, but I'm hopeful that Luna Trick will be among the first of the new pea varieties to be released. Why? Because most of its desirable traits are made by recessive genes. Recessives are the joy of a plant breeder's life because they are so easy to stabilise. For example, the yellow pods are made by a recessive gene called gp (golden pod). I can deduce that the Luna Trick prototype carried a perfect matched pair of gp genes ... because if it didn't it wouldn't be able to express yellow pods. If it had only one copy of gp it would default to green pods, with the yellows just showing up in a proportion of its offspring. The fact that it was yellow-podded means I can be fairly confident that all its offspring will be yellow-podded, because it has only gp genes to pass on. The same is true of many of its other traits ... it has matched pairs of recessive genes for fibreless pods (two genes), white flowers (one gene) and for sweet flavour (two or more genes), so I can expect it to have high levels of stability for all these traits. These characteristics are joyfully easy to predict.
Some of the variability is also predictable. Tallness is a dominant trait in peas, made by a gene called Le. The original Luna Trick plant was tall, but it was bred from a cross between a tall pea and a dwarf one so I don't yet know whether it has one copy of the Le gene or two. If it has inherited two, it will breed true for tallness. If it has only inherited one (which is statistically more likely) then I can expect to see the recessive dwarf gene show up in a quarter of the offspring, and I will have to keep selecting the tall ones for several generations until the dwarves stop showing up.
Fortunately with peas you can recognise tall and dwarf phenotypes very early on, while they're still young seedlings. This is because the difference between a tall pea and a short one is simply down to internode length ... the amount of stem it makes between each set of leaves ... which starts to show itself when the plants are only a few days old. Thus I should be able to "rogue out" any shorties before I even plant them in the garden. Though I will probably plant them separately from the others and keep some seed from them, just in case I ever want to create a short version of the variety. (My breeding work focuses on tall peas as they are wonderful and deserve a renaissance after being woefully neglected for the last 100 years, but some people do like dwarf peas so I'll keep the options open.)
You can also see from this picture that it has variability in the seed colour, and comes in cream or green. The colour of a pea seed is made by the cotyledons (seed leaves) hidden inside. The dominant cotyledon colour in peas is yellow/cream ... and clearly Luna Trick has inherited this ... but it has also inherited a recessive gene catchily called i, which produces green cotyledons. (Put into technical terms, it's heterozygous at the i locus.) I could select one colour or the other ... the green ones, being recessive, will breed true for greenness, while the dominant cream ones may be hiding recessives within them and will show some further variability. But I'm actually not fussed either way ... the seed colour is not especially relevant in this project, so I'm planting them all without selection. If I was a commercial plant breeder I would probably want to select more rigorously to get a uniform product ... but I'm not, so I'm more interested in maintaining a healthy bit of genetic diversity.
Having made all these predictions, "expect the unexpected" is the mantra of any gene-reshuffling endeavour. It's likely that I'll find some unforeseen variability in the twenty-five or so plants I'm growing in this generation. Some will be caused by hidden recessives making their presence felt, and some will be caused by pleiotropy (genes which have more than one function) and unexpected synergies between newly combined genes. But that's OK ... for me it's one of life's greatest joys to see these new plants emerge into the world, each one subtly unique, and see what gifts they have to offer.
