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Post by keen101 (Biolumo / Andrew B.) on May 15, 2011 18:32:07 GMT -5
I think that it's more complicated than that since having purple/red pods requires multiple genes on multiple chromosomes... For purple pods, all of the following alleles must be present: Pur, pu, and A. (two dominant alleles and a double dose of one recessive allele). Then if you have those three and add (a double dose of) one of the following recessive genes you get red pods: am, b, gp. Hmm... interesting. I hadn't thought about that. Certainly i was purposely ignoring the possible presence of transposons. But i hadn't really considered the possibility of multiple genes needing to be present for the purple to be present in the first place. So in that case if good records had been taken in the F1 generation, and the green pods were found to be a significantly higher ratio above 50% compared to the purple, then that could be a sign that more than two sets of genes are at play? Still, i like the visual punnit square even if it's not entirely correct. It gives me a rough estimate of the odds of getting a red podded pea in the F2 from seeds collected from purple podded F1 plants.
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Post by Joseph Lofthouse on May 16, 2011 2:20:05 GMT -5
So in that case if good records had been taken in the F1 generation, and the green pods were found to be a significantly higher ratio above 50% compared to the purple, then that could be a sign that more than two sets of genes are at play? When I'm dealing with corn, and cross a parent with two recessive alleles on different chromosomes (unlinked genes se and su) with a parent without the alleles of interest i figure that the chances of recovering the desired genotype in the F2 offspring is (1/4 x 1/4) = 1 plant in 16. I don't have to keep records for corn. In the F2 generation it's easy to see the genetics of the parents. To do that with pea pods you'd have to pick, and plant the offspring of each plant separately. And peas may have as many as 4 alleles that interact to determine the pod color so under similar circumstances if they were unlinked the math might be something like 3/4 x 1/4 x 3/4 x 1/4 = 1 in 28 F2 ending up with purple pods, but only 1 in 256 breeding true. And in my garden peas produce about 200 seeds per plant, so you might miss recovering the homozygous purple podded genotype altogether. I'm not interested enough in pea genetics to do the research to determine which alleles are linked and where all the modifier genes are located, and math drives me absolutely batty, but here's a link to some pea gene data: data.jic.bbsrc.ac.uk/cgi-bin/pgene/default.asp?ChrID=3&Search=linkage
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Post by keen101 (Biolumo / Andrew B.) on May 16, 2011 10:46:31 GMT -5
Okay.. been doing a little more reading. Been reading over a few of Rebsie's old posts about peas on her website, as well as visiting the links Joseph posted. So it looks like there are at least three major sets of genes for purple color. "A" and "a" which are the on/off genes for anthocyanin production in the first place. And apparently Pur and Pu are also needed, but im confused at how one tells them apart visually. a pigmented funiculus is supposed to differentiate between Pur and Pu, but I'm not sure if the funiculus is the part that connects the pod to the plant, or if it's the part that connects the pea to the pod. Anyway, so yeah... having three sets of genes for purple messes up my F1 hypothesis pretty badly. The F2 is probably messed up too, but at least it's on the right track.. Maybe I'll sit down and try to make a more accurate one. The math annoys me as well, which is why i like punnit squares.. they make the math visual instead. But in this case... it's not very nice... EDIT: Okay... i retried the F1 hypothesis, and i got a ratio of 38g:26p, which does indeed show that there are more green. When i try to scale that ratio down to 16 i get something around 9green:6purple. i1010.photobucket.com/albums/af224/keen101/science/Screenshot-5-1.pngBest case scenario is that you get a purple one that is homozygous for ALL purple traits which would be awesome, but worst case scenario would be that all the purple traits are heterozygous along with the 4th heterozygous of the yellow pod gene. When doing a punnit square for the F2 it is conceivable that the average purple pod from F1 will have 2 traits homozygous for purple and one heterozygous, along with heterozygous for yellow pod. In that case my original F2 square should be accurate. i1010.photobucket.com/albums/af224/keen101/science/Screenshot-3-1.png
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Post by Joseph Lofthouse on May 16, 2011 12:45:55 GMT -5
apparently Pur and Pu are also needed, but im confused at how one tells them apart visually. Edited on 2011-06-15 to correct my error regarding Pu. It's all or nothing... One Pur and one Pu have to be present to get purple pods. (Plus at least one A, plus the genes for green pod. ) p.s. I just saw the post from Rebsie on 10-28-2008 with the gloriously red pea pods. Oh my gosh those are pretty!!! I lust after something similar for inclusion in my shelling pea land-race. As recently as this morning I thought I'd never work on a pea breeding project... I thought I'd be satisfied with just maintaining a landrace. Ha! I've caught the pea breeding fever now. Sheesh. Good thing I have rearranged my schedule to spend 60 hours per week in the garden this summer.
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Post by raymondo on May 18, 2011 8:33:46 GMT -5
It gets very messy trying to use punnett squares when you have more than two genes. With four genes the F2 would need a 16x16 punnett square with 256 entries! Easier just to use probabilities. The probability of getting a pea that is, at worst, heterozygous in the three purple sites, A, Pu and Pur, and homozygous for yellow pod, gp, is
3/4 x 3/4 x 3/4 x 1/4 = 0.105 or about 1 in 10.
There's a lot of work from that point to get a pure breeding red-podded pea because of all the dominants you need to fix. But you'll have nice red pods to eat or sell while you're doing it. Of course, that doesn't take into account the sort of pod you want - shelling, snow or snap. It's even messier when you bring this in.
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Post by keen101 (Biolumo / Andrew B.) on Jun 29, 2011 13:53:13 GMT -5
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Post by Joseph Lofthouse on Jun 30, 2011 0:30:25 GMT -5
Woo Hoo!!!!
A lady brought yellow podded peas to my farmer's market tonight. She's agreed to save some seed for me. If I got really clever I'd go beg some pollen from her man.
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Post by raymondo on Jun 30, 2011 8:19:52 GMT -5
I found a maroon colored pea today. It's the only one in the whole garden like it. I believe it is supposed to be a Blauwschokkers. All the other Blauwschokkers and Midnight Snow peas are all purple, or purple/green. Fantastic. Looks like you have a red-podded pea. Saving seeds?
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Post by 12540dumont on Jun 30, 2011 14:40:35 GMT -5
Have any of you found peas that don't get powdery mildew? Of any color? Joseph, I have some yellow podded peas. They are drying down now. I'll send you seed when they get done. Attachments:
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Post by keen101 (Biolumo / Andrew B.) on Jun 30, 2011 15:22:53 GMT -5
Yes, of course. But, I'm not sure i can really call it a true red. I suspect that it will probably revert back to being purple podded in the next generation, but i could be wrong. It certainly does not have a yellow pod underneath, but maybe a light green.
I actually think it might be a mutant (or environmental stress) from Dan Quickert's Midnight Snow (snow pea) line. It's been hard to tell the difference between it and the Blauwschokkers line, because Dan's snow peas don't appear to have the constricted pod gene like Golden Sweet and Dwarf Gray Sugar.
I don't think i have ever seen a plant with powdery mildew unless it was near winter and the plant was going to die soon anyway (watermelon comes to mind). I think the air is just too dry here. But, i don't know much about the disease.
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Post by Joseph Lofthouse on Jun 30, 2011 17:17:15 GMT -5
My garden is not a good place to screen for powdery mildew resistance. (Every variety of every species is immune.) The only moisture in the garden from June through September is what I put on it. Relative humidity stays around 15% all summer. Dew points are almost always far below the overnight low temperature.
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Post by DarJones on Jul 4, 2011 1:22:55 GMT -5
Joseph,
I have a quart or so of Golden Sweet seed. I also have Yakumo Giant snowpea, Mayfair shelling pea, and Blue Pod Capucijners soup pea. Send me a message if you would like some seed of any of them.
DarJones
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Post by Joseph Lofthouse on Jul 16, 2011 8:55:35 GMT -5
Joseph, I have some yellow podded peas. They are drying down now. I'll send you seed when they get done. Received. Thanks. I've planted a few seeds of the yellow and a purple podded that was also sent. It may be too late in the season for me to be planting peas, but it's only a few seeds at risk.
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Post by toad on Jul 25, 2011 13:23:04 GMT -5
Joseph, now you've got the pea-fewer, and start breeding, be aware. Purple podded have a hint of bitterness.
It seems to be linked to the purple colour. As I understand, Carol Deppe gave up a pea breeding project for the very same reason. Good thing is, that some purple podded cultivars are less bitter than others. Personally I like the bitterness, when it is slightly present, as in 'Purple Podded', but I find 'Blauwschokker' too bitter. I guess Rebsie is the right person to ask, which purple podded pea has the sweetest taste of them all. Or you could start by evaluating them all by yourself. But be sure to start out with the right taste in the purple podded parent :-)
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Post by robertb on Jul 27, 2011 11:17:53 GMT -5
There's a range of tastes. Some can be quite bitter, but at the other end of the scale, Carruthers' Purple Podded is quite sweet. A lot depends on what you want them for. If you want a European-style heap of peas on the side of your plate, then maybe they aren't the best choice. If you want something filling for a soup or a stew, they're ideal.
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