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Post by steve1 on Nov 3, 2015 11:28:00 GMT -5
I don't know of a list either. Would be very useful. Actually, just a list of snow/snaps with parchment genes.
@t - I do remember seeing something about fiber on Rebsie's site, but it was 'some' or 'none'.
It occurred to me today only today whilst looking at the dried F1 (full parchment) of two snows, that the method is simple enough. You need two parchment tester lines with each having one of the recessive parchment genes (ie PPvv and ppVV). One cross of the variety you are interested in to each known parchment line and grow the F1. If the snow/snap you are testing has the recessive gene that's in the tester line the F1 will display it, so the F1 pod will be wrinkled when dry. If you get full parchment (non wrinkled pod) - the snow/snap has the other recessive gene, which should be confirmed by the second cross (as wrinkled dry pod). If both F1's are wrinkled and dry you have both recessive genes in the variety.
It had never occurred to me the answers could be in the F1.
I have inadvertently developed two tester lines whilst trying to explain my F2 segregation. If anyone is interested in doing this let me know, I'd be happy to share the tester lines.
Cheers
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Post by steve1 on Nov 2, 2015 20:33:12 GMT -5
Hi Templeton, Dry pods tell about the presence/absence of the recessive parchment traits. However the change is present with just one of the recessive parchment genes (pp or vv) and I don't think you can say more than that. Rasmusson 1927 'Genetically changed linkage values in Pisum' and Myers, Baggett and Lamborn. Plant Breeding Reviews Vol.21 Snap pea both have illustrations of this. These pics are from the parent (Sugar Snap) and one of my fully parchmented snap plants. dl.dropboxusercontent.com/u/94877168/SugarSnapdry.jpgdl.dropboxusercontent.com/u/94877168/SnapFullpmentdry.jpgHere is the peeled parchment in a red line (PPVV) note it's not a very mature pod either. dl.dropboxusercontent.com/u/94877168/redcomp.jpgMy method testing (with a mature non dry pod) is to halve the pod along the seams, then snap the pod in half outside to inside. If it peels its very likely PPVV. I only had the one recessive parchment gene in this cross (from staining the parents), so I hoped when I saw the pod adhering to the seed I was dealing with a (PPvv) line. You can see the semi-dried pods are shriveled around the peas indicating the presence of the single recessive genotype. dl.dropboxusercontent.com/u/94877168/RPL3drying.jpgI don't think you can classify this whilst the pod is growing however, you need mature dry pods. My line of Yakumo I have is a case in point. Hope that has added something and probably should be in another thread. I will try the grind to powder method when I have more dry pods of a line with both recessive parchment genes. Cheers
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Post by steve1 on Nov 2, 2015 19:04:00 GMT -5
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Post by steve1 on Nov 2, 2015 8:39:24 GMT -5
templeton - pod parchment happens in layers according to my reading. But some genotypes appear to really delay parchment formation. The Yakumo line I have has a peel able endocarp when mature and is basically a shelling type used as a snow. Hints: The ppVV genotype, I've noticed the dorsal ridge of the pod often has over expressed string and parchment that under a strong light shows up as a thick dark strip. I have some stained pod pictures showing this, and it confers with Rasmussons 1927 paper regarding this. The reverse PPvv genotype on the ones I have looked at is pretty subtle even stained though I believe it can be a bit variable. It's the result of the parchment being reduced very significantly by the presence of either pair of recessive genes. There is also the classical dried appearance of pods- stiff if fully parchmented and wrinkled on the seed if either or both recessive genes present. When the forum lets us I will post pictures I will give relevant examples. Hope that helps. Steve
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Post by steve1 on Nov 1, 2015 15:37:39 GMT -5
raymondo, I had read the early string-less varieties were not vigorous and that from memory these varieties also has 'slow pollen' resulting in less than Mendelian segregation in crosses. This gene is not so-common down here. This variety had near 100% germination from what i remember, but the seed was soaked till radical emergence then potted and placed on a heat bench till proper germination. Not the real world or even close. Seems pretty good though. @t I managed two red semi-snows in the last generation, which was more than I could reasonably expect, all my red lines are purple over yellow. When you say your purple snaps are a bit fibrous - are you talking peel-able endocarp on mature pods? To me this seems to be a both dominant gene phenomenon at least so far as I can tell at the moment. Interestingly, the line of sugar snap I have is ppVV (dorsal parchment) and the Golden Sweet snow is PPvv (thin parchment in patches across the pod). You guessed it - the F2 Golden Snap project had a lot of fully parchmented peas (including snaps). Was going to attach an endocarp picture but the forum has exceeded it's space allocation! Cheers.
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Post by steve1 on Nov 1, 2015 4:01:27 GMT -5
raymondo, got my first decent yellow snap six weeks ago. A few nice powdery mildew resistant snows fell out as well for further evaluation. Hoping there will be some more nice snaps in that group too. Haven't put much work into a lone purple snap line - one will likely come out of the red project. Saying that I did a cross just last week for a stringless purple snap line...
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Post by steve1 on Oct 31, 2015 17:38:28 GMT -5
I'm in Melbourne T. I'm not entirely convinced about the outcrossing but have not better explanation for the two plants in my golden line. What makes it harder to believe is that this was a late sowing flowering in December, and the flowers were so small and closed when pollen was dehiscing that crosses were nearly impossible to perform. Numbers are too far out to be much else. Oh well can't explain everything!
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Post by steve1 on Oct 31, 2015 16:05:39 GMT -5
Hey Phil, hmm I had missed the obituary. Sad. The Lamprecht purple pod explanation in the previous post is on p26 and a passing note on purple pod mutation which references Lamprecht (1953) that purple pods may mutate to green by as much as 40% p55, genotypes by flower colour p 17-23, red pod types fig 20-23 p 51-52. Plenty more in there though. I think the same thing on some purple podded Dutch peas from 2014. Cheers.
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Post by steve1 on Oct 31, 2015 8:05:37 GMT -5
Sorry T, dropped off the face for a bit. If you are into anthocyanins, pink flowers and recessive b genes this is for you. It's a Ph.D thesis, but has the reference for the Lamprect paper and much much more including flower colours and genotypes. (Google Statham anthocyanins UTas) URL won't paste. Of course the other option with the purple pod mischief is an outcross. I ended up with a purple splash on a single green pod and a purple funiculum on another (out of 50 f2 plants) in my in a golden snap project. F1's were grown together in the field. I saw blue banded bees working all the beans - tepararies, seven years and vulgaris, but never observed them on the peas. The bean grow out from that over the next year or two offers some mind boggling genetics. Have seen the same on purple podded Dutch but I don't bag flowers as a general rule so I can't call mutation. Cheers
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Post by steve1 on Oct 11, 2015 6:10:23 GMT -5
Hi Templeton, from what I've read the Pur purple gene behaves a bit differently. Lamprecht - who did extensive work on peas (mostly in German) identified three degrees of pod colouration related to multiple alleles at the pur locus. Pur with full colouration, pur a and pur b with progressively less colouration and pur with no colouration. My guess is you've had a spontaneous mutation at this locus. Let me know if you want the reference.
Cheers Steve
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